Multiple-seam gas coproduction is a technology with potential to achieve economic targets.Physical experiments could replicate gas flow dynamics in two seams.In this study,numerical simulation was conducted based on p...Multiple-seam gas coproduction is a technology with potential to achieve economic targets.Physical experiments could replicate gas flow dynamics in two seams.In this study,numerical simulation was conducted based on physical experiments.Through calibration,the simulated results agreed with the experimental results.Three findings were obtained.First,the pressure distribution intrinsically depends on the depressurization effectiveness in each coal seam.The gas pressure difference and interval distance influence the pressure distribution by inhibiting depressurization in the top seams and bottom seams,respectively.Second,the production contribution shows a logarithmic relationship with the permeability ratio.The range of the production contribution difference grows from 11.24%to 99.99%when the permeability ratio increases 50 times.By comparison,reservoir pressure has a limited influence,with a maximum of 13.64%.Third,the interlayer interference of the top seams and bottom seams can be intensified by the reservoir pressure difference and the interval distance,respectively.The proposed model has been calibrated and verified and can be directly applied to engineering,serving as a reference for reservoir combination optimization.In summary,coal seams with a permeability ratio within 10,reservoir pressure difference within 1.50 MPa,and interval distances within 50 m are recommended to coproduce together.展开更多
Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin o...Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin of Zhina coal field, we study the generation mechanism of interlayer interference, propagation rules of reservoir pressure drop and influencing factors of gas productivity in CBM multi-seam drainage in the paper. On the basis of the actual production data of X-2 well of Zhucang syncline in Bide-Santang basin,by simulating the gas production process of a CBM well under the condition of multiple seam with COMET3 numerical simulation software, we analyze the influencing factors of gas productivity during the process of multi-seam drainage, and illuminate the interlayer interference mechanism of multiseam drainage. The results show that permeability, reservoir pressure gradient, critical desorption pressure and fluid supply capacity of stratum have great influence on gas productivity of multi-seam drainage while coal thickness has little influence on it. Permeability, reservoir pressure gradient and fluid supply capacity of stratum affect the propagation velocity of reservoir pressure drop and thereby affect the final gas productivity. Moreover, the influence of critical desorption pressure on gas productivity of multiseam drainage is reflected in the gas breakthrough time and effective desorption area.展开更多
X oilfield is a typical multi-layer sandstone reservoir in offshore China. In the early stage, in order to obtain economic oil production, directional well was used to adopt a set of multi-layer combined production, w...X oilfield is a typical multi-layer sandstone reservoir in offshore China. In the early stage, in order to obtain economic oil production, directional well was used to adopt a set of multi-layer combined production, which resulted in serious interlayer interference, water injection inrush and low reserve utilization. Based on the theory of single-phase unstable seepage flow and the theory of oil-water two-phase non-piston displacement, the author innovatively established a mathematical model of interlayer dynamic interference in multilayer sandstone reservoirs, revealed the influence law of main controlling factors such as permeability, viscosity, starting pressure gradient and reservoir type on interlayer interference, and innovatively formed a quantitative characterization theory of interlayer interference in multilayer combined oil production. The technical demarcation of offshore multi-zone combined oil production reservoir system is formulated and the recombination of oil field development system is guided.展开更多
Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reser...Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reservoirs is essential for well performance evaluation and development strategy optimization.However,most analytical models for fractured vertical wells in stratified gas reservoirs focus on fully penetrated hydraulic fractures,neglecting the influence of partial penetration of hydraulic fractures.This paper presents a semi-analytical model to investigate the transient pressure behavior of vertically fractured wells in dual porosity multi-layered tight gas reservoirs.The partial penetration of hydraulic fracture,the vertical heterogeneities of layer properties,the differences between hydraulic fracture lengths in each layer and the stress sensitivity are all incorporated in the proposed model.The point-source solution,Laplace transformation,Fourier transformation,Pedrosa's transformation,perturbation technique,and the superposition principle are applied to obtain the analytical solution of transient pressure responses.The proposed model is validated against a commercial software,and the transient pressure behavior of vertically fractured wells in multi-layered tight gas reservoirs are