To predict complex reservoir spaces(with developed caves,pores,and fractures),based on the results of full-azimuth depth migration processing,we adopted reverse weighted nonlinear inversion to improve the accuracy of ...To predict complex reservoir spaces(with developed caves,pores,and fractures),based on the results of full-azimuth depth migration processing,we adopted reverse weighted nonlinear inversion to improve the accuracy of porous reservoir prediction.Scattering imaging three-parameter wavelet transform technology was used to accurately predict small-scale cave bodies.The joint inversion method of velocity and amplitude anisotropy was developed to improve the accuracy of small and medium-sized fracture prediction.The results of multiscale fracture modeling and characterization,interwell connectivity analysis,and connection path prediction are consistent with the production condition.Finally,based on the above prediction findings,favorable reservoir development areas were predicted.The above ideas and strategies have great application value for the efficient exploration and development of complex storage space reservoirs and the optimization of high-yield well locations.展开更多
The Three Gorges Reservoir Area(TGRA)is an important ecological barrier in the Yangtze River Basin,China.Therefore,it is of great importance to understand the spatio-temporal variation and the driving factors of produ...The Three Gorges Reservoir Area(TGRA)is an important ecological barrier in the Yangtze River Basin,China.Therefore,it is of great importance to understand the spatio-temporal variation and the driving factors of production-living-ecological spaces for sustainable and high-quality development in the TGRA.This study investigated the dynamic variation of production-living-ecological spaces in the TGRA by employing land use data in 2000,2005,2010,2015,and 2018,and detected the influencing factors by using the Geographic detector(GeoDetector).Results implied that the structure and dynamic trajectories of production-living-ecological spaces in the TGRA varied in both horizontal and vertical directions,and the study area was dominated by ecological space.A spatial orientation towards the northeast was detected in the evolution of production-living-ecological spaces during 2000-2018.In terms of quantity,the transition from ecological space(grassland and woodland)to agriculture land accounted for the largest proportion from 2000 to 2018.However,the reverse transition from agriculture land to ecological space has increased since 2000 with the efforts of“Grain for Green”.In terms of temporal scale,there was a fluctuating trend in production space with the continuous expansion of living space,while ecological space showed an inverted U-shaped trend during 2000-2018.The dynamic pattern of production-living-ecological spaces in the TGRA was influenced by both physical and socio-economic variables as basic determinants and dominant driving factors,respectively.Finally,the harmonization and protection of production-living-ecological spaces still require policy-makers’efforts.This work may have potential in advancing our understanding about land use conflicts,and provide a reference for rational layout of spatial functions and the realization of sustainable development in the TGRA.展开更多
Secondary storage spaces with very complex geometries are well developed in Ordovician carbonate reservoirs in the Tarim Basin,which is taken as a study case in this paper.It is still not clear how the secondary stora...Secondary storage spaces with very complex geometries are well developed in Ordovician carbonate reservoirs in the Tarim Basin,which is taken as a study case in this paper.It is still not clear how the secondary storage space shape influences the P-& S-wave velocities (or elastic properties) in complex carbonate reservoirs.In this paper,three classical rock physics models (Wyllie timeaverage equation,Gassmann equation and the Kuster-Toks z model) are comparably analyzed for their construction principles and actual velocity prediction results,aiming at determining the most favourable rock physics model to consider the influence of secondary storage space shape.Then relationships between the P-& S-wave velocities in carbonate reservoirs and geometric shapes of secondary storage spaces are discussed from different aspects based on actual well data by employing the favourable rock physics model.To explain the influence of secondary storage space shape on V P-V S relationship,it is analyzed for the differences of S-wave velocities between derived from common empirical relationships (including Castagna's mud rock line and Greenberg-Castagna V P-V S relationship) and predicted by the rock physics model.We advocate that V P-V S relationship for complex carbonate reservoirs should be built for different storage space types.For the carbonate reservoirs in the Tarim Basin,the V P-V S relationships for fractured,fractured-cavernous,and fractured-hole-vuggy reservoirs are respectively built on the basis of velocity prediction and secondary storage space type determination.Through the discussion above,it is expected that the velocity prediction and the V P-V S relationships for complex carbonate reservoirs should fully consider the influence of secondary storage space shape,thus providing more reasonable constraints for prestack inversion,further building a foundation for realizing carbonate reservoir prediction and fluid prediction.展开更多
