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1
Yadav, Saroj R., e Manoj N. Mehta. "Analytical Approximate Expression for Cocurrent Imbibition during Immiscible Two-Phase Flow through Porous Media". Mathematical Problems in Engineering 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/638409.
Testo completoAbstract (sommario):
Cocurrent and countercurrent imbibitions are the crucial mechanism in many multiphase flow processes. In cocurrent imbibition wetting phase displaces nonwetting phase such that the nonwetting phase moves in the same direction to the wetting phase, whereas in countercurrent imbibitions wetting and non-wetting phase flow in opposite directions. However for cocurrent imbibitions, mathematical models need total flux condition as both phases flow in the same direction. Thus cocurrent imbibitions have been considered neglecting pressure gradient of nonwetting phase and only pressure gradient of displacing phase is considered which gives additional velocity to the displacing phase. An approximate analytical solution is derived by the method of small parameter; an approximate expression for the wetting phase saturation has been obtained. From analytical expression graphical presentation of saturation of wetting phase shows that cocurrent imbibition is faster than countercurrent imbibition. Also, the small parameter is chosen from initial wetting phase saturation and wetting phase saturation at imbibition phase, thus giving comparative behavior of imbibition at initial and later stage. It is shown that cocurrent imbibition proceeds faster with more amount of wetting phase present in porous matrix.
2
Bochicchio, A., M. A. Coradeschi, P. Zienna, M. Bertolini e C. Vazzana. "Imbibitional injury in maize seed independent of chilling temperature". Seed Science Research 1, n. 2 (giugno 1991): 85–90. http://dx.doi.org/10.1017/s0960258500000702.
Testo completoAbstract (sommario):
AbstractLow and high moisture kernels and embryos were imbibed by soaking in distilled water at 5°C and 25°C. Leaching of seeds and embryos was measured by ion conductivity of imbibition water after fixed time intervals. Imbibed kernels were placed on moist filter paper after 1 h imbibition and embryos on a solid culture medium after 15 min imbibition and germinated at 25°C. Primary root length was measured 3 days after germination.The leakage from seeds or embryos was correlated with the velocity of water uptake but did not show its highest values when low moisture seeds or embryos were imbibed at chilling temperature. Furthermore germination was apparently not affected by imbibitional chilling of either low moisture content seeds or embryos. In one of the three genotypes tested (B73) seedlings from low moisture content seeds imbibed at 5°C showed a reduction of the primary root growth. However, this reduction was also seen in seedlings from low moisture B73 seeds imbided at 25°C and resulting in higher level of leaching. Thus, injury by imbibition of low moisture seeds appears independent of chilling temperature and not due to loss of semipermeability of membrane lipids. Our results suggest that, in the case of embryos, water inrush into the cells reaches levels injurious for membrane integrity independently of the two moisture contents and temperature considered.
3
Spaeth, Stephen C. "Imbibitional Stress and Transverse Cracking of Bean, Pea, and Chickpea Cotyledons". HortScience 21, n. 1 (febbraio 1986): 110–11. http://dx.doi.org/10.21273/hortsci.21.1.110.
Testo completoAbstract (sommario):
Abstract Transverse cracking was examined in cotyledon tissue of snap bean (Phaseolus vulgaris L. ‘Apollo’), pea (Pisum sativum L. ‘Garfield 81’), and chickpea (Cicer arietinum L. ‘Surutato 77’). The hypothesis that imbibitional cracks develop along lines of least resistance or along preexisting cracks was evaluated. Columns of tissue were cut from cotyledons. Time from the start of imbibition to detection of the first crack was compared between whole bean cotyledons and columns. Bean columns cracked transversely with respect to the long axes of the columns. They did not crack longitudinally, even if the long axis of a column was originally perpendicular to the long axis of the cotyledon. These results do not support the hypothesis that imbibitional cracks form along preexisting cracks or along lines of weakness. Imbibitional stresses induced new cracks to form. The mean time to first crack and SE associated with its measurement were both significantly reduced in columns relative to the corresponding values for whole cotyledons (40 ± 2.6 and 100 ± 8.0 min, respectively) at an imbibition temperature of 19.3°C. Pea and chickpea cotyledon tissues also cracked transversely when they were cut into long, narrow columns.
4
Fang, Sidong, Jing Sun, DeHua Liu, Zhiyuan Yao e Bin Nie. "Experimental Study on Spontaneous Imbibition Characteristics of Fracturing Fluid at Cores from Different Layers in Fuling Shale Gas Reservoir". Geofluids 2021 (14 settembre 2021): 1–12. http://dx.doi.org/10.1155/2021/1157626.
Testo completoAbstract (sommario):
With low porosity and low permeability, shale reservoirs cannot be mined economically without large-scale hydraulic fracturing operation. However, abundant fracturing fluid will enter the reservoirs during the process of fracture. Nevertheless, there have not been specific research findings on the imbibition law of Fuling shale gas reservoir in China. In this study, an imbibition experiment was carried out on the shale core of Jiaoshiba block of Fuling shale gas reservoir to learn spontaneous imbibition characteristic of Fuling shale gas reservoir. Based on the experimental results, the imbibition process of Fuling shale gas reservoir fracturing fluid is divided into two stages. During the first stage, i.e., the former 30 hours, imbibition velocity is high, with the cumulative imbibition occupying more than 70% of the total imbibition; during the second stage, i.e., the latter 30 hours, the imbibition velocity substantially drops towards balance. There is a typical power function relationship between the average imbibition velocity and imbibition time, and this function relationship runs throughout the whole imbibition process. Nonetheless, the imbibition process of shale core cannot be described directly by the Handy equation. The imbibition velocity is closely related to clay mineral content and pore structure characteristics of shale core. The higher the clay mineral content, the higher the imbibition velocity. According to the relationship between the average imbibition velocity and imbibition time, we derived the estimation equation of fracture area formed by fractured shale gas well to estimate the fracture scale formed by shale gas well fracturing.
5
LI, CAOXIONG, YINGHAO Shen, HONGKUI GE, SHUAI SU e ZHIHUI YANG. "ANALYSIS OF SPONTANEOUS IMBIBITION IN FRACTAL TREE-LIKE NETWORK SYSTEM". Fractals 24, n. 03 (30 agosto 2016): 1650035. http://dx.doi.org/10.1142/s0218348x16500353.
Testo completoAbstract (sommario):
Spontaneous imbibition in porous media is common in nature, imbibition potential is very important for understanding the imbibition ability, or the ability to keep high imbibition rate for a long time. Structure parameters have influence on imbibition potential. This work investigates the process of spontaneous imbibition of liquid into a fractal tree-like network, taking fractal structure parameters into consideration. The analytical expression for dimensionless imbibition rate with this fractal tree-like network is derived. The influence of structure parameters on imbibition potential is discussed. It is found that optimal diameter ratio [Formula: see text] is important for networks to have imbibition potential. Moreover, with liquid imbibed in more sub-branches, some structures of parameter combinations will show the characteristic of imbibition potential gradually. Finally, a parameter plane is made to visualize the percentage of good parameter in all possible combinations and to evaluate the imbibition potential of a specific network system more directly. It is also helpful to design and to optimize a fractal network with good imbibition potential.
6
Zhou, Changlin, Li Li, Rong Zeng, Weihua Chen e Yuxuan Liu. "Spontaneous imbibition in igneous rocks: effect of KCl concentration, confining pressure, and imbibition direction". Journal of Petroleum Exploration and Production Technology 10, n. 8 (4 settembre 2020): 3227–34. http://dx.doi.org/10.1007/s13202-020-00997-z.
Testo completoAbstract (sommario):
Abstract Understanding spontaneous imbibition helps to determine the fracturing fluid volume and optimize the flowback design. At present, many studies have mainly focused on shale, but few on igneous rocks. As such, in this study, imbibition experiments were conducted on igneous rocks. The effects of KCl concentration, confining pressure, and imbibition direction on the spontaneous imbibition were systematically investigated. This study then introduces a new imbibition capacity index. The results show that KCl concentration has certain inhibitory effects on igneous rock imbibition, which reduce the absorption of clay minerals to liquid. Different imbibition directions result in distinct imbibition volumes. The co-current imbibition process is similar to fluid leak-off, but this rule is not satisfied in countercurrent imbibition, the n of which is fitted as 0.1.0.3. Increasing the confining pressure will slightly decrease the imbibition capacity of igneous rock. Rock imbibition causes a decrease in the surface hardness and physical properties of igneous rock, and increasing the KCl concentration in the fluid will effectively hinder clay swelling.
7
Liu, Xiong, Xin Fan, Jian Yin e Yang Zhang. "Imbibition Characteristic of Fractured Tight Sandstone Reservoir". Processes 10, n. 11 (25 ottobre 2022): 2189. http://dx.doi.org/10.3390/pr10112189.
Testo completoAbstract (sommario):
“Fracture network stimulation + imbibition replacement” is a new attempt to effectively develop tight sandstone reservoirs, and the fractures provide conditions for fluid imbibition replacement. On the basis of nuclear magnetic resonance and pseudo-color processing technology, combined with the imbibition experiments, this paper studies the imbibition process of fractured tight sandstone reservoirs, clarifies the effect of each level of pore-throat on imbibition, and realizes the visualization of the imbibition process. The results show that, in fractured tight sandstone reservoirs, the fluid displacement occurs in fractures first, followed by pore-throat. Most of the imbibition recovery is contributed by the macropore, the contribution of the mesopore to imbibition recovery is very weak, and the contributions of the micropore and the pinhole are even less. In the process of imbibition, capillary force and gravitational force are key parameters controlling fluid flow in pores and fractures. The replacement of fluid normally takes place in the early stage of imbibition, especially on the first day of imbibition, then the imbibition rate gradually decreases and finally tends to be stable.
