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Auswahl der wissenschaftlichen Literatur zum Thema „Fractured weathered rock“
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Zeitschriftenartikel zum Thema "Fractured weathered rock"
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Colegial-Gutiérrez, Juan Diego, María Camila Forero-Quintero, María Alejandra Fuentes-Rueda und Sully Gomez Isidro. „Characterization of weathering profiles of the crystal rocks of eastern Bucaramanga and definition of hydrogeological properties“. Boletín de Ciencias de la Tierra, Nr. 41 (01.01.2017): 16–30. http://dx.doi.org/10.15446/rbct.n41.59347.
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In the process of improving the knowledge of the hydrogeological potential of weathered zones in crystalline rocks and compounds that can behave as aquifers, this article is performed whose area of study is located east of the metropolitan area of Bucaramanga, Santander Massif consists of two main lithological units; the Neis of Bucaramanga and Santander Group plutonic (diorite, granodiorite-tonalite gray quartz monzonite and monzogranite). These rocks have undergone brittle deformation, physico-chemical weathering mainly influenced by the tropical atmosphere of the area also are jointed and fractured creating conditions that facilitate the flow of water and in turn be optimized weathering processes in the region. He appealed to the identification and location of field weathering profiles made a detailed study of outcrops, presenting a thickness of 90.4 m for the profile of the Gneisic rock weathering and 68.5 m for the profile of granodiorite rock, made up 6 steps weathering of which samples each were taken and carry out macroscopic analysis, petrographic and geochemical using thin films, determining the percentage of porosity, humidity, dry unit weight, X-ray fluorescence, electron microscopy Sweeping and Grading; base characterizing weathering profiles and properties, highlighting the potential hydrogeological found in the Range II: Slightly weathered rock and interval V: Completely weathered rock profile of granodiorite rock and Rock Gneisic profile, the interval III : Moderately weathered rock and the range V: Completely weathered rock, since these stages of weathering, moisture peaks present, regular micro fractures and high porosities.
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Hasan, Muhammad, Yanjun Shang, Weijun Jin und Gulraiz Akhter. „Assessment of Aquifer Vulnerability Using Integrated Geophysical Approach in Weathered Terrains of South China“. Open Geosciences 11, Nr. 1 (31.12.2019): 1129–50. http://dx.doi.org/10.1515/geo-2019-0087.
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Abstract Despite being rich in groundwater resources, assessment of hard-rock aquifers in many areas of Asia is difficult given their strong heterogeneity. However, delineation of such aquifers is essential for estimation of the groundwater reserves. In addition, the vulnerability of hard-rock aquifers is controlled by the weathered/fractured zones because it is the place where most of the groundwater reserves are contained. In this work, an integrated approach of the electrical resistivity tomography (ERT), high precision magnetic, X-ray Diffraction (XRD), physicochemical analysis and pumping test data was performed to investigate the hard-rock aquifers occurring in the weathered terrains. This approach reveals seven fractures/faults (F1 to F7) and four discrete layers such as the topsoil cover, highly weathered, partly weathered and unweathered rock. The groundwater resources are estimated as a function of different parameters i.e., aquifer resistivity (ρo), transverse unit resistance (Tr), hydraulic conductivity (K), transmissivity (T), rock formation factor (F) and rock porosity (Φ). These parameters divide the groundwater resources into four aquifer potential zones with specific ranges of ρo, Tr, K, T, F and Φ i.e., high, medium, poor, and negligible potential aquifers. The results suggest that the high potential aquifer reserves are contained within the weathered/fractured and fault zones. The X-ray diffraction (XRD) technique analyzes quartz as the major mineral (>50%). The physicochemical and geophysical analysis suggests good groundwater quality in the investigated area. The integrated results are highly satisfied with the available borehole information. This integrated geophysical approach for the estimation of groundwater resources is not only applicable in the weathered terrains of South China, but also in many other areas of the weathered/fractured aquifer in Asia and beyond.
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Salami, A. S., und E. M. Babafemi. „Delineation of Near-Surface Structural Features Suitable for Groundwater Accommodation Using 1-D and 2-D Resistivity Methods in Igarra, Akoko-Edo, Southwestern Nigeria“. Journal of Applied Sciences and Environmental Management 24, Nr. 7 (07.08.2020): 1209–15. http://dx.doi.org/10.4314/jasem.v24i7.13.
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Electrical resistivity methods using dipole-dipole and Schlumberger configurations of Vertical Electrical Sounding (VES) were carried out to evaluate the near-surface structural and lithological features suitable for groundwater development in parts of Igarra, Southwestern Nigeria. Two profiles with lengths of greater than 350m were carried out. A total of fifteen sounding locations along the profile lines were occupied. Dipole-dipole data were interpreted using DiprofWin software while interpretation of the VES data followed two stages of qualitative and quantitative data interpretation using Resist software. Dipole-dipole interpretation results indicate the occurrence of local fractures while VES interpretation results reveal the typical basement rock profile ranging from topsoil, lateritic sand, weathered front, fractured to fresh basement. The significant variations in terms of persistence and thicknesses of these basement vertical rock profiles were revealed by the geoelectrical correlation panels, which indicate typical basement inhomogeneities over short distances. The local structural domains, the weathered front (where thick) and the fractured basement are demonstrably potential sources of groundwater, at least for domestic and small scale enterprises in this part of Igarra.
Keywords: 2-D Pseudosection, Dipole-dipole, Fracture Basement, Vertical Electrical Sounding
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Mahi, Shuaibu, Abubakar Yusuf und Garba Lawal. „Geoelectrical Assessment of Groundwater Potential within Zamfara and its Environs, Northwestern Nigeria“. Caliphate Journal of Science and Technology 4, Nr. 1 (10.02.2022): 54–70. http://dx.doi.org/10.4314/cajost.v4i1.8.
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Groundwater potential assessment was carried out within Zamfara environs, Northwestern Nigeria using geoelectrical technique with a view of solving the problem of incessant failure of boreholes in the study area. A total of one hundred and eighty-three (183) vertical electrical soundings (VES) were used to identify potential groundwater bearing zones capable of sustaining economic development of the study area. Two hydrogeological units were investigated (basement rock units and sedimentary rock unit), using Omega resistivity meter Model No. 122, to measure and record the resistance of the subsurface by Schlumberger configuration. The data obtained were interpreted quantitatively and qualitatively using the partial curve matching and computer iteration techniques to generate the first order geoelectric parameters. Generally, the VES result from the basement rock units revealed, four geoelectric layers which correspond to lateritic top soil, weathered basement (clay), partially fractured layer/fractured layer and fresh basement. The weathered/fractured layer was identified as the water bearing layer, within the basement rock units of the study area. From geospatial analysis of both weathered thickness/fracture thickness layers, South and Northeastern part tends to be the most prospective area with the best hydrogeologic conditions for borehole siting within the basement rock units. Consequently, three geo-electric layers were delineated from VES result obtained from Gundumi formation, which correspond to sandy clayey top/gravelly sandy top soil, second layer are mostly silty-clay/compacted sandstone/sandy gravel layers, the third layer were majorly saturated sandstone in some instances silty clay. However, the aquiferous layer is saturated sandstone/sandy gravel layer. The Dar Zarrouk result revealed excellent groundwater potential within the Gundumi formation. The values of coefficient anisotropy obtained from Gundumi rock units range from 0.44 to 3.79, which implies moderate saturation of groundwater. This is an indication that the aquifers of the Gundumi formation is more promising and it can be tap for both domestic and agricultural uses.