This paper discusses the reservoir space in carbonate rocks in terms of types,combination features,distribution regularity,and controlling factors,based on core observations and tests of the North Truva Oilfield,Caspi...This paper discusses the reservoir space in carbonate rocks in terms of types,combination features,distribution regularity,and controlling factors,based on core observations and tests of the North Truva Oilfield,Caspian Basin.According to the reservoir space combinations,carbonate reservoirs can be divided into four types,i.e.,pore,fracture-pore,pore-cavity-fracture,and pore-cavity.Formation and distribution of these reservoirs is strongly controlled by deposition,diagenesis,and tectonism.In evaporated platform and restricted platform facies,the reservoirs are predominately affected by meteoric fresh water leaching in the supergene-para-syngenetic period and by uplifting and erosion in the late stage,making both platform facies contain all the above-mentioned four types of reservoirs,with various pores,such as dissolved cavities and dissolved fractures,or structural fractures occasionally in favorable structural locations.In open platform facies,the reservoirs deposited continuously in deeper water,in an environment of alternative high-energy shoals(where pore-fracture-type reservoirs are dominant) and low-energy shoals(where pore reservoirs are dominant).展开更多
The Es3/3-Es1/4 shales in Dongying sag are source rocks with large reserves of shale oil and gas. For the iden- tification of development characteristics and geological significance of the reservoir space, FM1 logging...The Es3/3-Es1/4 shales in Dongying sag are source rocks with large reserves of shale oil and gas. For the iden- tification of development characteristics and geological significance of the reservoir space, FM1 logging, core observation, thin section analysis, X-ray diffraction, fluorescence microscopy, scanning electron microscopy, mercury porosimetry, low-temperature nitrogen adsorption, atomic force microscopy, and conventional physical property testing were used to study the petrology and reservoir space of the Es3/3-Es1/4 shale in Dongying sag. The results suggest that the shale is rich in carbonate minerals. Phanero- crystalline stratiform and lamellar argillaceous limestone and calcareous claystone are the oil- and gas-bearing lithofacies. The oil in the micropores is mainly present as membranes and clots. The shale reservoir space has a network structure with veins, carbonate and clay minerals, and micropores among pyrite and the matrix. The results provide the geological framework for future shale oil and gas explora- tion in Dongying sag.展开更多
In this paper,substantial domestic and foreign research results of microscopic shale reservoir space were systemically reviewed,the research history consisting of simple observation and qualitative classification,quan...In this paper,substantial domestic and foreign research results of microscopic shale reservoir space were systemically reviewed,the research history consisting of simple observation and qualitative classification,quantitative research,the combination of qualitative and quantitative research successively as well as the characteristics of each research stage were summarized.In addition,the current problems existing in the characterization methods of shale reservoir space were also analyzed.Furthermore,based on massive actual detection of typical core samples obtained from more than 50 global shale gas wells and relevant practical experience,a comprehensive characterization method of combining qualitative with the semiquantitative characterization was put forward.In detail,the indicators of the qualitative characterization include pore combination type and organic-matter microscopic morphology type,while the core elements of the semi-quantitative characterization include the percentage of the organic-matter area and the plane porosity of the pores of different types.Based on the reference of the naming and classification of rocks,the three-end-member diagram method was used to characterize microscopic shale reservoir space.This is achieved by plotting the three end-member diagram of 3 kinds of first-order critical reservoir spaces,i.e.,organic-matter pores,matrix pores,and micro-fractures,in order to intuitively present the features of the microscopic pore combination.Meanwhile,statistic histograms of organic-matter microscopic morphology type and the plane porosity of different types of pores were adopted to characterize the development degree of second-order pores quantitatively.By this comprehensive characterization method,the importance of both pore combination and the microscopic morphology of organic matter were emphasized,revealing the control of organic-matter microscopic morphology over the organic-matter pores.What is more,high-resolution FE-SEM was adopted to obtain semi-quantitative statistics results.In this way,the features of pore development and pore combination were quantified,not only reflecting the types and storage capacity of the microscopic shale reservoir space,but also presenting the hydrocarbongenerating potential of organic matter in shale.Therefore,the results of this research are capable of providing in-depth microscopic information for the assessment and exploration and development of shale gas resources.展开更多
