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Collaborating Authors
Results
A Two-Phase Type-Curve Method with Fracture Damage Effects for Hydraulically Fractured Reservoirs
Zhang, Fengyuan (National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum-Beijing, Beijing, China) | Pan, Yang (National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum-Beijing, Beijing, China) | Rui, Zhenhua (National Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum-Beijing, Beijing, China) | Emami-Meybodi, Hamid (Department of Energy and Mineral Engineering and EMS Energy Institute, The Pennsylvania State University, State College, Pennsylvania, USA) | Yang, Chia-Hsin (Department of Energy and Mineral Engineering and EMS Energy Institute, The Pennsylvania State University, State College, Pennsylvania, USA) | Wang, Ruiqi (Department of Oil Field Development, Research Institute of Petroleum Exploration & Development, Beijing, China) | Zhang, Wei (Department of Geoscience, University of Calgary, Calgary, Alberta, Canada)
Abstract Type-curve analysis on flowback and production data is a powerful tool in characterizing hydraulic fractures (HF) and reservoir properties. In order to evaluate HF characteristics and their dynamics for multi-fractured horizontal wells (MFHWs) in hydrocarbon reservoirs, we provide a novel type-curve method and an iterative workflow. The type curve incorporates the fracture damage effect, which is characterized by choked-fracture skin factor, into the two-phase flow in HF and matrix domains. The type-curve method can be applied to inversely estimate choked-fracture skin factor, fracture pore-volume, fracture premeability, and fracture permeability modulus through the analysis of two-phase production data. By introducing the new dimensionless parameters, the non-uniqueness problem of the proposed semianalytical method is significantly reduced by incorporating the complexity of fracture dynamics into one set of curves. The proposed type curve's accuracy is examined by numerical simulations of a shale gas and shale oil reservoir. The validation results demonstrate the good match of analytical type curves and numerical data plots and confirms the accuracy of the proposed approach in estimating the static and dynamic fracture properties. The flexibility and robustness of the proposed method are illustrated using the field example from a shale oil MFHW. The interpreted results from the flowback analysis of the field example offers a quantitative insight of fracture properties and dynamics.
- North America > United States (1.00)
- North America > Canada > Alberta (0.28)
- Geology > Geological Subdiscipline (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.90)
- North America > United States > Gulf of Mexico > Central GOM > West Gulf Coast Tertiary Basin > Walker Ridge > Block 628 > Julia Field (0.99)
- North America > United States > Gulf of Mexico > Central GOM > West Gulf Coast Tertiary Basin > Walker Ridge > Block 627 > Julia Field (0.99)
- North America > United States > Gulf of Mexico > Central GOM > West Gulf Coast Tertiary Basin > Walker Ridge > Block 584 > Julia Field (0.99)
- (2 more...)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- (8 more...)
A Real-Time Inversion Approach for Fluid-Flow Fractures in Unconventional Stimulated Reservoirs
Sheng, Guanglong (Hubei Key Laboratory of Drilling and Production Engineering for Oil and Gas, Yangtze University / School of Petroleum Engineering, Yangtze University) | Zhao, Hui (Hubei Key Laboratory of Drilling and Production Engineering for Oil and Gas, Yangtze University / School of Petroleum Engineering, Yangtze University (Corresponding author)) | Huang, Luoyi (Hubei Key Laboratory of Drilling and Production Engineering for Oil and Gas, Yangtze University / School of Petroleum Engineering, Yangtze University (Corresponding author)) | Huang, Hao (Hubei Key Laboratory of Drilling and Production Engineering for Oil and Gas, Yangtze University / School of Petroleum Engineering, Yangtze University) | Liu, Jinghua (Hubei Key Laboratory of Drilling and Production Engineering for Oil and Gas, Yangtze University / School of Petroleum Engineering, Yangtze University)
Summary Fluid-flow fractures, through which fluids can move under pressure, make a more significant contribution to increasing production than do microseismic and propagation fractures. An accurate description of the distribution of fluid-flow fractures is the basis for evaluating hydraulic fracturing and oil/gas recovery. In this study, a real-time inversion approach for fluid-flow fractures was proposed, and the complex fluid-flow fracture morphology was obtained in real time by updating the data of the fracturing construction curve. First, a dynamic permeability model was proposed to describe the filtration rate of the fracturing fluid during hydraulic fracturing. Combined with the point source function, the flowing bottomhole pressure (pwf) can be quickly calculated based on the fracture morphology and displacement of the fracturing fluid. The variance of pwf and bottomhole pressure (pwb) obtained by pump pressure were used as an objective function, and the length of fluid-flow fractures and fracture morphology were used as fitting parameters. The length of the fluid-flow fractures was updated with the simultaneous perturbation stochastic approximation (SPSA) to achieve a rough fitting of the bottomhole pressure. On this basis, a probability function was used to constrain the randomness of the fractures, and the fracture morphology with a fixed fracture length was continuously simulated and finely matched. Finally, a complex fluid-flow fracture morphology was obtained. The method was used to analyze the fluid-flow fracture morphology of multifractured horizontal wells in shale reservoirs, and the fitting rate of the fracturing construction curve was more than 95%. The results show that the total length of the fluid-flow fractures in one stage in naturally fractured reservoirs was approximately 629 m, and those in homogeneous reservoirs and high-stress difference reservoirs were 564 m and 532 m, respectively. The length of fluid-flow fractures with “grooves” in the fracturing construction curve was longer than the length of fluid-flow fractures with “bulges.” The effectively stimulated reservoir area with fluid-flow fractures was only approximately 28–51% of the stimulated reservoir area with microseismic fractures.