Keywords: Vertical electrical sounding; Fractured layer; Saturated Sandstone; Basement rock units; Gundumi formation
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Briški, Maja, Andrej Stroj, Ivan Kosović und Staša Borović. „Characterization of Aquifers in Metamorphic Rocks by Combined Use of Electrical Resistivity Tomography and Monitoring of Spring Hydrodynamics“. Geosciences 10, Nr. 4 (10.04.2020): 137. http://dx.doi.org/10.3390/geosciences10040137.
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Crystalline rocks are generally characterized by negligible porosity and permeability in terms of groundwater exploitability. However, alteration processes can greatly increase their fracture permeability and induce formation of modest, but locally important aquifers. Therefore, subsurface characteristics of alteration zones are of major importance for hydrogeological evaluation of crystalline terrains. Alteration processes greatly affect rock total porosity and water content, causing contrasting electrical resistivity of rocks affected by varying degrees of weathering. This makes electrical resistivity tomography (ERT) a preferable geophysical method for the exploration of alteration zones in crystalline rocks. In our research, we used an integrated approach, combining the ERT method with monitoring of spring discharge and hydrochemistry to characterize metamorphic aquifers on slopes of the Medvednica Mountain (Croatia). Significant fracture flow aquifers are found to be formed in intensely fractured but not highly weathered rock masses (medium to high resistivity values), while highly weathered masses (low resistivity values) form local barriers for fracture flows. Subsurface structure of the alteration zone proved to be highly irregular, with sharp contacts between more and less weathered rocks. Decrease of permeability below the alteration zone keeps the water level near the surface and enables spring occurrence on the mountain slopes. Studied aquifers have relatively limited extent, resulting in typical capacity of major springs of a few l/s. More frequent but less productive springs are attributed to the draining of the shallow part of the alteration zone (mostly saprolite). Combination of the ERT method with spring monitoring proved to be very effective as a first and relatively inexpensive methodology for hydrogeological characterization of crystalline terrains, both in local and catchment scales.
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Thi Luan, Bui, und Lieu Kim Phuong. „Petrographic characterization and petroleum potential of Mesozoic carbonate rock in Block 106, Northern Red river basin“. Science and Technology Development Journal - Natural Sciences 2, Nr. 6 (26.01.2020): 146–64. http://dx.doi.org/10.32508/stdjns.v2i6.876.
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Petroleum exploration and exploitation in Red River basin has been carried since the early 1960s of the 20th century, however until now its effectiveness has been still limited. Recently, the oil price is constantly changing so the efficiency of petroleum exploration and exploitation is particularly considered. Therefore, the assessment of petroleum potential and the direction of exploration are not only scientific research but also economic problem for developing countries in which there is Vietnam. The article considers that characteristic of carbonate petrography is along with intergration of interpreted seismic –stratigraphy and well logs, geochemistry analytic results of source rocks and related literatures as well. The purpose is to predict the petroleum potential of carbonate rock in block 106 and serve effectively in Petroleum exploration and exploitation in Red River basin Based on the analytic results, carbonate rock in the study area was impacted by tectonic activities such as mechanic compaction; dissolution forming fractures, stylolites; and post-depositional processes as recrystallization of minerals, creating vuggy, mouldic and intraparticle pores and dolomitization as well. Carbonate rock contains fossils as foraminifera, coral, algae, echinoderm with subordinate brachiopod, bryozoa. Most of them are mudstone, wackestone with mud-supported and packstone is made up of abundant fossils. Locally, carbonate rock was fractured and filled up by calcite and silic. Oil and gas traces have been discovered in Mesozoic carbonate rock, block 106, northern Red River basin. Fractured carbonate rock and weathered carbonate rock in the structures as A, C and E are oil fields. Oil migrates into traps that were early formed in fractured carbonate basement rock masses that were buried in pre-Kainozoi.
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Chang, Seeun, Wooyong Um, Won-Seok Kim und HyunJu Kim. „Effect of seawater intrusion on radioactive strontium (90Sr) sorption and transport at nuclear power plants“. Radiochimica Acta 106, Nr. 2 (26.01.2018): 147–60. http://dx.doi.org/10.1515/ract-2016-2724.
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Abstract Batch sorption and column experiments were conducted to investigate and compare sorption and transport behavior of 90Sr on the assumption of seawater intrusion at nuclear power plants. Batch sorption experiments were carried out on fractured rocks and bedrocks using synthetic groundwater and seawater both spiked with 90Sr. In general, higher 90Sr sorption occurred on fractured rock samples than on bedrocks, because of the presence of weathered secondary minerals (iron oxide and clay) on fractured rock surfaces. However, one particular bedrock sample (WSP-B) which has higher porosity and carbon amount than fractured rock samples also showed the higher 90Sr sorption than its comparable fractured rocks. For all batch sorption studies, 90Sr sorption distribution coefficient, Kd decreased from groundwater to seawater environment due to the higher ionic strength of seawater (6.4×10−1–7.7×10−1 M) compared to groundwater (4.0×10−3–6.0×10−3 M). The three different ionic strength solutions were used in column experiments, and the results showed that transport behavior of Sr through a fractured rock had similar sorption trend to batch sorption results. The highest mobility (or least retardation) for Sr was found for 100% seawater solution compared to the highest retardation (or least mobility) for 100% groundwater solution. These sorption and transport data of Sr on solid materials contacted with various ionic strength solutions corroborate empirically defensible information for assessment of radioactive contamination in groundwater below the NPP sites located nearby shores. In addition, the experimental data will be incorporated to improve transport models of 90Sr in the subsurface environment for severe nuclear accidents.
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Zhang, Qian, Shu Cai Li, Li Ping Li und Qian Qing Zhang. „Experimental Study on Creep of Highly-Weathered Breccia“. Applied Mechanics and Materials 477-478 (Dezember 2013): 588–91. http://dx.doi.org/10.4028/www.scientific.net/amm.477-478.588.
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Mechanical property of rock is the main research object of rock mechanics. In order to further learn the rheological characteristics of soft fractured rock mass, the creep test of highly-weathered breccia with different water content of 0.65%, 1.88%, 4.03% using low-intensity uniaxial creepmeter developed by Shandong University is processed, and the strain-time curves under different water conditions and the corresponding variation of creep curves with different stress levels and moisture states are obtained. The experimental results show that the higher water content is, the larger creep deformation is and the longer time of creep deformation reaching stable is, in other words, the influence of water content on the rheological characteristics of rock mass is also significant. Finally, the conclusion that softening critical load (long-term strength) and softening critical depth of soft rock are greatly reduced due to the effect of water on rock structure and mechanical parameters is obtained to provide the fundamental reference for the follow-up tests and similar engineering.
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Vafidis, A., A. Andronikidis, H. Hamdan, G. Kritikakis, N. Economou, G. Panagopoulos, S. Zanettidis et al. „Rock characterization for the foundation of two water reservoirs using geophysical and borehole data“. Bulletin of the Geological Society of Greece 47, Nr. 3 (21.12.2016): 1345. http://dx.doi.org/10.12681/bgsg.10919.