8
Aristoff, Jeffrey M., Camille Duprat e Howard A. Stone. "Elastocapillary imbibition". International Journal of Non-Linear Mechanics 46, n. 4 (maggio 2011): 648–56. http://dx.doi.org/10.1016/j.ijnonlinmec.2010.09.001.
Testo completo
9
Ren, Xiaoxia, Aifen Li, Piyang Liu e Bingqing He. "Experiments and Modeling on the Influence of Interfacial Tension on Imbibition Height of Low-Permeability Reservoir". Geofluids 2020 (25 agosto 2020): 1–10. http://dx.doi.org/10.1155/2020/8837897.
Testo completoAbstract (sommario):
Low-permeability reservoirs have tiny pores with winding and complicated pore throats. The oil recovery efficiency of low-permeability reservoirs can be enhanced through the displacement of reservoir oil through imbibition. In the present study, experiments were conducted to investigate variations in the imbibition height of hydrophilic and weakly-hydrophilic rock samples under different interfacial tensions. An imbibition model considering imbibition resistance and bending of pore throats was established based on fractal theory. According to the experimental results, variations in the imbibition height of low-permeability rock samples with time can be divided into three stages. In the first stage, the capillary force plays a dominant role, while the viscous force and gravity have very slight effects. The imbibition height first increases rapidly and then levels off to a constant rate. With the increase in interfacial tension, the imbibition rate in the first stage increases, the ultimate imbibition height increases initially and then decreases, and the contribution of the imbibition height in the first stage to the ultimate imbibition height becomes greater. There is an optimal interfacial tension that causes the ultimate imbibition height to reach its maximum. The calculated results obtained from the proposed imbibition model are consistent with the experimental results, indicating that the model can accurately reflect the change in the imbibition height in low-permeability reservoirs in the first stage.
10
Zhang, Zhenjie, Tianyi Zhao e Qingbang Meng. "A Novel Model of Counter-Current Imbibition in Interacting Capillaries with Different Size Distribution". Energies 15, n. 17 (29 agosto 2022): 6309. http://dx.doi.org/10.3390/en15176309.
Testo completoAbstract (sommario):
The imbibition phenomenon widely exists in nature and industrial applications. It is of great significance to study the mechanism of imbibition and the influence laws of related factors. In this paper, based on the assumption of interacting capillaries, a capillary bundle model of counter-current imbibition is established. In addition, the characteristics of imbibition and the influences of capillary size and fluid viscosity are analyzed. The results show that water is imbibed into the smaller capillaries and expelled from the larger capillaries. The rate of the meniscus in water-imbibition capillaries is proportional to the square root of time. In the interacting capillaries, oil production by counter-current imbibition decreases and then increases gradually with the increase of the capillary diameter difference. When the total cross-sectional area of the capillary remains unchanged, the cross-sectional area of the total water-imbibition capillaries is affected by the size distribution of the capillaries. The larger the viscosity of the non-wetting phase, the more uneven the imbibition front, the lower the imbibition efficiency. The higher the viscosity of the wetting phase, the more uniform the imbibition front, and the higher the imbibition efficiency.
11
Zhao, Zhihong, Yanyan He, Jianchun Guo, Xiaoqiang Zheng, Liang Tao e Xianan Deng. "Experimental Study on the Forcible Imbibition Law of Water in Shale Gas Reservoirs". Processes 11, n. 4 (31 marzo 2023): 1057. http://dx.doi.org/10.3390/pr11041057.
Testo completoAbstract (sommario):
Water imbibition is a key factor affecting the flowback regime of shale gas wells after volume fracturing. In this study, a set of experimental apparatus and corresponding test and evaluation methods were developed to analyze the laws of forcible imbibition of water in a shale reservoir, characterize the initiation time of microfractures induced by shale hydration quantitatively, and optimize the shut-in time of shale gas wells; the imbibition depths of different pore types are quantitatively calculated based on the multiple pore imbibition analytical model. The experimental results show that: according to imbibition saturation growth rate, the shale forcible imbibition can be divided into three periods, imbibition diffusion, imbibition transition, and imbibition balance. Among them, the imbibition diffusion period is the main period for imbibition capacity rise. The reason for this phenomenon is that due to the fluid pressure difference effect, the shale fills its large pores and microfractures rapidly in the early stage, and in the percolation transition period, the percolation rate decreases continuously due to the gradual increase of fluid saturation. Due to the Jamin effect, it is difficult for the fluid to enter the small pores and the fluid fills the pore roar channel, the seepage saturation tends to stabilize, and the seepage equilibrium period appears. In the early period of shut-in, the imbibition capacity of shale increases significantly under the action of fluid pressure, providing a large amount of imbibition fluid for the spontaneous imbibition later. The imbibition depth of a clay pore was much greater than that of a brittle mineral pore and an organic pore. The reservoir confining pressure has prohibition on shale imbibition, but even under reservoir confining pressure, imbibition can still improve the fracturing effect of the reservoir, resulting in an increase in porosity of 0.42–1.63 times and an increase in permeability of 17.6–67.3 times. Under the experimental conditions, the initiation time of induced microfractures is 98.5 h on average and is in negative correlation with imbibition capacity. On this basis, the optimized shortest shut-in time of a shale gas well is 5 days. The study results can provide a scientific basis for the optimization of the flowback regime of shale gas reservoirs.
12
Yang, Liu, Chuanqing Zhang, Jianchao Cai e Hongfeng Lu. "Experimental Investigation of Spontaneous Imbibition of Water into Hydrate Sediments Using Nuclear Magnetic Resonance Method". Energies 13, n. 2 (16 gennaio 2020): 445. http://dx.doi.org/10.3390/en13020445.
Testo completoAbstract (sommario):
Field observations show that less than one percent of dissociation water can be produced during gas hydrate production, resulting from spontaneous water imbibition into matrix pores. What’s more, the hydrate sediments are easily dispersed in water, and it is difficult to carry out spontaneous imbibition experiments. At present, there is little research work on the imbibition capacity of hydrate sediments. In this paper, a new method of water imbibition is proposed for hydrate sediments, and nuclear magnetic resonance (NMR) technique is used to monitor water migration. The results show that as the imbibition time increases, the water is gradually imbibed into matrix pores. Water imbibition can cause dramatic changes in pore structure, such as microfracture initiation, fracture network generation and skeleton dispersion. When the imbibition time exceeds a critical value, many secondary pores (new large pores and micro-fractures) start to appear. When imbibition time exceeds the dispersion time, fracture networks are generated, eventually leading to dispersion of the sediment skeleton. The imbibition curves of hydrate sediments can be divided into two linear stages, which corresponds, respectively, to water imbibition of primary pores and secondary pores. The imbibition rate of secondary pores is significantly larger than that of primary pores, indicating that the generation of new fractures can greatly accelerate the imbibition rate. Research on the characteristics of water imbibition in hydrate sediments is important for optimizing hydrate production regime and increasing natural gas production.
13
Wang, Zhiyuan, Zhengming Yang, Yunhong Ding, Wei Lin, Ying He e Xiaolang Duan. "A Generalized Capillary Imbibition Model for Porous Media in Tight Reservoirs". Advances in Civil Engineering 2018 (8 ottobre 2018): 1–8. http://dx.doi.org/10.1155/2018/4148734.
Testo completoAbstract (sommario):
Capillary imbibition models have been widely studied in oil and gas development field over the past decades. However, the existing models applied to the tight reservoirs rarely take fluid flow resistance and apparent viscosity into account. To investigate the capillary imbibition characteristics of fluids in tight porous media, a generalized capillary imbibition model considering the flow resistance and apparent viscosity of fluids in tight porous media is derived. By comparing with the results of other capillary imbibition models and experimental data, the derived capillary imbibition model is verified. In addition, compared with the conventional capillary imbibition models, the derived capillary imbibition model is more consistent with the experimental results and has a wider applicability. The imbibition distance of water in tight reservoirs can also be obtained using the derived capillary imbibition model, which will facilitate the study on water injection development in tight oil and gas reservoirs.
14
Dou, Liangbin, Min Yang, Hui Gao, Dongxing Jiang e Chenglu Liu. "Characterization of the Dynamic Imbibition Displacement Mechanism in Tight Sandstone Reservoirs Using the NMR Technique". Geofluids 2020 (16 dicembre 2020): 1–12. http://dx.doi.org/10.1155/2020/8880545.
Testo completoAbstract (sommario):
An experimental technique is developed to investigate the dynamic imbibition displacement mechanism in tight sandstone formations of the Yanchang group of the Ordos basin. By combining the dynamic imbibition core flooding experiments and NMR technique, the effects of the injection volume and rate on displacement efficiency are investigated. Moreover, the displacement efficiency of dynamic imbibition is compared with that of static imbibition. This study gains insights into the micromechanisms of dynamic imbibition in tight sandstone formations. It is found that the relative displacement efficiency of dynamic imbibition increases with the increase of injection volume. But the increment amplitude decreases with the increase of injection volume. With the same injection volume, the core displacement efficiency of dynamic imbibition with high permeability is obviously improved. However, the core displacement efficiency decreases rapidly with the increase of injection volume. Optimal injection volumes are recommended for tight sandstone formations with different permeabilities. With the increase of the displacement rate, the core displacement efficiency of dynamic imbibition shows a trend of first rising and then declining. There exists an optimal displacement rate in dynamic imbibition displacement, and the optimal displacement rate almost linearly increases with the increase of core permeability. The static imbibition displacement efficiency increases with the increase of soaking time, but the increment amplitude slows down obviously. The displacement efficiency of static imbibition in small pores is higher than that of dynamic imbibition. The displacement efficiency of dynamic imbibition in large pores or microcracks is significantly higher than that of static imbibition. This study provides theoretical support for the optimization and improvement of the waterflooding recovery process in tight sandstone reservoirs.
15
Neya, Oblé, Elena A. Golovina, Jaap Nijsse e Folkert A. Hoekstra. "Ageing increases the sensitivity of neem (Azadirachta indica) seeds to imbibitional stress". Seed Science Research 14, n. 2 (maggio 2004): 205–17. http://dx.doi.org/10.1079/ssr2004170.