analyzed.Based on the characteristics of the type curves,seven flow regimes can be identified,including wellbore storage,transitional flow period,reservoir linear flow period,vertical pseudo-radial flow in fracture system,inter-porosity flow period,late-time pseudo-radial flow period,and the boundary-dominated flow period.Sensitivity analyses reveal that the penetration ratio of hydraulic fracture has primary influence on early-time transient pressure behavior and production contribution,while the stress sensitivity mainly affects the late-time transient pressure behavior.Gas production at the initial stage is mainly contributed by the high-pressure/high-permeability layer,and gas backflow will occur during initial production stage for obviously unequal initial formation pressures.Finally,two field cases are conducted to illustrate the applicability of the proposed model.The model and corresponding conclusions can provide technical support for performance analysis of tight gas reservoirs.展开更多
Efficient detection of coalbed methane(CBM) co-production interference is the key to timely adjusting the development plan and improving the co-production efficiency. Based on production data of six typical CBM co-pro...Efficient detection of coalbed methane(CBM) co-production interference is the key to timely adjusting the development plan and improving the co-production efficiency. Based on production data of six typical CBM co-production wells in the Zhijin block of western Guizhou Province, China, the production characteristic curves, including production indication curve, curve of daily water production per unit drawdown of producing fluid level with time, and curve of water production per unit differential pressure with time have been analyzed to explore the response characteristics of co-production interference on the production characteristic curves. Based on the unit water inflow data of pumping test in coal measures, the critical value of in-situ water production of the CBM wells is 2 m^(3)/(d·m). The form and the slope of the initial linear section of the production indication curves have clear responses to the interference, which can be used to discriminate internal water source from external water source based on the critical slope value of 200 m^(3)/MPa in the initial linear section of the production indication curve. The time variation curves of water production per unit differential pressure can be divided into two morphological types: up-concave curve and down-concave curve. The former is represented by producing internal water with average daily gas production greater than 800 m^(3)/d, and the latter produces external water with average daily gas production smaller than 400 m^(3)/d. The method and critical indexes for recognition of CBM co-production interference based on the production characteristic curve are constructed. A template for discriminating interference of CBM co-production was constructed combined with the gas production efficiency analysis, which can provide reference for optimizing co-production engineering design and exploring economic and efficient co-production mode.展开更多
Based on a geology-engineering sweet spot evaluation,the high-quality reservoir zones and horizontal well landing points were determined.Subsequently,fracture propagation and production were simulated with a multilaye...Based on a geology-engineering sweet spot evaluation,the high-quality reservoir zones and horizontal well landing points were determined.Subsequently,fracture propagation and production were simulated with a multilayer fracturing scenario.The optimal hydraulic fracturing strategy for themultilayer fracturing networkwas determined by introducing a vertical asymmetry factor.This strategy aimed to minimize stress shadowing effects in the vertical direction while maximizing the stimulated reservoir volume(SRV).The study found that the small vertical layer spacing of high-quality reservoirs and the presence of stress-masking layers(with a stress difference of approximately 3∼8 MPa)indicate that interlayer stress interference from multilayers and multiwells fracturing between neighboring developed formations could affect the longitudinal propagation of the reservoirs.In addition,this study investigated well spacing optimization by comparing uniformly spaced wells(100–300 m)with asymmetric spaced wells(200 m upper layer,250 m lower layer).Numerical results indicated that asymmetric spaced well placement yielded the largest stimulated reservoir volume(SRV)of 73,082 m^(3),representing a 65.42%increase compared to 100 m spaced wells.Furthermore,four different hydraulic fracturing sequences(interlayer,up-down,down-up,and center-edge)were compared for multilayer and multiwell networks.The center-edge sequence exhibited the lowest vertical asymmetry factor(0.71)and the least stress shadowing effects compared to the other sequences(0.78 for interlayer,0.75 for up-down,and 0.76 for down-up).This sequence also achieved the largest SRV(486,194m^(3)),representing an 11.87%increase compared to the down-up sequence.Therefore,the center-edge fracturing sequence is recommended formultilayer development in this block.These results offer valuable insights for optimizing well placement and fracturing sequence design in multilayer well networks,ultimately advancing the development of multilayer fracturing technology in the region.展开更多
