N. Pavlyukov, R. Melikov, V. Pavlov, Aleksandr Ptashniy, A. Stepanov, A. Kalabin, A. Kuzovkov, A. Gordeev, A. Arzhilovskiy, M. Samoilov, D. Matveev, A. Prokhorov, Timur Khamidov, Aleksandr Korolev, O. Loznyuk, R. Shaybakov, Georgiy Gabuniya
The peculiarity of this work is in the planning of the pilot works and the development of low-permeability fractured gas reservoir by horizontal wells with multi-stage fracturing considering natural fractures impact which taken into account on the basis of integrated approach with petrophysical, geological, geomechanical and dynamic modelling. The article presents the results of multivariant calculations of hydraulic fracturing design dynamic modelling with and without natural fractures depending on the well placement, length and orientation of the horizontal well, geometry of hydraulic fracture, as well as possible effects that occur during the operation of the wells. Technological constraints (geomechanics input) were taken into account as a basis for evaluation of horizontal well trajectories with multi-stage fracturing for the pilot works and recommended for implementation during the subsequent fullfield development for target gas reservoir, as well as replication of the experience for the similar assets of the Company.
{"title":"An Integrated Approach for Planning of Multistage Hydraulic Fracturing in Low-Permeability Gas-Saturated Reservoirs with Natural Fractures","authors":"N. Pavlyukov, R. Melikov, V. Pavlov, Aleksandr Ptashniy, A. Stepanov, A. Kalabin, A. Kuzovkov, A. Gordeev, A. Arzhilovskiy, M. Samoilov, D. Matveev, A. Prokhorov, Timur Khamidov, Aleksandr Korolev, O. Loznyuk, R. Shaybakov, Georgiy Gabuniya","doi":"10.2118/196904-ms","DOIUrl":"https://doi.org/10.2118/196904-ms","url":null,"abstract":"\u0000 The peculiarity of this work is in the planning of the pilot works and the development of low-permeability fractured gas reservoir by horizontal wells with multi-stage fracturing considering natural fractures impact which taken into account on the basis of integrated approach with petrophysical, geological, geomechanical and dynamic modelling.\u0000 The article presents the results of multivariant calculations of hydraulic fracturing design dynamic modelling with and without natural fractures depending on the well placement, length and orientation of the horizontal well, geometry of hydraulic fracture, as well as possible effects that occur during the operation of the wells.\u0000 Technological constraints (geomechanics input) were taken into account as a basis for evaluation of horizontal well trajectories with multi-stage fracturing for the pilot works and recommended for implementation during the subsequent fullfield development for target gas reservoir, as well as replication of the experience for the similar assets of the Company.","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88752831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
These days more and more gas and gas condensate fields are reaching the late stage of development, which characterized with an increasing amount of challenges impeding recovery of reserves. In order to solve the problems, oil and gas companies employ different solutions which have certain conditions of practical application and different efficiency. Gas distributed compression solutions based on mobile wellsite compressors can be considered as one of the most modern and efficient solution. This technology has already established an excellent reputation in CIS countries and overseas by demonstrating the high result of implementation. However, in order to decide whether to implement this technology or not, it is required to elaborate a good feasibility study. The low level of the elaboration can easily overestimate the efficiency of the project as well as underestimate it thereby ensuing refusal of potentially efficient project. Since each project of technology implementation is unique it is not enough just utilize a common approach of project implementation to prepare an excellent feasibility study. Currently, it is quite difficult to find a methodology to prepare a decent feasibility study for mobile wellsite compressor implementation. The author while working on mobile wellsite compressor project has obtained solid experience which is reflected in this paper. Based on a dozen of integrated asset modeling simulations system of criteria for candidate selection for wellsite compressor installation was elaborated. In order to improve the efficiency and flexibility of the wellsite compressor operation an optimized approach to well hookup was advised. With the intention of improving the economic efficiency of mobile wellsite implementation set of recommendations was provided. The paper can be used as a basis for creating a solid feasibility study for wellsite compressor implementation. Recommendations provided in the article will enable not only improve the feasibility study but also minimize time and computational power allocated on the project.