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.49)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- North America > United States > Texas > Permian Basin > Midland Basin (0.99)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- (3 more...)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- (5 more...)
A Comprehensive Review of Fracture-Driven Interaction in Unconventional Oil and Gas Plays: Characterization, Real-Time Diagnosis, and Impact on Production
Singh, Harpreet (CNPC USA, Houston) | Cheng, Peng (CNPC USA, Houston) | Pan, Yuwei (CNPC, Beijing) | Li, Chengxi (CNPC USA, Houston) | Liu, Yu (CNPC, Beijing) | Wu, Xi (CNPC, Beijing) | Van Domelen, Mary (Well Data Labs) | Rogers, Samuel (RevSolz Corp.) | Taleghani, Arash Dahi (Pennsylvania State University) | Cao, Meng (The University of Texas at Austin)
Abstract The objective of this paper is to provide a comprehensive review of fracture-driven interaction (FDI) in unconventional oil and gas plays. This review aims to characterize FDI, diagnose it in real-time, and predict its impact on production. Methods, Procedures, Process The methodology of this study involves conducting a comprehensive literature review by collecting and analyzing data from various sources, including published literature, technical reports, and field data. The paper focuses on the characterization of FDI in terms of its controlling factors, types of FDI, and FDIs measured in different plays. Real-time diagnosis of FDI is explored using pressure timeseries analysis (PTA) and strain data analysis (SDA). Additionally, methods for predicting the impact of FDI on production were reviewed. Results, Observations, Conclusions Factors influencing FDI are reviewed, such as parent/off-set well depletion, petrophysical and geomechanical properties, well spacing, completion/stimulation parameters, and compressibility of fluid. The study outlines the characteristics of three FDI types (undrained poroelastic, indirect frac-hit, and direct frac-hit), and provides statistics of FDI pressures in various plays utilizing legacy monitoring and sealed wellbores. The study reviews real-time diagnosis and characterization of FDI and proposes three low-hanging fruit approaches for its improvement. Workflows for quantifying the impact of FDI on hydrocarbon production are not as effective as those for its diagnosis. Further research is needed to understand the impact of geological features, develop advanced diagnostic techniques, and quantitative methods to predict FDI's impact on production. Novel/Additive Information The study's findings and recommendations can inform the development of advanced real-time techniques to diagnose and characterize FDIs, improving fracturing designs. Gaps in knowledge are identified for further research.
- North America > United States > Texas (1.00)
- Asia > China (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.69)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (0.67)
- North America > United States > West Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Virginia > Appalachian Basin > Marcellus Shale Formation (0.99)
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- (54 more...)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- (10 more...)
