Academic literature on the topic 'Leak-off analysis'
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Journal articles on the topic "Leak-off analysis"
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Cai, Bo, Yun Hong Ding, Yong Jun Lu, Chun Ming He, and Gui Fu Duan. "Leak-Off Coefficient Analysis in Stimulation Treatment Design." Advanced Materials Research 933 (May 2014): 202–5. http://dx.doi.org/10.4028/www.scientific.net/amr.933.202.
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Hydraulic fracturing was first used in the late 1940s and has become a common technique to enhance the production of low-permeability formations.Hydraulic fracturing treatments were pumped into permeable formations with permeable fluids. This means that as the fracturing fluid was being pumped into the formation, a certain proportion of this fluid will being lost into formation as fluid leak-off. Therefore, leak-off coefficient is the most leading parameters of fracturing fluids. The accurate understanding of leak-off coefficient of fracturing fluid is an important guidance to hydraulic fracturing industry design. In this paper, a new field method of leak-off coefficient real time analysis model was presented based on instantaneous shut-in pressure (ISIP). More than 100 wells were fractured using this method in oil field. The results show that average liquid rates of post-fracturing was 22m3/d which double improvement compared with the past treatment wells. It had an important role for hydraulic fracturing stimulation treatment design in low permeability reservoirs and was proven that the new model for hydraulic fracturing treatment is greatly improved.
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Shelukhin, Vladimir, and Mikhail Epov. "Ionic Fracture Fluid Leak-Off." Fluids 4, no. 1 (February 19, 2019): 32. http://dx.doi.org/10.3390/fluids4010032.
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The study is motivated by monitoring the space orientation of a hydrolic fracture used in oil production. Streaming potential arises due to the leakage of ionic fracking fluid under the rock elastic forces which make the fracture disclosure disappear after pumping stops. The vector of electric field correlates with the fracture space orientation since the fluid leakage is directed normally to the fracture surfaces. We develop a mathematical model for the numerical evaluation of the streaming potential magnitude. To this end, we perform an asymptotic analysis taking advantage of scale separation between the fracture disclosure and its length. The contrast between the virgin rock fluid and the fluid invading from the fracture is proved to be crucial in a build up of a net charge at the invasion front. Calculations reveal that an increase of the viscosity and resistivity contrast parameters results in an increase of the streaming potential magnitude. Such a conclusion agrees with laboratory experiments.
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Zhou, Desheng, and Andrew K. Wojtanowicz. "Analysis of Leak-off Tests in Shallow Marine Sediments." Journal of Energy Resources Technology 124, no. 4 (November 20, 2002): 231–38. http://dx.doi.org/10.1115/1.1506322.
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Typical analysis of the Leak-off testing (LOT) in wells assumes elastic wellbore and involves identification of diversion points from linear trends of the recorded plots. However, LOTs from wells in the shallow marine sediments (SMS) are inherently nonlinear and their analysis becomes a problem. The paper presents mathematical models of the pressure-volume behavior for two different possible failures around the casing shoe, annular crack (cement-rock parting) and formation fracture. The study submits that these two failure modes would control abnormal LOT patterns. A general pressure-volume model of LOT has been developed including volumetric effects of wellbore expansion, mud loss into the rock, and propagation of an annular crack or plastic fracture. A diagnostic method is proposed to identify LOT-control mechanisms (i.e., formation fracture, annular crack, or mud loss) by analyzing the shut-in section of the LOT’s plot.
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GARAGASH, DMITRY I., EMMANUEL DETOURNAY, and JOSE I. ADACHI. "Multiscale tip asymptotics in hydraulic fracture with leak-off." Journal of Fluid Mechanics 669 (February 16, 2011): 260–97. http://dx.doi.org/10.1017/s002211201000501x.