{"title":"Mobile Wellsite Compressors: New Lease on Life for Mature Gas Field","authors":"Ilnur Sayfullin, S. Vasyutkin, A. Ermilov","doi":"10.2118/196924-ms","DOIUrl":"https://doi.org/10.2118/196924-ms","url":null,"abstract":"\u0000 These days more and more gas and gas condensate fields are reaching the late stage of development, which characterized with an increasing amount of challenges impeding recovery of reserves. In order to solve the problems, oil and gas companies employ different solutions which have certain conditions of practical application and different efficiency. Gas distributed compression solutions based on mobile wellsite compressors can be considered as one of the most modern and efficient solution. This technology has already established an excellent reputation in CIS countries and overseas by demonstrating the high result of implementation. However, in order to decide whether to implement this technology or not, it is required to elaborate a good feasibility study. The low level of the elaboration can easily overestimate the efficiency of the project as well as underestimate it thereby ensuing refusal of potentially efficient project. Since each project of technology implementation is unique it is not enough just utilize a common approach of project implementation to prepare an excellent feasibility study. Currently, it is quite difficult to find a methodology to prepare a decent feasibility study for mobile wellsite compressor implementation. The author while working on mobile wellsite compressor project has obtained solid experience which is reflected in this paper. Based on a dozen of integrated asset modeling simulations system of criteria for candidate selection for wellsite compressor installation was elaborated. In order to improve the efficiency and flexibility of the wellsite compressor operation an optimized approach to well hookup was advised. With the intention of improving the economic efficiency of mobile wellsite implementation set of recommendations was provided. The paper can be used as a basis for creating a solid feasibility study for wellsite compressor implementation. Recommendations provided in the article will enable not only improve the feasibility study but also minimize time and computational power allocated on the project.","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88350624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Y. Shumakov, F. Hollaender, Andrew Williams, J. Munro, B. Theuveny
Exploration, appraisal, and production well tests have always been a primary source of information for reservoir characterization, well deliverability estimation, and monitoring of field development. Well test operations are one of the most challenging operations performed at the wellsite today, especially in tight oil and gas reservoirs with limited capability or inability of the well to flow naturally and produce reservoir hydrocarbons to surface. Conventional drill stem tests (DSTs) may also not be applicable in some cases due to the high cost of operations or other constraints. Over time, environmental considerations and regulations have become stricter and one of the most significant limiting factors for conducting conventional DST operations in some geographical areas. DST operations in tight reservoirs have always been limited and deemed challenging due to complexities associated with the ability to create enough pressure drawdown, high risks associated with the inability of the well to flow to surface to unload the liquids from the wellbore, and clean-up of the well to unlock true reservoir potential. Therefore, for the last several decades, the oil industry has been trying to find the most effective ways to flow test these wells to determine essential reservoir information and minimize field development risks. Impulse testing is not a new concept and enables testing a well using a simple DST or tubing-conveyed perforating (TCP) string with no flow of hydrocarbon to surface. This method also reduces cost in comparison with conventional DST operations or other standard testing methods. Until recently, the application of this type of test has been limited, mainly by the complexity of interpreting the test data, limited functionalities of the tools, low success rate, and poor quality of acquired data. With the evolution of downhole DST tool technology and enhancements in well test design, along with the appropriate equipment selection, a new generation of low flow rate impulse tests have been engineered for success by bringing together a multidisciplinary team and emphasizing the importance of the job design. The paper describes cost-effective, practical, and proven impulse testing methods for tight oil and gas reservoirs. The proposed methods are versatile and adaptive to the operating environment and the operator's requirements. The zero-emission well testing solution is based on proven conventional well test interpretation methods and a combination of technologies, workflows, and unique equipment arrangements that make it possible to flow test the wells to determine key reservoir dynamic parameters and the productivity indices of new wells during DST or TCP operations or during workover operations if the wells are currently in production. This paper also presents several field examples from operations performed around the globe, with results of the successful pressure transient analysis of the data recorded during the tests that enab
{"title":"New Generation Impulse Testing: An Environmentally Friendly Well Testing Solution for Tight Reservoirs to Acquire Accurate Reservoir Information","authors":"Y. Shumakov, F. Hollaender, Andrew Williams, J. Munro, B. Theuveny","doi":"10.2118/196840-ms","DOIUrl":"https://doi.org/10.2118/196840-ms","url":null,"abstract":"\u0000 Exploration, appraisal, and production well tests have always been a primary source of information for reservoir characterization, well deliverability estimation, and monitoring of field development. Well test operations are one of the most challenging operations performed at the wellsite today, especially in tight oil and gas reservoirs with limited capability or inability of the well to flow naturally and produce reservoir hydrocarbons to surface. Conventional drill stem tests (DSTs) may also not be applicable in some cases due to the high cost of operations or other constraints. Over time, environmental considerations and regulations have become stricter and one of the most significant limiting factors for conducting conventional DST operations in some geographical areas.\u0000 DST operations in tight reservoirs have always been limited and deemed challenging due to complexities associated with the ability to create enough pressure drawdown, high risks associated with the inability of the well to flow to surface to unload the liquids from the wellbore, and clean-up of the well to unlock true reservoir potential. Therefore, for the last several decades, the oil industry has been trying to find the most effective ways to flow test these wells to determine essential reservoir information and minimize field development risks.\u0000 Impulse testing is not a new concept and enables testing a well using a simple DST or tubing-conveyed perforating (TCP) string with no flow of hydrocarbon to surface. This method also reduces cost in comparison with conventional DST operations or other standard testing methods. Until recently, the application of this type of test has been limited, mainly by the complexity of interpreting the test data, limited functionalities of the tools, low success rate, and poor quality of acquired data. With the evolution of downhole DST tool technology and enhancements in well test design, along with the appropriate equipment selection, a new generation of low flow rate impulse tests have been engineered for success by bringing together a multidisciplinary team and emphasizing the importance of the job design.\u0000 The paper describes cost-effective, practical, and proven impulse testing methods for tight oil and gas reservoirs. The proposed methods are versatile and adaptive to the operating environment and the operator's requirements. The zero-emission well testing solution is based on proven conventional well test interpretation methods and a combination of technologies, workflows, and unique equipment arrangements that make it possible to flow test the wells to determine key reservoir dynamic parameters and the productivity indices of new wells during DST or TCP operations or during workover operations if the wells are currently in production. This paper also presents several field examples from operations performed around the globe, with results of the successful pressure transient analysis of the data recorded during the tests that enab","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82317002","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