Testo completoAbstract (sommario):
Imbibitional stress was imposed on neem (Azadirachta indica) seeds by letting them soak for 1 h in water at unfavourable, low temperatures before further incubation at 30°C. Sensitivity to low imbibition temperatures increased with a decrease in seed moisture content (MC). To investigate a possible involvement of seed age in the extent of imbibitional damage, initially high-quality seed lots that differed in storage history (10 weeks versus 10 months) were examined at 4 and 7% MC (fresh weight basis). After 10 months of storage, the 7% MC seeds had become sensitive to imbibitional stress. Further drying (1 week) to 4% MC affected aged seeds more than non-aged seeds. Barrier properties of cellular membranes in axes excised after 1 d of rehydration were estimated using a spin-probe technique. The proportion of cells with intact membranes increased with increasing imbibition temperature. For each temperature tested, there were more cells with leaky membranes after 10 months than after 10 weeks of dry storage. Localization of embryo cells displaying loss of turgor and abnormal cellular structure was accomplished using cryo-planing, followed by cryo-scanning electron microscopy. Inspection of the cryo-planed surfaces confirmed that imbibitional damage was temperature dependent, occurring at the periphery. Ageing increased the number of imbibitionally damaged, peripheral cell layers. Germination was estimated to fail when less than 70% of axis cells were alive. We conclude that ageing increases the sensitivity to imbibitional stress. Both the fast ageing and the sensitivity to imbibitional stress might explain the apparent controversies about neem seed desiccation tolerance and storage behaviour.
16
Bhatia, Ramesh C. "Imbibition and germination in the seeds of Heliotropium supinum L." Acta Societatis Botanicorum Poloniae 52, n. 1 (2014): 45–51. http://dx.doi.org/10.5586/asbp.1983.005.
Testo completoAbstract (sommario):
Imbibition in the seeds of <em>Heliotropium supinum</em> L. varies under different temperatures. The optimum temperatures for imbibition and germination are also different. For germination 39% imbibition is essential, and this capability is achieved by 12-week-old seeds. With duration of dry storage imbibition increases. The imbibition and germination percentages decline on re-dry storage of seeds after embeding in mud. A soil moisture of 44% is optimal for germination. A correlation exists between imbibition and germination.
17
Yue, Ming, Bingbing Li, Qiang Chen, Jidong Gao, Weiyao Zhu e Zhiyong Song. "Experimental Investigation on the Effect of Pore Size on Spontaneous Imbibition Recovery in Oil-Wet Reservoirs". Geofluids 2022 (19 gennaio 2022): 1–8. http://dx.doi.org/10.1155/2022/4319832.
Testo completoAbstract (sommario):
Spontaneous imbibition has been considered as a significant method to enhanced oil recovery (EOR) in unconventional reservoirs. The main impediment to comprehending the variation characteristics of spontaneous imbibition at different pore scales was the reservoir’s opacity. To this end, a series of spontaneous imbibition experiments of visualized oil-wet microtubes with six different diameters (10 μm~60 μm) were performed, as were the corresponding macroscopic core imbibition tests with six different permeabilities under the same conditions. The results showed that formation brine mostly advanced along the wall surface of a capillary during the imbibition process, and some were even isolated within a capillary. The imbibition recovery in the capillary with a diameter of 10 μm was the highest (27.81%), which was more than three times that of the capillary with a diameter of 60 μm (8.3%). There was a good power function decline relationship between capillary diameter and imbibition recovery, and 30 μm appeared to be a critical inflection point in both capillary tube and macroscopic core imbibition tests. In addition, the majority of the detained residual oil clusters not only cut off the continuity of formation brine but also increased the imbibition flow resistance, accelerating the imbibition to balance. This research provides a new perspective for comprehending the imbibition characteristics at different pore scales.
18
Jitsuyama, Yutaka, Yuma Hagihara e Yutaro Konno. "Two imbibition properties independently influence the cultivar-specific flooding tolerance of dried soybean seeds". Seed Science Research 24, n. 1 (17 febbraio 2014): 37–48. http://dx.doi.org/10.1017/s0960258513000378.
Testo completoAbstract (sommario):
AbstractSoybean seeds are prone to flooding injury just after planting if they are exposed to excess moisture. We investigated the flooding tolerance of soybean seeds to clarify the relationship between flooding injury and imbibition, to identify factors that could provide fundamental information for the breeding of flooding-tolerant cultivars. Seven cultivars were used for this study. The seeds were geminated in a paper towel after a flooding treatment and then evaluated for survival. The imbibition of submerged seeds (passive imbibition) was evaluated as the seed fresh weight change during the flooding process. The imbibition of seeds with capillary effect (capillary imbibition) was measured by the bottom water supply method. Furthermore, the conductivity of the seed coat and seed osmolarity were measured. After 3 h of flooding, significant differences in survival were detected among cultivars. In addition, the passive imbibition during 10–30 min of flooding, and the capillary imbibition during 0–10 min of flooding were caused by significant differences in the imbibition rate among cultivars. Although neither imbibition showed a significant correlation with the survival directly, the ratio between the passive and the capillary imbibition rate was significantly correlated with survival. Factors affecting imbibition included the hydraulic conductivity of the seed coat and seed osmolarity, which were significantly correlated with the passive and the capillary imbibition rate, respectively. Thus, the balance between the capillary and passive imbibition behaviour of seeds, affected by the hydraulic conductivity of the seed coat and seed osmolarity, was closely correlated with the occurrence of flooding injury in soybean seeds.
19
Liu, Junrong, e James J. Sheng. "Investigation of Countercurrent Imbibition in Oil-Wet Tight Cores Using NMR Technology". SPE Journal 25, n. 05 (13 aprile 2020): 2601–14. http://dx.doi.org/10.2118/201099-pa.
Testo completoAbstract (sommario):
Summary Countercurrent spontaneous imbibition is one of the most significant mechanisms for the mass transfer between fractures and matrixes in tight reservoirs. Adding surfactants and pressurization are two common methods to enhance the imbibition. In this study, we used the low-field nuclear magnetic resonance (NMR) instrument to monitor the dynamic imbibition processes with surfactants added and fluid pressure applied. The T2 relaxation distribution and corresponding water saturation profiles during the imbibition process were obtained by analyzing NMR responses. We found that sodium alpha-olefin sulfonate (AOS) could improve the oil recoveries of laboratory-scale cores to 22.31 and 29.59% with different concentrations (0.1 and 0.5 wt%). The surfactant addition not only expands the imbibition area, but also reduces the residual oil saturation in the imbibition profile. However, the actual maximum imbibition distances are only approximately a centimeter long (0.9412 and 1.1372 cm), which is insignificant for field scale. Due to the minimal imbibition distance, high-quality hydraulic fracturing is required to generate a large number of fractures for imbibition to ensure considerable oil recovery at the field scale. In addition, surfactant is consumed during spontaneous imbibition of oil-wet rocks and increasing surfactant concentration facilitates the imbibition process. However, arbitrarily increasing the concentration does not achieve the expected oil recovery because of the high adsorption capacity resulting from the high concentration. We need to consider economic efficiency to optimize a reasonable surfactant concentration. It was found that traditional dimensionless scaling models are not applicable in the complicated surfactant-enhanced imbibition. Hence, we proposed a new scaling group for scaling laboratory date to the field in fractured oil-wet formations. Moreover, we compared the imbibition process under different pressure conditions (7.5 and 15 MPa) and found that the effect of fluid pressure on countercurrent imbibition is not obvious.
20
Liu, Jian, Xuefeng Qu, Jiwei Wang, Qiang Liu, Lei Zhang, Tao Huang e Haiyang Yu. "Investigating the Influencing Factors of Imbibition of Fracturing Fluids in Tight Reservoirs". Processes 12, n. 1 (22 gennaio 2024): 236. http://dx.doi.org/10.3390/pr12010236.
Testo completoAbstract (sommario):
Tight reservoirs are the focus of unconventional oil and gas resource development, but most tight reservoirs exhibit complex pore structures, strong non-homogeneity, and limited water drive development. Fracturing fluid imbibition is a critically important way to improve the recovery of tight reservoirs. In this paper, an NMR experimental device was used to conduct imbibition experiments in tight reservoirs, and the relationship between temperature, pressure, matrix permeability, and imbibition recovery was investigated. Based on the fracturing fluid imbibition recovery curve, the imbibition process is divided into the fast imbibition stage, slow imbibition stage, and imbibition equilibrium. In addition, based on the pore structure division, the recovery changes of each pore under different experimental conditions were quantitatively analyzed. The results indicate that the highest imbibition recovery is achieved at an experimental pressure of 5 MPa within the range of 0 MPa to 15 MPa. Increasing the experimental pressure can increase the imbibition rate but will not increase imbibition recovery. Within the investigated range in this paper, fracturing fluid imbibition increases with rising temperature and matrix permeability. Moreover, the recovery of each pore gradually increases with the experimental pressure ranging from 0 MPa to 5 MPa. The recovery of each pore is positively correlated with matrix permeability and temperature. During the experiment, micropores contributed the most to the recovery, while macropores contributed the least. The study in this paper guides the efficient development of tight reservoirs.
21
Meng, Qingbang, Jianchao Cai e Jing Wang. "Scaling of Countercurrent Imbibition in 2D Matrix Blocks With Different Boundary Conditions". SPE Journal 24, n. 03 (28 gennaio 2019): 1179–91. http://dx.doi.org/10.2118/194207-pa.