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In this work, we present the results of a geophysical survey at Malia, Crete, Greece. This survey combines VES, electrical tomography and seismic refraction at two sites where equal number of water reservoirs is planned to be constructed for the needs of a hybrid power station using wind-hydro pumping renewable energy. The geophysical sections are interpreted using geological and borehole data. This survey determines the thickness of the overburden, defines the quality of the carbonate bedrock, detects faults and weathered zones in carbonates. One major very low resistivity anomaly was detected at the northern investigated area, which corresponds to completely fractured or weathered limestone, while a 25m deep fracture zone, was detected at the southern investigated area.
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OLICHWER, Tomasz. „HYDROGEOLOGICAL CHARACTERIZATION OF LOCAL GROUNDWATER RESERVOIRS IN THE KŁODZKO LAND (SUDETES - SW POLAND) BASED ON AN ANALYSIS OF THE DISCHARGES OF SPRINGS“. Carpathian Journal of Earth and Environmental Sciences 18, Nr. 1 (07.02.2023): 171–82. http://dx.doi.org/10.26471/cjees/2023/018/249.
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The hydrogeological characteristics of the two types of local groundwater reservoirs found in the Kłodzko Land (Sudetes) have been made based on the analysis of the discharge of springs in Szczytna and Różanka. In the first of these spring discharge points, water flows out of Upper Cretaceous sandstones and mudstones. The other spring is associated with fractured and weathered mica schists and gneisses. The Różanka spring characterized by greater discharge variability than the fissured porous outflow in Szczytna. The latter one, due to the slower rate of water filtration in the rock medium, belongs to stable springs in terms of discharge. The local groundwater reservoir located in sedimentary rocks characterized by a much higher value of the groundwater volume stored (264,000 m3) than the reservoir consisting of weathered and fractured crystalline rocks (1,918 m3). In the case of the reservoir draining by Szczytna spring, the rate of groundwater exchange in the active zones is about 66 weeks. A distinctly shorter time (12 weeks) is necessary to exchange water in the fractured crystalline bedrock. The hydraulic conductivity for the aquifers in Szczytna and Różanka, calculated based on the recession coefficient, differ substantially from each other. They are 4.64 and 24.9 m/d, respectively.
Dissertationen zum Thema "Fractured weathered rock"
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Rusagara, Radegonde. „Développement d'un modèle conceptuel de recharge des aquifères de socle cristallin dans la zone sahélienne du Burkina Faso en Afrique de l'Ouest“. Electronic Thesis or Diss., Sorbonne université, 2022. http://www.theses.fr/2022SORUS319.
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Les données de la recharge des aquifères de socle au Sahel en Afrique de l'Ouest sont limitées en raison d'une connaissance insuffisante sur les mécanismes de recharge. Cette étude a été initiée dans le bassin versant à la rivière éphémère de Tougou (37 km2) pour améliorer la compréhension des mécanismes de recharge d'un aquifère de socle dans la zone sahélienne du Burkina Faso. Elle est basée sur des investigations menées de 2016 à 2020 sur un transect piézométrique et des puits de grand diamètre, respectivement perpendiculaires et longitudinaux à la rivière. L'analyse du profil de tomographie de résistivités électriques et des logs des forages, des tests de perméabilité, le traçage à la conductivité électrique et à la température des eaux souterraines, le suivi piézométrique et des hauteurs d'eau dans la rivière ainsi que des mesures pluviométriques ont été entrepris. Les résultats ont montré un aquifère de la saprolite latéralement continu (10-22 m d'épaisseur) surmonté par des sols résiduels sous la rivière et de la latérite discontinue sur les rives. Sous la rivière, la saprolite se trouve au-dessus de l'aquifère localisé dans les schistes légèrement altérés avec une drainance verticale ascendant ou descendant indépendamment des saisons. La saprolite est alimentée par la recharge concentrée au niveau de la rivière et par la recharge diffuse provenant des précipitations sur les rives, selon les informations fournies par les variations des niveaux piézométriques, le traçage des eaux souterraines et la corrélation croisée entre les niveaux piézométriques et les deux sources potentielles de recharge (la pluie et la rivière). Les valeurs de conductivité hydraulique du sol et la présence des argiles dans le profil d'altération indiquent une restriction l'infiltration de la matrice du sol. Ceci qui suggère l'occurrence de la recharge diffuse et concentrée à travers les voies de recharge préférentielles. Pour la période 2018-2020, la méthode de fluctuation des niveaux piézométriques fournit des estimations de recharge de 14-51 mm/an sur la rive gauche, 10-36 mm/an sur la rive droite et 148-194 mm/an dans le lit de la rivièreGroundwater recharge rate for weathered rock aquifers in the Sahel of West Africa are sparse due to insufficient knowledge of the recharge pathways. This study was initiated in the Tougou ephemeral river catchment (37 km2) to improve understanding of recharge pathways to a weathered rock aquifer in the dryland of Burkina Faso. It is based on field investigations conducted in 2016–2020 on a piezometric transect and large-diameter wells, perpendicular and longitudinal to the river, respectively. Geophysical measurements, lithologs analysis, permeability tests, measurements of groundwater electrical conductivity and temperature, groundwater and river level monitoring, and rainfall measurements were undertaken. The results showed a laterally continuous saprolite aquifer (10–22 m thick) overlain by residual soils beneath the river and discontinuous laterite on the banks. Below the river, the saprolite overlays the weathered schist aquifer with an upward or downward hydraulic gradient regardless of the seasons. The saprolite is replenished by focused recharge from the river and diffuse recharge from the rainfall on the banks, according to information from the groundwater hydrographs, groundwater tracing results, and cross-correlation between the groundwater levels and the two potential recharge sources (rainfall and river water). The values of soil hydraulic conductivity and the presence of the clay in the soil profile indicate restriction of diffuse and focused recharge through soil matrix infiltration, suggesting there are preferential recharge pathways. For the 2018–2020 period, the water table fluctuation method provides recharge estimates of 14-51 mm/year on the left bank, 10-36 mm/year on the right bank and 148-194 mm/year in the riverbed
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Nicolas, Madeleine. „Impact de l’hétérogénéité sur la recharge naturelle et artificielle des aquifères cristallins altérés et fracturés : application aux sites de Maheshwaram et Choutuppal (Inde du Sud)“. Thesis, Rennes 1, 2019. http://www.theses.fr/2019REN1B016/document.