E. Sayfutdinov, S. Suetin, Oleg Olender, R. Gaynetdinov, E. Kazakov
As part of the implementation of unique projects of "Gazprom neft" in the regions located above the Arctic Circle, in difficult conditions of occurrence of Achimov deposits, it is necessary to apply new technical and technological approaches and solutions that are different from the standard conditions of hydraulic fracturing operations. The peculiarities of the mining and geological structure of the formations include the presence of abnormally high reservoir pressure with anomaly coefficient of 1.7 and high reservoir temperatures. One of the critical conditions is the autonomy of fields and climate conditions, which introduces additional challenges in the timing of the preparation and conducting of large-scale operations for hydraulic fracturing. This article reviews the experience of the Company's specialists in preparing and implementing operations of the Company's first multi-stage hydraulic fracturing at Achimov facilities with abnormally high reservoir pressure during the winter period of 2019, provides technical features and limitations for well completion, features of selection and adjustment of hydraulic fracturing equipment and process fluids different from standard operations. The features of the objects, which are under consideration, require more detailed and correct planning of each operation, starting from the completion stage, which includes features of the choice of the multi-stage HF arrangements, activation balls, sealing and locking devices. The article provides examples of calculating the required diameter of the balls to hold them in the saddle and prevent the "rollback" effect with high residual back pressure, especially the docking of the "stinger" in the tubing and liner suspension. An important role is assigned to the integrated process of assessing and calculating potential risks within the framework of the cross-functional team. The method of "mastering on paper" is shown, in which the planning of each activity and stage is prescribed step by step, both within the Company and within the service organizations involved in the process (stocks of equipment capacity, spare parts, logistics, decision-making, etc.). The principle of drawing up and maintaining "road maps" as a method for monitoring and assessing the quality of current preparation and implementation of the process is also considered. On the basis of conducted earlier single hydraulic fracturing on directional wells, the main "weaknesses" were identified, which were not previously taken into account when such projects were preparing and implementing. Conclusions based on this experience allowed more qualitative approach to the implementation of multi-stage HF, but did not take into account the changed features associated with the pumping of large volumes of proppant at 7-stage completion. Conducting the first operation of the multi-stage pilot operation showed that the standard approach is not enough. The time spent on the full cycle of hydraulic fracturi
{"title":"Technical and Technological Solutions for the Implementation of Hydraulic Fracturing in Conditions of Overpressured Reservoirs Beyond the Arctic Circle","authors":"E. Sayfutdinov, S. Suetin, Oleg Olender, R. Gaynetdinov, E. Kazakov","doi":"10.2118/196990-ms","DOIUrl":"https://doi.org/10.2118/196990-ms","url":null,"abstract":"\u0000 As part of the implementation of unique projects of \"Gazprom neft\" in the regions located above the Arctic Circle, in difficult conditions of occurrence of Achimov deposits, it is necessary to apply new technical and technological approaches and solutions that are different from the standard conditions of hydraulic fracturing operations. The peculiarities of the mining and geological structure of the formations include the presence of abnormally high reservoir pressure with anomaly coefficient of 1.7 and high reservoir temperatures. One of the critical conditions is the autonomy of fields and climate conditions, which introduces additional challenges in the timing of the preparation and conducting of large-scale operations for hydraulic fracturing.\u0000 This article reviews the experience of the Company's specialists in preparing and implementing operations of the Company's first multi-stage hydraulic fracturing at Achimov facilities with abnormally high reservoir pressure during the winter period of 2019, provides technical features and limitations for well completion, features of selection and adjustment of hydraulic fracturing equipment and process fluids different from standard operations.\u0000 The features of the objects, which are under consideration, require more detailed and correct planning of each operation, starting from the completion stage, which includes features of the choice of the multi-stage HF arrangements, activation balls, sealing and locking devices. The article provides examples of calculating the required diameter of the balls to hold them in the saddle and prevent the \"rollback\" effect with high residual back pressure, especially the docking of the \"stinger\" in the tubing and liner suspension.\u0000 An important role is assigned to the integrated process of assessing and calculating potential risks within the framework of the cross-functional team. The method of \"mastering on paper\" is shown, in which the planning of each activity and stage is prescribed step by step, both within the Company and within the service organizations involved in the process (stocks of equipment capacity, spare parts, logistics, decision-making, etc.). The principle of drawing up and maintaining \"road maps\" as a method for monitoring and assessing the quality of current preparation and implementation of the process is also considered.\u0000 On the basis of conducted earlier single hydraulic fracturing on directional wells, the main \"weaknesses\" were identified, which were not previously taken into account when such projects were preparing and implementing. Conclusions based on this experience allowed more qualitative approach to the implementation of multi-stage HF, but did not take into account the changed features associated with the pumping of large volumes of proppant at 7-stage completion. Conducting the first operation of the multi-stage pilot operation showed that the standard approach is not enough. The time spent on the full cycle of hydraulic fracturi","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77513767","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pressure-transient solutions for homogeneous and composite elliptical flow models have been presented by several authors over the past 40 years, but all have computational limitations, either with respect to time range or degree of eccentricity of elliptical boundaries. This paper removes these limitations on time and eccentricity with a new fully flexible computational scheme for unbounded and bounded homogeneous and composite elliptical flow also extended to cases with a limited-height inner boundary, thus also covering horizontal well scenarios in composite elliptic models. Kuchuk and Brigham's (1979) Laplace-space solution is fully flexible with respect to the shape of ellipses, but has a lower limit on time that does not reach purely linear early data unless slow extended precision computations are used. However, this limitation can be removed with the approach of Riley et al. (1991) using asymptotic expansions for early data and Kuchuk and Brigham's (1979) solution for late data. This works for a fracture as inner boundary but has restrictions on the outer boundary. Another asymptotic expansion was used by van den Hoek (2016) to derive a more flexible but not fully flexible solution, since limitations remain for highly eccentric scenarios. This paper extends results from these references with other asymptotic expansions to achieve full flexibility on time and eccentricity. A wide range of examples are included to highlight the flexibility and utility of the new solutions, with cases ranging from damage-zone dimensions to long-time injection-falloff scenarios, but only as stationary cases with emphasis on the dimensions of the scenarios. Contrasts between exact degenerate elliptical models and standard solutions for infinite-conductivity fractures based on uniform-flux models and an equivalent pressure point are also discussed briefly. This concerns a solution artifact that might be overlooked. With a limited-height fracture used as a horizontal well replacement, cases are also included for horizontal wells in composite elliptical models.