- Information Technology > Architecture > Real Time Systems (1.00)
- Information Technology > Communications > Networks > Sensor Networks (0.45)
Transient Flow Performance of a Vertical Well With Multiple Varying Conductivity Fractures in a Tight Oil Reservoir
Xing, Guoqiang (School of Petroleum and Natural Gas Engineering, Changzhou University) | Dou, Xiangji (School of Petroleum and Natural Gas Engineering, Changzhou University (Corresponding author)) | Liu, Xianyong (Binnan Oil Production Plant of Shengli Oilfield Company, Sinopec) | Guo, Wenmin (School of Petroleum and Natural Gas Engineering, Changzhou University) | Wang, Mingxian (School of Earth Science and Engineering, Xi’an Shiyou University) | Tang, Ying (School of Earth Science and Engineering, Xi’an Shiyou University)
Summary Due to uneven proppant distribution and varied proppant sizes during hydraulic fracturing, artificial fractures of varying length, asymmetry, and varying conductivity are easily formed near the wellbore. The principal focus of this work is to investigate the pressure transient performance of a vertical well penetrated by multiple asymmetrical fractures with varying lengths and varying conductivities in a tight oil reservoir. A novel fracture flow equation was developed specifically to describe the flow behavior inside the complex artificial fractures mentioned above. By combining with the point source solution of the tight oil reservoir, a semianalytical solution was further obtained to analyze the pressure transient behavior of a vertical well with multiple varying-conductivity fractures in a tight oil reservoir. The accuracy and reliability of the newly-developed solution were verified by comparing with the result of a numerical model. With this new solution, fracture flux distribution for different conductivity modes, namely, linearly declining mode, exponentially declining mode, and elliptically declining mode, shows that the near-wellbore fracture flux of the exponential mode is greater than that of the other two modes, but the flux distribution near the fracture tips is on the contrary. Meanwhile, the transient flow characteristics under the above varying conductivity modes indicate that the exponentially varying conductivity has a significant influence on the early linear flow regimes, while the linear and elliptical mode only has a slight influence on the bilinear flow regime under high conductivity. Parameter sensitivity analysis reveals that the obvious inversion point occurring in the pressure derivative curves of uniform conductivity fractures disappears on the pressure derivative curves of varying conductivity fractures, and a weaker asymmetry, a greater adjacent fracture angle, and a larger fracture number and fracture length ratio are conducive to improve the fracturing stimulation effect. This study deepens our understanding of the transient flow performance of vertically fractured wells and helps to estimate artificial fracture properties and evaluate hydraulic fracturing performance.
- Asia > China (0.93)
- North America > United States > Texas (0.46)
- Geology > Geological Subdiscipline > Economic Geology > Petroleum Geology (1.00)
- Geology > Geological Subdiscipline > Geomechanics (0.93)
- North America > United States > Texas > Fort Worth Basin > Barnett Shale Formation (0.99)
- Asia > China > Shandong > North China Basin > Shengli Field (0.99)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (1.00)
- (4 more...)
Validation of Continuous Wavelet Transform Closure Detection Technique Using Strain Measurements
Adel Gabry, Mohamed (The University of Houston) | Eltaleb, Ibrahim (The University of Houston) | Soliman, M. Y. (The University of Houston) | Farouq-Ali, S. M. (The University of Houston) | Cook, Paul. J. (Lawrence Berkeley National Laboratory) | Soom, Florian. A. (Lawrence Berkeley National Laboratory) | Guglielmi, Yves (Lawrence Berkeley National Laboratory)
Abstract Although closure detection has a crucial role in hydraulic fracturing operations, significant debate surrounds the various methodologies to determine its value. Several competing methodologies have been presented in the literature that sometimesyield significantly different estimates of closure pressure and time. The conventional techniques rely on assumptions that may be competing or even contradictory. The continuous wavelets transform technique is a data transform technique that convolves the pressure and/or temperature data using a short wavy signal called "wavelet". The wavelet transform provides a representation of the pressure signal by letting the translation and scale parameters of the wavelets vary continuously. That enables the analyst to find the details of the pressure data by observing the wavelet energy spectrum for the monitored signal (pressure and/or temperature) signal. In this case the event of contact between two fracture faces and complete fracture closure is clearly identified. As a part of The EGS Collab project, a series of fracture injection tests have been conducted to estimate the minimum principal stress with direct observation of well bore deformation using the SIMFIP tool (Step-Rate Injection Method for Fracture In-Situ Properties). The tool monitors the deformation using strain gauges as a fracture opens and closes during multiple tests. The publicly available data provide a great opportunity to experimentally calibrate the new technique for detecting the closure event using continuous wavelet transform. The effect of fracture closure events and fracture faces contact events detected using continuous wavelet transform were compared to the experimental measured deformation. The continuous wavelet transform technique for closure detection showed an agreement with the deformation measurement. The effect of the presence of natural fractures and complex fracture closure events were recognized using the continuous wavelet transform technique. The Contineous Wavelet Transform (CWT) is a global technique that can be applied to the pressure decline data without requiring further information about the reservoir geomechanical parameters or pumping data. The technique can be easily embedded in machine learning algorithms for hydraulic fracturing diagnostics.