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Les facteurs qui régissent l'intensité et la répartition de la recharge naturelle et artificielle dans les aquifères cristallins altérés et fracturés sont mal connus. Ce sont cependant les caractéristiques déterminantes de ce type de roche—ces roches sont très hétérogènes—qui rendent difficile l’estimation des flux dans ces milieux ainsi que des propriétés hydrauliques qui les contrôlent. La première partie de ce manuscrit fournit un état des connaissances sur la recharge des eaux souterraines et ses méthodes d’estimation, permettant de comprendre les défis scientifiques et sociétaux abordés dans cette thèse. La deuxième partie présente les travaux numériques et expérimentaux menés pour approfondir notre compréhension de la dynamique des flux d’eaux souterraines dans ces milieux hétérogènes à plusieurs échelles. Le premier axe de recherche porte sur les processus de recharge naturelle à l’échelle du bassin versant. La recharge diffuse a été modélisée avec un modèle physique simple d’infiltration et comparée à des estimations préalables de recharge totale. Nos résultats illustrent la forte dépendance de la recharge aux précipitations et à l’irrigation, et l’importance de la recharge focalisée. Les facteurs responsables de la distribution spatiale de la recharge sont aussi étudiés. Le deuxième axe est basé sur le suivi de la mise en eau d’un bassin de recharge artificielle dans un site hautement monitoré et bien équipé. Ces observations ont été interprétées avec des modèles analytiques et numériques. Ces modèles ont mis en évidence l’existence de flux préférentiels horizontaux, mais aussi d’une compartimentation latérale qui entrave la propagation des intrants de rechargeThe factors governing the intensity and distribution of natural and artificial recharge in weathered and fractured crystalline aquifers are poorly understood. However, it is the defining characteristics of this type of rock—these rocks are very heterogeneous—that make the estimation of fluxes and the hydraulic properties controlling them difficult. The first of its two parts provides the theoretical framework on groundwater recharge processes and its estimation methods for comprehending the scientific and societal challenges discussed in this thesis. The second part presents the numerical and experimental work carried out to deepen our understanding of the dynamics of groundwater flows in these heterogeneous underground environments at several scales. The first line of research focuses on natural recharge processes at the watershed scale. Diffuse recharge was modeled with a simple physical infiltration model and compared to previous estimates of total recharge. Our results highlight the strong dependence of recharge on rainfall and irrigation, and the importance of focused recharge. The factors responsible for the spatial distribution of recharge are also studied. The second axis is based on the monitoring of the filling of an artificial recharge basin at a highly monitored and well-equipped site. These observations were interpreted with analytical and numerical models to improve our knowledge of flow dynamics in fractured crystalline rocks at the medium scale. These models illustrated the existence of preferential horizontal flows, but also of a lateral compartmentalization that hinders the propagation of recharge inputs
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Jeanpert, Julie. „Structure et fonctionnement hydrogéologiques des massifs de péridotites de Nouvelle-Calédonie“. Thesis, La Réunion, 2017. http://www.theses.fr/2017LARE0047/document.
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Le fonctionnement et la structure hydrogéologiques des aquifères de socle des granites et des gneiss sont aujourd'hui relativement bien compris. En revanche, dans cet ensemble, les aquifères dans les péridotites sont très peu étudiés et mal compris. Dans ce contexte, les massifs obductés de Nouvelle-Calédonie présentent un laboratoire naturel exceptionnel pour améliorer la connaissance de cet hydrosystème original en contexte tropical. Ainsi l'objectif du présent travail de thèse est d'approfondir la connaissance de la structure et du fonctionnement hydrogéologiques de ces massifs. L'analyse porte d’abord sur le manteau d'altération constitué de la cuirasse, des latérites, des saprolites grossières et du saprock. Plus de 60 essais hydrauliques sont menés sur les massifs de péridotites et les résultats sont compilés aux données existantes. La conductivité hydraulique moyenne des latérites est évaluée à 1.10-7 m/s et celle des saprolites grossières et du saprock à 8.10-7 m/s. L'hétérogénéité de cet horizon altéré est marquée par une gamme de variation de la conductivité hydraulique sur six ordres de grandeur et l'analyse piézométrique met en évidence des connexions hydrauliques avec le substratum fracturé profond. Le substratum est ensuite considéré. L'étude de la fracturation est réalisée à partir de mesures structurales sur affleurement et de la description de près de 1000 m de carottes de forages. L'analyse de la fracturation met en évidence l'importance du réseau serpentineux par sa densité d’une part, et par son lien avec l'altération supergène d'autre part. De plus, il est vérifié que la conductivité hydraulique du substratum diminue avec la profondeur. Cette variation est liée à la diminution de la densité de fractures altérées. Ainsi, à l'issue de ces analyses, la structure des massifs de péridotites est définie. Un réseau primaire de fractures d’espacement décimétrique lié au réseau serpentineux préstructure les péridotites. Sur ce réseau se surimpose un réseau de fractures dont l'espacement est décamétrique et caractérisé par une altération supergène. Les fractures altérées présentent localement de fortes conductivités hydrauliques, de l'ordre de 10-5 m/s. En profondeur l'espacement des fractures est hectométrique et les fractures sont majoritairement fermées, scellées par les minéraux néoformés ou par l'effet de la pression lithostatique. Les réseaux de fractures déca et hectométriques, visibles également sur l'effet d’échelle de la conductivité hydraulique, sont majoritairement verticaux, développés par instabilité de dissolution lors des processus d’altération. Cependant, des structures à faible pendage existent également et permettent la percolation du réseau. Enfin, à partir de ces nouveaux résultats et de l’intégration de l'ensemble des données acquises sur les différents massifs, un modèle de structure et de fonctionnement hydrogéologiques est proposé à l'échelle du massif. Ce modèle comprend l'horizon des latérites qui constitue un aquitard homogène sous lequel se développe l'aquifère dont l'épaisseur est de l'ordre de cinquante mètres. Le substratum est discrétisé en trois couches dont la conductivité hydraulique décroît de 2.10-7 à 2.10-8 m/s entre 50 m et 250 m environ sous le mur de l'aquifère. Les modèles numériques construits permettent de valider le modèle conceptuel unitaire et montrent que l'état de saturation des massifs est contraint par leur géomorphologie. Au terme de ce travail, plusieurs aspects doivent encore être approfondis. Le rôle hydrogéologique de la cuirasse doit être précisé et considéré dans le modèle hydrogéologique. Enfin, compte tenu du développement possible de structures très perméables, voire pseudo-karstiques, la connaissance de la distribution des structures drainantes doit être améliorée. Les résultats appliqués de ce travail de recherche sont exposés dans un rapport final et un guide méthodologique livrés dans le cadre du projet CNRT « HYPERK »Water resources of hard-rock (gneisses or granites) aquifers have significantly been studied in the past two decades. The hydrogeological behavior and structure of these aquifers are thus relatively well understood. On the other hand, aquifers in mantle-type basements, such as peridotites, are poorly studied and understood, mainly because they are not common and of limited extent. In this context, New Caledonia is a great laboratory offering unique opportunity to improve the knowledge of these original types of hydrosystems in tropical climate. Thus, the objective of this thesis is to improve the knowledge of these aquifer systems within weathered peridotites. Firstly, the study focuses on the characterization of the weathered layers of the peridotites composed of, from top to bottom, iron oxides/ferricrete, laterite, coarse saprolite and saprock (ie. top of the bedrock, with up to 20 % of weathered material). More than 60 hydraulic tests are performed and results were compiled with existing data. Mean hydraulic conductivity (K) of laterites is estimated around 1.10-7 m/s while mean value in coarse saprolites and saprock is around 8.10-7 m/s. Heterogeneity of this altered layer is high; K varies between six orders of magnitude and hydraulic head data analysis reveals a hydraulic connection with the deep fractured bedrock. Secondly, the fresh rock part of peridotites is studied. Fracture network analysis is derived from outcrop structural measurements and from the description of about 1000 m of cumulated borehole cores. This work highlights the importance of serpentine network, because of its high density and its critical impact on weathering. Moreover, the observations reveal that hydraulic conductivity decreases with depth within the substratum, due to the vertical decrease of weathered fractures density. These new results allow defining a structural framework of the massifs. It is characterized by a primary decimetrical fracture network closely related to the serpentine network. This network is overprinted by a secondary weathering network which reveals decametric spacing (ca. 30 m) and in places K values of 10-5 m/s. At depth, spacing is hectometrical and fractures are sealed by lithostatic pressure and/or subsequent mineral precipitations. These deca- and hectometric fracture networks, which are also visible on the scale effect of hydraulic conductivity, are primarily vertical and are the result of dissolution instabilities occurring during weathering processes. However, low- angle fractures do occur and allow the percolation of the network. Finally, on the basis of these new results and the integration of all existing data from different massifs a new hydrogeological conceptual model is proposed at the scale of a massif. The model includes a homogeneous lateritic aquitard and a coarse saprolite and saprock aquifer which is about 50 m thick. The bedrock is subdivided into three layers whose hydraulic conductivity decreases from 2.10-7 m/s to 2.10-8 m/s, respectively 50 and 250 m below the aquifer base. Numerical modelling validates this unitary conceptual model and reveals that the saturation of the massifs depends on their morphology. At last, several aspects require further research. The role of the ferricrete layer must be specified and considered in the hydrological model. Moreover, distribution of the fracture network remains to be fully addressed and should be studied with care given the potential development of highly permeable structures that could conform to pseudo-karstic drains. The applied results of this work are available in a “Technical guide” and a “Technical report” of the “HYPERK” CNRT Project
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Jaunat, Jessy. „Caractérisation des écoulements souterrains en milieu fissuré par approche couplée hydrologie-géochimie-hydrodynamisme : application au massif de l'Ursuya (Pays Basque, France)“. Phd thesis, Université Michel de Montaigne - Bordeaux III, 2012. http://tel.archives-ouvertes.fr/tel-00778427.
