Tight glutenite reservoirs are known for strong heterogeneity,complex wettability,and challenging development.Gas-Assisted Gravity Drainage(GAGD)technology has the potential to significantly improve recovery efficienc...Tight glutenite reservoirs are known for strong heterogeneity,complex wettability,and challenging development.Gas-Assisted Gravity Drainage(GAGD)technology has the potential to significantly improve recovery efficiency in glutenite reservoir.However,there is currently limited research on GAGD processes specifically designed for glutenite reservoirs,and there is a lack of relevant dimensionless numbers for predicting recovery efficiency.In this study,we developed a theoretical model based on the characteristics of glutenite reservoirs and used phase-field method to track the oil-gas interface for numerical simulations of dynamic GAGD processes.To explore the factors influencing gas-driven recovery,we simulated the effects of strong heterogeneity and dynamic wettability on the construction process under gravity assistance.Additionally,we introduced multiple dimensionless numbers(including capillary number,viscosity ratio,and Bond number)and conducted a series of numerical simulations.The results demonstrate that gravity enhances the stability of the oil-gas interface but causes unstable pressure fluctuations when passing through different-sized throat regions,particularly leading to front advancement in smaller throats.Although strong heterogeneity has negative impacts on GAGD,they can be mitigated by reducing injection velocity.Increasing oil-wettability promotes oil displacement by overcoming capillary forces,particularly in narrower pores,allowing residual oils to be expelled.Among the dimensionless numbers,the recovery efficiency is directly proportional to the Bond number and inversely proportional to the capillary number and viscosity ratio.Through sensitivity analysis of the dimensionless numbers’impact on the recovery efficiency,a new dimensionless N_(Glu) considering heterogeneity is proposed to accurately predict GAGD recovery of tight glutenite reservoirs.展开更多
The glutenite reservoir is strongly heterogeneous due to the random distribution of gravels, making it challenging to perform hydraulic fracturing effectively. To solve this issue, it is essential to study interaction...The glutenite reservoir is strongly heterogeneous due to the random distribution of gravels, making it challenging to perform hydraulic fracturing effectively. To solve this issue, it is essential to study interaction behavior between hydraulic fractures(HFs) and gravels. A coupled hydro-mechanical model is proposed for HF propagation in glutenite using a grain-based discrete element method. This paper first investigates the dynamic evolution of HFs in glutenite, then analyzes the influences of various factors such as horizontal stress difference(Δσ), minimum horizontal stress(σh), gravel content(Vg), gravel size(dg), and stiffness ratio of gravel to matrix(Rs) on HF propagation geometries. Results show that penetrating the gravel is the primary HF-gravel interaction behavior, which follows sequential and staggered initiation modes. Bypassing the gravel is the secondary behavior, which obeys the sequential initiation mode and occurs when the orientation of the gravel boundary is inclined to the maximum horizontal stress(σH). An offset along the gravel boundary is usually formed while penetrating gravels, and the offsets may cause fracture widths to decrease by 37.8%-84.4%. Even if stress dominates the direction of HF propagation, HFs still tend to deflect within gravels. The deviation angle from σH decreases with rising Δσand increases with the increase of dgand Rs. Additionally, intra-gravel shear HFs(IGS-HFs) are prone to be generated in coarse-grained glutenite under high Δσ, while more gravel-bypassing shear HFs(GBSHFs) tend to be created in argillaceous glutenite with high Rsthan in sandy glutenite with low Rs. The findings above prompt the emergence of a novel HF propagation pattern in glutenite, which helps to understand the real HF geometries and to provide theoretical guidance for treatments in the field.展开更多
Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and ...Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and minerals were characterized microscopically,the measured trap sealing indexes were compared,the biomarker compounds of crude oil were extracted,the genesis of condensate gas was identified,and the reservoir-forming conditions were examined.On this basis,the Paleogene Enping Formation in the Huizhou 26 subsag was systematically analyzed for the potential of oil and gas resources,the development characteristics of large-scale high-quality conglomerate reservoirs,the trapping effectiveness of faults,the hydrocarbon migration and accumulation model,and the formation conditions and exploration targets of large-and medium-sized glutenite-rich oil and gas fields.The research results were obtained in four aspects.First,the Paleogene Wenchang Formation in the Huizhou 26 subsag develops extensive and thick high-quality source rocks of semi-deep to deep lacustrine subfacies,which have typical hydrocarbon expulsion characteristics of"great oil generation in the early stage and huge gas expulsion in the late stage",providing a sufficient material basis for hydrocarbon accumulation in the Enping Formation.Second,under the joint control of the steep slope zone and transition zone of the fault within the sag,the large-scale near-source glutenite reservoirs are highly heterogeneous,with the development scale dominated hierarchically by three factors(favorable facies zone,particle component,and microfracture).The(subaqueous)distributary channels near the fault system,with equal grains,a low mud