Number of reservoirs in China ranks the first in the world. Due to the complex geology, and superimposing rainfall and reservoir water fluctuation, the bank collapse chain is prone to disasters. The Yangtze River Rese...Number of reservoirs in China ranks the first in the world. Due to the complex geology, and superimposing rainfall and reservoir water fluctuation, the bank collapse chain is prone to disasters. The Yangtze River Reservoir is key geological disaster prevention area. Studying the process of reservoir disaster is significant because of the limited territorial space utilization. Scientific and technological issues, i.e., the mechanism of bank collapse disaster chain of large reservoirs, the interaction mechanism of bank collapse disaster chain and territorial space utilization, the early identification, monitoring technology and ecological prevention and control technology system of disaster chain, and the territorial space geological safety and control technology system are focused. We consider the material transformation, energy transfer and information transmission in disaster chain;adopt the survey, Space-Air-Ground integrated monitoring, theoretical analysis, numerical simulation and the multidisciplinary research methods;reveal the chain source development, evolution process of secondary and derivative disasters;explore the interaction mechanism of disaster chain and territorial space utilization;construct the system of early identification, monitoring, early warning, control and ecological preven-tion to achieve Emission Peak and Carbon Neutrality;provide theoretical and technical support for the territorial space geological safety, regulation and utilization of large reservoirs.展开更多
Optimal spacing for vertical wells can be effectively predicted with several published methods,but methods suitable for assessing the proper horizontal well spacing are rare.This work proposes a method for calculating...Optimal spacing for vertical wells can be effectively predicted with several published methods,but methods suitable for assessing the proper horizontal well spacing are rare.This work proposes a method for calculating the optimal horizontal well spacing for an ultra-low permeability reservoir e the Yongjin reservoir in the Juggar Basin,northwestern China.The result shows that a spacing of 640m is the most economical for the development of the reservoir.To better develop the reservoir,simulation approaches are used and a new model is built based on the calculated well spacing.Since the reservoir has an ultralow permeability,gas injection is regarded as the preferred enhanced oil recovery(EOR)method.Injection of different gases including carbon dioxide,methane,nitrogen and mixed gas are modelled.The results show that carbon dioxide injection is the most efficient and economical for the development of the reservoir.However,if the reservoir produces enough methane,reinjecting methane is even better than injecting carbon dioxide.展开更多
Methods for horizontal well spacing calculation in tight gas reservoirs are still adversely affected by the complexity of related control factors,such as strong reservoir heterogeneity and seepage mechanisms.In this s...Methods for horizontal well spacing calculation in tight gas reservoirs are still adversely affected by the complexity of related control factors,such as strong reservoir heterogeneity and seepage mechanisms.In this study,the stress sensitivity and threshold pressure gradient of various types of reservoirs are quantitatively evaluated through reservoir seepage experiments.On the basis of these experiments,a numerical simulation model(based on the special seepage mechanism)and an inverse dynamic reserve algorithm(with different equivalent drainage areas)were developed.The well spacing ranges of Classes I,II,and III wells in the Q gas field are determined to be 802–1,000,600–662,and 285–400 m,respectively,with their average ranges as 901,631,and 342.5 m,respectively.By considering both the pairs of parallel well groups and series well groups as examples,the reliability of the calculation results is verified.It is shown that the combination of the two models can reduce errors and provide accurate results.展开更多