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This paper is concerned with an analysis of the near-tip region of a fluid-driven fracture propagating in a permeable saturated rock. The analysis is carried out by considering the stationary problem of a semi-infinite fracture moving at constant speed V. Two basic dissipative processes are taken into account: fracturing of the rock and viscous flow in the fracture, and two fluid balance mechanisms are considered – leak-off and storage of the fracturing fluid in the fracture. It is shown that the solution is characterized by a multiscale singular behaviour at the tip, and that the nature of the dominant singularity depends both on the relative importance of the dissipative processes and on the scale of reference. This solution provides a framework to understand the interaction of representative physical processes near the fracture tip, as well as to track the changing nature of the dominant tip process(es) with the tip velocity and its impact on the global fracture response. Furthermore, it gives a universal scaling of the near-tip processes on the scale of the entire fracture and sets the foundation for developing efficient numerical algorithms relying on accurate modelling of the tip region.
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Cheng, Weiping, and Yongxin Shen. "Frequency Characteristic Analysis of Acoustic Emission Signals of Pipeline Leakage." Water 14, no. 24 (December 7, 2022): 3992. http://dx.doi.org/10.3390/w14243992.
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The leakage detection of a water distribution system (WDS) needs the support of a large number of field data. This paper collected over 6800 leak detection signals from cast iron pipelines used in a WDS. We found that 3280 signals indicated leakage, and the remaining indicated no leakage. The characteristics of the signals were extracted and analyzed from three perspectives: the central frequency of the power spectrum, the spectral roll-off rate, and the spectral flatness. Significant statistical distributions were found. The central frequencies of the leakage signals followed the normal distribution, and their spectral roll-off rates demonstrated the Burr distribution; the Birnbaum–Saunders distribution could describe the spectral flatness of the signals. Based on these characteristics, the recognition rate of the ML model for leak detection was improved. The Random Forest model was used to classify the leakage detection signals. The recall rate was 100%, and the false positive rate was 8.27%.
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Shen, Yue, and Ling Tan Zhang. "Eddy Current Detecting of Leak Hole in Pipeline by Wavelet Packet Signal Analysis Method." Applied Mechanics and Materials 291-294 (February 2013): 2486–91. http://dx.doi.org/10.4028/www.scientific.net/amm.291-294.2486.
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In the process of detecting leak hole in pipeline by intelligent pig with eddy current measuring method, the cut off effect of eddy current field in the closed cross section of leak hole in steel plate is weak due to geometric deformation of eddy current on the edge of the hole produced by destroyed drilling. As a result, the measured signal is very unobvious. Meanwhile, owing to the rough surface of steel plate, the periodic interference generated by movement of the detecting probe cannot be eliminated or be inhibited easily by conventional signal processing methods for its large amplitude and approximate frequency band with the leak hole signals, the signal to noise ratio (SNR) of measured signal is very low and the accurate identification of leak hole cannot be guaranteed. The wavelet transform, with characteristics of time-frequency localization and multiple scales, is a useful and effective method for identifying singularity of the signals and adapts to detect the transient signal or extract non-stationary information in the signals with strong periodic interference and noise. The reconstructing signal SNR will be increased greatly in eddy current detecting of leak hole in the pipeline with wavelet packet analysis of the signal by constructing the self-defined cost function based on maximum SNR to obtain optimal wavelet packet basis function. This ensures good detection and location of leak hole in the pipeline.
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Řezáč, Tomáš, Martin Stašek, Pavel Zbořil, and Petr Špička. "The role of CRP in the diagnosis of postoperative complications in rectal surgery." Polish Journal of Surgery 93, no. 5 (April 22, 2021): 1–5. http://dx.doi.org/10.5604/01.3001.0014.6591.