Testo completoAbstract (sommario):
Summary Scaling of imbibition data is of essential importance in predicting oil recovery from fractured reservoirs. In this work, oil recovery by countercurrent spontaneous imbibition from 2D matrix blocks with different boundary conditions was studied using numerical calculations. The numerical results show that the shape of imbibition-recovery curves changes with different boundary conditions. Therefore, the imbibition curves could not be closely correlated with a constant parameter. A modified characteristic length was proposed by a combination of Ma et al. (1997) and theoretical characteristic length. The modified characteristic length is a function of imbibition time, and the shape of imbibition curves could be changed using the modified characteristic length. The overall imbibition curves were closely correlated using the modified characteristic length. Finally, the modified characteristic length was verified by experimental data for imbibition with different boundary conditions.
22
Feng, Xuegang, Xiang’an Yue, Weiqing An e Jirui Zou. "Experimental Study of Influence of Core Wettability on Imbibition Properties". Energies 15, n. 11 (28 maggio 2022): 3984. http://dx.doi.org/10.3390/en15113984.
Testo completoAbstract (sommario):
Through new core wettability simulation technology and the single-sided unidirectional imbibition experimental method, the influence of core wettability on oil imbibition characteristics was studied by using artificial cores with wettability index in the range of −0.9~0.95. Results show that for the cores with permeability from ultra-low to medium–high, the imbibition time shows a monotonically decreasing law with the increase in the wettability index. In the weak water-wet range, the imbibition time increases significantly with the weakening of water-wet. Oil imbibition rate goes up with the increase in wettability index. In the strong water-wet range, the imbibition rate will change significantly with wettability. In the water-wet zone, there is a positive correlation between imbibition oil limit recovery and wettability index, according to which a power exponent model of them is established. The imbibition–displacement ratio, which characterizes the contribution rate of oil recovery by imbibition to that by waterflooding, is also positively correlated with the wettability index. In addition, imbibition–displacement ratios of extra-low permeability cores are very close to that of medium–high permeability cores. According to the analysis of the research results, compared with the strongly water-wet oil layer, the weakly water-wet oil layer with a wettability index of 0–0.5 has a greater contribution to oil recovery by using the enhanced imbibition method.
23
Li, Caoxiong, Chenggang Xian, Jun Wang, Dandan Geng e Yinghao Shen. "The Spontaneous Imbibition of Micro/Nano Structures in Tight Matrix and the Influence on Imbibition Potential". Micromachines 11, n. 9 (21 agosto 2020): 794. http://dx.doi.org/10.3390/mi11090794.
Testo completoAbstract (sommario):
Tight matrix has relatively low permeability and porosity, with abundant micro/nano pores. The capillary force in these pores are relatively strong, making the wetting liquid easier to be imbibed in the matrix. This process is called spontaneous imbibition. The complexity of pore structure is identified as one of the key factors influencing the imbibition process, but the detailed mechanism is not clear. Thus, in this work, a method is proposed to evaluate the influence of pore structure on imbibition process. Pore structure has fractal properties in a specific scale. By using the fractal theory, an imbibition model is provided to analyze the influence of microscopic structures on spontaneous imbibition, considering the pore size distribution and pore connectivity. Also, based on this model, the influencing factors on dimensionless imbibition and diffusion rate are discussed. Results show that the pore structure has more branches, larger and shorter sub-throats has higher chance to gain a high imbibition rate. Finally, a 3D imbibition parameter cube is constructed to determine the parameter combinations in favor of strong water diffusion potential. By utilizing the analysis method based on the fractal theory, we can effectively evaluate the imbibition potential. It is helpful to provide a guidance to evaluate the water imbibition to gas production.
24
LI, CAOXIONG, YINGHAO SHEN, HONGKUI GE, ZHIHUI YANG, SHUAI SU, KAI REN e HEYU HUANG. "ANALYSIS OF CAPILLARY RISE IN ASYMMETRIC BRANCH-LIKE CAPILLARY". Fractals 24, n. 02 (giugno 2016): 1650024. http://dx.doi.org/10.1142/s0218348x16500249.
Testo completoAbstract (sommario):
Transport in porous media is common in nature, attracting many attentions for a long time. Tree-like network model is often used as a simplification for porous space, expressing the complexity of pore spaces instead of capillary bundle. To investigate spontaneous imbibition characteristics in this network, a dynamic asymmetric branch-like capillary model is used to represent basic network structure, using fractal method to represent tortuosity. This work investigates the influence of parameters on imbibition process in the branch-like capillary model. An analytical equation for the imbibition mass versus time is derived. Parameters from capillary structures to liquid properties are taken into account and analyzed based on the numerical solution of the equation. It is found that the imbibition process in asymmetric branch-like capillary model can be recognized by four sections and brunching tubes are positive for imbibition process. Concomitantly, meniscus arrest event is simulated and discussed. Moreover, the influence of parameters on imbibition process is discussed. These parameters can be classified as static and dynamic. Static parameters mainly change the capillary force, which are related to the ultimate imbibition mass or imbibition ability, while dynamic parameters mainly have influence on resistance of flowing fluid, which are related to the imbibition speed in the imbibition process.
25
Zhou, Zhou, Xiaopeng Li e Tadesse Weldu Teklu. "A Critical Review of Osmosis-Associated Imbibition in Unconventional Formations". Energies 14, n. 4 (5 febbraio 2021): 835. http://dx.doi.org/10.3390/en14040835.
Testo completoAbstract (sommario):
In petroleum engineering, imbibition is one of the most important elements for the hydraulic fracturing and water flooding processes, when extraneous fluids are introduced to the reservoir. However, in unconventional shale formations, osmosis has been often overlooked, but it can influence the imbibition process between the working fluid and the contacting formation rocks. The main objective of this study is to understand effects of fluid–rock interactions for osmosis-associated imbibition in unconventional formations. This paper summarizes previous studies on imbibition in unconventional formations, including shale, tight carbonate, and tight sandstone formations. Various key factors and their influence on the imbibition processes are discussed. Then, the causes and role of osmotic forces in fluid imbibition processes are summarized based on previous and recent field observations and laboratory measurements. Moreover, some numerical simulation approaches to model the osmosis-associated imbibition are summarized and compared. Finally, a discussion on the practical implications and field observations of osmosis-associated imbibition is included.
26
Yue, Jiwei, Zhaofeng Wang e Jinsheng Chen. "Dynamic response characteristics of water and methane during isobaric imbibition process in remolded coal containing methane". Energy Exploration & Exploitation 37, n. 1 (13 settembre 2018): 83–101. http://dx.doi.org/10.1177/0144598718798083.
Testo completoAbstract (sommario):
Addition of water to the coal is actually an isobaric imbibition process. To study the dynamic response characteristics of water and methane, the isobaric imbibition process was stimulated by a self-designed experimental device which can eliminate the reabsorbing phenomenon. The results indicate that adding water can displace absorbed gas. The displacement mechanism is attributed to the capillary effect and competitive adsorption during isobaric imbibition process. A competitive adsorption phenomenon exists between gas molecules and water molecules. Since oxygen-containing functional groups in coal and the hydrogen bond of water, water can easily occupy high-energy sites and only the low-energy sites are available for methane. The imbibition quantity increases with increasing water content or adsorption equilibrium pressure. Moreover, the imbibition quantity would reach a maximum value. The relationship between water content and maximum imbibition quantity or the maximum imbibition rate can be described by a Langmuir function under the same adsorption equilibrium pressure. The maximum imbibition quantity increases with increasing adsorption equilibrium pressure under the same water content, which also can be described by a Langmuir function. However, the maximum imbibition rate decreases with increasing adsorption equilibrium pressures under the same water content, which can be described by an exponential function. Compared to the adsorption equilibrium pressure, the water content has a greater effect on the imbibition quantity and imbibition rate. This study revealed the mechanisms of the dynamic response characteristics of water and methane during isobaric imbibition process based on the transformation form of Hagen–Poiseuille equation, adsorption force of coal and gas and adsorption force of coal and water, which can provide a new method to control gas in deep coal seams.
27
Lu, Li, Jianting Li, Xuhui Zhang, Yingjun Li e Fujian Ma. "Effects of Clay Minerals and External Pressures on Imbibition in Shales". Energies 14, n. 22 (11 novembre 2021): 7528. http://dx.doi.org/10.3390/en14227528.
Testo completoAbstract (sommario):
Imbibition is an important mechanism of recovery during waterflooding and low flow-back during fracking in shale reservoirs. Experiments were carried out to study the development of imbibition in shale samples. The effects of clay minerals, especially the illite and IS, were mainly investigated and discussed. The imbibition under different pressures was conducted and compared. The influence of clay minerals on imbibition in shale is significant and complex. It is shown that the low content of illite and IS and small capillary force lead to small imbibition mass and speed. Formation of new micro fractures due to the swelling of clay minerals can cause the permeability to increase and the imbibition to be speeded up. The pore structure, the content of IS, and the capillary force affect the imbibition process significantly. The external pressure obviously affects the imbibition speed and the final imbibition mass. The content of clay minerals is more important to the formation of new micro fractures than the external pressure. There is a peak in the curve of displacement efficiency versus the content of either clay minerals or illite and IS. The effect of illite and IS more remarkable.
28
Hu, Yafei, Fei Ren, Junshi Li, Zhiying Wu, Huanhuan Peng e Jianfeng Hou. "Effect of Dynamic Imbibition on the Development of Ultralow Permeability Reservoir". Geofluids 2021 (27 aprile 2021): 1–12. http://dx.doi.org/10.1155/2021/5544484.