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Les aquifères fracturés sont un enjeu majeur de l'hydrogéologie actuelle. Ils constituent une ressource essentielle pour de nombreuses populations. Le massif de l'Ursuya (France, 64), en est une illustration. Constitué de formations métamorphiques fracturées, il est intensément exploité pour l'alimentation en eau potable. Une approche multidisciplinaire a permis la compréhension du fonctionnement de ce système. Les résultats obtenus constituent une avancée dans la connaissance des aquifères discontinus et offrent des pistes pour une gestion raisonnée de cette ressource.Le signal d'entrée est caractérisé dans sa composante quantitative et qualitative. Le suivi des paramètres climatiques permet d'estimer la lame d'eau participant à la recharge de l'aquifère. La caractérisation isotopique de l'eau précipitée met ensuite en évidence une origine majoritairement atlantique des masses d'air, responsables des précipitations sur le nord-ouest du Pays Basque. Des circulations atmosphériques sur la péninsule Ibérique, l'Europe du Nord et la région méditerranéenne sont cependant responsables de certains événements pluvieux. La composition chimique de l'eau de pluie, résultant de ces origines, est caractérisée par une faible acidité et par des concentrations en éléments anthropiques parfois élevées.L'hydrochimie des eaux souterraines est étudiée conjointement avec des données de temps de séjour acquises par l'interprétation des concentrations en 3H, CFC et SF6. Les caractéristiques physico-chimiques, les temps de séjours mesurés (moins de 10 ans à plus de 50 ans) et les phénomènes de mélanges associés permettent de proposer un modèle conceptuel des écoulements souterrains. Celui-ci met en exergue le rôle prépondérant du profil d'altération développé dans les milieux cristallins (de la surface vers la profondeur : altérites, roche fissurée et roche saine), du point de vue de la minéralisation de l'eau comme de celui des modalités d'écoulement.Une approche quantitative est finalement proposée. Du point de vue hydrodynamique, l'hétérogénéité spatiale est importante (10-4 m s-1 < K < 10-8 m s-1). Les altérites offrent une capacité de stockage et de régulation de la recharge. Un modèle numérique synthétise et valide ces résultats. Les simulations montrent de fortes interactions entre les réseaux d'écoulements superficiel et souterrain et de faibles impacts de l'exploitation actuelle sur les flux d'eau souterraine. Les évolutions climatiques ne modifieront pas significativement les écoulements durant les prochaines décennies. Une diminution des débits des sources et des cours d'eau est toutefois probable. Ce modèle numérique et l'ensemble des résultats obtenus serviront de base pour une gestion raisonnée de la ressource en eau de l'aquifère de l'Ursuya.
Bücher zum Thema "Fractured weathered rock"
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Pilchak, Angela M. Contemporary Musicians. Thomson Gale, 2004.
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Pilchak, Angela M. Contemporary Musicians: Profiles of the People in Music (Contemporary Musicians). Thomson Gale, 2005.
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Pilchak, Angela M. Contemporary Musicians: Profiles of the People in Music (Contemporary Musicians). Thomson Gale, 2005.
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Contemporary Musicians: Profiles of the People in Music (Contemporary Musicians). Thomson Gale, 2004.
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Pilchak, Angela M. Contemporary Musicians: Profiles Of The People In Music (Contemporary Musicians). Thomson Gale, 2005.
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Pilchak, Angela M. Contemporary Musicians. Thomson Gale, 2007.
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Pilchak, Angela M. Contemporary Musicians: Profiles of the People in Music (Contemporary Musicians). Thomson Gale, 2004.
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Pilchak, Angela M. Contemporary Musicians: Profiles of the People in Music (Contemporary Musicians). Thomson Gale, 2005.
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Contemporary Musicians: Profiles Of The People In Music (Contemporary Musicians). Thomson Gale, 2005.
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Pilchak, Angela M. Contemporary Musicians: Profiles Of The People In Music (Contemporary Musicians). Thomson Gale, 2005.
Den vollen Inhalt der Quelle findenBuchteile zum Thema "Fractured weathered rock"
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Noland, Scott, und Edward Winner. „Activated Carbon Injection for In-Situ Remediation of Petroleum Hydrocarbons“. In Advances in the Characterisation and Remediation of Sites Contaminated with Petroleum Hydrocarbons, 549–89. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-34447-3_16.
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AbstractIn-situ remediation of petroleum hydrocarbons (PHCs) using activated carbon (AC) is an emerging technology intended to enhance sorption and biodegradation mechanisms in soil and groundwater systems. The combination of pore types, source material, activation process, and grind of a particular AC influences its efficacy in subsurface remediation. When high-energy injection techniques are employed, installation of carbon-based injectate (CBI) slurries can be conducted in practically any geological setting, from sandy aquifers to low-permeability zones and weathered or fractured rock. Following an adequate CBI installation throughout the target treatment zone or as a permeable reactive barrier, dissolved PHC concentrations are typically observed to rapidly decrease. After a new equilibrium is formed, PHC concentrations typically decrease over time due to the biodegradation. PHC biodegradation, in association with the CBIs, is indicated by the presence of appropriate microbial communities found to grow on AC and is supported by multiple lines of evidence. Further research is encouraged to optimize the biodegradation and regeneration processes of CBI products for in-situ remediation of PHCs.
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„The conceptual model of weathered hard rock aquifers and its practical applications“. In Fractured Rock Hydrogeology, 35–68. CRC Press, 2014. http://dx.doi.org/10.1201/b17016-7.
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„Similarities in groundwater occurrence in weathered and fractured crystalline basement aquifers in the Channel Islands and in Zimbabwe“. In Fractured Rock Hydrogeology, 69–82. CRC Press, 2014. http://dx.doi.org/10.1201/b17016-8.
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R, Abinaya, Antony Ravindran A, Moorthy G.M, Muthusamy S, Vinoth Kingston J und Antony Alosanai Promilton A. „ASSESSMENT OF GROUNDWATER CHARACTERISTIC STUDIES USING THE MAGNETO TELLURIC METHOD IN KALUGUMALAI, TAMIL NADU, INDIA“. In Futuristic Trends in Physical Sciences Volume 2 Book 14, 62–69. Iterative International Publishers, Selfypage Developers Pvt Ltd, 2023. http://dx.doi.org/10.58532/v2bs14p1ch7.