content(<5%),and a high content of feldspar composition,are conducive to the development of sweet spot reservoirs.Third,the strike-slip pressurization trap covered by stable lake flooding mudstone is a necessary condition for oil and gas preservation,and the NE and nearly EW faults obliquely to the principal stress have the best control on traps.Fourth,the spatiotemporal configuration of high-quality source rocks,fault transport/sealing,and glutenite reservoirs controls the degree of hydrocarbon enrichment.From top to bottom,three hydrocarbon accumulation units,i.e.low-fill zone,transition zone,and high-fill zone,are recognized.The main area of the channel in the nearly pressurized source-connecting fault zone is favorable for large-scale hydrocarbon enrichment.The research results suggest a new direction for the exploration of large-scale glutenite-rich reservoirs in the Enping Formation of the Pearl River Mouth Basin,and present a major breakthrough in oil and gas exploration.展开更多
Due to the existence of gravel,glutenite is heterogeneous and different from fine-grained rocks such as sandstone and shale in structure.To fully understand the effect of gravel on failure mode in glutenite,we perform...Due to the existence of gravel,glutenite is heterogeneous and different from fine-grained rocks such as sandstone and shale in structure.To fully understand the effect of gravel on failure mode in glutenite,we performed triaxial compression tests on different glutenites.The results indicate that failure modes of glutenite are complex due to the existence of gravel.Under different confining pressures,three failure modes were observed.The first failure mode,a tensile failure under uniaxial compression,produces multiple tortuous longitudinal cracks.In this failure mode,the interaction between gravels provides the lateral tensile stress for rock splitting.The second failure mode occurs under low and medium confining pressure and produces a crack band composed of micro-cracks around gravels.This failure mode conforms to the Mohr-Coulomb criterion and is generated by shear failure.In this failure mode,shear dilatancy and shear compaction may occur under different confining pressures to produce different crack band types.In the second failure mode,gravel-induced stress concentration produces masses of initial micro-cracks for shear cracking,and gravels deflect the fracture surfaces.As a result,the fracture is characterized by crack bands that are far broader than in fine-grained rocks.The third failure mode requires high confining pressure and produces disconnected cracks around gravels without apparent crack bands.In this failure mode,the gravel rarely breaks,indicating that the formation of these fractures is related to the deformation of the matrix.The third failure mode requires lower confining pressure in glutenite with weak cement and matrix support.Generally,unlike fine-grained rocks,the failure mode of glutenite is not only controlled by confining pressure but also by the gravel.The failure of glutenite is characterized by producing cracks around gravels.These cracks are produced by different mechanisms and distributed in different manners under different confining pressures to form different fracture patterns.Therefore,understanding the rock microstructure and formation stress state is essential in guiding glutenite reservoir development.展开更多
1 Introduction Sareke glutenite-type copper deposit is the large size copper deposit discovered in recent years,and it is located Sarekebayi intracontinental pull-apart basin in the western margin of the Tarim basin.C...1 Introduction Sareke glutenite-type copper deposit is the large size copper deposit discovered in recent years,and it is located Sarekebayi intracontinental pull-apart basin in the western margin of the Tarim basin.Conglomerate of展开更多
The glutenite in the fourth member of Shahejie Formation(Es^4) in northern Dongying depression straightforwardly penetrated into the muddy bathyal -abyss facies.The conditions of reservoir is very superior:(1) the hig...The glutenite in the fourth member of Shahejie Formation(Es^4) in northern Dongying depression straightforwardly penetrated into the muddy bathyal -abyss facies.The conditions of reservoir is very superior:(1) the high quality thick bedded oil source rock is developed very well in the Lijin sag and Minfeng sag of the study area,and it has the higher capability of generating hydrocarbon;(2) the展开更多
Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior o...Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior of hydraulic fractures in these glutenite reservoirs,the geological feature of reservoirs in Bohai Bay Basin is studied firstly,including the reservoir vertical distribution feature and the heterogeneous lithology.Then,hydraulic fracturing treatments in block Yan 222 are carried out and the fracturing processes are monitored by the microseismic system.Results show the hydraulic fractures generated in the reservoirs are mostly in X shape.The cause of X-shaped hydraulic fractures in this study is mainly ascribed to(I)the reservoir heterogeneity and(II)the stress shadow effect of two close hydraulic fractures propagating in the same orientation,which is confirmed by the following numerical simulation and related research in detail.This study can provide a reference for the research on the fracturing behavior of the deep thick glutenite reservoirs.展开更多