在过去的40年里，已经有几位作者提出了均匀和复合椭圆流模型的压力瞬态解，但它们都有计算局限性，要么是时间范围，要么是椭圆边界的偏心度。本文采用了一种新的完全灵活的计算方案，消除了这些时间和偏心的限制，该方案适用于无界和有界均匀和复合椭圆流，并扩展到具有有限高度内边界的情况，从而也涵盖了复合椭圆模型中的水平井场景。Kuchuk和Brigham(1979)的拉普拉斯空间解在椭圆形状方面是完全灵活的，但在时间上有下限，除非使用缓慢的扩展精度计算，否则不能达到纯线性的早期数据。然而，这种限制可以通过Riley等人(1991)对早期数据使用渐近展开式和Kuchuk和Brigham(1979)对晚期数据的解决方案来消除。这适用于作为内边界的裂缝，但对外边界有限制。van den Hoek(2016)使用了另一个渐近展开来推导出一个更灵活但不是完全灵活的解决方案，因为对于高度偏心的场景仍然存在限制。本文用其他渐近展开式推广了这些文献的结果，以获得在时间和偏心上的充分灵活性。为了突出新解决方案的灵活性和实用性，包括从损伤区域尺寸到长时间注入脱落场景的各种案例，但仅作为固定案例，强调了场景的尺寸。并简要讨论了基于均匀通量模型和等效压力点的无限导流裂缝精确简并椭圆模型与标准解的对比。这涉及到一个可能被忽略的解决方案工件。随着有限高度裂缝被用作水平井的替代，在复合椭圆模型中也包括了水平井的情况。
{"title":"Unrestricted Pressure-Transient Solutions for Homogeneous and Composite Elliptical Flow Models with Limited and Full Height Inner Boundary","authors":"Leif Larsen","doi":"10.2118/196842-ms","DOIUrl":"https://doi.org/10.2118/196842-ms","url":null,"abstract":"\u0000 Pressure-transient solutions for homogeneous and composite elliptical flow models have been presented by several authors over the past 40 years, but all have computational limitations, either with respect to time range or degree of eccentricity of elliptical boundaries. This paper removes these limitations on time and eccentricity with a new fully flexible computational scheme for unbounded and bounded homogeneous and composite elliptical flow also extended to cases with a limited-height inner boundary, thus also covering horizontal well scenarios in composite elliptic models.\u0000 Kuchuk and Brigham's (1979) Laplace-space solution is fully flexible with respect to the shape of ellipses, but has a lower limit on time that does not reach purely linear early data unless slow extended precision computations are used. However, this limitation can be removed with the approach of Riley et al. (1991) using asymptotic expansions for early data and Kuchuk and Brigham's (1979) solution for late data. This works for a fracture as inner boundary but has restrictions on the outer boundary. Another asymptotic expansion was used by van den Hoek (2016) to derive a more flexible but not fully flexible solution, since limitations remain for highly eccentric scenarios. This paper extends results from these references with other asymptotic expansions to achieve full flexibility on time and eccentricity.\u0000 A wide range of examples are included to highlight the flexibility and utility of the new solutions, with cases ranging from damage-zone dimensions to long-time injection-falloff scenarios, but only as stationary cases with emphasis on the dimensions of the scenarios. Contrasts between exact degenerate elliptical models and standard solutions for infinite-conductivity fractures based on uniform-flux models and an equivalent pressure point are also discussed briefly. This concerns a solution artifact that might be overlooked. With a limited-height fracture used as a horizontal well replacement, cases are also included for horizontal wells in composite elliptical models.","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82151938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Temirlan Zhekenov, K. Chettykbayeva, A. Cheremisin, Alexey Sobolev, Y. Petrakov
Successful well planning and stimulation in complex geological settings (especially in the horizontal wells and wells with a high degree of deviation) is bound with conducting geomechanical estimations. Identification of the stress regime, which is an imperative basis for the geomechanical modeling, can significantly alter the reservoir production scheme. Moreover, knowledge of the stress regime directly impacts the efficiency of hydraulic fracturing procedures and wellbore stability. For example, in case of reverse stress regime, the hydraulic fracturing operations could be inefficient due to the problems with the fracture initiation, high injection pressures, and risks associated with the proppant fallout in the wellbore. Fields experiencing hydraulic fracturing problems should be assessed via the geomechanical frame of reference for the comprehensive understanding of the issue. Assessing the state of stress is challenged by the absence of direct measurement tools of maximum horizontal stress. Application of the stress estimation methods commonly used in the industry (including the breakout width, acoustic anisotropy inversion and poroelastic modeling with the assumption of tectonic coefficients) have certain limitations which often lead to a broad range of obtained values of maximum horizontal stress, thus adding uncertainty to the drilling and hydraulic fracturing recommendations. Thus, the main goal of this work is to develop and apply an instrument for qualitative assessment of stress regime and direction. The reliable mathematical model, built upon the minimal set of required data, which is able to forecast the rock behavior under far-field and near wellbore stresses can be an extremely useful instrument for effective operations of drilling, fracturing, well placement and reservoir development. The underlying method for the development of the stress inversion algorithm was based on limiting the range of possible values of horizontal stresses using Anderson's definition of stress regimes, the frictional theory of Mohr-Coulomb and Kirch equations. The subsequent analysis of the breakout azimuths at the wellbore walls of several inclined wells from the image log data results in a reliable prediction of reservoir stress regime and direction. The optimal usage of the method required knowledge of vertical stress and the borehole failures logged in the deviated wells with the inclination of at least 20° and varying azimuthal directions. The developed algorithm of the improved identification of stress regime was then applied for a real field case in order to understand the geomechanical roots of the problems experienced during hydraulic fracturing treatment. Learning the stress regime and the orientation of the horizontal stresses allowed building reliable geomechanical models, necessary for the optimization of the hydraulic fracturing program and improvement of well operating efficiency. The conclusion upon the conducted work was that the