In this study,a fully coupled hydromechanical model within the extended finite element method(XFEM)-based cohesive zone method(CZM)is employed to investigate the simultaneous height growth behavior of multi-cluster hy...In this study,a fully coupled hydromechanical model within the extended finite element method(XFEM)-based cohesive zone method(CZM)is employed to investigate the simultaneous height growth behavior of multi-cluster hydraulic fractures in layered porous reservoirs with modulus contrast.The coupled hydromechanical model is first verified against an analytical solution and a laboratory experiment.Then,the fracture geometry(e.g.height,aperture,and area)and fluid pressure evolutions of multiple hydraulic fractures placed in a porous reservoir interbedded with alternating stiff and soft layers are investigated using the model.The stress and pore pressure distributions within the layered reservoir during fluid injection are also presented.The simulation results reveal that stress umbrellas are easily to form among multiple hydraulic fractures’tips when propagating in soft layers,which impedes the simultaneous height growth.It is also observed that the impediment effect of soft layer is much more significant in the fractures suppressed by the preferential growth of adjoining fractures.After that,the combined effect of in situ stress ratio and fracturing spacing on the multi-fracture height growth is presented,and the results elucidate the influence of in situ stress ratio on the height growth behavior depending on the fracture spacing.Finally,it is found that the inclusion of soft layers changes the aperture distribution of outmost and interior hydraulic fractures.The results obtained from this study may provide some insights on the understanding of hydraulic fracture height containment observed in filed.展开更多
In Wangjiatun area of the Northern Songliao Basin, reservoir space can be divided into three types: primary pore, secondary pore and fissure according to their origins,which can be subdivided into eight subtypes: macr...In Wangjiatun area of the Northern Songliao Basin, reservoir space can be divided into three types: primary pore, secondary pore and fissure according to their origins,which can be subdivided into eight subtypes: macro-vesicule, shrank primary vesicule, alteration pore, groundmass corrosive pore, normal structural crack, corrosive structural crack, filled structural crack and groundmass shrank crack according to texture and origin of the pore space. It has characteristic of double pore medium. Volcanic porosities of small diameter samples (with diameter of ca. 2.5 cm) and large diameter samples (with diameter of ca. 21.5 cm) were tested in accordance with the characteristic of volcanic reservoir space. Volcanic porosities for small diameter samples correspond with matrix porosities and those of large diameter samples correspond with total porosities including matrix and fractured porosities. Models of the calculated porosity by acoustic wave or density of volcanic reservoir are established in view of those measured data. Comparison of calculated and measuredporosities shows that precision of calculated porosities is lower for rhyolite and tuffites, and higher for basaltand andesite. Relative errors of calculated porosities by model of large diameter samples are lower than those of small diameter samples, i. e. precision of the former is higher than that of the later.展开更多
The Shanggu gas field is the low porosity and low permeability. Single well controlled reserves, economic limit well spacing and economic rational spacing through different methods are calculated. With the development...The Shanggu gas field is the low porosity and low permeability. Single well controlled reserves, economic limit well spacing and economic rational spacing through different methods are calculated. With the development experience of Su Lige gas field as guidance, the rational spacing of Shanggu gas reservoir is 700m×900m by calculating daily gas production rate and cumulative gas production with different well spacing using numerical simulation method.展开更多
文摘To predict complex reservoir spaces(with developed caves,pores,and fractures),based on the results of full-azimuth depth migration processing,we adopted reverse weighted nonlinear inversion to improve the accuracy of porous reservoir prediction.Scattering imaging three-parameter wavelet transform technology was used to accurately predict small-scale cave bodies.The joint inversion method of velocity and amplitude anisotropy was developed to improve the accuracy of small and medium-sized fracture prediction.The results of multiscale fracture modeling and characterization,interwell connectivity analysis,and connection path prediction are consistent with the production condition.Finally,based on the above prediction findings,favorable reservoir development areas were predicted.The above ideas and strategies have great application value for the efficient exploration and development of complex storage space reservoirs and the optimization of high-yield well locations.
基金the National Natural Science Foundation of China(41971215,42371205)the Youth Innovation Promotion Association of Chinese Academy of Sciences(2022317).