It is known that the pore media characteristics of glutenite reservoirs are different from those of conventional sandstone reservoirs.Low reservoir permeability and naturally developed microfractures make water inject...It is known that the pore media characteristics of glutenite reservoirs are different from those of conventional sandstone reservoirs.Low reservoir permeability and naturally developed microfractures make water injection in this kind of reservoir very difficult.In this study,new exploitation methods are explored.Using a real glutenite reservoir as a basis,a three-dimensional fine geological model is elaborated.Then,combining the model with reservoir performance information,and through a historical fitting analysis,the saturation abundance distribution of remaining oil in the reservoir is determined.It is shown that,using this information,predictions can be made about whether the considered reservoir is suitable for horizontal well fracturing or not.The direction,well length,well spacing and productivity of horizontal well are also obtained.展开更多
The dolomite in dolomitic glutenite of the shahejie formation in the eastern steep slope of the Shijiutuo bulge in Bohai is a high-quality reservoir, and the content of dolomite is positively correlated with reservoir...The dolomite in dolomitic glutenite of the shahejie formation in the eastern steep slope of the Shijiutuo bulge in Bohai is a high-quality reservoir, and the content of dolomite is positively correlated with reservoir physical properties. In this paper, by using thin section, core, wall core, geochemical data and analyzing petrology and mineralogy characteristic, we systematically analyzed the paleogeographic environment and genetic mechanism of this kind of dolomite and established the genetic models. The dolomite in the glutenite body has many characteristics of development, which is formed by three kinds of genesis: quasi-synergy dolomitization, buried dolomitization and hydrothermal dolomitization. The dolomite in glutenite is produced in the form of matrix, grain (sandstone, oolith), biological skeleton (conch, ostracod), clastic shell and dolomite cement. The minor elements, carbon and oxygen isotopes, trace minerals and paleontological combinations reveal that the paleogeographic environment was closed continental salt-brackish water bay, the climate was arid and hot, and the evaporation was strong. It provides favorable conditions for the production of the dolomite in dolomitic glutenite. There are three genetic models of dolomite. The first model is penecontemporaneous dolomitization. The climate was arid and hot, the aragonite and high-magnesium calcite deposited with sand and gravel. Due to the effect of evaporation, dolomitization occurred. The second model is buried dolomitization. The water from dehydration of clay minerals causes the Mg2+ in the high-magnesium formation migrating into the rock, leading to the occurrence of dolomitization. The third model is hydrothermal dolomitization. Deep faults can bring geothermal fluids into the overlying reservoir and form the hydrothermal dolomite.展开更多
Glutenite(coarse-grained clastic)reservoirs of intergranularesecondary dissolution pore type are dominated by residual intergranular pores and secondary dissolution pores,and characterized by low porosity,low permeabi...Glutenite(coarse-grained clastic)reservoirs of intergranularesecondary dissolution pore type are dominated by residual intergranular pores and secondary dissolution pores,and characterized by low porosity,low permeability,strong heterogeneity,and highly variable physical properties.It is difficult to conduct a quantitative quality assessment of these reservoirs while their primary control factors remain unclear.In this paper,experimental core data and drilling,logging and seismic data are used to assess the effect of sedimentary facies on reservoir quality.Favorable sedimentary facies zones are identified by analyzing the characteristics of glutenite reservoirs,which includes investigating rock components and their effects on reservoir quality.Argillaceous matrix content and rigid particle content are identified as the primary control factors for these reservoirs.Logging curves sensitive to reservoir quality are selected and examined to continuously characterize the physical parameters of the reservoirs.It establishes a calculation model of reservoir assessment parameters through multivariate regression and determines the quantitative assessment parameter Fr.The quality of the glutenite reservoirs is defined using conventional logging curves.This study also predicts the plane distribution of high-quality reservoirs through geostatistical inversion of the reservoir assessment parameters based on conventional wave impedance inversion,thus providing insight and guidance for quantitative assessment and quality prediction of glutenite reservoirs of the intergranular-secondary dissolution pore type.The application of this method to well deployment based on qualitative evaluation of the glutenite reservoirs in oilfields yielded favorable results.展开更多
Although the Triassic Xujiahe Formation in Yuanba area of northern Sichuan has a large amount of resources,the proportion of proved reserves to the amount of resources is low.Production of most of the pilot production...Although the Triassic Xujiahe Formation in Yuanba area of northern Sichuan has a large amount of resources,the proportion of proved reserves to the amount of resources is low.Production of most of the pilot production wells is high at the initial stage,but it declines rapidly,mainly due to tight rock properties and strong heterogeneity of Xujiahe Formation.Thus,it is important to investigate the distribution of high-quality reservoirs.The Member 3 of Xujiahe Formation develops sandstone interbedded with mudstone,and its lateral thickness of different sandstone groups varies greatly,so it is a challenge to identify appropriate time windows for seismic attribute analysis,thus,so the prediction effect of the glutenite in the Member 3 of Xujiahe Formation.In this study,through analysis of core data and logging