{"title":"Development and Application of Algorithm for Stress Inversion Based on Image Log Data","authors":"Temirlan Zhekenov, K. Chettykbayeva, A. Cheremisin, Alexey Sobolev, Y. Petrakov","doi":"10.2118/196902-ms","DOIUrl":"https://doi.org/10.2118/196902-ms","url":null,"abstract":"\u0000 Successful well planning and stimulation in complex geological settings (especially in the horizontal wells and wells with a high degree of deviation) is bound with conducting geomechanical estimations. Identification of the stress regime, which is an imperative basis for the geomechanical modeling, can significantly alter the reservoir production scheme. Moreover, knowledge of the stress regime directly impacts the efficiency of hydraulic fracturing procedures and wellbore stability. For example, in case of reverse stress regime, the hydraulic fracturing operations could be inefficient due to the problems with the fracture initiation, high injection pressures, and risks associated with the proppant fallout in the wellbore. Fields experiencing hydraulic fracturing problems should be assessed via the geomechanical frame of reference for the comprehensive understanding of the issue.\u0000 Assessing the state of stress is challenged by the absence of direct measurement tools of maximum horizontal stress. Application of the stress estimation methods commonly used in the industry (including the breakout width, acoustic anisotropy inversion and poroelastic modeling with the assumption of tectonic coefficients) have certain limitations which often lead to a broad range of obtained values of maximum horizontal stress, thus adding uncertainty to the drilling and hydraulic fracturing recommendations.\u0000 Thus, the main goal of this work is to develop and apply an instrument for qualitative assessment of stress regime and direction. The reliable mathematical model, built upon the minimal set of required data, which is able to forecast the rock behavior under far-field and near wellbore stresses can be an extremely useful instrument for effective operations of drilling, fracturing, well placement and reservoir development.\u0000 The underlying method for the development of the stress inversion algorithm was based on limiting the range of possible values of horizontal stresses using Anderson's definition of stress regimes, the frictional theory of Mohr-Coulomb and Kirch equations. The subsequent analysis of the breakout azimuths at the wellbore walls of several inclined wells from the image log data results in a reliable prediction of reservoir stress regime and direction. The optimal usage of the method required knowledge of vertical stress and the borehole failures logged in the deviated wells with the inclination of at least 20° and varying azimuthal directions.\u0000 The developed algorithm of the improved identification of stress regime was then applied for a real field case in order to understand the geomechanical roots of the problems experienced during hydraulic fracturing treatment. Learning the stress regime and the orientation of the horizontal stresses allowed building reliable geomechanical models, necessary for the optimization of the hydraulic fracturing program and improvement of well operating efficiency.\u0000 The conclusion upon the conducted work was that the ","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82243451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Yudin, M. Rakhmatullin, D. Sadykova, O. Olennikova, Andrey O. Fedorov, Yuri Miklin, Mikhail Bernyaev, A. Kovalevskiy
Western Siberia has a long and successful history of channel hydraulic fracturing technology implementation. However, there is an urgent need to further reduce the cost of hydraulic fracturing. As a solution, it was proposed to use local suppliers of quartz sand to replace a substantial proportion of the more expensive ceramic proppant. Based on the principles of the classical channel fracturing, fracture permeability is provided by creating open channels in the intervals between proppant clusters. Open channels are created by feeding proppant in pulses simultaneously with a continuous supply of fiber, which subsequently dissolves under the action of reservoir temperature. The use of quartz sand during hydraulic fracturing in reservoirs with high stresses is thus possible only with the channel fracture method of proppant placement and is justified by the fact that the fracture conductivity in this case does not depend on the permeability of the proppant itself. Open channels play a key role. Thus, the need to reduce the cost of service is justified not only economically, but also technologically. The first step in the implementation of the technology was the successful application of traditional channel fracturing using ceramic and resin-coated proppant at the fields in the Uvat region, more than 60 operations in total. The best results on productivity were obtained in multi-stage hydraulic fracturing operations in horizontal wells, where additional effects of up to 20% relative to the standard method were obtained. Advantages in the form of accelerated operations (up to 15%) were also confirmed by reducing the duration of the preparatory work; minimize workover cleanouts after premature screen-out due to minimized risks since fibers and pulses of pure liquid ensure better proppant admittance. Significantly reduced costs for logistics and storage of proppaant, which is most relevant in the conditions of autonomous fields. As a result of a successful pilot campaign, it was decided to test injection of quartz sand during channel fracturing operations. Laboratory tests have been carried out and a risk analysis has been formalized, which described in detail in following sections. The first candidates during the pilot campaign were injection wells followed by a testing plan at a producing well stock. The experience of using quartz sand during hydraulic fracturing is innovative for sandstones after numerous attempts at the hydraulic fracturing dawn decades ago that revealed insufficient sand conductivity and required a switch to expensive ceramic proppant. The reincarnation of the perspectives of quartz sand in medium permeability reservoirs was provided by the channel fracturing method, which removes the connection between proppant permeability and fracture conductivity due to the presence of open channels. The experience in the Uvat region will be the first published in Russia and will allow further developments in this direction.