Testo completoAbstract (sommario):
To explore the methodology for improving ultralow permeability reservoir recovery, cores of ultralow permeability reservoirs in China’s Ordos Basin were selected to study the dynamic imbibition micromechanism of crude oil in nanopore throat through core-flooding laboratory experiment and nuclear magnetic resonance (NMR) observation. In the meantime, the microimbibition characteristics and dynamic discharge of oil between matrix and fracture in partially closed boundary reservoirs were simulated to utmostly reflect the actual reservoir conditions. Our findings suggest that dynamic imbibition between fracture and matrix serves the core technology for improving the recovery of ultralow permeability reservoirs, while the main factors affecting dynamic imbibition efficiency include wettability, permeability, injection rate, fracture, water huff and puff cycles, and soaking time. Wettability, in particular, weighs the most, and imbibition can take place either on water-wet rocks or transformed oil-wet rocks with an imbibition agent added in during the waterflooding process. Meanwhile, the higher the permeability is in place, the greater the dynamic imbibition recovery might achieve. The experiments indicate that the dynamic imbibition recovery of a fractured core is 16.26% higher than that of a nonfractured core. Additionally, fractures can not only enhance imbibition recovery but also accelerate the occurrence of dynamic imbibition. The optimal water injection rate of dynamic imbibition is 0.1 mL/min; the reasonable huff and puff cycle of the ultralow permeability reservoirs tends to be two to three cycles; the optimal soaking time of ultralow permeability reservoir is speculated to be 30 days. Finally, the field practice shows that after Stimulated Reservoir Volume (SRV) and dynamic imbibition in 5 horizontal wells in An83 oilfield, there is a remarkable drop in water cut and a noticeable rise in oil production. This research underpins the significance of a dynamic imbibition effect in the development of ultralow permeability oilfield.
29
Lyu, Chaohui, Qing Wang, Zhengfu Ning, Mingqiang Chen, Mingqi Li, Zhili Chen e Yuxuan Xia. "Investigation on the Application of NMR to Spontaneous Imbibition Recovery of Tight Sandstones: An Experimental Study". Energies 11, n. 9 (6 settembre 2018): 2359. http://dx.doi.org/10.3390/en11092359.
Testo completoAbstract (sommario):
In this paper, the nuclear magnetic resonance (NMR) technique is applied to exploring the spontaneous imbibition mechanism in tight sandstones under all face open (AFO) boundary conditions, which will benefit a better understanding of spontaneous imbibition during the development of oil & gas in tight formations. The advantages of nuclear magnetic resonance imaging (NMRI) and NMR T2 are used to define the distribution of remaining oil, evaluate the effect of micro structures on imbibition and predict imbibition recovery. NMR T2 results show that pore size distributions around two peaks are not only the main oil distributions under saturated condition but also fall within the main imbibition distributions range. Spontaneous imbibition mainly occurs in the first 6 h and then slows down and even ceases. The oil signals in tiny pores stabilize during the early stage of imbibition while the oil signal in large pores keeps fluctuating during the late stage of imbibition. NMRI results demonstrate that spontaneous imbibition is a replacement process starting slowly from the boundaries to the center under AFO and ending with oil-water mixing. Furthermore, the wetting phase can invade the whole core in the first 6 h, which is identical with the main period of imbibition occurring according to NMR T2 results. Factors influencing the history of oil distribution and saturation differ at different periods, while it is dominated by capillary imbibition at the early stage and allocated by diffusion at later time. Two imbibition recovery curves calculated by NMRI and NMR T2 are basically consistent, while there still exists some deviations between them as a result of the resolutions of NMRI and NMR T2. In addition, the heterogeneity of pore size distributions in the two samples aggravates this discrepancy. The work in this paper should prove of great help to better understand the process of the spontaneous imbibition, not only at the macroscopic level but also at the microscopic level, which is significant for oil/gas recovery in tight formations.
30
Cai, Shaobin, Li Zhang, Lixin Kang, Yongfei Yang, Wenlong Jing, Lei Zhang, Chao Xu, Hai Sun e Mozhdeh Sajjadi. "Spontaneous Imbibition in a Fractal Network Model with Different Wettabilities". Water 13, n. 17 (29 agosto 2021): 2370. http://dx.doi.org/10.3390/w13172370.
Testo completoAbstract (sommario):
In this work, we derived a mathematical model for spontaneous imbibition in a Y-shaped branching network model. The classic Lucas–Washburn equation was used for modeling the imbibition process occurring in the Y-shape model. Then, a mathematical model for the Newtonian fluid’s imbibition was derived to reveal the relationship between dimensionless imbibition time and length ratio, radius ratio, and wetting strength. The dimensionless imbibition time in the model was adopted to compare with that of the capillary bundle model. Different length and radius ratios were considered in the adjacent two-stage channels, and different wettabilities were considered in the different branches. The optimal radius ratio, length ratio, and wetting strength were calculated under the condition of the shortest imbibition time. In addition, the shortest dimensionless imbibition time of the three-stage Y-shaped branching network model was calculated when the wettability changes randomly. The results indicate that the imbibition time changed mostly when the wettability of the second branch changed, and the second branch was the most sensitive to wettability in the model.
31
SHEN, YINGHAO, CAOXIONG LI, HONGKUI GE, XUEJING GUO e SHAOJUN WANG. "SPONTANEOUS IMBIBITION PROCESS IN MICRO–NANO FRACTAL CAPILLARIES CONSIDERING SLIP FLOW". Fractals 26, n. 02 (aprile 2018): 1840002. http://dx.doi.org/10.1142/s0218348x18400029.
Testo completoAbstract (sommario):
An imbibition process of water into a matrix is required to investigate the influences of large-volume fracturing fluids on gas production of unconventional formations. Slip flow has been recognized by recent studies as a major mechanism of fluid transport in nanotubes. For nanopores in shale, a slip boundary is nonnegligible in the imbibition process. In this study, we established an analytic equation of spontaneous imbibition considering slip effects in capillaries. A spontaneous imbibition model that couples the analytic equation considering the slip effect was constructed based on fractal theory. We then used a model for various conditions, such as slip boundary, pore structure, and fractal dimension of pore tortuosity, to capture the imbibition characteristics considering the slip effect. A dynamic contact angle was integrated into the modeling. Results of our study verify that the slip boundary influences water imbibition significantly. The imbibition speed is significantly improved when slip length reaches the equivalent diameter of a tube. Therefore, disregarding the slip effect will underestimate the imbibition speed in shale samples.
32
McClure, G. B., e N. S. Lang. "LEAKAGE AND MOBILIZATION OF STORAGE RESERVES DURING IMBIBITION OF SWEET CORN." HortScience 28, n. 5 (maggio 1993): 530b—530. http://dx.doi.org/10.21273/hortsci.28.5.530b.
Testo completoAbstract (sommario):
Interconversion and transport of seed storage reserves during imbibition may influence subsequent germination. Sweet corn (Zea mays L. cv. Florida Staysweet) seeds were imbibed in aerated distilled water for either 0, 3, 6,9,12, or 24 h intervals. Seed leachate electrical conductivity, leachate soluble carbohydrate concentrations, and seed moisture were quantified at each interval. Lipid, non-structural carbohydrate, and protein concentrations of embryo and endosperm tissue were quantified for each imbibition interval. After imbibition treatments, seed germination performance was evaluated at 10 and 25C. Leachate conductivity and seed moisture increased with duration of imbibition. Glucose and fructose were the major soluble carbohydrates found in the seed leachate. Embryo lipid and sucrose concentrations significantly increased within 6 h of imbibition, while endosperm lipid decreased. Endosperm sucrose concentration remained constant throughout the duration of imbibition. Germination percentage was not significantly improved at 10 or 25C during the course of imbibition. Conversely, time to germination decreased significantly at 10C within 3 h. Storage reserve mobilization during imbibition may be responsible for the decreased time to germination observed at 10C.
33
Liu, Yishan, Zhewei Chen, Dongqi Ji, Yingfeng Peng, Yanan Hou e Zhengdong Lei. "Pore Fluid Movability in Fractured Shale Oil Reservoir Based on Nuclear Magnetic Resonance". Processes 11, n. 12 (4 dicembre 2023): 3365. http://dx.doi.org/10.3390/pr11123365.
Testo completoAbstract (sommario):
Gulong shale oil is found in a typical continental shale oil reservoir, which is different from marine shale oil reservoirs. The Gulong shale oil reservoir is a pure shale-type oil reservoir with abundantly developed nanoscale pores, making it extremely difficult to unlock fluids. Pressure drive does not easily achieve fluid unlock conditions; thus, it is necessary to utilize imbibition to unlock nanoscale pore fluids. In this study, experiments were conducted on oil displacement by high-speed centrifugal pressure and imbibition under different conditions, respectively, and simulations were used to evaluate the effects of pressure differential drive and imbibition efficiency on the utilization of crude oil following fracturing. Combined with the mixed wettability of the reservoir, the imbibition efficiency was analyzed, and the imbibition efficiency at different soaking stages was evaluated. When the fracturing pressure was higher than the matrix pore pressure, the imbibition efficiency was the most obvious, which was 27.9%. Spontaneous imbibition depending solely on capillary force had poor efficiency, at 16.8%. When the fracturing pressure was lower than the matrix pore pressure, the imbibition efficiency was the lowest, at only 1.3%. It is proposed that strengthening fracture pressure and promoting pressurized imbibition are the keys to improving shale oil development.
34
Bhatia, Ramesh C. "Imbibition and germination in the seeds of Glinus lotoides L." Acta Agrobotanica 40, n. 1-2 (2013): 15–20. http://dx.doi.org/10.5586/aa.1987.002.
Testo completoAbstract (sommario):
Imbibition in the seeds of <i>Glinus lotoides</i> L. varied under different temperatures. The optimum temperatures for imbibition and germination were different. Fifty-five percent imbibition was essential for germination and this capability was achieved by 12 weeks old seeds. With growing duration of dry storage, imbibition and germination increased, although germination declined on prolonged dry storage for over 36 weeks. A soil moisture of 50% was essential and 100% was optimal for germination. A correlation was found between imbibition and germination.
35
Mirzaei, Mohammad, David A. DiCarlo e Gary A. Pope. "Visualization and Analysis of Surfactant Imbibition Into Oil-Wet Fractured Cores". SPE Journal 21, n. 01 (18 febbraio 2016): 101–11. http://dx.doi.org/10.2118/166129-pa.