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Introduction: Postoperative anastomotic leak after rectal resection is a life-threatening complication. Late diagnosis and a severe symptomatic leak may cause almost 18 % mortality. Early diagnosis is a challenging issue because of nonspecific clinical signs in the early postoperative period. Minimally invasive rectal surgery and the implementation of ERAS protocol require appropriate markers of inflammatory complications and leak with high sensitivity. Postoperative serum C-reactive protein values seem to be the right answer for this question. Aim: The presented study aimed to determine the importance and cut-off level of serum C-reactive protein as a possible predictive factor for early anastomotic leak diagnosis in rectal surgery. Material and methods: The retrospective observational analysis of patients after resection for rectal cancer in a period of one year. The observation included risk factors (age, sex, BMI, bowel preparation and the acuteness of surgery), recording of complications and serum values of CRP. Results: The study included 178 patients. 63 patients (35,4 %) had non-complicated postoperative course. The complications were present in 115 cases (64,6 %), including surgical site infection (16,3 %) and anastomotic leak (7,3 %). The mortality was 2,2 %. CRP serum value reached the sensitivity 94,7 % and specificity 72,5 % at POD 4 with cut off value of 131,8 mg/l and the sensitivity of 84,2 % and specificity 82,4 % with cut off 175,4 mg/l, respectively. Conclusions: Postoperative serum C-reactive protein may be used as a predictor of anastomotic leakage. The examination of CRP on the 4th postoperative day may lead to early and safe discharge from the hospital after rectal resection. The implementation of the cut off values detects more than 90 % of anastomotic leaks or septic complications.
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Mazur, Z., A. Carvajal-Martínez, R. Muñoz-Quezada, and R. García-Illescas. "Failure analysis of a leak-off oil pipe from injection valves of an off-shore operating diesel engine." Engineering Failure Analysis 14, no. 1 (January 2007): 196–208. http://dx.doi.org/10.1016/j.engfailanal.2005.10.019.
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Choi, Jung Chan, Zhongqiang Liu, Suzanne Lacasse, and Elin Skurtveit. "Leak-Off Pressure Using Weakly Correlated Geospatial Information and Machine Learning Algorithms." Geosciences 11, no. 4 (April 19, 2021): 181. http://dx.doi.org/10.3390/geosciences11040181.
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Leak-off pressure (LOP) is a key parameter to determine the allowable weight of drilling mud in a well and the in situ horizontal stress. The LOP test is run in situ and is frequently used by the petroleum industry. If the well pressure exceeds the LOP, wellbore instability may occur, with hydraulic fracturing and large mud losses in the formation. A reliable prediction of LOP is required to ensure safe and economical drilling operations. The prediction of LOP is challenging because it is affected by the usually complex earlier geological loading history, and the values of LOP and their measurements can vary significantly geospatially. This paper investigates the ability of machine learning algorithms to predict leak-off pressure on the basis of geospatial information of LOP measurements. About 3000 LOP test data were collected from 1800 exploration wells offshore Norway. Three machine learning algorithms (the deep neural network (DNN), random forest (RF), and support vector machine (SVM) algorithms) optimized by three hyperparameter search methods (the grid search, randomized search and Bayesian search) were compared with multivariate regression analysis. The Bayesian search algorithm needed fewer iterations than the grid search algorithms to find an optimal combination of hyperparameters. The three machine learning algorithms showed better performance than the multivariate linear regression when the features of the geospatial inputs were properly scaled. The RF algorithm gave the most promising results regardless of data scaling. If the data were not scaled, the DNN and SVM algorithms, even with optimized parameters, did not provide significantly improved test scores compared to the multivariate regression analysis. The analyses also showed that when the number of data points in a geographical setting is much smaller than that of other geographical areas, the prediction accuracy reduces significantly.
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Kim, Youngseok, Haewook Jung, Jaesuk Ryou, and Jaehyuk Choi. "A Basic Experimental Study on Analysis of Leak Signal and Monitoring Method for Water Supply Pipe." Applied Sciences 11, no. 5 (February 26, 2021): 2097. http://dx.doi.org/10.3390/app11052097.
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Water supply systems are essential elements for human life and industry, and water leaks and water supply cut-off may cause major problems. Local water leaks and pipe failures in the water supply system are inevitable problems due to the aging of pipes. Therefore, leakage detection and prevention are required to monitor the integrity of the water supply system. This paper is a fundamental study on the applicability of the smart bolt, which was developed as a monitoring system to detect water leakage in water supply monitoring. Detection experiments were conducted using a smart bolt with a built-in strain sensor and an accelerometer. Through finite element analysis using ANSYS 2019 R2 and tensile strength testing, the strength of the smart bolt was confirmed to have the acceptable tensile strength. The smart bolt used in this study was verified to meet the allowable criteria of torque and tensile stress for a municipal water supply system. The frequency responses of the simulated leakage pipe system, according to the leakage of the valve and the main pipe, were analyzed, and a leak signal at the valve leak point was detected in the 60-Hz band. The main pipe leaking point was observed to produce a leak signal with a much higher-order mode than that of the valve leak point. Therefore, the smart bolt can be applied to detect warning leak signs from water supply valves and to monitor for loosening of the bolts.