{"title":"Local-Sand-Enabled Channel Fracturing. Case Study from Jurassic Formations in Uvat Region","authors":"A. Yudin, M. Rakhmatullin, D. Sadykova, O. Olennikova, Andrey O. Fedorov, Yuri Miklin, Mikhail Bernyaev, A. Kovalevskiy","doi":"10.2118/196972-ms","DOIUrl":"https://doi.org/10.2118/196972-ms","url":null,"abstract":"\u0000 Western Siberia has a long and successful history of channel hydraulic fracturing technology implementation. However, there is an urgent need to further reduce the cost of hydraulic fracturing. As a solution, it was proposed to use local suppliers of quartz sand to replace a substantial proportion of the more expensive ceramic proppant.\u0000 Based on the principles of the classical channel fracturing, fracture permeability is provided by creating open channels in the intervals between proppant clusters. Open channels are created by feeding proppant in pulses simultaneously with a continuous supply of fiber, which subsequently dissolves under the action of reservoir temperature. The use of quartz sand during hydraulic fracturing in reservoirs with high stresses is thus possible only with the channel fracture method of proppant placement and is justified by the fact that the fracture conductivity in this case does not depend on the permeability of the proppant itself. Open channels play a key role. Thus, the need to reduce the cost of service is justified not only economically, but also technologically.\u0000 The first step in the implementation of the technology was the successful application of traditional channel fracturing using ceramic and resin-coated proppant at the fields in the Uvat region, more than 60 operations in total. The best results on productivity were obtained in multi-stage hydraulic fracturing operations in horizontal wells, where additional effects of up to 20% relative to the standard method were obtained. Advantages in the form of accelerated operations (up to 15%) were also confirmed by reducing the duration of the preparatory work; minimize workover cleanouts after premature screen-out due to minimized risks since fibers and pulses of pure liquid ensure better proppant admittance. Significantly reduced costs for logistics and storage of proppaant, which is most relevant in the conditions of autonomous fields. As a result of a successful pilot campaign, it was decided to test injection of quartz sand during channel fracturing operations. Laboratory tests have been carried out and a risk analysis has been formalized, which described in detail in following sections. The first candidates during the pilot campaign were injection wells followed by a testing plan at a producing well stock.\u0000 The experience of using quartz sand during hydraulic fracturing is innovative for sandstones after numerous attempts at the hydraulic fracturing dawn decades ago that revealed insufficient sand conductivity and required a switch to expensive ceramic proppant. The reincarnation of the perspectives of quartz sand in medium permeability reservoirs was provided by the channel fracturing method, which removes the connection between proppant permeability and fracture conductivity due to the presence of open channels. The experience in the Uvat region will be the first published in Russia and will allow further developments in this direction.","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78113571","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Osiptsov, A. Vainshtein, S. Boronin, I. Faizullin, G. Paderin, Andrei Shurunov, R. Uchuev, I. Garagash, K. Tolmacheva, Konstantin Lezhnev, D. Prunov, N. Chebykin
Selection of an optimum scenario of well flowback and startup after multistage fracturing and the design of the field experiment are based on mathematical modeling of filtration in a propped fracture, taking into account the compaction of a proppant pack, embedment of proppant into the fracture faces, tensile failure of the fracture walls and proppant flowback. For this purpose, we have proposed a simulation-based process for the development of a series of field trials for the well flowback after multistage fracturing. There are two different scenarios of flowback regime (smooth and aggressive) with a step-wise increase in the diameter of the choke to determine the upper and lower limits of the safe operating envelope of the well flowback. Based on the results of a series of parametric calculations, the preferred ranges of implementation of the flowback technology are formulated in terms of the steps of change and the duration of the periods of constant diameter of the choke, which are planned to be tested in the field. Several horizontal wells with hydraulic fracturing at the terrigenous field of Western Siberia will be planned to study the impact of inflow dynamics on the pipeline. To test the research hypotheses, two limiting scenarios of the flowback were proposed in terms of the dynamics of the opening of the choke with time: "smooth" and "aggressive" (the well is flowing without assistance, before the installation of the ESP). In addition to monitoring the parameters of well production (flow rate, water cut, bottom hole and wellhead pressure), suspension samples will be taken to analyze the particulate content, according to a pre-approved schedule for the purpose of granulometric analysis of the solid phase. The results of parametric numerical calculations, based on our in-house hydrodynamic and geomechanical models, allowed us to determine the critical values of drawdown, in which undesirable geomechanical phenomena are realized (primarily proppant flowback, proppant embedment into the fracture walls and compression of the proppant pack under the action of closure stresses and associated reduction in the width of the propped fracture, as well as the risk of rock failure). Parametric model-based studies suggest a hypothesis for testing in the field that the accumulated production after hydraulic fracturing depends on the dynamics of flowback and well startup. To select candidate wells, we use the results of solving the inverse problem to determine the governing parameters of the formation, in which undesirable geomechanical effects are most pronounced, as well as to take into account the requirements for the representativeness and repeatability of field tests. On the basis of the field data, a decision tree will be formed to maximize the efficiency of the experiment and operational supervision. The authors are aware of the scale of uncertainties associated with the interpretation of data obtained as a result of field experiments. The dema