facies,single-well sedimentary microfacies subdivision is carried out.Single-well lithological interpretation is also studied with application of lithological identification technique.Then,lithological associations and its seismic responses at the top and bottom interfaces of each sandstone group in the Member 3 of Xujiahe Formation are well investigated,The lithological association with the glutenite above and the mudstone below the stratigraphic interface respectively,corresponds to a trough in seismic profiles;in this case,when extracting the seismic attributes of sandstone groups above the stratigraphic interface,only the difference of between drilling horizons and seismic horizons needs to be considered.The lithological association with the mudstone above and glutenite below the stratigraphic interface respectively,corresponds to a peak in seismic profiles;in this case,when extracting the seismic attributes of sandstone groups above the stratigraphic interface,influence of which should be eliminated;thus,a method of time window determination for seismic attribute extraction is established.Among amplitude,frequency,and phase attributes,the total peak energy has the good correlation with thickness of the glutenite at well sites and it also can reflect the distribution of distributary channels well.The results show that belt-like glutenite in each sandstone group in the Member 3 of Xujiahe Formation extends in a NW-SE direction and thins out toward the southeast,and the distribution of glutenite has certain inheritance in the longitudinal direction,the glutenite in the third sandstone group in the Member 3 of Xujiahe Formation(TX33)and the first sandstone group in the Member 3 of Xujiahe Formation(TX31)are both developed.展开更多
The BZ19-6 deep buried-hill structural belt in the southwest of Bozhong Sag,Bohai Bay Basin,is a newly discovered super-giant oil and gas bearing area.The study on its reservoirs is still in the early stage,and the ch...The BZ19-6 deep buried-hill structural belt in the southwest of Bozhong Sag,Bohai Bay Basin,is a newly discovered super-giant oil and gas bearing area.The study on its reservoirs is still in the early stage,and the characteristics and control factors of reservoir development are not understood deeply.In this paper,cores,sidewall cores,rock sections were analyzed and described.Then,based on regional structural setting,mud logging and logging data,the buried-hill reservoirs in this area were analyzed from the aspects of petrological characteristics,reservoir space types and physical properties,the inherent factors influencing the development of the reservoirs were discussed,and distribution laws of the reservoirs were investigated.And the following research results were obtained.First,the deep buried-hill reservoirs of this belt are a pan-buried hill reservoir system composed of the Palaeocene-Eocene Kongdian Fm glutenite in the upper part and the Archean buried-hill metamorphic granite in the lower part.A multi-layer reservoir structure of glutenite pore zone,weathering crust dissolution fracture zone and inner fracture zone is formed.These reservoirs are complex in genesis and diverse in type.Second,the Archean buried-hill metamorphic granite reservoir can be vertically divided into weathering crust,inner fracture zone and tight zone,and it presents the dual characteristics of porous and fractured media.Third,the buried-hill weathering crust is mainly affected by strong dissolution and leaching superimposed with fracturing,forming fractured-porous reservoir space.The reservoir of inner fracture zone is mainly controlled by the superimposition of three-phrase fractures,which forms the main development period of buried-hill fractures since the Yanshanian.Fourth,the glutenite of Kongdian Fm is a typical sieve deposit and it is mainly controlled by the late dissolution.Fifth,migmatization and supercritical fluid cryptoexplosion play a constructive role in the development of the reservoirs.In conclusion,the understanding of buried-hill glutenite and metamorphic reservoir system developed in this belt is conductive to determining the target and direction of next oil and gas exploration in this area.展开更多
The 4th Member of Shahejie Formation in Yanjia Area is located in the north wing of the central uplift zone of Dongying Depression, facing Chenjiazhuang Uplift in the north and Minfeng subsag in the south. Large-scale...The 4th Member of Shahejie Formation in Yanjia Area is located in the north wing of the central uplift zone of Dongying Depression, facing Chenjiazhuang Uplift in the north and Minfeng subsag in the south. Large-scale glutenite bodies developed during the 4th Member of Shahejie Formation, forming a distribution pattern of "canal and segment correspondence" with relatively low degree of exploration. Based on the study of Yanjia deep paleogeomorphology, sand body distribution characteristics and seismic facies characteristics, combined with the drilling situation, the source system and sedimentary evolution of glutenite are studied to determine the source direction and sedimentary evolution characteristics of deep glutenite in Yanjia area. Based on the detailed description of the glutenite reservoir by various geophysical methods, the main controlling factors for the formation of deep oil and gas reservoirs in this area are determined by means of oil source correlation, source rock analysis, oil and gas thermal evolution law, reservoir anatomy, matching relationship between oil and gas phase state and lower limit of oil and gas-bearing physical properties, etc.展开更多
基金supported by the National Natural Science Foundation of China(U22B2075)the Fundamental Research Funds for the Central Universities(2024ZKPYSB03)support from Beijing University of Science and Technology.