- North America > United States > Texas (0.46)
- North America > United States > California (0.28)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.46)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Reservoir geomechanics (1.00)
- (5 more...)
A Review of Hydraulic Fracturing and Latest Developments in Unconventional Reservoirs
Temizel, Cenk (Saudi Aramco) | Canbaz, Celal Hakan (Ege University) | Palabiyik, Yildiray (ITU) | Hosgor, Fatma Bahar (Petroleum Experts LLC) | Atayev, Hakmyrat (ITU) | Ozyurtkan, Mustafa Hakan (ITU) | Aydin, Hakki (METU) | Yurukcu, Mesut (UTPB) | Boppana, Narendra (UTPB)
Abstract Hydraulic fracturing is a widely accepted and applied stimulation method in the unconventional oil and gas industry. With the increasing attention to unconventional reservoirs, hydraulic fracturing technologies have developed and improved more in the last few years. This study explores all applications of hydraulic fracturing methods to a great extent. It can be used as a guideline study, covering all the procedures and collected data for conventional reservoirs by considering the limited parameters of unconventional reservoirs. This paper intends to be a reference article containing all the aspects of the hydraulic fracturing method. A comprehensive study has been created by having a wide scope of examinations from the applied mechanisms to the technological materials conveyed from the different industries to utilize this technique efficiently. Furthermore, this study analyses the method, worldwide applications, advantages and disadvantages, and comparisons in different unconventional reservoirs. Various case studies that examine the challenges and pros & cons of hydraulic fracturing are included. Hydraulic fracturing is a promising stimulation technique that has been widely applied worldwide. It is challenging due to the tight and nanoporous nature, low permeability, complex geological structure, and in-situ stress field in unconventional reservoirs. Consequently, economic conditions and various parameters should be analyzed individually in each case for efficient applications. Therefore, this study provides the primary parameters and elaborate analysis of the techniques applied for a successful stimulation under SPECIFIC circumstances and provides a full spectrum of information needed for unconventional field developments. All the results are evaluated and detailed for each field case by providing the principles of applying hydraulic fracturing technologies. Many literature reviews provide different examples of hydraulic fraction methods; however, no study covers and links up both the main parameters and learnings from real cases worldwide. This study will fill this gap and illuminate the application of the hydraulic fracturing method.
- North America > United States > Texas (1.00)
- North America > United States > North Dakota (1.00)
- Europe (1.00)
- (4 more...)
- Research Report > Experimental Study (0.67)
- Research Report > New Finding (0.45)
- Overview > Innovation (0.45)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play > Shale Gas Play (1.00)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock (0.94)
- Geophysics > Seismic Surveying > Passive Seismic Surveying > Microseismic Surveying (1.00)
- Geophysics > Borehole Geophysics (1.00)
- Energy > Oil & Gas > Upstream (1.00)
- Materials > Chemicals > Commodity Chemicals > Petrochemicals (0.67)
- Well Drilling > Wellbore Design > Wellbore integrity (1.00)
- Well Drilling > Drilling Operations > Directional drilling (1.00)
- Well Completion > Hydraulic Fracturing > Multistage fracturing (1.00)
- (20 more...)
