The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform
Zhongwei Wu - One of the best experts on this subject based on the ideXlab platform.
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pressure analysis for volume fracturing vertical well considering low velocity non darcy Flow and stress sensitivity
Geofluids, 2019Co-Authors: Zhongwei Wu, Ning Ai, Wenhao TangAbstract:In general, there is stress sensitivity damage in tight reservoirs and Fractures. Furthermore, the Flow in tight reservoirs is the low-velocity non-Darcy Flow. Currently, few researches of pressure analysis for volume fracturing vertical well are conducted simultaneously considering the low-velocity non-Darcy Flow and stress sensitivity. In the paper, a novel Flow model of a volume Fractured vertical well is proposed and solved numerically. Firstly, the threshold pressure gradient, permeability modulus, and experimental data are, respectively, utilized to characterize the low-velocity non-Darcy Flow, matrix stress sensitivity, and Fracture stress sensitivity. Then, a two-region composite reservoir is established to simulate the vertical well with volume fracturing. After that, the logarithm meshing method is used to discrete the composite reservoir, and the Flow model is solved by the method of finite difference and IMPES. Finally, the model verification is conducted, and the effects of the low-velocity non-Darcy Flow and stress sensitivity on the pressure and pressure derivative are analyzed. The six Flow regimes are identified by the dimensionless pressure and pressure derivative curve. They are, respectively, the Fracture Linear Flow regime, early transition Flow regime, radial Flow regime, crossFlow regime, advanced transition Flow regime, and boundary controlling Flow regime. The stress sensitivity and threshold pressure gradient have a great effect on the dimensionless pressure and pressure derivative. With the increase of reservoir stress sensitivity, the pressure and pressure derivative are upward at the advanced transition Flow and boundary controlling regimes. However, the pressure and pressure derivative are downward at the advanced transition Flow and boundary controlling regimes when the Fracture sensitivity increases. An increase in the threshold pressure gradient results in a high dimensionless pressure and pressure derivative. This work reveals the effects of low-velocity non-Darcy Flow and stress sensitivity on pressure and provides a more accurate reference for reservoir engineers in pressure analysis when developing a tight reservoir by using the volume fracturing vertical well.
Wenhao Tang - One of the best experts on this subject based on the ideXlab platform.
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pressure analysis for volume fracturing vertical well considering low velocity non darcy Flow and stress sensitivity
Geofluids, 2019Co-Authors: Zhongwei Wu, Ning Ai, Wenhao TangAbstract:In general, there is stress sensitivity damage in tight reservoirs and Fractures. Furthermore, the Flow in tight reservoirs is the low-velocity non-Darcy Flow. Currently, few researches of pressure analysis for volume fracturing vertical well are conducted simultaneously considering the low-velocity non-Darcy Flow and stress sensitivity. In the paper, a novel Flow model of a volume Fractured vertical well is proposed and solved numerically. Firstly, the threshold pressure gradient, permeability modulus, and experimental data are, respectively, utilized to characterize the low-velocity non-Darcy Flow, matrix stress sensitivity, and Fracture stress sensitivity. Then, a two-region composite reservoir is established to simulate the vertical well with volume fracturing. After that, the logarithm meshing method is used to discrete the composite reservoir, and the Flow model is solved by the method of finite difference and IMPES. Finally, the model verification is conducted, and the effects of the low-velocity non-Darcy Flow and stress sensitivity on the pressure and pressure derivative are analyzed. The six Flow regimes are identified by the dimensionless pressure and pressure derivative curve. They are, respectively, the Fracture Linear Flow regime, early transition Flow regime, radial Flow regime, crossFlow regime, advanced transition Flow regime, and boundary controlling Flow regime. The stress sensitivity and threshold pressure gradient have a great effect on the dimensionless pressure and pressure derivative. With the increase of reservoir stress sensitivity, the pressure and pressure derivative are upward at the advanced transition Flow and boundary controlling regimes. However, the pressure and pressure derivative are downward at the advanced transition Flow and boundary controlling regimes when the Fracture sensitivity increases. An increase in the threshold pressure gradient results in a high dimensionless pressure and pressure derivative. This work reveals the effects of low-velocity non-Darcy Flow and stress sensitivity on pressure and provides a more accurate reference for reservoir engineers in pressure analysis when developing a tight reservoir by using the volume fracturing vertical well.