Dissertations / Theses on the topic "Leak-off analysis"
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Kayael, Burak. "An Investigation Of The Leak-off Tests Conducted In Oil And Natural Gas Wells Drilled In Thrace Basin." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614030/index.pdf.
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This study aims to analyze the leak-off tests carried out in the Thrace Basin of Turkey by Turkish Petroleum Corporation and find any relationship that may exist between leak-off test results and drilled formations as well as drilling parameters, such as mud weight, depth.
The analysis of 77 leak-off tests indicated that there is no close correlation between the mud weight of test fluid and equivalent mud weight (fracture gradient) if the test is carried out within impermeable sections. On the other hand, the correlation between mud weight and equivalent mud weight increase while running the test within permeable-productive zones. It is also found that the leak-off test results are not dependent on the depth but the formation to be tested.
The analyzed leak-off test results from Thrace Basin showed that the fracture gradient is not the limiting factor to set the casing of any section unless a gas show is observed during drilling operation which occurred only in 5 wells out of 78 wells
analyzed.
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Shaghaghi, Tahereh. "FEM and XFEM approaches to Investigate the Hydromechanical Interactions within a jointed soft-rock slope." Thesis, Federation University Australia, 2020. http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/177426.
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One of the most significant challenges of open-cut mining is to provide stability for the excavated slopes. Unrealistic predictions of the slopes’ behaviour during and after mining operations can lead to the failure of slopes, and this may pose a threat to human lives, the economy, and the environment. By excavating soft rock masses in open-cut mines, pre-existing joints can open and new joints can form behind excavated slopes. This phenomenon is due to the geotechnical character of the materials and stress relief movements of the excavated slopes. The stability of slopes in the rock masses is significantly influenced by the existence of discontinuities such as joints. The water flows in the opened joints can change the pore water pressure distribution in the slopes. The interaction between the joints and the water may impose different loading scenarios on the open-cut mines and put the safety of mining operations at risk. The analysis of slope stability can become more complicated because of the presence of water, discontinuities, and their interaction within the slopes in open-cut mines. This study investigates the hydromechanical interactions in the saturated jointed slopes due to pore water pressure changes. The second-largest open-cut mine in Australia, the Yallourn brown coal open-cut mine located in Victoria, was chosen as the case study for this research. In this study, several coupled pore fluid diffusion and stress-strain analyses are conducted using the extended finite element method (XFEM) in conjunction with the finite element method (FEM). This study firstly examines a joint aperture and pore water pressure changes of the excavated jointed slope due to installing a drainage system and backfilling in front of the slope. Secondly, a series of sensitivity analyses are carried out on the pore water pressure distribution changes to the variation of the permeability magnitude of the material and leakage properties of the joint surfaces. Finally, to control the pore water pressure of the saturated jointed slope, a series of drainage systems is designed. The arrangement and length of the drains are optimised by conducting a series of sensitivity analyses on the leakage properties of the joint and the permeability of the soft rock.Doctor of Philosophy
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Xiang, Jing. "A PKN Hydraulic Fracture Model Study and Formation Permeability Determination." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10212.
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Hydraulic fracturing is an important method used to enhance the recovery of oil and gas from reservoirs, especially for low permeability formations. The distribution of pressure in fractures and fracture geometry are needed to design conventional and unconventional hydraulic fracturing operations, fracturing during water-flooding of petroleum reservoirs, shale gas, and injection/extraction operation in a geothermal reservoir. Designing a hydraulic fracturing job requires an understanding of fracture growth as a function of treatment parameters.