{"title":"Towards Field Testing of the Flowback Technology for Multistage-Fractured Horizontal Wells: Modeling-Based Design and Practical Implications","authors":"A. Osiptsov, A. Vainshtein, S. Boronin, I. Faizullin, G. Paderin, Andrei Shurunov, R. Uchuev, I. Garagash, K. Tolmacheva, Konstantin Lezhnev, D. Prunov, N. Chebykin","doi":"10.2118/196979-ms","DOIUrl":"https://doi.org/10.2118/196979-ms","url":null,"abstract":"\u0000 Selection of an optimum scenario of well flowback and startup after multistage fracturing and the design of the field experiment are based on mathematical modeling of filtration in a propped fracture, taking into account the compaction of a proppant pack, embedment of proppant into the fracture faces, tensile failure of the fracture walls and proppant flowback. For this purpose, we have proposed a simulation-based process for the development of a series of field trials for the well flowback after multistage fracturing. There are two different scenarios of flowback regime (smooth and aggressive) with a step-wise increase in the diameter of the choke to determine the upper and lower limits of the safe operating envelope of the well flowback. Based on the results of a series of parametric calculations, the preferred ranges of implementation of the flowback technology are formulated in terms of the steps of change and the duration of the periods of constant diameter of the choke, which are planned to be tested in the field. Several horizontal wells with hydraulic fracturing at the terrigenous field of Western Siberia will be planned to study the impact of inflow dynamics on the pipeline. To test the research hypotheses, two limiting scenarios of the flowback were proposed in terms of the dynamics of the opening of the choke with time: \"smooth\" and \"aggressive\" (the well is flowing without assistance, before the installation of the ESP). In addition to monitoring the parameters of well production (flow rate, water cut, bottom hole and wellhead pressure), suspension samples will be taken to analyze the particulate content, according to a pre-approved schedule for the purpose of granulometric analysis of the solid phase. The results of parametric numerical calculations, based on our in-house hydrodynamic and geomechanical models, allowed us to determine the critical values of drawdown, in which undesirable geomechanical phenomena are realized (primarily proppant flowback, proppant embedment into the fracture walls and compression of the proppant pack under the action of closure stresses and associated reduction in the width of the propped fracture, as well as the risk of rock failure). Parametric model-based studies suggest a hypothesis for testing in the field that the accumulated production after hydraulic fracturing depends on the dynamics of flowback and well startup. To select candidate wells, we use the results of solving the inverse problem to determine the governing parameters of the formation, in which undesirable geomechanical effects are most pronounced, as well as to take into account the requirements for the representativeness and repeatability of field tests. On the basis of the field data, a decision tree will be formed to maximize the efficiency of the experiment and operational supervision. The authors are aware of the scale of uncertainties associated with the interpretation of data obtained as a result of field experiments. The dema","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87052271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhaozhong Yang, Rui He, Jianlin Chen, Xiaogang Li, Bing Xie, J. Meng, Wenhong Li
The North Mahu Oilfield in western China contains abundant tight glutenite oil resources. The use of horizontal well fracturing has become the main development method in the region. However, the tight oil reservoirs have poor physical properties. After a period of production, some hydraulic fractures in the horizontal wells close, resulting in rapid decline in production. Therefore, Re-fracturing must be implemented to restore and increase oil production. In this paper, a comprehensive evaluation model for the horizontal well selection of tight oil re-fracturing is established, and a three - hierarchy system including the target layer, the criterion layer and the scheme layer is structured. The analytic hierarchy process (AHP) method, grey correlation (GR) method and entropy weight (EW) method are used to calculate the weights of factors influencing re-fracturing effects, and TOSIS method is combined to quantify the re-fracturing potential of the candidate wells, so that well H is selected to implement re-fracturing construction based on the established mathematical model. From the aspects of oil reserves, reservoir energy, wellbore conditions and reservoir fracability, the feasibility of re-fracturing of well H was carried out, and the degradable granular chemical diverting agent was preferentially used. The design of "re-open old fractures + perforate new holes+ supply reservoir energy+ real time microseismic monitoring" was designed. Re-fracturing construction of well H was implemented smoothly, and the obtained stimulated reservoir volume (SRV) exceeded 107m3. According to the production data, the daily oil production continued to rise initially, which was once over 30t/d.