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The aim of the study is to present the principles and procedures of the magneto telluric approach. The resistivity characteristics of the rocks in Tamil Nadu's Thoothukudi district's Kalugumalai hamlet were the basis for the aquifer investigation. The research region has granitic hard rock, worn gneiss, and black soil. The magneto telluric method will employ resistivity variations to assess the connection of permeable rock and groundwater in land and underground discharges. The natural electromagnetic field strength is determined by the rock structure of the underground earth and its resistivity variations. In order to increase spacing transmission and get more information, two copper electrodes are used for the M and N electrodes. For hydrogeological objectives, the approach has given information on the rocks and structural relationships up to a depth of 300 m. The study demonstrates that fractured and weathered zones in the region have a major role in controlling groundwater occurrence. At the saprock zone, it is very likely that you may run into groundwater. Between the overburden and the bedrock are fractured and weathered zones. The MT approach is efficient for investigating groundwater in a geological setting
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Adelana, S. „Water pollution by nitrate in a weathered/fractured basement rock aquifer“. In Research Basins and Hydrological Planning, 93–98. Taylor & Francis, 2004. http://dx.doi.org/10.1201/9781439833858.ch12.
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Jain, Prabhat, Abhay Soni und Rahul Shende. „Management of Hard Rock Basaltic Aquifer through Aquifer Mapping: A Case Study of Nashik District, Maharashtra, India“. In Environmental Sciences. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.111644.
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In the Maharashtra State of India, Deccan Trap basaltic lava flows are spread over around 82% of the area and form the most prominent aquifer in the entire state. Nasik district occurring in the northern part of Maharashtra also known as Khandesh represents a typical area of Deccan Trap basalt. The storage and transmission capabilities of the basaltic lava flow aquifer are very limited due to the inherent absence of primary pore spaces. These basaltic rocks act as aquifers only when they are weathered, jointed or fractured, thus giving rise to secondary porosity and permeability. Due to wide variations in secondary openings, the potential areas for groundwater are generally localized. In this way, Deccan Trap basalt possesses a unique challenge to aquifer mapping, both spatially and vertically due to its hydrogeological heterogeneity. In the current study, this challenge of aquifer mapping and management in basalt was tackled through a multidisciplinary, multipronged approach involving data integration of various thematic layers viz., geomorphology, soil, drainage, land use-land cover, hydrometeorology, and geophysical techniques etc., as indirect tools and combining it with direct tools such as drilling, well inventory, water level monitoring, groundwater quality checks, and aquifer pumping tests for obtaining reliable results. By following the above methodology, the 3-D aquifer geometry, lithological sections, fence diagrams, aquifer characteristics, yield potentials, and aquifer-wise resources were deciphered. The results showed that the area has two aquifer systems comprising of Aquifer-I, that is. shallow aquifer, which is generally tapped by the dug wells of 8 to 32 m depth with water levels of 1.2 to 15 meters below ground level (m bgl) and yield varies from 10 to 100 m3/day. Whereas, the Aquifer-II, that is, deeper aquifer is being tapped by bore wells with a depth ranging from 30 to 200 m bgl and a water level from 8 to 55 m bgl. However, their pumping sustainability was limited to 0.5 to 3 hours due to low storage potential resulting in overexploitation. The given aquifer maps indicate that major parts of the area have limited yield (Aquifer-I: between the depth of 10 m - 15 m bgl and Aquifer-II: between the depth of 80 m −140 m bgl). In hard rock areas, especially basaltic aquifers due to their low storage potential, groundwater development is always a challenging task unless it is combined with the management of the resources. Considering the issues plaguing the area, the aquifer management plan encompassing supply and demand-side interventions, and groundwater development has been devised. It is concluded that 139.30 MCM of groundwater resources can be augmented by artificial recharge under supply-side interventions. Whereas the groundwater demand for irrigation can also be reduced by 272 MCM by adopting drip irrigation in 117 sq. km. of sugarcane and 790 sq. km. of onion cultivated areas under the demand-side interventions. The implementation of these measures will minimize the stress on groundwater by bringing down the stage of groundwater development from 88–55% (safe category) in six water-stressed blocks/taluka, whereas the overall stage of groundwater development will be reduced from 58.45% to 40.70%. Thus, the adoption of both supply-side and demand-side interventions interlinked with water budgeting through community participation will provide long-term solutions to combat the overexploitation, water level decline, low storage potential, recurring droughts and other issues of the area and also help in improving socioeconomic conditions of the area.
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Power, T., B. J. Smith und W. B. Whalley. „Fracture Patterns and Grain Release in Physically Weathered Granitic Rocks“. In Soil Micro-Morphology: A Basic and Applied Science, Proceedings of the VIIIth International Working Meeting of Soil Micromorphology, 545–50. Elsevier, 1990. http://dx.doi.org/10.1016/s0166-2481(08)70371-4.
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Cor, Thomas, Véronique Merrien-Soukatchoff, Damien Rangeard, Céline Rescourio und Jérôme Simon. „Comparisons of different modelling of an excavation realized in fractured and weathered rocks“. In Numerical Methods in Geotechnical Engineering, 851–56. CRC Press, 2014. http://dx.doi.org/10.1201/b17017-152.
Der volle Inhalt der QuelleKonferenzberichte zum Thema "Fractured weathered rock"
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González, J. A. Mézquita, und J. Comte. „Sensitivity and Uncertainty of Petrophysical Models to Predict Storage Properties in Weathered/Fractured Hard-Rock Aquifers“. In 25th European Meeting of Environmental and Engineering Geophysics. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.201902380.
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Kumar, Rajeev Ranjan, Sanjoy Kumar Mukherjee, S. K. Biswal, Rajasekar V, Surej Kumar Subbiah, Joseph Zacharia, Rahul Talreja, Atanu Bandyopadhyay und Manish Singh. „Field Scale Geo-Mechanical Analysis To Identify Fracture Sweet Spots Within Deccan Trap, Western Onshore, India“. In Offshore Technology Conference. OTC, 2021. http://dx.doi.org/10.4043/31206-ms.
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Abstract Hydrocarbon exploration continues to venture into new avenues. This paper elaborates the 3D geomechanical study carried out to identify sweet spots in Deccan Trap Basalts in depth ranging from 500m-1100m in Cambay basin field of India. The main challenge is wide variation in the rock mechanical properties and stress profiles along various azimuths resulting from different tectonic incidents over the geological ages. Several drilling complications and held ups during electro logging in highly deviated wells are also reported. The normal fault tectonic framework has the imprint of two sets of faults viz., NNW-SSE and ENE-WSW. Deccan Trap acts as reservoirs due to the presence of connected open fracture network and to assess the potential reserves a comprehensive 3D Critically stressed fracture analysis has been performed using 3D numerical simulation-based rock properties, in-situ stress and seismic data. Open hole geophysical logs like sonic dipole and borehole images have been used to estimate rock mechanical properties and stress profiles in 18 key wells. Available core data of Basalt in the area have been used for dynamic to static rock properties estimation along with available published literature data. Critically stressed fracture analysis using 1D MEM outputs and dips dataset has been performed at well scale to history match production logging and testing results of 23 wells located in different fault blocks. 3D stress model has been built using plasticity model while taking into account faults and fracture sets. Utilizing 3D Geomechanical properties and Discrete fracture network model, critically stressed fracture sets have been identified across the field with slip tolerance and effective drawdown pressures. The study suggests that structurally high locations are good producers if seals are present above Trap. Sub-horizontal fractures have a higher closing tendency with decline in pressure in layers with SHmax>SHmin>Sv inside stiff Trap layer. There is variation of slip tolerance in the range of 0.2-1.4 in fracture sets which indicates slip tendency to be varying both vertically and laterally. Faults with ENE-WSW strike seem to be fluid migratory conduits and their intersection with NNW-SSE discontinuities are the areas where fracture sets have a higher slip tendency. Most of the producing layers are within 25m-55m of Trap with water being encountered at deeper depth intervals. These are mostly weathered fractured layers within the trap. The stress map suggests rotation of the maximum horizontal stress azimuth from NW to E which also affects fracture intensity in the field. Few fracture sets have tendency to be slip prone even with depletion up to 300psi-800psi while others will require stimulation or acid clean up job. Eight exploration wells drilled based on the study have shown good flow rate on initial well testing in the area providing validation to the study.