Testo completoAbstract (sommario):
Summary Imbibition of surfactant solution into the oil-wet matrix in fractured reservoirs is a complicated process that involves gravity, capillary, viscous, and diffusive forces. The standard experiment for testing imbibition of surfactant solution involves an imbibition cell, in which the core is placed in the surfactant solution and the recovery is measured vs. time. Although these experiments prove the effectiveness of surfactants, little insight into the physics of the problem is achieved. In this study, we performed water and surfactant flooding into oil-wet fractured cores and monitored the imbibition of the surfactant solution by use of computed-tomography (CT) scanning. From the CT images, the surfactant-imbibition dynamics as a function of height along the core was obtained. Although the waterflood only displaced oil from the fracture, the surfactant solution imbibed into the matrix; the imbibition is frontal, with the greatest imbibition rate at the bottom of the core, and the imbibition decreases roughly linearly with height. Experiments with cores of different sizes showed that increase in either the height or the diameter of the core causes decrease in imbibition and fractional oil-recovery rate. We also perform numerical simulations to model the observed imbibition. On the basis of the experimental measurements and numerical-simulation results, we propose a new scaling group that includes both the diameter and the height of the core. We show that the new scaling groups scale the recovery curves better than the traditional scaling group.
36
Li, Kewen, Kevin Chow e Roland N. Horne. "Influence of Initial Water Saturation on Recovery by Spontaneous Imbibition in Gas/Water/Rock Systems and the Calculation of Relative Permeability". SPE Reservoir Evaluation & Engineering 9, n. 04 (1 agosto 2006): 295–301. http://dx.doi.org/10.2118/99329-pa.
Testo completoAbstract (sommario):
Summary It has been a challenge to understand why recovery by spontaneous imbibition could both increase and decrease with initial water saturation. To this end, mathematical models were developed with porosity, permeability, viscosity, relative permeability, capillary pressure, and initial water saturation included. These equations foresee that recovery and imbibition rate can increase, remain unchanged, or decrease with an increase in initial water saturation, depending on rock properties, the quantity of residual gas saturation, the range of initial water saturation, and the units used in the definitions of gas recovery and imbibition rate. The theoretical predictions were verified experimentally by conducting spontaneous water imbibition at five different initial water saturations, ranging from 0 to approximately 50%. The effects of initial water saturation on residual saturation, relative permeability, capillary pressure, imbibition rate, and recovery in gas/water/rock systems by cocurrent spontaneous imbibition were investigated both theoretically and experimentally. Water-phase relative permeabilities and capillary pressures were calculated with the experimental data of spontaneous imbibition. Experimental results in different rocks were compared. Introduction Spontaneous water imbibition is an important mechanism during water injection. Prediction of recovery and imbibition rate by spontaneous water imbibition is essential to evaluate the feasibility and the performance of water injection. For example, is water injection effective in the case of high initial water saturation in reservoirs? Answers to such a question may be found by investigating the effect of initial water saturation on spontaneous water imbibition. It has been observed experimentally that initial water saturation affects recovery and production rate significantly (Blair 1964; Zhou et al. 2000; Viksund et al. 1998; Cil et al. 1998; Tong et al. 2001; Li and Firoozabadi 2000; Akin et al. 2000). However, the experimental observations from different authors (Zhou et al. 2000; Cil et al. 1998; Li and Firoozabadi 2000; Akin et al. 2000) are not consistent. On the other hand, few studies have investigated the effect of initial water saturation on recovery and imbibition rate theoretically, especially in gas reservoirs. Using numerical-simulation techniques, Blair (1964) found that the quantity and the rate of oil produced after a given period of imbibition increased with a decrease in initial water saturation for countercurrent spontaneous imbibition. Zhou et al. (2000) found that both imbibition rate and final oil recovery in terms of oil originally in place (OOIP) increased with an increase in initial water saturation, whereas oil recovery by waterflooding decreased. Viksund et al. (1998) found that the final oil recovery (OOIP) by spontaneous water imbibition in Berea sandstone showed little variation with a change in initial water saturation from 0 to approximately 30%. For the chalk samples tested by Viksund et al. (1998), the imbibition rate first increased with an increase in initial water saturation and then decreased slightly as initial water saturation increased above 34%.Cil et al. (1998) reported that the oil recovery (in terms of recoverable oil reserves) for zero and 20% initial water saturation showed insignificant differences in behavior. However, the oil recovery for initial water saturation above 20% increased with an increase in initial water saturation. Li and Firoozabadi (2000) found that the final gas recovery in the units of gas originally in place (GOIP) by spontaneous imbibition decreased with an increase in initial water saturation in both gas/oil/rock and gas/water/rock systems. The imbibition rate (GOIP/min) increased with an increase in initial water saturation at early time but decreased at later time. Akin et al. (2000) found that the residual oil saturation was unaffected significantly by initial water saturation. In this study, equations, derived theoretically, were used to study the effect of initial water saturation on gas recovery and imbibition rate. The equations correlate recovery, imbibition rate, initial water saturation, rock/fluid properties, and other parameters. Experiments of spontaneous water imbibition in gas-saturated rocks were conducted to confirm the theoretical predictions. The effect of rock properties on gas recovery and imbibition rate was also studied. An X-ray CT scanner was used to monitor the distribution of the initial water saturation to confirm that the initial distribution of the water saturation was uniform. In this study, we only focused on cocurrent spontaneous imbibition. It was assumed that there were no chemical reactions or mass transfer between gas and liquid.
37
Wang, Xiukun, e James J. Sheng. "Dynamic Pore-Scale Network Modeling of Spontaneous Water Imbibition in Shale and Tight Reservoirs". Energies 13, n. 18 (10 settembre 2020): 4709. http://dx.doi.org/10.3390/en13184709.
Testo completoAbstract (sommario):
Spontaneous water imbibition plays an imperative role in the development of shale or tight oil reservoirs. Spontaneous water imbibition is helpful in the extraction of crude oil from the matrix, although it decreases the relative permeability of the hydrocarbon phase dramatically. The dynamic pore-scale network modeling of water imbibition in shale and tight reservoirs is presented in this work; pore network generation, local capillary pressure function, conductance calculation and boundary conditions for imbibition are all presented in detail in this paper. The pore network is generated based on the characteristics of Barnett shale formations, and the corresponding laboratory imbibition experiments are matched using this established dynamic pore network model. The effects of the wettability, throat aspect ratio, viscosity, shape factor, micro-fractures, etc. are all investigated in this work. Attempts are made to investigate the water imbibition mechanisms from a micro-scale perspective. According to the simulated results, wettability dominates the imbibition characteristics. Besides this, the viscous effects including viscosity, initial capillary pressure and micro-fractures increase the imbibition rate, while the final recovery factor is more controlled by the capillarity effect including the cross-area shape factor, contact angle and the average pore-throat aspect ratio.
38
Nie, Xiangrong, e Junbin Chen. "Nuclear Magnetic Resonance Measurement of Oil and Water Distributions in Spontaneous Imbibition Process in Tight Oil Reservoirs". Energies 11, n. 11 (10 novembre 2018): 3114. http://dx.doi.org/10.3390/en11113114.
Testo completoAbstract (sommario):
Spontaneous imbibition of water into tight oil reservoirs is considered an effective way to improve tight oil recovery. We have combined testing techniques such as nuclear magnetic resonance, mercury injection capillary pressure, and magnetic resonance imaging to reveal the distribution characteristics of oil and water during the spontaneous imbibition process of tight sandstone reservoir. The experimental results were used to describe the dynamic process of oil–water distribution at the microscopic scale. The water phase is absorbed into the core sample by micropores and mesopores under capillary forces that dry away the original oil phase into the hydraulically connected macropores. The oil phase entering the macropores will drive away the oil in place and expel the original oil from the macropores. The results of magnetic resonance imaging clearly show that the remaining oil accumulates in the central region of the core because a large amount of water is absorbed in the late stage of spontaneous imbibition, and the water in the pores gradually connects to form a “water shield” that blocks the flow of the oil phase. We propose the spontaneous imbibition pathway, which can effectively explain the internal mechanisms controlling the spontaneous imbibition rate. The surface of the core tends to form many spontaneous imbibition pathways, so the rate of spontaneous imbibition is fast. The deep core does not easily form many spontaneous imbibition pathways, so the rate of spontaneous imbibition is slow. This paper reveals the pore characteristics and distribution of oil and water during the spontaneous imbibition process, which is of significance for the efficient development of tight oil.
39
Meng, Mianmo, Hongkui Ge, Yinghao Shen, Wenming Ji e Fei Ren. "Fluid saturation evolution with imbibition in unconventional natural gas reservoirs". Interpretation 6, n. 4 (1 novembre 2018): T849—T859. http://dx.doi.org/10.1190/int-2017-0206.1.
Testo completoAbstract (sommario):
Hydraulic fracturing plays an important role in developing unconventional natural gas. The large amount of fracturing fluid retention becomes a significant phenomenon in gas fields. Much research has been carried out to explain this mechanism. Imbibition is regarded as one of the important factors and has been investigated extensively. However, the saturation evolution of different types of fluids (liquid, free gas, and trapped gas) has been less researched during imbibition. A porosity experiment combined with an imbibition experiment was conducted to research the fluids-saturation evolution. There are three types of experimental rocks: tight sand, volcanic rock, and shale. The free-gas saturation decreases with the increasing liquid saturation in all samples. However, the sum of these two types of saturation is approximately 100% during imbibition in tight sand. This indicates that the pore space is almost totally filled by liquid and free gas. The sum of these two types of saturation is less than 100% during imbibition in volcanic rock. This indicates that there is trapped gas by liquid. Trapped-gas saturation increases at the early period and decreases at the late period. The sum of these two types of saturation greatly exceeds 100% during imbibition and increases with the imbibition time in shale rocks. This means that there is large amount of extra imbibition liquid. At the same time, the free-gas saturation fluctuates with the increasing liquid saturation. Based on the above results, it can be concluded that tight sand reservoirs have nearly no trapped gas and extra imbibition liquid, volcanic reservoirs have trapped gas and a little extra imbibition liquid, and shale reservoirs have some trapped gas and a large amount of extra imbibition liquid. This research contributes to understanding the fluid saturation evolution during hydraulic fracturing in unconventional natural gas reservoirs.