Integration of Pressure-Transient and Fracture Area for Detecting Unconventional Wells Interference
Ibrahim, Mazher (Shear Frac Group LLC) | Sinkey, Matt (Shear Frac Group LLC) | Johnston, Thomas (Shear Frac Group LLC) | Marouf, Shabnam (Shear Frac Group LLC) | Noynay, John (Shear Frac Group LLC) | Becerril, Joseph (Shear Frac Group LLC)
Abstract Hydraulic fractures created during completion operations are assumed to produce back to the original well. While multi-well pad completions increase efficiencies, it complicates fracture connectivity between wells. The proximity of newly completed wells to a pre-existing producing well suggests a depleted zone that can "steal" fracture surface area. Correlations between real-time shear fracture measurements and post-stage Pressure Transient Analysis (PTA) can shed light on the fracture surface area connected to the original well vs. fracture surface area "stolen" by offset wells. During hydraulic fracturing operations, shear fractures per slurry barrel are measured on the active stage. The connected fracture surface area is then calculated using the end of stage fall-off pressure data via PTA. This allows for the correlation of the fracture surface area created and the fracture surface area connected back to the original stage. Variations off a straight-line correlation suggest interactions with offset wells. For example, when fracture interaction with an offset depleted zone is present, PTA will calculate an extremely high fracture surface area when compared to the number of fractures created during the active stage. This reduces the effective production as the area created is not able to produce back to the original well. This paper presents a new real-time method to estimate the stage-to-stage interference and well-to-well interference and their implications on completions efficiency. This paper also presents a solution to minimize frac hits between parent and child well based on generated fracture surface area to improve a pad's Estimated Ultimate Recovery (EUR). This is supported by a case history which shows a positive correlation between the created fracture surface area and its connectivity back to the wellbore. The new method does not require any well surveillance compared with existing methods and does not incur extra cost to operator.
- North America > United States (0.29)
- Asia > Middle East > UAE (0.29)
- Oceania > Australia (0.28)
- Well Completion > Hydraulic Fracturing > Multistage fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Seismic processing and interpretation (1.00)
- (4 more...)
Case Studies of Integrated Flowback Analysis: Examples from the Montney and Duvernay Formations
Clarkson, Christopher R. (University of Calgary) | Williams-Kovacs, Jesse (University of Calgary and Sproule Associated Limited) | Zhang, Zhenzihao (University of Calgary) | Yuan, Bin (University of Calgary) | Ghanizadeh, Amin (University of Calgary) | Hamdi, Hamidreza (University of Calgary) | Islam, Arshad (Baytex Energy Corp.)
Abstract Recently it has been demonstrated that rate-transient analysis (RTA) performed on flowback data frommulti-fractured horizontal wells (MFHWs) can provide timely estimates of hydraulic fracture properties. This information can be used to inform stimulation treatment design on upcoming wells as well as other important operational and development decisions. However, RTA of flowback data may be complicated by rapidly changing operating conditions, dynamic hydraulic fracture properties and multi-phase flow in the fractures, complex fracture geometry, and variable fracture and reservoir properties along the MFHW, among other factors. While some constraints on RTA model assumptions may be applied through a carefully-designed surveillance and testing program in the field (e.g. to constrain fracture geometry), still others require laboratory measurements. In this work, an integrated flowback RTA workflow, designed to reduce uncertainty in derived hydraulic fracture properties, is demonstrated using flowback data from MFHWs producing black oil from low-permeability reservoirs in the Montney and Duvernay formations. The workflow includes rigorous flow-regime identification used for RTA model selection, straight-line analysis (SLA) to provide initial estimates of hydraulic fracture properties, and model history matching of flowback data to refine hydraulic fracture property estimates. The model history matching is performed using a recently-introduced semi-analytical, dual-porosity, dynamic drainage area (DP-DDA) model that incorporates primary (propped) hydraulic fractures (PHF) as well as a dual-porosity enhanced fracture region (EFR) with an unpropped (secondary) fracture network. Inclusion of both the PHF and EFR components addresses the need to incorporate both propped and unpropped fractures and fracture complexity in the modeling. The DP-DDA model is constrained using estimates of propped fracture conductivity and unpropped fracture permeability (measured as a function of stress), and unpropped fracture compressibility values, obtained in the laboratory for Montney and Duvernay core samples. Use of these critical laboratory data serves to improve the confidencein the modeling results. The case studies provided herein demonstrate a rigorous workflow for obtaining more confident hydraulic fracture property estimates from flowback data through the application of RTA techniques constrained by both field and laboratory data.
- North America > United States (1.00)
- North America > Canada > Alberta (1.00)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- North America > United States > New Mexico > Permian Basin > Wolfcamp Formation (0.99)
- North America > Canada > Alberta > Western Canada Sedimentary Basin > Alberta Basin > Duvernay Field > Duvernay Formation > Acl Duv 13-12-57-13 Well (0.94)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics > Flow in porous media (1.00)
- (4 more...)