文摘The Three Gorges Reservoir Area(TGRA)is an important ecological barrier in the Yangtze River Basin,China.Therefore,it is of great importance to understand the spatio-temporal variation and the driving factors of production-living-ecological spaces for sustainable and high-quality development in the TGRA.This study investigated the dynamic variation of production-living-ecological spaces in the TGRA by employing land use data in 2000,2005,2010,2015,and 2018,and detected the influencing factors by using the Geographic detector(GeoDetector).Results implied that the structure and dynamic trajectories of production-living-ecological spaces in the TGRA varied in both horizontal and vertical directions,and the study area was dominated by ecological space.A spatial orientation towards the northeast was detected in the evolution of production-living-ecological spaces during 2000-2018.In terms of quantity,the transition from ecological space(grassland and woodland)to agriculture land accounted for the largest proportion from 2000 to 2018.However,the reverse transition from agriculture land to ecological space has increased since 2000 with the efforts of“Grain for Green”.In terms of temporal scale,there was a fluctuating trend in production space with the continuous expansion of living space,while ecological space showed an inverted U-shaped trend during 2000-2018.The dynamic pattern of production-living-ecological spaces in the TGRA was influenced by both physical and socio-economic variables as basic determinants and dominant driving factors,respectively.Finally,the harmonization and protection of production-living-ecological spaces still require policy-makers’efforts.This work may have potential in advancing our understanding about land use conflicts,and provide a reference for rational layout of spatial functions and the realization of sustainable development in the TGRA.
基金co-supported by the National Basic Research Program of China(Grant No.2011CB201103)the National Science and Technology Major Project(Grant No.2011ZX05004003)
文摘Secondary storage spaces with very complex geometries are well developed in Ordovician carbonate reservoirs in the Tarim Basin,which is taken as a study case in this paper.It is still not clear how the secondary storage space shape influences the P-& S-wave velocities (or elastic properties) in complex carbonate reservoirs.In this paper,three classical rock physics models (Wyllie timeaverage equation,Gassmann equation and the Kuster-Toks z model) are comparably analyzed for their construction principles and actual velocity prediction results,aiming at determining the most favourable rock physics model to consider the influence of secondary storage space shape.Then relationships between the P-& S-wave velocities in carbonate reservoirs and geometric shapes of secondary storage spaces are discussed from different aspects based on actual well data by employing the favourable rock physics model.To explain the influence of secondary storage space shape on V P-V S relationship,it is analyzed for the differences of S-wave velocities between derived from common empirical relationships (including Castagna's mud rock line and Greenberg-Castagna V P-V S relationship) and predicted by the rock physics model.We advocate that V P-V S relationship for complex carbonate reservoirs should be built for different storage space types.For the carbonate reservoirs in the Tarim Basin,the V P-V S relationships for fractured,fractured-cavernous,and fractured-hole-vuggy reservoirs are respectively built on the basis of velocity prediction and secondary storage space type determination.Through the discussion above,it is expected that the velocity prediction and the V P-V S relationships for complex carbonate reservoirs should fully consider the influence of secondary storage space shape,thus providing more reasonable constraints for prestack inversion,further building a foundation for realizing carbonate reservoir prediction and fluid prediction.
基金supported by the National Major Science and Technology Project (No.2016ZX05030002)
文摘This paper discusses the reservoir space in carbonate rocks in terms of types,combination features,distribution regularity,and controlling factors,based on core observations and tests of the North Truva Oilfield,Caspian Basin.According to the reservoir space combinations,carbonate reservoirs can be divided into four types,i.e.,pore,fracture-pore,pore-cavity-fracture,and pore-cavity.Formation and distribution of these reservoirs is strongly controlled by deposition,diagenesis,and tectonism.In evaporated platform and restricted platform facies,the reservoirs are predominately affected by meteoric fresh water leaching in the supergene-para-syngenetic period and by uplifting and erosion in the late stage,making both platform facies contain all the above-mentioned four types of reservoirs,with various pores,such as dissolved cavities and dissolved fractures,or structural fractures occasionally in favorable structural locations.In open platform facies,the reservoirs deposited continuously in deeper water,in an environment of alternative high-energy shoals(where pore-fracture-type reservoirs are dominant) and low-energy shoals(where pore reservoirs are dominant).
基金funded by the Scientific and Technological Brainstorm Project of Sinopec Corp (No. P12062)
文摘The Es3/3-Es1/4 shales in Dongying sag are source rocks with large reserves of shale oil and gas. For the iden- tification of development characteristics and geological significance of the reservoir space, FM1 logging, core observation, thin section analysis, X-ray diffraction, fluorescence microscopy, scanning electron microscopy, mercury porosimetry, low-temperature nitrogen adsorption, atomic force microscopy, and conventional physical property testing were used to study the petrology and reservoir space of the Es3/3-Es1/4 shale in Dongying sag. The results suggest that the shale is rich in carbonate minerals. Phanero- crystalline stratiform and lamellar argillaceous limestone and calcareous claystone are the oil- and gas-bearing lithofacies. The oil in the micropores is mainly present as membranes and clots. The shale reservoir space has a network structure with veins, carbonate and clay minerals, and micropores among pyrite and the matrix. The results provide the geological framework for future shale oil and gas explora- tion in Dongying sag.