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Kumar, Rajeev Ranjan, Joseph Zacharia, Surej Kumar Subbiah, Rajasekar V, Sanjoy Kumar Mukherjee, Sanjay Lalchand Bagde, P. C. Chaturvedi, K. Vasudevan und B. S. Haldia. „Geomechanics Aided Successful Well Delivery Through Abrasive Rock While Adding New Unconventional Reserves“. In Offshore Technology Conference. OTC, 2022. http://dx.doi.org/10.4043/31698-ms.
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Abstract Deep wells drilled down to 4000 m to 4500 m true vertical depth (TVD) in the offshore Kutch-Saurashtra rift basin encounter more than 1500 m of abrasive Deccan Trap volcanics in a 12.25-in. section with target stiff Mesozoic sandstone formations in an 8.5-in. section. Weathered basalt flows, fractured sandstones, tightly cemented siltstones, pyritic shales, abnormal pressures, and complicated transverse isotropic layers test the limits of well construction and engineering design at high-pressure, high-temperature (HPHT) conditions. This reduces the rate of penetration (ROP) and sidetracks with premature termination of wells. Traditional prognosis methods fail to predict the abnormal pore pressure regimes and stress anisotropy created by the disturbed tectonic history and complex geological setting. The operator faced unpredictable flow events and wellbore instability incidents such as cavings, tight pulls, breakouts, and equivalent circulating density fluctuations during drilling. Apart from the drilling and completions challenges, the wellbore instabilities affected openhole logging and coring operations, leading to inadequate formation evaluation. In this paper we present an integrated approach to using geomechanical analyses for determining the mud-weight window, drilling bottomhole assembly (BHA), and optimizing mud chemicals. An anisotropic Mechanical Earth Model (MEM) was built using both horizontal and vertical elastic properties to estimate an accurate stress profile that can guide mud loss zones and completion quality. Engineered drilling bits based on the estimated rock mechanical and stress analysis were selected to improve effective ROP through the more abrasive and compacted rocks. High risk zones were flagged inside the Deccan Trap for mud loss while look-ahead mud weight design for the Bhuj and Jhuran formations were optimized by considering plane of weakness mode of failure. Dynamic hydraulics simulation was conducted for the tripping speed of the Casing and BHA. The casing run-in speed was optimized across the Deccan Trap by pumping lost-circulation material (LCM) additives to mitigate losses. This helped to set casing until the 12.25-in. section at total depth (TD) with a narrow mud-weight window of 0.2 to 0.3 ppg. A mud weight of 12.7 to 13.0 ppg was used initially in the 8.5-in. section based on the look-ahead model and was proactively increased to 13.7 ppg to minimize nonproductive time (NPT) with very few borehole breakouts or fracture plane slippage. This result was quite different from offset wells that were drilled with only 11.5 to 12.2 ppg mud weight, which resulted in many tight-hole and stuck-pipe incidents. Bits were changed to manage mean stress, which was expected in the range of 15,000 to 17,500 psi, with formation strength ranging 9,500 to 23,000 psi. The 8.5-in. section was drilled successfully with fewer bit trips, and the hole condition was in better shape compared to the offset wells. The formation evaluation and completion quality review led to the successful discovery of four new zones with minimal near-wellbore damage. Despite the extreme conditions, there was improvement in the instantaneous ROP by 15 to 20% while drilling an additional 250 m of abrasive formation without any wellbore instability.
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Arrofi, Daffa, Israa S. Abu-Mahfouz, Jawad Rafiq, Jarvis R. Cline, Mutaz Al-Jafari und Mohamed Al-Ghamdi. „Natural Fracture Characterization Through Digital Outcrop Model in Southwestern Saudi Arabia Geothermal Field“. In International Petroleum Technology Conference. IPTC, 2024. http://dx.doi.org/10.2523/iptc-24657-ea.
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Geothermal energy is the heat energy stored in the subsurface of the Earth due to the decay of radioactive elements within the mantle and the crust (Schubert et al., 1980). This energy is continuously produced, making it a sustainable and renewable energy source (Owusu and Asumadu-Sarkodie, 2016). One of the key advantages of geothermal energy is its capacity to provide baseload power that can be run constantly to fulfill the energy demands of any society, making it a dependable and persistent source of energy. Unlike other renewable energy sources such as solar and wind, geothermal energy, it is not affected by weather or daylight and can supply a consistent source of electricity day and night. Saudi Arabia possesses significant geothermal resources along of western boundary for both volcanic and non-volcanic geothermal systems (Chandrasekharam et al., 2014; Lashin et al., 2014; Al-Douri et al.,2019; Abu-Mahfouz et al., 2023). One of the potential geothermal areas is in Jizan, Southwestern Saudi Arabia (Hussein et al., 2013; Chandrasekharam et al., 2016; Arrofi and Abu-Mahfouz, 2023). Despite the fact that Jizan has a medium-high enthalpy system, it is largely underutilized. One of the most prevalent challenges encountered during exploitation is a low permeability reservoir to allow fluid circulation. However, it can be addressed by undertaking a detailed study of characterizing natural fractures both in the surface and subsurface. Natural fractures might enhance fluid circulation and permeability, making geothermal extraction a more viable option (Arrofi et al., 2022; Viswanathan et al., 2022; Abu-Mahfouz et al., 2023). It is crucial to investigate the distribution, orientation, and connectivity of fractures in geothermal systems. In the Al-Ardah geothermal field, located in Jizan, hydrothermal fluid is believed to flow from the eastern region, following the dip direction of the regional faults, and discharge on the western side (Arrofi et al., 2023). The reservoir area is indicated to be in the eastern region of Al-Ardah within the granitic rock (Fig. 1). Additionally, the granitic rock in the Al-Ardah area had undergone significant alteration due to intense interaction with the thermal water (Lashin and Al Arifi, 2014). It also suggests that the reservoir is located in the eastern part of the hot springs area. This study aims to characterize fractures and investigate fluid flow in the eastern part of Al-Ardah, Jizan, using an outcrop analogue (see the study location in Fig. 1).
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Al-Marri, Saad Zayed, Gary Peach und Hernan Vigil Fernandez. „TBM Challenges on Musaimeer outfall tunnel“. In The 2nd International Conference on Civil Infrastructure and Construction. Qatar University Press, 2023. http://dx.doi.org/10.29117/cic.2023.0017.