There are various models used to approximately define the development of fracture geometry, which can be broadly classified into 2D and 3D categories. 2D models include, the Perkins-Kern-Nordgren (PKN) fracture model, and the Khristianovic-Geertsma-de. Klerk (KGD) fracture model, and the radial model. 3D models include fully 3D models and pseudo-three-dimensional (P-3D) models. The P-3D model is used in the oil industry due to its simplification of height growth at the wellbore and along the fracture length in multi-layered formations.
In this research, the Perkins-Kern-Nordgren (PKN) fracture model is adopted to simulate hydraulic fracture propagation and recession, and the pressure changing history. Two different approaches to fluid leak-off are considered, which are the classical Carter's leak-off theory with a constant leak-off coefficient, and Pressure-dependent leak-off theory. Existence of poroelastic effect in the reservoir is also considered.
By examining the impact of leak-off models and poroelastic effects on fracture geometry, the influence of fracturing fluid and rock properties, and the leak-off rate on the fracture geometry and fracturing pressure are described. A short and wide fracture will be created when we use the high viscosity fracturing fluid or the formation has low shear modulus. While, the fracture length, width, fracturing pressure, and the fracture closure time increase as the fluid leak-off coefficient is decreased.
In addition, an algorithm is developed for the post-fracture pressure-transient analysis to calculate formation permeability. The impulse fracture pressure transient model is applied to calculate the formation permeability both for the radial flow and linear fracture flow assumption. Results show a good agreement between this study and published work.
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Pierdominici, S. "Studio multidisciplinare per la caratterizzazione ed identificazione di aree sismicamente attive in Appennino: metodi geologici, geofisici e statistici." Thesis, 2004. http://hdl.handle.net/2122/7887.
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Lo studio effettuato in questa tesi di Dottorato ha lo scopo di integrare metodologie di analisi diverse - geologiche, geofisiche e statistiche - per contribuire alla determinazione del potenziale sismico, che è la diretta espressione dell’attività del campo di stress attualmente agente e responsabile della sismicità. Queste tre diverse metodologie sono state applicate in due aree selezionate ubicate lungo la catena appenninica, in corrispondenza delle conche intramontane di origine tettonica. La scelta di queste aree si basa anche sul presupposto che esse possano avere un notevole potenziale sismico essendo caratterizzate da importanti eventi storici di elevata magnitudo.
Tra le metodologie applicate in questo studio, i metodi geologici mirano alla comprensione dell’evoluzione quaternaria delle depressioni intrappenniniche con particolare riguardo al riconoscimento ed alla valutazione delle evidenze di tettonica attiva. I metodi geofisici sono stati applicati per studiare e definire meglio il campo di stress attraverso l’analisi dei dati di borehole breakout, dei meccanismi focali dei terremoti e del test di Leak-off. Tutte le tecniche sono volte a determinare le componenti relative al campo di stress quali orientazione (Shmin ed asse-T), tipo di regime (normale, trascorrente o inverso) e sua quantificazione (pressioni in MPa). È stato inizialmente affrontato uno studio della sismicità storica e strumentale, attraverso l’analisi dei vari cataloghi, per integrare le conoscenze sulla geodinamica dell’Appennino, sull’assetto geologico-strutturale profondo, sulla definizione delle strutture sismogeniche, sulla distribuzione e sul potenziale sismico delle aree campioni. È stata affrontata l’analisi delle sequenze sismiche per determinare la distribuzione areale ed in profondità degli eventi, l’orientazione ed il tipo di regime di stress e la stima del tensore dello stress regionale mediante il metodo di inversione di GEPHART & FORSYTH (1984).
Infine, sono stati applicati due metodi statistici per studiare la distribuzione spazio-temporale dei terremoti tramite due approcci non-parametrici: l’analisi multivariata che implementa il dato di sismicità con quello geologico-strutturale (FAENZA et al., 2003) ed il metodo di TANNER & WONG, 1984) che utilizza solo i dati di sismicità relativi ad un campione omogeneo. Infine, è stata calcolata la probabilità di evento nelle due aree campioni.Universitá di Bologna "Alma Mater Studiorum" e INGV
Unpublished
3.2. Tettonica attiva
open
Conference papers on the topic "Leak-off analysis"
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Hamzah, K. "Pressure Transient Analysis in Tight Oil Reservoir, Leak-Off Test Vs PBU Test." In Indonesian Petroleum Association 42nd Annual Convention and Exhibition. Indonesian Petroleum Association, 2018. http://dx.doi.org/10.29118/ipa19.e.445.