基金This study was supported by the National Scientific and Technological Major Special Project titled“Research on Evaluation Method and Exploration Technology on Shale Gas Resources”(2016ZX05034)“Shale Gas Basic Geological Survey Project in South China”(121201229000160021)initiated by CGSinter-governmental cooperation project titled“China-USA Cooperation Research Project of Carboniferous-Permian Shale Reservoir Evaluation Technology”(2017YFE0106300).
文摘In this paper,substantial domestic and foreign research results of microscopic shale reservoir space were systemically reviewed,the research history consisting of simple observation and qualitative classification,quantitative research,the combination of qualitative and quantitative research successively as well as the characteristics of each research stage were summarized.In addition,the current problems existing in the characterization methods of shale reservoir space were also analyzed.Furthermore,based on massive actual detection of typical core samples obtained from more than 50 global shale gas wells and relevant practical experience,a comprehensive characterization method of combining qualitative with the semiquantitative characterization was put forward.In detail,the indicators of the qualitative characterization include pore combination type and organic-matter microscopic morphology type,while the core elements of the semi-quantitative characterization include the percentage of the organic-matter area and the plane porosity of the pores of different types.Based on the reference of the naming and classification of rocks,the three-end-member diagram method was used to characterize microscopic shale reservoir space.This is achieved by plotting the three end-member diagram of 3 kinds of first-order critical reservoir spaces,i.e.,organic-matter pores,matrix pores,and micro-fractures,in order to intuitively present the features of the microscopic pore combination.Meanwhile,statistic histograms of organic-matter microscopic morphology type and the plane porosity of different types of pores were adopted to characterize the development degree of second-order pores quantitatively.By this comprehensive characterization method,the importance of both pore combination and the microscopic morphology of organic matter were emphasized,revealing the control of organic-matter microscopic morphology over the organic-matter pores.What is more,high-resolution FE-SEM was adopted to obtain semi-quantitative statistics results.In this way,the features of pore development and pore combination were quantified,not only reflecting the types and storage capacity of the microscopic shale reservoir space,but also presenting the hydrocarbongenerating potential of organic matter in shale.Therefore,the results of this research are capable of providing in-depth microscopic information for the assessment and exploration and development of shale gas resources.
文摘Number of reservoirs in China ranks the first in the world. Due to the complex geology, and superimposing rainfall and reservoir water fluctuation, the bank collapse chain is prone to disasters. The Yangtze River Reservoir is key geological disaster prevention area. Studying the process of reservoir disaster is significant because of the limited territorial space utilization. Scientific and technological issues, i.e., the mechanism of bank collapse disaster chain of large reservoirs, the interaction mechanism of bank collapse disaster chain and territorial space utilization, the early identification, monitoring technology and ecological prevention and control technology system of disaster chain, and the territorial space geological safety and control technology system are focused. We consider the material transformation, energy transfer and information transmission in disaster chain;adopt the survey, Space-Air-Ground integrated monitoring, theoretical analysis, numerical simulation and the multidisciplinary research methods;reveal the chain source development, evolution process of secondary and derivative disasters;explore the interaction mechanism of disaster chain and territorial space utilization;construct the system of early identification, monitoring, early warning, control and ecological preven-tion to achieve Emission Peak and Carbon Neutrality;provide theoretical and technical support for the territorial space geological safety, regulation and utilization of large reservoirs.