Abstract Fractal techniques are used to create networks with fracture swarm geometry that resembles that of exploratory cores recently reported in the literature. The networks have desired total pore volume, maximum and minimum fracture spacing and fractional dimension. These properties together with fracture conductivity control their hydraulic behavior. Numerical simulation of individual fragments and the addition of production to obtain total production is shown to be consistent with simulations of the entire network when fracture conductivity is high. In this case, the network exhibits sub-linear flow (pressure derivative slope between 0.5 and 1). When fracture conductivity is low, it exhibits sub-radial flow (pressure derivative slope between 0 and 0.5) at early times with transition to sub-linear or boundary dominated flow (BDF) at later times. Longer duration of sub-radial flow is achieved by reducing fracture conductivity. These types of flow behavior cover the entire range seen in unconventional wells. They show how the power-law behavior, frequently observed in diagnostic plots, can be produced by the combined effect of matrix fragments that individually can only show linear, bi-linear or BDF flow. The relatively simple geometry of fracture swarms allows calculation of properties for sub-radial flow that complement those already known for sub-linear flow. New insights into production mechanisms of unconventional wells are discussed. Introduction The very low matrix permeability of unconventional wells causes the pressure transient response to last a long time, typically years. This makes pressure transient analysis (PTA), that relies on analysis of shut-in periods, limited in its ability to characterize flow behavior. Rate transient analysis (RTA), on the other hand, is especially suited to deal with long flowing periods. But there have been two different problems with the application of RTA to unconventional wells. The first is that the theoretical framework for RTA is not as developed as that of PTA. The second problem is that RTA responses of unconventional wells do not exhibit the familiar flow regimes (bi-linear, linear and radial) but rather power-law behavior with log-log derivative slopes different from the expected values for those flow regimes. To tackle the first problem, we developed a new theoretical framework by rewriting and solving the diffusivity equation in terms of cumulative production (Acuna, 2017). This new solution for constant pressure complies with theoretical expectations with respect to the constant flow rate solution as shown in Appendix B. It also handles all flow regimes seen in unconventional wells including the familiar ones mentioned before. To address the second problem, we proposed the simple idea that the flow behavior of an unconventional well is the result of many matrix fragments of different size acting together (Acuna, 2018a b), a concept further developed in this paper.
- North America > United States > Texas > West Gulf Coast Tertiary Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Sabinas - Rio Grande Basin > Eagle Ford Shale Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (4 more...)
- Well Completion > Hydraulic Fracturing (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Characterization > Faults and fracture characterization (1.00)
- (3 more...)
Nuances and Frequently Asked Questions in Field-Scale Hydraulic Fracture Modeling
McClure, Mark (ResFrac Corporation) | Picone, Matteo (ResFrac Corporation) | Fowler, Garrett (ResFrac Corporation) | Ratcliff, Dave (ResFrac Corporation) | Kang, Charles (ResFrac Corporation) | Medam, Soma (ResFrac Corporation) | Frantz, Joe (ResFrac Corporation)
Abstract Hydraulic fracturing and reservoir simulation are used by operators in shale to optimize design parameters such as well spacing, cluster spacing, and injection schedule. In this paper, we address ‘freqently asked questions’ that we encounter when working on hydraulic fracture modeling projects with operators. First, we discuss three high-level topics: (1) data-driven and physics-based models, (2) the modeling workflow, and (3) planar-fracture modeling versus ‘complex fracture network’ modeling. Next, we address specific technical topics related to modeling and the overall physics of hydraulic fracturing: (1) interrelationships between cluster spacing and other design parameters, (2) processes affecting fracture size, (3) fracture symmetry/asymmetry, (4) proppant settling versus trapping, (5) applications of Rate-Transient Analysis (RTA), (6) net pressure matching, (7) Initial Shut-In Pressure (ISIP) trends along the wellbore, and (8) the effect of understressed/underpressured layers. We discuss practical modeling decisions in the context of field observations.
- North America > United States > Texas (1.00)
- Europe (0.93)
- Overview (0.46)
- Frequently Asked Questions (FAQ) (0.40)
- Geology > Geological Subdiscipline > Geomechanics (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock > Shale (0.51)
- Geology > Petroleum Play Type > Unconventional Play > Shale Play (0.47)
- Well Completion > Hydraulic Fracturing > Fracturing materials (fluids, proppant) (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Shale gas (1.00)
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Naturally-fractured reservoirs (1.00)
- (7 more...)