Oilfield geothermal energy is one important part of geothermal resources,and it can be developed and used for power generation and heating.The geothermal reserves and production ofmulti-layer sandstone oil reservoirs ...Oilfield geothermal energy is one important part of geothermal resources,and it can be developed and used for power generation and heating.The geothermal reserves and production ofmulti-layer sandstone oil reservoirs account for 50%of the total geothermal reserves and production in China,respectively,but due to the influence of interlayer heterogeneity,interlayer interference is common in the process of geothermal development by water injection.Therefore,it is in an urgent need to evaluate the heat extraction performance of oil-bearing geothermal reservoirs in multi-layer commingled production.Taking a depleted oil reservoir(and even a high-or an extra-high water-saturation oil reservoir)as the research object,this paper establishes a numerical model of coupled oilewater two-phase heat flow in a multi-layer commingled production oil reservoir.Then,interlayer interference characteristics and temperature and pressure distribution situations under different porosity,permeability and initial oil saturation are compared.Finally,the influence of interlayer interference on heat extraction performance is analyzed.And the following research results are obtained.First,under the research conditions and model settings of this paper,the injectioneproduction pressure difference and production temperature difference between low-permeability layers and high-permeability layers of the reservoir with different permeability after 20 years'production are up to 3.27MPa and 24.5 K,respectively,which are much higher than the corresponding differences of oil-bearing homogeneous reservoirs.Second,the lower the initial oil saturation,the smaller the reservoir production temperature and injectioneproduction pressure difference.And after 20 years,the maximum difference is 1.32MPa.Third,interlayer interference is sensitive to permeability.The fluid in the high-permeability layers comes from the injection well of the same layer and low-permeability layers.The production temperature of the reservoirs with different permeability can rise by 5.33 K at most.In conclusion,permeability is the key parameter influencing production temperature and injectioneproduction pressure difference of oil-bearing reservoirs while porosity has less influence on production behaviors.In addition,injectioneproduction pressure difference is more sensitive to the change of initial oil saturation and the existence of oil phase can increase the injection pressure significantly.Furthermore,if there is a boundary geothermal source,the reservoirs with strong interlayer interference can obtain high heat extraction more easily,so this type of reservoirs can be given priority in the heat extraction of abandoned wells.展开更多
The extraction of coal measure gas has been shifted toward thin gas reservoirs due to the depletion of medium-thick gas reservoirs.The coproduction of coalbed gas,shale gas,and tight sandstone gas(called a multisuperp...The extraction of coal measure gas has been shifted toward thin gas reservoirs due to the depletion of medium-thick gas reservoirs.The coproduction of coalbed gas,shale gas,and tight sandstone gas(called a multisuperposed gas system)is a key low-cost technology for the enhancement of natural gas production from thin gas reservoirs in coal measure.As an emerging engineering exploitation technology at its early stage of development,gas coproduction confronts various engineering challenges in hydraulic fracturing,bottom-hole pressure regulation,well network arrangement,and extraction sequence.The current understanding of the opportunities and challenges in the gas coproduction from the multisuperposed gas system is not comprehensive enough.In this case,the previous achievements in the field of gas coproduction should be urgently reviewed to provide valuable guidance and recommendations for further development.This review first discusses the regional and spatial distribution characteristics and possible reservoir combinations of gas reservoirs in coal measure.Then,the basic properties of different reservoirs,engineering challenges,and interlayer interference are comparatively analyzed and discussed.The current simulation models for gas coproduction and potential future research directions are further explored.The results indicate that the coupling effects of reservoir heterogeneity,interwell interference,and geological structure for increasing coproduction prediction accuracy should be included in future simulation models for gas coproduction.Careful investigation is required to explore the mechanisms and their further quantifications on the effects of interlayer interference in gas coproduction.The fractal dimension as a scale can play an important role in the characterization of the gas and water transport in different reservoirs.The machine learning methods have tremendous potential to provide accurate and fast predictions for gas coproduction and interlayer interference.展开更多
基金This research was supported by National Science and Technology Major Project(No.2016ZX05044002-005)and National Natural Science Foundation of China(No.41772155)The first author gratefully acknowledges financial support from China Scholarship Council(No.CSC201906420044)and expresses thanks to Richard Smith and Eric Lysczek for grammar check.