40
Wang, Dongmei, Jin Zhang, Raymond Butler e Kayode Olatunji. "Scaling Laboratory-Data Surfactant-Imbibition Rates to the Field in Fractured-Shale Formations". SPE Reservoir Evaluation & Engineering 19, n. 03 (19 febbraio 2016): 440–49. http://dx.doi.org/10.2118/178489-pa.
Testo completoAbstract (sommario):
Summary By use of existing methods, typical oil-recovery factors from the Bakken and other shale formations are low, typically less than 5% of original oil in place (OOIP). We are investigating the use of surfactant imbibition to enhance oil recovery from oil shale or other tight rocks. Much of our previous work has measured surfactant-imbibition rates and oil-recovery values in laboratory cores from the Bakken shale, Niobrara chalk/shale, and Eagle Ford formations. With optimized surfactant formulations at reservoir conditions, we observed oil-recovery values up to 20% of OOIP incremental over brine imbibition. However, whether surfactant imbibition will be a viable recovery process depends on achieving sufficiently high oil-production rates in a field setting. This, in turn, depends on three factors: the area of formation contact (through fractures and microfractures) when/where the surfactant formulation is introduced; the rates of surfactant imbibition; and the distances of surfactant imbibition into the rock and ultimate oil-displacement effectiveness. In this paper, we use analytical models to scale laboratory surfactant-imbibition rates to a field scale in fractured-shale formations. In laboratory cores, we observed imbibition rates that varied inversely with time. Dimensionless scaling groups were applied that compensate for the effects of sample size and shape, boundary conditions, permeability, porosity, and viscosity. Calculations were made of available fracture area, assuming typical horizontal-well lengths and transverse-induced-fracture spacing in typical Bakken wells. These fracture areas were coupled with our imbibition-scaling groups to estimate oil-recovery rates in a field setting. Considering realistic timing, surfactant imbibition will generally not proceed more than a few meters into the low-permeability shale/chalk formations. These calculations indicate insufficient fracture area to provide a viable imbibition process if only the induced-fracture area is considered. However, recent results from geological, microseismic, and pressure-transient studies indicate considerably greater area associated with natural microfractures in our target formations. When the increased area suggested by the presence of microfractures is included in our analyses, the surfactant-imbibition process appears quite promising.
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Shi, Junjie, Linsong Cheng, Renyi Cao, Zhihao Jia e Gaoling Liu. "Phase-Field Simulation of Imbibition for the Matrix-Fracture of Tight Oil Reservoirs Considering Temperature Change". Water 13, n. 7 (6 aprile 2021): 1004. http://dx.doi.org/10.3390/w13071004.
Testo completoAbstract (sommario):
Injection water temperature is often different from that of the reservoir during water injection development in the tight reservoir. Temperature change causes different fluid properties and oil-water interface properties, which further affects the imbibition process. In this paper, a matrix-fracture non-isothermal oil-water imbibition flow model in tight reservoirs is established and solved by the finite element method based on the phase-field method. The ideal inhomogeneous rock structure model was used to study the influence of a single factor on the imbibition. The actual rock structure model was used to study the influence of temperature. The mechanism of temperature influence in the process of imbibition is studied from the micro-level. It is found that the imbibition of matrix-fracture is a process in which the water enters the matrix along with the small pores, and the oil is driven into the macropores and then into the fractures. Temperature affects the imbibition process by changing the oil-water contact angle, oil-water interfacial tension, and oil-water viscosity ratio. Reducing oil-water contact angle and oil-water viscosity ratio and increasing oil-water interfacial tension are conducive to the imbibition process. The increase in injection water temperature is usually beneficial to the occurrence of the imbibition. Moreover, the actual core structure imbibition degree is often lower than that of the ideal core structure. The inhomogeneous distribution of rock particles has a significant influence on imbibition. This study provides microscale theoretical support for seeking reasonable injection velocity, pressure gradient, injection temperature, and well-shutting time in the field process. It provides a reference for the formulation of field process parameters.
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Dang, Hailong, Hanqiao Jiang, Binchi Hou, Xiaofeng Wang, Tao Gao, Chengjun Wang e Chunhua Lu. "Analysis of Controlling Factors at Separate Imbibition Stages for Ultra-Low-Permeability Reservoirs". Energies 14, n. 21 (30 ottobre 2021): 7093. http://dx.doi.org/10.3390/en14217093.
Testo completoAbstract (sommario):
Spontaneous imbibition is an important mechanism in naturally fractured reservoirs. In our previous studies on the effect of imbibition efficiency of ultra-low permeability reservoirs, we mostly focused on the relationship between macroscopic core recovery rate and influential factors. Additionally, we also mainly focused on the factors that control the final imbibition recovery for ultra-low permeability reservoirs. Through a large number of experiments, it was found that the factors affecting imbibition are different in separate stages. However, the relative importance of those factors in different imbibition stages was hardly studied. In this work, we tested six key factors, i.e., the core length, RQI, salinity, interfacial characteristics, initial oil saturation, and oil viscosity, in natural sandstone samples from Chang 6 in the Zichang area. Based on experimental results, we divided the imbibition process into three stages (i.e., the early stage, the middle stage, and the late stage) to quantify the effects of the controlling factors. The results show that the relative importance of the controlling factors is changing during the imbibition process. The weight of importance is obtained for those factors at each stage. In addition, a comparative model is established for the dual-porosity media from Chang 6 formation. The results show that the increase of the rock size can extend the imbibition period for the early and middle stages. Moreover, the weight of importance for the initial oil saturation, interfacial characteristics, and salinity are also analyzed in three imbibition stages. This study provides theoretical support to guide water injection in ultra-low-permeability reservoirs and to understand the formation of energy supplements and oil recovery during the imbibition process.
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Liu, Xiong, Le Yan, Qian Gao, Yafei Liu, Hai Huang e Shun Liu. "Effect of Salinity on the Imbibition Recovery Process of Tight Sandstone Reservoirs". Processes 10, n. 2 (26 gennaio 2022): 228. http://dx.doi.org/10.3390/pr10020228.
Testo completoAbstract (sommario):
Fracture network fracturing combined with oil–water infiltration and replacement is an effective approach to develop tight sandstone reservoirs. How to further improve oil recovery based on imbibition is a problem encountered during production. In this study, the core of the CHANG-7 tight sandstone reservoir in the Changqing oilfield of the China National Petroleum Corporation (CNPC) is studied. Combined with the newly designed core self-imbibition experiment, the mechanisms of salinity action are studied, and the influence of salinity on the process of imbibition oil recovery is quantitatively characterized. Research results show that the influence of salinity on the imbibition process of tight sandstone reservoirs takes place mainly through two ways; one is to reduce the oil–water interfacial tension, and the other is to construct an osmotic pressure displacement model. The salinity has significant influences on interfacial tension. The interfacial tension of low-salinity brine is only 1/5 of that of distilled water, but in the presence of high-efficiency surfactants, the influence of the salinity on the interfacial tension can be ignored; the greater the difference in salt concentration, the higher the core permeability and the greater the influence of salinity on the process of imbibition and oil recovery in tight sandstone reservoirs. At the initial stage of imbibition, the effect of salinity is less important than that of capillary force. On the contrary, the effect of salinity is much more important than that of capillary force in the middle of imbibition, and the imbibition curve shows a downward trend. At the later stage of imbibition, the fluid tends toward imbibition equilibrium, and the effects of capillary force and salinity are not obvious.
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Wang, Xiaoxiang, Yang Zhang, Xinmeng Wu, Xin Fan, Desheng Zhou e Jinze Xu. "Analysis of the Influence Mechanism of Nanomaterials on Spontaneous Imbibition of Chang 7 Tight Reservoir Core". Processes 12, n. 5 (27 aprile 2024): 890. http://dx.doi.org/10.3390/pr12050890.
Testo completoAbstract (sommario):
This study investigates the impact of nanomaterials on different surfactant solutions. By measuring the parameters (including emulsification property, zeta potential, DLS, CA, IFT, etc.) of imbibition liquid system with nanoparticles and without nanoparticles, combining with imbibition experiments, the law and mechanism of improving the imbibition recovery of nanomaterials were obtained. The findings demonstrate that the nano-silica sol enhances the emulsification and dispersion of crude oil in the surfactant system, resulting in smaller and more uniform particle sizes for emulsified oil droplets. Non-ionic surfactant AEO-7 has the best effect under the synergistic action of nanomaterials. Zeta potential and DLS tests also showed that AEO-7 exhibits smaller particle sizes due to their insignificant electrostatic interaction with nanoparticles. Furthermore, the addition of nanomaterials enhances the hydrophilicity of core and reduces the interfacial tension. Under the synergistic action of nanoparticles, AEO-7 still showed the best enhanced core hydrophilicity (CA 0.61° after imbibition) and the lowest interfacial tension (0.1750 mN·m−1). In the imbibition experiment, the imbibition recovery of the system with nanomaterials is higher than that of the non-nanomaterials. The mixed system of AEO-7 and nano-silica sol ZZ-1 has the highest imbibition recovery (49.27%). Combined with the experiments above, it shows that nanomaterials have a good effect on enhancing the recovery rate of tight core, and the synergistic effect of non-ionic surfactant AEO-7 with nanomaterials is the best. Moreover, nanomaterials reduce adhesion work within the system while improving spontaneous imbibition recovery. These findings provide theoretical guidance for better understanding the mechanism behind nanomaterial-induced imbibition enhancement as well as improving tight oil’s imbibition recovery.