文摘Tight glutenite reservoirs are known for strong heterogeneity,complex wettability,and challenging development.Gas-Assisted Gravity Drainage(GAGD)technology has the potential to significantly improve recovery efficiency in glutenite reservoir.However,there is currently limited research on GAGD processes specifically designed for glutenite reservoirs,and there is a lack of relevant dimensionless numbers for predicting recovery efficiency.In this study,we developed a theoretical model based on the characteristics of glutenite reservoirs and used phase-field method to track the oil-gas interface for numerical simulations of dynamic GAGD processes.To explore the factors influencing gas-driven recovery,we simulated the effects of strong heterogeneity and dynamic wettability on the construction process under gravity assistance.Additionally,we introduced multiple dimensionless numbers(including capillary number,viscosity ratio,and Bond number)and conducted a series of numerical simulations.The results demonstrate that gravity enhances the stability of the oil-gas interface but causes unstable pressure fluctuations when passing through different-sized throat regions,particularly leading to front advancement in smaller throats.Although strong heterogeneity has negative impacts on GAGD,they can be mitigated by reducing injection velocity.Increasing oil-wettability promotes oil displacement by overcoming capillary forces,particularly in narrower pores,allowing residual oils to be expelled.Among the dimensionless numbers,the recovery efficiency is directly proportional to the Bond number and inversely proportional to the capillary number and viscosity ratio.Through sensitivity analysis of the dimensionless numbers’impact on the recovery efficiency,a new dimensionless N_(Glu) considering heterogeneity is proposed to accurately predict GAGD recovery of tight glutenite reservoirs.
基金supported by the National Natural Science Foundation of China(Grant No.52304003)the Natural Science Foundation of Sichuan Province(Grant No.2024NSFSC0961)the Postdoctoral Fellowship Program of CPSF(Grant No.GZB20230090).
文摘The glutenite reservoir is strongly heterogeneous due to the random distribution of gravels, making it challenging to perform hydraulic fracturing effectively. To solve this issue, it is essential to study interaction behavior between hydraulic fractures(HFs) and gravels. A coupled hydro-mechanical model is proposed for HF propagation in glutenite using a grain-based discrete element method. This paper first investigates the dynamic evolution of HFs in glutenite, then analyzes the influences of various factors such as horizontal stress difference(Δσ), minimum horizontal stress(σh), gravel content(Vg), gravel size(dg), and stiffness ratio of gravel to matrix(Rs) on HF propagation geometries. Results show that penetrating the gravel is the primary HF-gravel interaction behavior, which follows sequential and staggered initiation modes. Bypassing the gravel is the secondary behavior, which obeys the sequential initiation mode and occurs when the orientation of the gravel boundary is inclined to the maximum horizontal stress(σH). An offset along the gravel boundary is usually formed while penetrating gravels, and the offsets may cause fracture widths to decrease by 37.8%-84.4%. Even if stress dominates the direction of HF propagation, HFs still tend to deflect within gravels. The deviation angle from σH decreases with rising Δσand increases with the increase of dgand Rs. Additionally, intra-gravel shear HFs(IGS-HFs) are prone to be generated in coarse-grained glutenite under high Δσ, while more gravel-bypassing shear HFs(GBSHFs) tend to be created in argillaceous glutenite with high Rsthan in sandy glutenite with low Rs. The findings above prompt the emergence of a novel HF propagation pattern in glutenite, which helps to understand the real HF geometries and to provide theoretical guidance for treatments in the field.
基金Supported by the CNOOC Major Technology Project During the 14th FIVE-YEAR PLAN PERIOD(KJGG2022-0403)CNOOC Major Technology Project(KJZH-2021-0003-00).
文摘Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and minerals were characterized microscopically,the measured trap sealing indexes were compared,the biomarker compounds of crude oil were extracted,the genesis of condensate gas was identified,and the reservoir-forming conditions were examined.On this basis,the Paleogene Enping Formation in the Huizhou 26 subsag was systematically analyzed for the potential of oil and gas resources,the development characteristics of large-scale high-quality conglomerate reservoirs,the trapping effectiveness of faults,the hydrocarbon migration and accumulation model,and the formation conditions and exploration targets of large-and medium-sized glutenite-rich oil and gas fields.The research results were obtained in four aspects.First,the Paleogene Wenchang Formation in the Huizhou 26 subsag develops extensive and thick high-quality source rocks of semi-deep to deep lacustrine subfacies,which have typical hydrocarbon expulsion characteristics of"great oil generation in the early stage and huge gas expulsion in the late stage",providing a sufficient material basis for hydrocarbon accumulation in the Enping Formation.Second,under the joint control of the steep slope zone and transition zone of the fault within the sag,the large-scale near-source glutenite reservoirs are highly heterogeneous,with the development scale dominated hierarchically by three factors(favorable facies zone,particle component,and microfracture).The(subaqueous)distributary channels near the fault system,with equal grains,a low mud content(<5%),and a high content of feldspar composition,are conducive to the development of sweet spot reservoirs.Third,the strike-slip pressurization trap covered by stable lake flooding mudstone is a necessary condition for oil and gas preservation,and the NE and nearly EW faults obliquely to the principal stress have the best control on traps.Fourth,the spatiotemporal configuration of high-quality source rocks,fault transport/sealing,and glutenite reservoirs controls the degree of hydrocarbon enrichment.From top to bottom,three hydrocarbon accumulation units,i.e.low-fill zone,transition zone,and high-fill zone,are recognized.The main area of the channel in the nearly pressurized source-connecting fault zone is favorable for large-scale hydrocarbon enrichment.The research results suggest a new direction for the exploration of large-scale glutenite-rich reservoirs in the Enping Formation of the Pearl River Mouth Basin,and present a major breakthrough in oil and gas exploration.