文摘Optimal spacing for vertical wells can be effectively predicted with several published methods,but methods suitable for assessing the proper horizontal well spacing are rare.This work proposes a method for calculating the optimal horizontal well spacing for an ultra-low permeability reservoir e the Yongjin reservoir in the Juggar Basin,northwestern China.The result shows that a spacing of 640m is the most economical for the development of the reservoir.To better develop the reservoir,simulation approaches are used and a new model is built based on the calculated well spacing.Since the reservoir has an ultralow permeability,gas injection is regarded as the preferred enhanced oil recovery(EOR)method.Injection of different gases including carbon dioxide,methane,nitrogen and mixed gas are modelled.The results show that carbon dioxide injection is the most efficient and economical for the development of the reservoir.However,if the reservoir produces enough methane,reinjecting methane is even better than injecting carbon dioxide.
基金the Major Science and Technology Project of Southwest Oil and Gas Field Company(2022ZD01-02).
文摘Methods for horizontal well spacing calculation in tight gas reservoirs are still adversely affected by the complexity of related control factors,such as strong reservoir heterogeneity and seepage mechanisms.In this study,the stress sensitivity and threshold pressure gradient of various types of reservoirs are quantitatively evaluated through reservoir seepage experiments.On the basis of these experiments,a numerical simulation model(based on the special seepage mechanism)and an inverse dynamic reserve algorithm(with different equivalent drainage areas)were developed.The well spacing ranges of Classes I,II,and III wells in the Q gas field are determined to be 802–1,000,600–662,and 285–400 m,respectively,with their average ranges as 901,631,and 342.5 m,respectively.By considering both the pairs of parallel well groups and series well groups as examples,the reliability of the calculation results is verified.It is shown that the combination of the two models can reduce errors and provide accurate results.
文摘In this study,a fully coupled hydromechanical model within the extended finite element method(XFEM)-based cohesive zone method(CZM)is employed to investigate the simultaneous height growth behavior of multi-cluster hydraulic fractures in layered porous reservoirs with modulus contrast.The coupled hydromechanical model is first verified against an analytical solution and a laboratory experiment.Then,the fracture geometry(e.g.height,aperture,and area)and fluid pressure evolutions of multiple hydraulic fractures placed in a porous reservoir interbedded with alternating stiff and soft layers are investigated using the model.The stress and pore pressure distributions within the layered reservoir during fluid injection are also presented.The simulation results reveal that stress umbrellas are easily to form among multiple hydraulic fractures’tips when propagating in soft layers,which impedes the simultaneous height growth.It is also observed that the impediment effect of soft layer is much more significant in the fractures suppressed by the preferential growth of adjoining fractures.After that,the combined effect of in situ stress ratio and fracturing spacing on the multi-fracture height growth is presented,and the results elucidate the influence of in situ stress ratio on the height growth behavior depending on the fracture spacing.Finally,it is found that the inclusion of soft layers changes the aperture distribution of outmost and interior hydraulic fractures.The results obtained from this study may provide some insights on the understanding of hydraulic fracture height containment observed in filed.
文摘In Wangjiatun area of the Northern Songliao Basin, reservoir space can be divided into three types: primary pore, secondary pore and fissure according to their origins,which can be subdivided into eight subtypes: macro-vesicule, shrank primary vesicule, alteration pore, groundmass corrosive pore, normal structural crack, corrosive structural crack, filled structural crack and groundmass shrank crack according to texture and origin of the pore space. It has characteristic of double pore medium. Volcanic porosities of small diameter samples (with diameter of ca. 2.5 cm) and large diameter samples (with diameter of ca. 21.5 cm) were tested in accordance with the characteristic of volcanic reservoir space. Volcanic porosities for small diameter samples correspond with matrix porosities and those of large diameter samples correspond with total porosities including matrix and fractured porosities. Models of the calculated porosity by acoustic wave or density of volcanic reservoir are established in view of those measured data. Comparison of calculated and measuredporosities shows that precision of calculated porosities is lower for rhyolite and tuffites, and higher for basaltand andesite. Relative errors of calculated porosities by model of large diameter samples are lower than those of small diameter samples, i. e. precision of the former is higher than that of the later.
文摘The Shanggu gas field is the low porosity and low permeability. Single well controlled reserves, economic limit well spacing and economic rational spacing through different methods are calculated. With the development experience of Su Lige gas field as guidance, the rational spacing of Shanggu gas reservoir is 700m×900m by calculating daily gas production rate and cumulative gas production with different well spacing using numerical simulation method.