文摘Multiple-seam gas coproduction is a technology with potential to achieve economic targets.Physical experiments could replicate gas flow dynamics in two seams.In this study,numerical simulation was conducted based on physical experiments.Through calibration,the simulated results agreed with the experimental results.Three findings were obtained.First,the pressure distribution intrinsically depends on the depressurization effectiveness in each coal seam.The gas pressure difference and interval distance influence the pressure distribution by inhibiting depressurization in the top seams and bottom seams,respectively.Second,the production contribution shows a logarithmic relationship with the permeability ratio.The range of the production contribution difference grows from 11.24%to 99.99%when the permeability ratio increases 50 times.By comparison,reservoir pressure has a limited influence,with a maximum of 13.64%.Third,the interlayer interference of the top seams and bottom seams can be intensified by the reservoir pressure difference and the interval distance,respectively.The proposed model has been calibrated and verified and can be directly applied to engineering,serving as a reference for reservoir combination optimization.In summary,coal seams with a permeability ratio within 10,reservoir pressure difference within 1.50 MPa,and interval distances within 50 m are recommended to coproduce together.
基金supported by the National Major Special Project of Science and Technology of China (No.2011ZX05034)the Innovation Projects of University Graduates in Jiangsu Province (No.CXLX13_948)+1 种基金the National Natural Science Foundation of China (No.41272178)the Natural Science Foundation of Hunan Province (No.2016JJ4031)
文摘Based on the characteristics of the strong volatility of physical property in vertical direction, high gas content, high resource abundance and large exploitation potentiality of coal reservoir in Bide-Santang basin of Zhina coal field, we study the generation mechanism of interlayer interference, propagation rules of reservoir pressure drop and influencing factors of gas productivity in CBM multi-seam drainage in the paper. On the basis of the actual production data of X-2 well of Zhucang syncline in Bide-Santang basin,by simulating the gas production process of a CBM well under the condition of multiple seam with COMET3 numerical simulation software, we analyze the influencing factors of gas productivity during the process of multi-seam drainage, and illuminate the interlayer interference mechanism of multiseam drainage. The results show that permeability, reservoir pressure gradient, critical desorption pressure and fluid supply capacity of stratum have great influence on gas productivity of multi-seam drainage while coal thickness has little influence on it. Permeability, reservoir pressure gradient and fluid supply capacity of stratum affect the propagation velocity of reservoir pressure drop and thereby affect the final gas productivity. Moreover, the influence of critical desorption pressure on gas productivity of multiseam drainage is reflected in the gas breakthrough time and effective desorption area.
文摘X oilfield is a typical multi-layer sandstone reservoir in offshore China. In the early stage, in order to obtain economic oil production, directional well was used to adopt a set of multi-layer combined production, which resulted in serious interlayer interference, water injection inrush and low reserve utilization. Based on the theory of single-phase unstable seepage flow and the theory of oil-water two-phase non-piston displacement, the author innovatively established a mathematical model of interlayer dynamic interference in multilayer sandstone reservoirs, revealed the influence law of main controlling factors such as permeability, viscosity, starting pressure gradient and reservoir type on interlayer interference, and innovatively formed a quantitative characterization theory of interlayer interference in multilayer combined oil production. The technical demarcation of offshore multi-zone combined oil production reservoir system is formulated and the recombination of oil field development system is guided.
基金supported by the National Natural Science Foundation of China(Grant Nos.52174036,52234003)the Sichuan Province Science and Technology Program(Grant No.2024NSFSC0199)the Joint Fund for Innovation and Development of Chongqing Natural Science Foundation(Grant No.2023NSCQ-LZX0184).