基金supported by the Strategic Cooperation Technology Projects of CNPC and CUPB(ZLZX2020-01)Natural Science Youth Project of university scientific research plan in Xinjiang(XJEDU2021Y053).
文摘Due to the existence of gravel,glutenite is heterogeneous and different from fine-grained rocks such as sandstone and shale in structure.To fully understand the effect of gravel on failure mode in glutenite,we performed triaxial compression tests on different glutenites.The results indicate that failure modes of glutenite are complex due to the existence of gravel.Under different confining pressures,three failure modes were observed.The first failure mode,a tensile failure under uniaxial compression,produces multiple tortuous longitudinal cracks.In this failure mode,the interaction between gravels provides the lateral tensile stress for rock splitting.The second failure mode occurs under low and medium confining pressure and produces a crack band composed of micro-cracks around gravels.This failure mode conforms to the Mohr-Coulomb criterion and is generated by shear failure.In this failure mode,shear dilatancy and shear compaction may occur under different confining pressures to produce different crack band types.In the second failure mode,gravel-induced stress concentration produces masses of initial micro-cracks for shear cracking,and gravels deflect the fracture surfaces.As a result,the fracture is characterized by crack bands that are far broader than in fine-grained rocks.The third failure mode requires high confining pressure and produces disconnected cracks around gravels without apparent crack bands.In this failure mode,the gravel rarely breaks,indicating that the formation of these fractures is related to the deformation of the matrix.The third failure mode requires lower confining pressure in glutenite with weak cement and matrix support.Generally,unlike fine-grained rocks,the failure mode of glutenite is not only controlled by confining pressure but also by the gravel.The failure of glutenite is characterized by producing cracks around gravels.These cracks are produced by different mechanisms and distributed in different manners under different confining pressures to form different fracture patterns.Therefore,understanding the rock microstructure and formation stress state is essential in guiding glutenite reservoir development.
基金supported by the metallogenic regularities and prediction of glutenite type Cu-Pb-Zn deposit in Tarim west margin(201511016-1)the special mapping techniques and its application demonstration in Sareke overall-exploration area in Xinjiang(12120114081501)
文摘1 Introduction Sareke glutenite-type copper deposit is the large size copper deposit discovered in recent years,and it is located Sarekebayi intracontinental pull-apart basin in the western margin of the Tarim basin.Conglomerate of
文摘The glutenite in the fourth member of Shahejie Formation(Es^4) in northern Dongying depression straightforwardly penetrated into the muddy bathyal -abyss facies.The conditions of reservoir is very superior:(1) the high quality thick bedded oil source rock is developed very well in the Lijin sag and Minfeng sag of the study area,and it has the higher capability of generating hydrocarbon;(2) the
基金Projects(51879041,51774112,U1810203)supported by the National Natural Science Foundation of ChinaProject(2020M672224)supported by the China Postdoctoral Science FoundationProject(B2020-41)supported by the Doctoral Fund of Henan Polytechnic University,China。
文摘Tight glutenite reservoirs are widely developed in Bohai Bay Basin,East China.They are mostly huge thick and rely on hydraulic fracturing treatment for commercial exploitation.To investigate the propagation behavior of hydraulic fractures in these glutenite reservoirs,the geological feature of reservoirs in Bohai Bay Basin is studied firstly,including the reservoir vertical distribution feature and the heterogeneous lithology.Then,hydraulic fracturing treatments in block Yan 222 are carried out and the fracturing processes are monitored by the microseismic system.Results show the hydraulic fractures generated in the reservoirs are mostly in X shape.The cause of X-shaped hydraulic fractures in this study is mainly ascribed to(I)the reservoir heterogeneity and(II)the stress shadow effect of two close hydraulic fractures propagating in the same orientation,which is confirmed by the following numerical simulation and related research in detail.This study can provide a reference for the research on the fracturing behavior of the deep thick glutenite reservoirs.