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Sung, Yu, Daniel J. Cantliffe e Russell Nagata. "Using a Puncture Test to Identify the Role of Seed Coverings on Thermotolerant Lettuce Seed Germination". Journal of the American Society for Horticultural Science 123, n. 6 (novembre 1998): 1102–6. http://dx.doi.org/10.21273/jashs.123.6.1102.
Testo completoAbstract (sommario):
Temperature is an important environmental factor that affects lettuce (Lactuca sativa L.) germination. The present research was conducted to determine the role of seed coverings on lettuce seed germination at high temperature. Five lettuce genotypes were primed in order to bypass thermoinhibitional effects on germination. During germination of primed and nonprimed seeds, imbibition followed a normal triphasic pattern. Primed seeds had higher final water content, a decreased imbibitional phase II, and germinated at 36 °C compared to nonprimed seeds of thermosensitive genotypes, which did not germinate at 36 °C. Puncture tests were conducted to determine the force required to penetrate the whole seed or endosperm of the five genotypes at 24 and 33 °C. `Dark Green Boston', a thermosensitive genotype, had the highest mean resistance (0.207 N) and PI 251245, a thermotolerant genotype, had the lowest (0.139 N). Resistance to penetration of the endopserm of the five genotypes was different at both temperatures. However, three thermotolerant genotypes had lower endosperm resistance than two thermosensitive types. At 36 °C, the penetration force for primed and nonprimed seeds was compared after the first hour of imbibition and 1 hour before radicle protrusion. The force required to penetrate the seed was affected by genotype, seed priming, and duration of imbibition. Puncture force decreased as imbibition time at 36 °C increased in primed and nonprimed seed of each thermotolerant genotype but not in the thermosensitive genotypes. Priming reduced the initial force necessary to penetrate the seed and endosperm in all genotypes. Thus, for radicle protrusion to occur, there must first be a decrease in the resistance of the endosperm layer as evidenced by priming or thermotolerant genotype. Then, the pericarp and integument are sufficiently weakened so that tissue resistance is lower than the turgor pressure of the expanding embryo, allowing germination to be completed.
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Coryniken, Siti, Didin Kustantiningtyastuti e Afriwardi Afriwardi. "IMBIBITION EFFECT OF IMMERSION HYDROCOLLOID IRREVERSIBLE ALGINATE IN SODIUM HYPOCHLORITE SOLUTIO". Andalas Dental Journal 3, n. 2 (3 dicembre 2015): 59–67. http://dx.doi.org/10.25077/adj.v3i2.51.
Testo completoAbstract (sommario):
materials have character that absorb water it is imbibition that can affect the dimensional stability when immersed in disinfectant . The purpose of this study is to see the effect of imbibition at alginate impression material immersed in a disinfectant solution of Sodium Hypochlorite .The method used was experimental with pretest and posttest with control group design . The mold were diameter of 28 mm and height 18 mm .the impression were immersed in sodium hypochlorite 0.5 % and 1 % for 3 minutes , 5 minutes and 10 minutes . Imbibition weight calculation is done by using digital scales.The results showed that the presence of imbibition on impression material alginate that immersed in Sodium Hypochlorite solution for 3 minutes , 5 minutes and 10 minutes . Statistical Test Two Way Repeated Measure ANOVA showed a significant difference ( p< 0.05 ) in minutes imbibition , while the concentration of the solution had a significant difference ( p > 0.05 ) .The conclusion of this study is the alginate impression material has the effect of imbibition to immersion Sodium Hypochlorite solution.
Keywords : hydrocolloid Alginate , Sodium Hypochlorite , imbibition effects , immersio
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Hershey, David R. "Bean Seed Imbibition". Science Activities: Classroom Projects and Curriculum Ideas 35, n. 2 (gennaio 1998): 25–27. http://dx.doi.org/10.1080/00368129809602077.
Testo completo
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Standnes, Dag Chun. "Estimation of Imbibition Capillary Pressure Curves from Spontaneous Imbibition Data". Energy & Fuels 24, n. 2 (18 febbraio 2010): 1081–87. http://dx.doi.org/10.1021/ef900938h.
Testo completo
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Qi, Zi Yuan, Ye Fei Wang e Xiao Li Xu. "Effects of Interfacial Tension Reduction and Wettability Alteration on Oil Recovery by Surfactant Imbibition". Advanced Materials Research 868 (dicembre 2013): 664–68. http://dx.doi.org/10.4028/www.scientific.net/amr.868.664.
Testo completoAbstract (sommario):
Surfactant imbibition experiments were carried out with four surfactants and effects of interfacial tension and surface wettability on oil recovery were studied. A convenient imbibition process with quartz sands was used, and the experimental results suggest that anionic and non-ionic surfactants have higher oil recovery than cationic surfactant, and the sand surface wettability plays an important role in influencing oil recovery during spontaneous imbibition. Altering the wettability of oil sand surface from oil-wet to water-wet can enhance the oil recovery of imbibition process. The maximum ultimate imbibition recovery appeared in the area where both contact angle and interfacial tension were low.
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Kantzas, Apostolos, Minghua Ding e Jong Lee. "Residual Gas Saturation Revisited". SPE Reservoir Evaluation & Engineering 4, n. 06 (1 dicembre 2001): 467–76. http://dx.doi.org/10.2118/75116-pa.
Testo completoAbstract (sommario):
Summary The determination of residual gas saturation in gas reservoirs from long spontaneous and forced-imbibition tests is addressed in this paper. It is customarily assumed that when a gas reservoir is overlaying an aquifer, water will imbibe into the gas-saturated zone with the onset of gas production. The process of gas displacement by water will lead to forced imbibition in areas of high drawdown and spontaneous imbibition in areas of low drawdown. It is further assumed that in the bulk of the reservoir, spontaneous imbibition will prevail and the reservoir will be water-wet. A final assumption is that the gas behaves as an incompressible fluid. All these assumptions are challenged in this paper. A series of experiments is presented in which it is demonstrated that the residual gas saturation obtained by a short imbibition test is not necessarily the correct residual gas saturation. Imbibition tests by different methods yield very different results, while saturation history and core cleaning also seem to have a strong effect on the determination of residual gas saturation. It was found, in some cases, that the residual gas by spontaneous imbibition was unreasonably high. This was attributed to weak wetting conditions of the core (no water pull by imbibition). It is expected that this work will shed some new light on an old, but not-so-well-understood, topic. Introduction When a porous medium is partially or fully saturated with a nonwetting phase, and a wetting phase is allowed to invade the porous medium, the process is called imbibition. For the problem addressed in this work, the nonwetting phase is assumed to be gas, and the wetting phase is assumed to be the aquifer water. If the medium is dry and the water is imbibing, then the imbibition is primary (Swi=0). If the water is already in the medium, the imbibition is secondary (Swi>0). If there is no driving force other than the affinity to wet, the imbibition is spontaneous. If there is any other positive pressure gradient, the imbibition is called forced. Numerous papers have been written on the subject of residual oil saturation from imbibition, but fewer have been prepared on the subject of residual gas saturation from imbibition. The common perception is that many of the principles that cover oil and gas reservoirs are the same. Agarwal1 addressed the relationship between initial and final gas saturation from an empirical perspective. He worked with 320 imbibition experiments and segmented the database to develop curve fits for common rock classifications. Land2 noted that available data seemed to fit very well to an empirical functional form given asEquation 1 In this model, the only free parameter is the maximum observable trapped nonwetting phase saturation corresponding to Sgr (Sgi=1). This expression does not predict residual phase saturation, only how residual saturation scales with initial saturation. Zhou et al.3 studied the effect of wettability, initial water saturation, and aging time on oil recovery by spontaneous imbibition and waterflooding. A correlation between water wetness and oil recovery by waterflooding and spontaneous imbibition was observed. Geffen et al.4 investigated some factors that affect the residual gas saturation, such as flooding rate, static pressure, temperature, sample size, and saturation conditions before flooding. They found that water imbibition on dry-plug experiments was different from waterflooding experiments with connate water. However, they concluded that the residual gas saturation from the two types of experiments was essentially the same. Keelan and Pugh5 concluded that trapped gas saturation existed after gas displacement by wetting-phase imbibition in carbonate reservoirs. Their experiments showed that the trapped gas varied with initial gas in place and that it was a function of rock type. Fishlock et al.6 investigated the residual gas saturation as a function of pressure. They focused on the mobilization of residual gas by blowdown. Apparently, the trapped gas did not become mobile immediately as it expanded. The gas saturation had to increase appreciably to a critical value for gas remobilization. Tang and Morrow7 introduced the effect of composition on the microscopic displacement efficiency of oil recovery by waterflooding and spontaneous imbibition. They concluded that the cation valency was important to crude/oil/rock interactions. Chierici et al.8 tested whether a reliable value of reserves could be obtained from reservoir past-production performance by analyzing results from six gasfield experiments. They concluded that different gas reservoir aquifer systems could show the same pressure performance in response to a given production schedule. Baldwin and Spinler9 investigated residual oil saturation starting from different initial water saturation using magnetic resonance imaging (MRI). They concluded that at low initial water saturation, the presence of a significant waterfront during spontaneous water imbibition indicated that the rate of water transport was less than that of oil. At high initial water saturation, the more uniform saturation change during spontaneous water imbibition indicated that the rate of water transport was greater than that of oil. The pattern of spontaneous imbibition depended on sample wettability, with less effect from frontal movement in less water-wet samples. Pow et al.10 addressed the imbibition of water in fractured gas reservoirs. Field and laboratory information suggested that a large amount of gas was trapped through fast water imbibition through the fractures and premature water breakthrough. The postulation was made that such gas reservoirs would produce this gas if and when the bypassed gas was allowed to flow to the production intervals under capillary-controlled action. The question of whether the rate of imbibition could enhance the production of this trapped gas was raised. Preliminary experiments on full-diameter core pieces showed that the rates of imbibition were extremely slow and that if the different imbibition experiments were performed in full-diameter plugs, the duration of the experiments would be prohibitively long. These experiments formulated the experimental strategy presented in the following sections.