文摘Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reservoirs is essential for well performance evaluation and development strategy optimization.However,most analytical models for fractured vertical wells in stratified gas reservoirs focus on fully penetrated hydraulic fractures,neglecting the influence of partial penetration of hydraulic fractures.This paper presents a semi-analytical model to investigate the transient pressure behavior of vertically fractured wells in dual porosity multi-layered tight gas reservoirs.The partial penetration of hydraulic fracture,the vertical heterogeneities of layer properties,the differences between hydraulic fracture lengths in each layer and the stress sensitivity are all incorporated in the proposed model.The point-source solution,Laplace transformation,Fourier transformation,Pedrosa's transformation,perturbation technique,and the superposition principle are applied to obtain the analytical solution of transient pressure responses.The proposed model is validated against a commercial software,and the transient pressure behavior of vertically fractured wells in multi-layered tight gas reservoirs are analyzed.Based on the characteristics of the type curves,seven flow regimes can be identified,including wellbore storage,transitional flow period,reservoir linear flow period,vertical pseudo-radial flow in fracture system,inter-porosity flow period,late-time pseudo-radial flow period,and the boundary-dominated flow period.Sensitivity analyses reveal that the penetration ratio of hydraulic fracture has primary influence on early-time transient pressure behavior and production contribution,while the stress sensitivity mainly affects the late-time transient pressure behavior.Gas production at the initial stage is mainly contributed by the high-pressure/high-permeability layer,and gas backflow will occur during initial production stage for obviously unequal initial formation pressures.Finally,two field cases are conducted to illustrate the applicability of the proposed model.The model and corresponding conclusions can provide technical support for performance analysis of tight gas reservoirs.
基金National Natural Science Foundation of China(42002195)National Science and Technology Major Project(2016ZX05044)National Natural Science Foundation of China(42130802)。
文摘Efficient detection of coalbed methane(CBM) co-production interference is the key to timely adjusting the development plan and improving the co-production efficiency. Based on production data of six typical CBM co-production wells in the Zhijin block of western Guizhou Province, China, the production characteristic curves, including production indication curve, curve of daily water production per unit drawdown of producing fluid level with time, and curve of water production per unit differential pressure with time have been analyzed to explore the response characteristics of co-production interference on the production characteristic curves. Based on the unit water inflow data of pumping test in coal measures, the critical value of in-situ water production of the CBM wells is 2 m^(3)/(d·m). The form and the slope of the initial linear section of the production indication curves have clear responses to the interference, which can be used to discriminate internal water source from external water source based on the critical slope value of 200 m^(3)/MPa in the initial linear section of the production indication curve. The time variation curves of water production per unit differential pressure can be divided into two morphological types: up-concave curve and down-concave curve. The former is represented by producing internal water with average daily gas production greater than 800 m^(3)/d, and the latter produces external water with average daily gas production smaller than 400 m^(3)/d. The method and critical indexes for recognition of CBM co-production interference based on the production characteristic curve are constructed. A template for discriminating interference of CBM co-production was constructed combined with the gas production efficiency analysis, which can provide reference for optimizing co-production engineering design and exploring economic and efficient co-production mode.
基金supported by the National Natural Science Foundation of China(51704324,52374027)Shandong Natural Science Foundation of China(ZR2022ME025,ZR2023ME158).
文摘Based on a geology-engineering sweet spot evaluation,the high-quality reservoir zones and horizontal well landing points were determined.Subsequently,fracture propagation and production were simulated with a multilayer fracturing scenario.The optimal hydraulic fracturing strategy for themultilayer fracturing networkwas determined by introducing a vertical asymmetry factor.This strategy aimed to minimize stress shadowing effects in the vertical direction while maximizing the stimulated reservoir volume(SRV).The study found that the small vertical layer spacing of high-quality reservoirs and the presence of stress-masking layers(with a stress difference of approximately 3∼8 MPa)indicate that interlayer stress interference from multilayers and multiwells fracturing between neighboring developed formations could affect the longitudinal propagation of the reservoirs.In addition,this study investigated well spacing optimization by comparing uniformly spaced wells(100–300 m)with asymmetric spaced wells(200 m upper layer,250 m lower layer).Numerical results indicated that asymmetric spaced well placement yielded the largest stimulated reservoir volume(SRV)of 73,082 m^(3),representing a 65.42%increase compared to 100 m spaced wells.Furthermore,four different hydraulic fracturing sequences(interlayer,up-down,down-up,and center-edge)were compared for multilayer and multiwell networks.The center-edge sequence exhibited the lowest vertical asymmetry factor(0.71)and the least stress shadowing effects compared to the other sequences(0.78 for interlayer,0.75 for up-down,and 0.76 for down-up).This sequence also achieved the largest SRV(486,194m^(3)),representing an 11.87%increase compared to the down-up sequence.Therefore,the center-edge fracturing sequence is recommended formultilayer development in this block.These results offer valuable insights for optimizing well placement and fracturing sequence design in multilayer well networks,ultimately advancing the development of multilayer fracturing technology in the region.