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Verweij, J. M. "Integrated Hydrodynamic Analysis of Fluid Pressure and Leak-off Pressure Distributions to Evaluate Seal Effectiveness." In 2nd EAGE International Conference on Fault and Top Seals - From Pore to Basin Scale 2009. European Association of Geoscientists & Engineers, 2009. http://dx.doi.org/10.3997/2214-4609.20147229.
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Lerohl, David, Justin Mayorga, Brent Vering, Erica Coenen, and Sean Spicer. "Combining Pressure-Based Fracture Maps and Post-Stimulation Leak-Off Analysis Lead to Informed Unconventional Development." In Unconventional Resources Technology Conference. Tulsa, OK, USA: American Association of Petroleum Geologists, 2020. http://dx.doi.org/10.15530/urtec-2020-2677.
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Zhao, Liang, and Kunjie Luo. "Root Cause Analysis of a Leak Off Tube of the Primary Loop in a CANDU 6 Unit." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66710.
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Chemical composition analysis, microstructure analysis, macro and micro fracture morphology analysis were conducted on a cracked leak off tube in primary heat transport and heavy water collection system of a CANDU6 unit. The results show that the material conforms to the original design requirements. The leaked fluid vaporized at the penetration and stress corrosion crack initiated because of cl-concentration. The leaked fluid drains periodically and lead the wall surface temperature periodically changes. The SCC crack transformed to corrosion fatigue crack and the tube finally fractured. In order to prevent the similar tubes crack again, preventive maintenance strategies were given in this paper.
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Antono, Ari, Ade Irawan, and Badrul Munir. "The failure analysis of a leak-off oil pipe ASTM A106 on compact separator at an offshore facility." In PROCEEDINGS OF THE 13TH AUN/SEED-NET REGIONAL CONFERENCE ON MATERIALS (RCM 2020) AND THE 1ST INTERNATIONAL CONFERENCE ON MATERIALS ENGINEERING AND MANUFACTURING (ICMEM 2020). AIP Publishing, 2021. http://dx.doi.org/10.1063/5.0066664.
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Kim, Eui Youl, Min Soo Kim, and Sang Kwon Lee. "Analysis of Acoustic Wave Due to Gas Leakage in Buried Gas Pipe." In ASME 2009 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2009. http://dx.doi.org/10.1115/detc2009-86743.
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A time frequency technique for locating leaks in buried gas distribution pipes involves the use of the cross-correlation on two measured acoustic signals on either side of a leak. This technique can be problematic for locating leaks in steel pipes, as the acoustic signals in these pipes are generally narrowband and low frequency. The effectiveness of the time-frequency technique for detecting leaks in steel pipes was investigated experimentally in an earlier study. The object of this paper is to identify the characteristics of this dispersive acoustic wave through analysis of the cut-off frequency by using the time-frequency method experimentally and BEM (boundary element method) theoretically for the development of an experimental tool to analyze the leak signals in steel pipe. The tool is based on experimental work and theoretical formulation of wave propagation in a fluid-filled pipe. This tool uses the time-frequency method to explain some of the features of wave propagation measurements made in gas pipes. Leak noise signals are generally passed through a time-frequency filter for detection of impulse signal related leakage.
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Scortegagna de Medeiros, Nathan, and Joe Quinn. "Experiences With a Complex Leak Detection System in an Offshore Basin." In 2004 International Pipeline Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ipc2004-0492.