{"title":"A Hybrid Model for Selecting Horizontal Candidate Wells for Re-Fracturing of Tight Oil Reservoirs—A Case Study in the Baikouquan Formation, North Mahu Oil Field, Western China","authors":"Zhaozhong Yang, Rui He, Jianlin Chen, Xiaogang Li, Bing Xie, J. Meng, Wenhong Li","doi":"10.2118/196975-ms","DOIUrl":"https://doi.org/10.2118/196975-ms","url":null,"abstract":"\u0000 The North Mahu Oilfield in western China contains abundant tight glutenite oil resources. The use of horizontal well fracturing has become the main development method in the region. However, the tight oil reservoirs have poor physical properties. After a period of production, some hydraulic fractures in the horizontal wells close, resulting in rapid decline in production. Therefore, Re-fracturing must be implemented to restore and increase oil production. In this paper, a comprehensive evaluation model for the horizontal well selection of tight oil re-fracturing is established, and a three - hierarchy system including the target layer, the criterion layer and the scheme layer is structured. The analytic hierarchy process (AHP) method, grey correlation (GR) method and entropy weight (EW) method are used to calculate the weights of factors influencing re-fracturing effects, and TOSIS method is combined to quantify the re-fracturing potential of the candidate wells, so that well H is selected to implement re-fracturing construction based on the established mathematical model. From the aspects of oil reserves, reservoir energy, wellbore conditions and reservoir fracability, the feasibility of re-fracturing of well H was carried out, and the degradable granular chemical diverting agent was preferentially used. The design of \"re-open old fractures + perforate new holes+ supply reservoir energy+ real time microseismic monitoring\" was designed. Re-fracturing construction of well H was implemented smoothly, and the obtained stimulated reservoir volume (SRV) exceeded 107m3. According to the production data, the daily oil production continued to rise initially, which was once over 30t/d.","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84546460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Narkes Gaysina, A. Bochkarev, D. Chernyshev, N. Parshin, A. Ryazanov
In this paper authors present pressure decline analysis after injection tests using diagnostic plots with focus on events that occur before the fracture closure (PCA). The main feature of used method is that analysis is performed by identifying mistakes during interpretation that can disrupt pressure decline curve. The essential instrument of interpretation in our method is Log-Log plot. Some effects which were earlier relating to "nonideal behavior" are removed from the analysis as they are not result of work of a reservoir – fracture system, but mistakenly interpreted factors. The last is made by standardizing of Log-Log plot to a "normal" form at the dominating in time period of the linear flow in a fracture. GdP/dG plot is referential instrument whereby fracture closure pressure can be determined in small point vicinities explicit in Log-Log plot. This paper discusses the existing methods of fracturing parameters determination, the analysis of completeness and clarity of these methods is carried out. Approaches to interpretation of J-shaped curves of pressure decline and the most probable causes of such behavior of pressure were discussed in the context of "nonideal behavior" in many papers. According to our method, Interpretation of pressure decline should at first been carried out according to "ideal behavior". Interpretation of S-shaped curves of pressure decline can be also carried out in the context of "ideal behavior", and leads, according to this paper authors, to correct assessment of efficiency and net pressure in fracture. Paper is aimed at presenting of practical actions of the engineer in pressure decline analysis in low-permeable reservoirs. In this case, fracture can have the sufficient sizes to observation allowing to identify on Log-Log plot the characteristic flow states. This factor causes limits of applicability of the offered method. Definition of application, requires carrying out the analysis of statistics on fields, including the analysis as behavior of pressure decline after injection tests, so and production performance. Described method was applied on field in Western Siberia. Occurred production problems were the cause to start investigation of pressure decline analysis methods.
{"title":"Specifics of Pressure Analysis of Multi-Stage Hydraulic Fracturing of Horizontal Wells Completed in Low Permeable Reservoir","authors":"Narkes Gaysina, A. Bochkarev, D. Chernyshev, N. Parshin, A. Ryazanov","doi":"10.2118/196987-ms","DOIUrl":"https://doi.org/10.2118/196987-ms","url":null,"abstract":"\u0000 In this paper authors present pressure decline analysis after injection tests using diagnostic plots with focus on events that occur before the fracture closure (PCA). The main feature of used method is that analysis is performed by identifying mistakes during interpretation that can disrupt pressure decline curve. The essential instrument of interpretation in our method is Log-Log plot. Some effects which were earlier relating to \"nonideal behavior\" are removed from the analysis as they are not result of work of a reservoir – fracture system, but mistakenly interpreted factors. The last is made by standardizing of Log-Log plot to a \"normal\" form at the dominating in time period of the linear flow in a fracture. GdP/dG plot is referential instrument whereby fracture closure pressure can be determined in small point vicinities explicit in Log-Log plot.\u0000 This paper discusses the existing methods of fracturing parameters determination, the analysis of completeness and clarity of these methods is carried out. Approaches to interpretation of J-shaped curves of pressure decline and the most probable causes of such behavior of pressure were discussed in the context of \"nonideal behavior\" in many papers. According to our method, Interpretation of pressure decline should at first been carried out according to \"ideal behavior\". Interpretation of S-shaped curves of pressure decline can be also carried out in the context of \"ideal behavior\", and leads, according to this paper authors, to correct assessment of efficiency and net pressure in fracture.\u0000 Paper is aimed at presenting of practical actions of the engineer in pressure decline analysis in low-permeable reservoirs. In this case, fracture can have the sufficient sizes to observation allowing to identify on Log-Log plot the characteristic flow states. This factor causes limits of applicability of the offered method. Definition of application, requires carrying out the analysis of statistics on fields, including the analysis as behavior of pressure decline after injection tests, so and production performance.\u0000 Described method was applied on field in Western Siberia. Occurred production problems were the cause to start investigation of pressure decline analysis methods.","PeriodicalId":10977,"journal":{"name":"Day 2 Wed, October 23, 2019","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2019-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81310859","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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