基金National Natural Science Foundation of China major project“High-temperature rock dynamic damage mechanism and high-efficiency crushing method”(No.52192624)National Natural Science Foundation of China key research and development plan project“Multi-field coupled flow heat transfer mechanism and heat extraction performance optimization in thermal storage”(No.:2018YFB1501804)China University of Petroleum(Beijing)State Key Laboratory of Oil and Gas Resources and Exploration Fund Project“Research on Fracture Damage Mechanism during Hot Dry Rock Exploitation”(No.PRP/open-2110).
文摘Oilfield geothermal energy is one important part of geothermal resources,and it can be developed and used for power generation and heating.The geothermal reserves and production ofmulti-layer sandstone oil reservoirs account for 50%of the total geothermal reserves and production in China,respectively,but due to the influence of interlayer heterogeneity,interlayer interference is common in the process of geothermal development by water injection.Therefore,it is in an urgent need to evaluate the heat extraction performance of oil-bearing geothermal reservoirs in multi-layer commingled production.Taking a depleted oil reservoir(and even a high-or an extra-high water-saturation oil reservoir)as the research object,this paper establishes a numerical model of coupled oilewater two-phase heat flow in a multi-layer commingled production oil reservoir.Then,interlayer interference characteristics and temperature and pressure distribution situations under different porosity,permeability and initial oil saturation are compared.Finally,the influence of interlayer interference on heat extraction performance is analyzed.And the following research results are obtained.First,under the research conditions and model settings of this paper,the injectioneproduction pressure difference and production temperature difference between low-permeability layers and high-permeability layers of the reservoir with different permeability after 20 years'production are up to 3.27MPa and 24.5 K,respectively,which are much higher than the corresponding differences of oil-bearing homogeneous reservoirs.Second,the lower the initial oil saturation,the smaller the reservoir production temperature and injectioneproduction pressure difference.And after 20 years,the maximum difference is 1.32MPa.Third,interlayer interference is sensitive to permeability.The fluid in the high-permeability layers comes from the injection well of the same layer and low-permeability layers.The production temperature of the reservoirs with different permeability can rise by 5.33 K at most.In conclusion,permeability is the key parameter influencing production temperature and injectioneproduction pressure difference of oil-bearing reservoirs while porosity has less influence on production behaviors.In addition,injectioneproduction pressure difference is more sensitive to the change of initial oil saturation and the existence of oil phase can increase the injection pressure significantly.Furthermore,if there is a boundary geothermal source,the reservoirs with strong interlayer interference can obtain high heat extraction more easily,so this type of reservoirs can be given priority in the heat extraction of abandoned wells.
基金China Scholarship Council,Grant/Award Number:202206420091National Natural Science Foundation of China,Grant/Award Numbers:42030810,51674246。
文摘The extraction of coal measure gas has been shifted toward thin gas reservoirs due to the depletion of medium-thick gas reservoirs.The coproduction of coalbed gas,shale gas,and tight sandstone gas(called a multisuperposed gas system)is a key low-cost technology for the enhancement of natural gas production from thin gas reservoirs in coal measure.As an emerging engineering exploitation technology at its early stage of development,gas coproduction confronts various engineering challenges in hydraulic fracturing,bottom-hole pressure regulation,well network arrangement,and extraction sequence.The current understanding of the opportunities and challenges in the gas coproduction from the multisuperposed gas system is not comprehensive enough.In this case,the previous achievements in the field of gas coproduction should be urgently reviewed to provide valuable guidance and recommendations for further development.This review first discusses the regional and spatial distribution characteristics and possible reservoir combinations of gas reservoirs in coal measure.Then,the basic properties of different reservoirs,engineering challenges,and interlayer interference are comparatively analyzed and discussed.The current simulation models for gas coproduction and potential future research directions are further explored.The results indicate that the coupling effects of reservoir heterogeneity,interwell interference,and geological structure for increasing coproduction prediction accuracy should be included in future simulation models for gas coproduction.Careful investigation is required to explore the mechanisms and their further quantifications on the effects of interlayer interference in gas coproduction.The fractal dimension as a scale can play an important role in the characterization of the gas and water transport in different reservoirs.The machine learning methods have tremendous potential to provide accurate and fast predictions for gas coproduction and interlayer interference.