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Silvertech have implemented a large, complex leak detection system for an offshore basin with some 80 pipeline sectors in a number of multiple input-multiple output configurations with varying pipeline operational scenarios. This paper addresses two key issues. First a systematic approach to the determination of the risk and consequencees of a pipeline leak and hence the performance criteria and economic justification for a leak detection system is outlined. The challenges associated with the Campos Basin leak detection system implementation are then described, including operational issues and the continuing verification of the performance of the leak detection system. Leak detection systems are often specified as a requirement without a sound basis of leak risk and consequence analysis and quantification of the risk reduction that will be afforded by any leak detection system and the system performance required to ensure the risk reduction is achieved and maintained. Silvertech have adopted a methodology that provides a systematic, sound approach to the quantification of pipeline leak risk, the commercial and environmental consequences and the risk reduction required to provide acceptable risk and consequence. The implicit trade-off between impact on production and leak consequence reduction is also considered. Finally the lessons learnt from the analysis and system implementation experience are used to derive the key issues that apply to the implementation of leak detection in large, complex pipeline configurations. The particular challenges of applying leak detection to existing installations are also highlighted.
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Li, Yuanchun, and Iraj Ershaghi. "The Behavior of Unconsolidated Rocks in California Waterfloods Under High-Pressure Gradients." In SPE Western Regional Meeting. SPE, 2021. http://dx.doi.org/10.2118/200878-ms.
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Abstract Most waterfloods in California target sandstone formations that are unconsolidated in nature with high porosities and high permeabilities. These formations are also characterized by high Poisson ratios and low values of Young's Moduli. There has been a concern if, during the waterfloods of these types of formations, fracturing takes place at high-injection gradients. The influence of various factors on leak-off is studied in detail, indicating that with an increase in rock permeability, the leak-off velocity increases. This study included a comprehensive analysis of the characteristics of such soft formations and their responses to high injection gradients. We show that if the leak-off factors are adjusted to reflect high permeability and proper geomechanical properties, the probability of fracture formation is nil at injection gradients up to 0.9 psi/ft, for unconsolidated rooks. We computed estimated fracture width, fracture height, fracture length and noted for all three calculations, it takes gradients approaching 1psi/ft to note a non-trivial estimated value for these characteristics. This study shows that for unconsolidated formations like those in California targeted for waterfloods, the probability of fracture formation under pressure gradients of 0.9 psi/ft. is nil, and high injectivities can be exercised without the fear of fracture formation.
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Gentile, D., G. Iannitti, and N. Bonora. "COD of Off-Centered Cracks in Pipes Under Bending: Experimental Measures and Model Validation." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97347.
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The leak area of circumferential part-through crack in pipe under bending depends on the location of the crack with respect to the bending plane. In LBB analysis, taking the crack symmetrically placed with respect to the bending plane no necessarily is a conservative assumption. In this work the COD distribution of circumferential cracks in pipes, off-centered placed with respect to the bending plane, was investigated experimentally. Thick and thin pipe geometries have been analyzed examining different crack lengths and off-axis angle values. The COD distributions have been measured by means of digital image correlation (DIC) technique and used to validate an analytical model (HCM Hodograph Cone Method) proposed by the authors.
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Chalgham, Wadie, Mihai Diaconeasa, Raju Gottumukkala, and Abdennour Seibi. "A Numerical and Experimental Study Supporting a Methodology for Live Monitoring, Leak Detection, and Automatic Response in Water Pipelines." In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11861.
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Abstract This paper describes a numerical analysis supported by small scale experiments for demonstrating a monitoring and leak detection methodology. This study can be used to build a full-scale water pipeline monitoring and response system. The monitoring system is able to monitor the pipeline health and respond to hazard conditions through the use of multiple sensors driven by a hybrid rule-based and statistical monitoring control strategy. The system is programmed to automatically shut off its pump in the event of out-of-bounds/out-of-statistical control conditions detected by its sensors. In addition, this paper presents a numerical simulation analysis approach supported by an experiment that aims at finding a relationship between the location and size of an induced leak and the reported sensor data. The obtained results are used to inform a probabilistic model that can be used to estimate the leak location and size based on flow rate variations. The proposed project will enhance remote pipeline monitoring and structural safety by offering real-time data and automatic emergency response capabilities.