文摘It is known that the pore media characteristics of glutenite reservoirs are different from those of conventional sandstone reservoirs.Low reservoir permeability and naturally developed microfractures make water injection in this kind of reservoir very difficult.In this study,new exploitation methods are explored.Using a real glutenite reservoir as a basis,a three-dimensional fine geological model is elaborated.Then,combining the model with reservoir performance information,and through a historical fitting analysis,the saturation abundance distribution of remaining oil in the reservoir is determined.It is shown that,using this information,predictions can be made about whether the considered reservoir is suitable for horizontal well fracturing or not.The direction,well length,well spacing and productivity of horizontal well are also obtained.
文摘The dolomite in dolomitic glutenite of the shahejie formation in the eastern steep slope of the Shijiutuo bulge in Bohai is a high-quality reservoir, and the content of dolomite is positively correlated with reservoir physical properties. In this paper, by using thin section, core, wall core, geochemical data and analyzing petrology and mineralogy characteristic, we systematically analyzed the paleogeographic environment and genetic mechanism of this kind of dolomite and established the genetic models. The dolomite in the glutenite body has many characteristics of development, which is formed by three kinds of genesis: quasi-synergy dolomitization, buried dolomitization and hydrothermal dolomitization. The dolomite in glutenite is produced in the form of matrix, grain (sandstone, oolith), biological skeleton (conch, ostracod), clastic shell and dolomite cement. The minor elements, carbon and oxygen isotopes, trace minerals and paleontological combinations reveal that the paleogeographic environment was closed continental salt-brackish water bay, the climate was arid and hot, and the evaporation was strong. It provides favorable conditions for the production of the dolomite in dolomitic glutenite. There are three genetic models of dolomite. The first model is penecontemporaneous dolomitization. The climate was arid and hot, the aragonite and high-magnesium calcite deposited with sand and gravel. Due to the effect of evaporation, dolomitization occurred. The second model is buried dolomitization. The water from dehydration of clay minerals causes the Mg2+ in the high-magnesium formation migrating into the rock, leading to the occurrence of dolomitization. The third model is hydrothermal dolomitization. Deep faults can bring geothermal fluids into the overlying reservoir and form the hydrothermal dolomite.
基金the National Natural Science Foundation of China(Grant No.:41872116)early projects initiated by the China National Petroleum Corporation‘Assessment of Permian and Triassic Hydrocarbon Accumulation Conditions and Targets in the Junggar Basin’and‘Assessment of Carboniferous Hydrocarbon Accumulation Conditions and Zones in the Junggar Basin’.
文摘Glutenite(coarse-grained clastic)reservoirs of intergranularesecondary dissolution pore type are dominated by residual intergranular pores and secondary dissolution pores,and characterized by low porosity,low permeability,strong heterogeneity,and highly variable physical properties.It is difficult to conduct a quantitative quality assessment of these reservoirs while their primary control factors remain unclear.In this paper,experimental core data and drilling,logging and seismic data are used to assess the effect of sedimentary facies on reservoir quality.Favorable sedimentary facies zones are identified by analyzing the characteristics of glutenite reservoirs,which includes investigating rock components and their effects on reservoir quality.Argillaceous matrix content and rigid particle content are identified as the primary control factors for these reservoirs.Logging curves sensitive to reservoir quality are selected and examined to continuously characterize the physical parameters of the reservoirs.It establishes a calculation model of reservoir assessment parameters through multivariate regression and determines the quantitative assessment parameter Fr.The quality of the glutenite reservoirs is defined using conventional logging curves.This study also predicts the plane distribution of high-quality reservoirs through geostatistical inversion of the reservoir assessment parameters based on conventional wave impedance inversion,thus providing insight and guidance for quantitative assessment and quality prediction of glutenite reservoirs of the intergranular-secondary dissolution pore type.The application of this method to well deployment based on qualitative evaluation of the glutenite reservoirs in oilfields yielded favorable results.
基金This work was supported by the Sinopec Scientific Research Project“Reservoir evaluation and sweet spot prediction of Xujiahe Formation in northeastern Sichuan Basin”(No.:P19012-2).