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Musaimeer outfall tunnel is the longest outfall tunnel in the Middle East. The tunnel was excavated by Earth Pressure Balance (EPB), Tunnel Boring Machine (TBM) and encountered three distinct rock masses namely Rus Formation, Midra-Shale, and Simsima Limestone along with water inflows at high pressure, complex mixed ground, and weaker ground strata prone to cavities with the presence of vertical and lateral fractures connected to the seabed. These conditions resulted in the TBM operating in very dry conditions where the addition of soil conditioners and water sprayed in the excavations chamber and cutter head were required to avoid clogging situations and create a pasty excavation material, which impacted TBM operation. The opposite scenario occurred when the TBM encountered very wet conditions while passing through weathered Simsima Limestone fully connected hydrostatically with the seabed. Such situations directly impacted the productions rates, quantities of consumables, extra cost on the tunnel enabling activities and finally, the need of both atmospheric and hyperbaric interventions into the cutter head up to 3.5 bar to replace cutting tools. Long tunnels with only one access shaft pose many programme problems for logistics, combine these with the requirement to drive directly out under the seabed for 10.2 km, and the programme issues become even more challenging. To meet and eventually improve on the planned completion date required a complex and extensive management of all tunnel logistics activities required to support consistent tunnelling for a two-year period. This technical paper will discuss the management issues and solutions implemented to meet the challenges of the outfall tunnel construction.
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Aadnøy, Bernt S., und Mesfin A. Belayneh. „High Geostress Advantageous for Arctic Field Developments“. In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78629.
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The Arctic areas of Norway has brought many new challenges. In addition to harsh weather, drilling conditions are different. The Barents Sea is different geologically compared to the North Sea area. A considerable amount of erosion bring older rocks higher up. It is observed that leak-off tests measured in Barents Sea wells shows abnormally high values. This is interpreted as a high stress state. The paper analyze the stresses around a number of wells and conclude that it is very likely that a reverse fault stress state exists in these areas of the Barents Sea. This can bring positive effects because such a stress state may constrain induced fractures to propagate in a horizontal plane rather than towards surface, reducing the risk for reservoir leaks to surface. Also, a high compressive state may lead to more sealed faults, indicating a higher possibility for oil in place. The paper will present the stress model and compare Barent Sea area to the North Sea. It will also show implications for wellbore stability, leaks from reservoirs and effects on sealing of major faults. Of particular interest is that leak potential from the reservoir is reduced in the Barent Sea as compared to other Norwegian oil fields. This may encourage more development in the Arctic areas.
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Carvalho, Ana, Ricardo Ribeiro, Rui Moura und Alexandre Lima. „GEOPHYSICAL EXPLORATION OF ANTIMONY MINERALIZATIONS: ALTO DO SOBRIDO AND RIBEIRO DA SERRA MINES (PORTUGAL)“. In 22nd SGEM International Multidisciplinary Scientific GeoConference 2022. STEF92 Technology, 2022. http://dx.doi.org/10.5593/sgem2022/1.1/s03.033.
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The Alto do Sobrido and Ribeiro da Serra Mines, are two antimony-gold mines located in Gondomar, Portugal, and are part of the Durico-Beirao Mining District (DBMD). In this work, we use four geophysical methods, such as gravity, radiometry, magnetic and electromagnetic, to improve the knowledge about these mineralizations and the lithologies and structures associated with them. These four methods allowed us to study these mineralizations through different physical properties. The gravimetric method allowed us to add more data to the hypothesis that the goldantimony mineralizations of the DBMD could be genetically associated with a nonoutcropping granite intrusion, which functioned either as a heat engine that promoted the circulation of fluids and/or as a source of fluids and metals itself. A 2D model was proposed, created with both modelling and inversion, to show that the presence of this granite could indeed fit the response of the negative anomalies found in the residual anomaly. The radiometric method was used mainly as a mapping tool, where we were able to distinguish between some of the lithologies of the area, like the Lower Ordovician quartzites and the metasediments of the Middle Ordovician to the Carboniferous, but also to observe different element concentrations within the Pre-Ordovician SchistGreywacke Complex (SGC). These variations within the SGC lithology don�t have a clear explanation as to why they occur. Still, we believe that they could occur due to the influence of the abovementioned non-outcropping granite. With the very low frequency (VLF) electromagnetic method, it was possible to locate areas of lower resistivities that correspond to the location of several known mineralized veins, as well as the probable location for a new vein. It was also possible to observe some weathered rocks near faults and fractures associated with the Durico-Beirao Shear Zone (DBSZ). With the magnetic method, it is possible to contribute to areas with the prevalence of lithologies and minerals with higher magnetic susceptibilities. Several magnetic anomalies found near the Alto do Sobrido mining works correspond to the mineralized veins paragenesis. Other anomalies appear to be related to the location of faults and fractures associated with the DBSZ. The use of all these methods allowed us to observe the mineralization responses and its associated lithologies and structures through the different geophysical properties while adding knowledge about the genesis of these mineralizations and possibly the location of new mineralized veins.
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Nozaki, M., N. R. Zwarich, M. Prosvirnov, R. Ruysschaert, M. A. Habib und L. A. Johnson. „Completion and Stimulation Design Evolution in Tight Chalk Formations in Offshore Norway“. In SPE International Conference and Exhibition on Formation Damage Control. SPE, 2024. http://dx.doi.org/10.2118/217898-ms.
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Abstract Lower completion and acid stimulation design for low permeability chalk formations in a series of North Sea Fields were modified from historical/legacy approaches, to improve well performance for both production and injection purposes. The modifications include 1) a stimulation change from high-rate matrix acidizing to acid fracturing, and 2) optimization of ball-activated sliding sleeve design. The improvement in well performance was validated with actual productivity comparison to offset wells. Further improvements are being developed for future extended reach wells. A ball-activated sliding sleeve completion was chosen for the new, improved, horizontal well completion. Sleeve spacing, the number of sleeves and port sizes were subsequently optimized over the targeted stimulated lateral length by pipe flow modeling and by limited-entry design methods. Optimization of acid fracturing designs was achieved after incorporating critical findings from various laboratory tests that include rotating disk tests, acid-etched fracture conductivity tests, and gel shear history simulator tests. The new acid fracturing treatment designs were generated with the help of numerical simulation that were continuously fine-tuned based on new observations made during treatments and rigorous analysis of bottomhole injection pressures during the treatment. As a result of the lower completion design optimization process, different size nozzles were introduced into the sliding sleeves to treat up to 5 sleeves per stimulation stage with effective fluid diversion. This allowed 1) using available pumping weather windows effectively in the offshore environment, 2) reducing or eliminating time-consuming wireline perforation runs, 3) limiting the acid exposure to mitigate ball/seat zonal isolation events (i.e., dissolvable balls are not compatible with acid). The new and improved acid fracturing design enabled a reduction of the number of gel/acid cycles from 5 to 3 which reduced stimulation cost without losing stimulation effectiveness. The new design also resulted in productivity enhancements depending on the well location within the structure. The largest performance improvement was observed on wells that were placed further down-flank where reservoir rock is stronger and permeabilities are lower. These wells require more intensive acid fracturing treatment to generate economical and sustainable production rates. Finally, these wells also tend to require less restimulation frequency with time. This type of analysis work has not been presented previously and it optimizes lower completion for acid fracturing stimulation on a well-by-well basis. Further improvement is expected as stimulation designs and completion technology continue to evolve.