Liang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Pressure transient analysis for vertical Fractured wells with fishbone Fracture patterns
Journal of Natural Gas Science and Engineering, 2018Co-Authors: Qiushi Zhang, Jie Zeng, Xiangzeng Wang, Daohan Wang, Fanhua Zeng, Liang ZhangAbstract:Abstract Many diagnostic technologies have proven that complex Fracture pattern would be generated during the operation of Fracture treatment for vertical well. However, there had been very little research reported on fishbone Fracture pattern for vertical well, which is one of the typical Fracture geometries. To analysis the pressure behavior of this kind Fracture pattern, a semi-analytical method is proposed and some typical Fracture patterns are compared in this work. Based on the theory of superposition, the physical model is divided into two sub-systems: (a) a formation/Fracture sub-system and (b) a Fracture sub-system. A flexible discretization and coupling method is developed to investigate irregular Fracture geometry and non-orthogonal between two Fractures. The mathematical model is solved in the Laplace domain and the Stehfest inversion algorithm is applied to determine the corresponding pressure distribution in the real-time domain. Type curves are generated and Flow regimes are identified. Sensitivity analysis and actual field case are conducted. It is found that there are five Flow regimes, they are biLinear Flow, Flow feed, Fracture Linear Flow, formation Linear Flow, bi-radial Flow and pseudoradial Flow. The pressure depletion decreases with increase of the number, length and conductivity of secondary Fractures, and their effect on contribution of primary Fracture have a similar tendency. Effects of Inclined angle between secondary and primary Fractures on pressure transit behavior occurs during Flow feed and later regimes, while Fractures pattern with different geometries can influence all the Flow regimes. The derived analytical pressure transient solution may provide a theoretical basis for the analysis of the pressure transient behavior of the fishbone Fracture pattern in a vertical well.
Peter J Mccabe - One of the best experts on this subject based on the ideXlab platform.
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investigation of increasing hydraulic Fracture conductivity within producing ultra deep coal seams using time lapse rate transient analysis a long term pilot experiment in the cooper basin australia
International Journal of Coal Geology, 2020Co-Authors: Erik C Dunlop, Alireza Salmachi, Peter J MccabeAbstract:Abstract Ultra-low permeability, inertinite-rich, poorly cleated, dehydrated, overpressured coal seams deeper than 9000 ft (2740 m) in the Cooper Basin of central Australia represent a fundamentally different play type to shallow and “deep” coal seam gas reservoirs. Proof-of-concept gas Flow was achieved in 2007. Four Patchawarra Formation coal seams were subjected to low-proppant concentration slick-water hydraulic Fracture stimulation within a dedicated vertical wellbore at a depth of 9500 ft (2900 m). Gas was produced for 81/2 years at a slowly increasing base Flow rate, averaging 0.1 MMscfd (2.8 Mscmd). Experimental data were gathered for characterising dynamic reservoir behaviour. This included multiple extended pressure build-up tests. The authors have previously investigated the three largest of these using time-lapse pressure transient analysis. The published results reveal a dominant biLinear Flow regime, associated with an isolated domain of increasing coal fabric permeability surrounding the hydraulic Fracture. This paper builds upon the time-lapse pressure transient analysis study by specifically investigating conductivity of the hydraulic Fracture, which the authors postulate to have also increased. The hypothesis is tested by applying time-lapse rate transient analysis to the two specially designed pressure drawdown tests to atmospheric pressure that immediately follow the first two pressure build-up tests of the time-lapse pressure transient analysis. Between the two pressure drawdown tests, spaced 586 days apart, the wellbore Flowed gas continuously for 327 days, at an average Flowing bottom-hole pressure of 580 psig (4.0 MPag). Hence, there was ample opportunity for hydraulic Fracture conductivity to change between the tests. Both pressure drawdown tests were monitored for 24 h using high-resolution surface pressure gauges. Each was initiated from the same surface shut-in pressure of 2500 psig (17.2 MPag). The Flow pressure data are initially used to construct “diagnostic plots” that clearly identify the hydraulic Fracture Linear Flow regime, early in each test, immediately after the dissipation of wellbore storage. Hydraulic Fracture properties are then extracted using “specialty plots” that display rate-normalised pseudo-pressure difference versus Linear superposition time. Comparing the slopes of the two speciality plot trends indicates that the hydraulic Fracture Flow property b f k f ∅ f increased during the 327-day gas Flow period by a factor of 4. This is supported by a 60% increase in the initial gas Flow rate from “hydraulic Fracture storage”, from 7.5 to 12.0 MMscfd (212.4 to 340.0 Mscmd). Additionally, despite a significantly larger volume of “hydraulic Fracture storage” gas being produced to surface during the second test, the duration of the hydraulic Fracture Linear Flow regime is less than for the first. These observations are consistent with an increasingly more conductive hydraulic Fracture over Flowback time that allows compressed gas within it to discharge more rapidly.
Jie Zeng - One of the best experts on this subject based on the ideXlab platform.
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Shale gas reservoir modeling and production evaluation considering complex gas transport mechanisms and dispersed distribution of kerogen
Petroleum Science, 2020Co-Authors: Jie Zeng, Jishan Liu, Yee-kwong Leong, Derek Elsworth, Jianchun GuoAbstract:Stimulated shale reservoirs consist of kerogen, inorganic matter, secondary and hydraulic Fractures. The dispersed distribution of kerogen within matrices and complex gas Flow mechanisms make production evaluation challenging. Here we establish an analytical method that addresses kerogen-inorganic matter gas transfer, dispersed kerogen distribution, and complex gas Flow mechanisms to facilitate evaluating gas production. The matrix element is defined as a kerogen core with an exterior inorganic sphere. Unlike most previous models, we merely use boundary conditions to describe kerogen-inorganic matter gas transfer without the instantaneous kerogen gas source term. It is closer to real inter-porosity Flow conditions between kerogen and inorganic matter. Knudsen diffusion, surface diffusion, adsorption/desorption, and slip corrected Flow are involved in matrix gas Flow. Matrix-Fracture coupling is realized by using a seven-region Linear Flow model. The model is verified against a published model and field data. Results reveal that inorganic matrices serve as a major gas source especially at early times. Kerogen provides limited contributions to production even under a pseudo-steady state. Kerogen properties’ influence starts from the late matrix-Fracture inter-porosity Flow regime, while inorganic matter properties control almost all Flow regimes except the early-mid time Fracture Linear Flow regime. The contribution of different Linear Flow regions is also documented.