文摘Although the Triassic Xujiahe Formation in Yuanba area of northern Sichuan has a large amount of resources,the proportion of proved reserves to the amount of resources is low.Production of most of the pilot production wells is high at the initial stage,but it declines rapidly,mainly due to tight rock properties and strong heterogeneity of Xujiahe Formation.Thus,it is important to investigate the distribution of high-quality reservoirs.The Member 3 of Xujiahe Formation develops sandstone interbedded with mudstone,and its lateral thickness of different sandstone groups varies greatly,so it is a challenge to identify appropriate time windows for seismic attribute analysis,thus,so the prediction effect of the glutenite in the Member 3 of Xujiahe Formation.In this study,through analysis of core data and logging facies,single-well sedimentary microfacies subdivision is carried out.Single-well lithological interpretation is also studied with application of lithological identification technique.Then,lithological associations and its seismic responses at the top and bottom interfaces of each sandstone group in the Member 3 of Xujiahe Formation are well investigated,The lithological association with the glutenite above and the mudstone below the stratigraphic interface respectively,corresponds to a trough in seismic profiles;in this case,when extracting the seismic attributes of sandstone groups above the stratigraphic interface,only the difference of between drilling horizons and seismic horizons needs to be considered.The lithological association with the mudstone above and glutenite below the stratigraphic interface respectively,corresponds to a peak in seismic profiles;in this case,when extracting the seismic attributes of sandstone groups above the stratigraphic interface,influence of which should be eliminated;thus,a method of time window determination for seismic attribute extraction is established.Among amplitude,frequency,and phase attributes,the total peak energy has the good correlation with thickness of the glutenite at well sites and it also can reflect the distribution of distributary channels well.The results show that belt-like glutenite in each sandstone group in the Member 3 of Xujiahe Formation extends in a NW-SE direction and thins out toward the southeast,and the distribution of glutenite has certain inheritance in the longitudinal direction,the glutenite in the third sandstone group in the Member 3 of Xujiahe Formation(TX33)and the first sandstone group in the Member 3 of Xujiahe Formation(TX31)are both developed.
基金supported by the National Major Science and Technology Project“Comprehensive Study on Buried-Hill Reservoir-Forming in the Bohai Sea and Favorable Exploration Direction”(No.:2016ZX05024-003-010)the Scientific Research Project of CNOOC“Petroleum Geological Characteristics,Forming Mechanism of Typical Oil&Gas Reservoir and Prediction of Prospects of the Buried Hill in the Bohai Sea Area”(No.:CCL2014TJXZSS0870).
文摘The BZ19-6 deep buried-hill structural belt in the southwest of Bozhong Sag,Bohai Bay Basin,is a newly discovered super-giant oil and gas bearing area.The study on its reservoirs is still in the early stage,and the characteristics and control factors of reservoir development are not understood deeply.In this paper,cores,sidewall cores,rock sections were analyzed and described.Then,based on regional structural setting,mud logging and logging data,the buried-hill reservoirs in this area were analyzed from the aspects of petrological characteristics,reservoir space types and physical properties,the inherent factors influencing the development of the reservoirs were discussed,and distribution laws of the reservoirs were investigated.And the following research results were obtained.First,the deep buried-hill reservoirs of this belt are a pan-buried hill reservoir system composed of the Palaeocene-Eocene Kongdian Fm glutenite in the upper part and the Archean buried-hill metamorphic granite in the lower part.A multi-layer reservoir structure of glutenite pore zone,weathering crust dissolution fracture zone and inner fracture zone is formed.These reservoirs are complex in genesis and diverse in type.Second,the Archean buried-hill metamorphic granite reservoir can be vertically divided into weathering crust,inner fracture zone and tight zone,and it presents the dual characteristics of porous and fractured media.Third,the buried-hill weathering crust is mainly affected by strong dissolution and leaching superimposed with fracturing,forming fractured-porous reservoir space.The reservoir of inner fracture zone is mainly controlled by the superimposition of three-phrase fractures,which forms the main development period of buried-hill fractures since the Yanshanian.Fourth,the glutenite of Kongdian Fm is a typical sieve deposit and it is mainly controlled by the late dissolution.Fifth,migmatization and supercritical fluid cryptoexplosion play a constructive role in the development of the reservoirs.In conclusion,the understanding of buried-hill glutenite and metamorphic reservoir system developed in this belt is conductive to determining the target and direction of next oil and gas exploration in this area.
文摘The 4th Member of Shahejie Formation in Yanjia Area is located in the north wing of the central uplift zone of Dongying Depression, facing Chenjiazhuang Uplift in the north and Minfeng subsag in the south. Large-scale glutenite bodies developed during the 4th Member of Shahejie Formation, forming a distribution pattern of "canal and segment correspondence" with relatively low degree of exploration. Based on the study of Yanjia deep paleogeomorphology, sand body distribution characteristics and seismic facies characteristics, combined with the drilling situation, the source system and sedimentary evolution of glutenite are studied to determine the source direction and sedimentary evolution characteristics of deep glutenite in Yanjia area. Based on the detailed description of the glutenite reservoir by various geophysical methods, the main controlling factors for the formation of deep oil and gas reservoirs in this area are determined by means of oil source correlation, source rock analysis, oil and gas thermal evolution law, reservoir anatomy, matching relationship between oil and gas phase state and lower limit of oil and gas-bearing physical properties, etc.