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A 3-D analytical model for multi-stage Fractured shale gas reservoirs with damaged Fractures
Day 3 Wed June 05 2019, 2019Co-Authors: Jie Zeng, Jishan Liu, Yee-kwong Leong, Derek Elsworth, Jianwei Tian, Jianchun GuoAbstract:Abstract After performing hydraulic fracturing treatments in shale reservoirs, the hydraulic Fractures and their adjacent reservoir rocks can be damaged. Typically, the following Fracture damage scenarios may occur: (1) choked Fractures with near-wellbore damage; (2) partially propped Fractures with unpropped or poorly propped sections within the Fractures; (3) Fracture face damage; and (4) multiple damage cases. The basic equations of Fracture skin factors, which are widely used to depict Fracture damage, are derived under steady-state conditions. They are not accurate when the damaged length is relatively long and are not applicable for multiple Fracture damage and partially propped Fractures. In this paper, a new composite Linear Flow model is established considering all above-mentioned Fracture damage mechanisms, complex gas transport mechanisms, and the stimulated reservoir volume (SRV) of shale gas reservoirs. The matrix model is modified from de Swaan-O's spherical element model considering the slip Flow, Knudsen diffusion, surface diffusion, and desorption. Natural Fractures are idealized as a thin layer that evenly covers the matrix. The reservoir-Fracture Flow model is extended from the seven-region Linear Flow model with four additional sub-regions to handle single and multiple Fracture damage mechanisms. Specifically, the inner reservoir region near the primary hydraulic Fracture is treated as the SRV where the secondary Fracture permeability is higher than that of other unstimulated dual-porosity regions and obeys a power-law decreasing trend due to the attenuate stimulation intensity within the SRV. The Flows in different regions are coupled through flux and pressure continuity conditions at their interfaces. This model is validated by matching with the Marcellus Shale production data. And the degraded model's calculation matches well with that of the seven-region Linear Flow model validated by KAPPA software. Type curves with five typical Flow regimes are generated and sensitivity analyses are conducted. Results indicate that the presence of the SRV diminishes pressure and derivative values in certain Flow regimes depending on the SRV properties. Fracture face damage, choked Fracture damage, and partially propped Fractures all control specific Flow regimes but the Fracture face damage shows the smallest influence, only dominating the late Fracture Linear Flow regime and the matrix-Fracture transient regime. In the multiple Fracture damage case, some typical Flow regimes can be easily identified except the partially propped Fractures. The field application example further ensures the applicability in dealing with real field data.
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Pressure transient analysis for vertical Fractured wells with fishbone Fracture patterns
Journal of Natural Gas Science and Engineering, 2018Co-Authors: Qiushi Zhang, Jie Zeng, Xiangzeng Wang, Daohan Wang, Fanhua Zeng, Liang ZhangAbstract:Abstract Many diagnostic technologies have proven that complex Fracture pattern would be generated during the operation of Fracture treatment for vertical well. However, there had been very little research reported on fishbone Fracture pattern for vertical well, which is one of the typical Fracture geometries. To analysis the pressure behavior of this kind Fracture pattern, a semi-analytical method is proposed and some typical Fracture patterns are compared in this work. Based on the theory of superposition, the physical model is divided into two sub-systems: (a) a formation/Fracture sub-system and (b) a Fracture sub-system. A flexible discretization and coupling method is developed to investigate irregular Fracture geometry and non-orthogonal between two Fractures. The mathematical model is solved in the Laplace domain and the Stehfest inversion algorithm is applied to determine the corresponding pressure distribution in the real-time domain. Type curves are generated and Flow regimes are identified. Sensitivity analysis and actual field case are conducted. It is found that there are five Flow regimes, they are biLinear Flow, Flow feed, Fracture Linear Flow, formation Linear Flow, bi-radial Flow and pseudoradial Flow. The pressure depletion decreases with increase of the number, length and conductivity of secondary Fractures, and their effect on contribution of primary Fracture have a similar tendency. Effects of Inclined angle between secondary and primary Fractures on pressure transit behavior occurs during Flow feed and later regimes, while Fractures pattern with different geometries can influence all the Flow regimes. The derived analytical pressure transient solution may provide a theoretical basis for the analysis of the pressure transient behavior of the fishbone Fracture pattern in a vertical well.
