The Yitong（伊通） basin is a Late Mesozoic and Cenozoic continental sedimentary basin in Northeast China.On the basis of well tests and seismic data,we use the 2D modeling technique to rebuild the pressure evolution ...The Yitong（伊通） basin is a Late Mesozoic and Cenozoic continental sedimentary basin in Northeast China.On the basis of well tests and seismic data,we use the 2D modeling technique to rebuild the pressure evolution and hydrocarbon migration in the Moliqing（莫里青） fault depression of the Yitong basin.Based on the modeling results,four conclusions are drawn as follows.（1） The Eocene Shuangyang（双阳） Formation within the Moliqing fault depression had entirely undergone three epi-sodic cycles of pressure accumulation and release in geological history,and the three tectonic move-ments since the Middle Eocene played important roles in the episodic changes of excess pressure.（2） The present formation pressure distribution is characterized by normal pressure in almost the entire fault depression with some residual overpressure.The differential distribution of pressure results mainly from the difference in rock facies,sedimentation rate,hydrocarbon generation,and fault activi-ties.（3） The hydrocarbon migration is more active during the release of pressure in the Moliqing fault depression,which happened mainly in the Middle-Late Oligocene and provided the driving force for hydrocarbon migration.（4） The hydrocarbon migration was mostly directed to the Shuangyang For-mation within the Jianshan（尖山） uplift and the Kaoshan（靠山） sag.With the superior condition ofhydrocarbon accumulation and the higher de-gree of hydrocarbon concentration,the north-west part of Kaoshan sag is considered a favor-able area for oil and gas exploration in the Moliqing fault depression.展开更多
The pressure evolution associated with the transient shock-induced infiltration of gas flow through granular media consisting of mobile particles is numerically investigated using a coupled Eulerian–Lagrangian approa...The pressure evolution associated with the transient shock-induced infiltration of gas flow through granular media consisting of mobile particles is numerically investigated using a coupled Eulerian–Lagrangian approach.The coupling between shock compaction and interstitial flow has been revealed.A distinctive two-stage diffusing pressure field with deflection occurring at the tail of the compaction front is found,with corresponding spikes in both gaseous velocity and temperature profiles emerging within the width of the compaction front.The compaction front,together with the deflection pressure,reaches a steady state during the later period.An analytical prediction of the steady deflection pressure that considers the contributions of porosity and the non-isothermal effect is proposed.The isothermal single-phase method we developed,combining the porosity jump condition across the compaction front,shows consistent pressure evolution with the non-isothermal CMP-PIC one under weak shock strength and low column permeability.Lastly,the microscale mechanism governing the formation of not only pressure deflection but also gaseous velocity and temperature spikes within the width of the compaction front has been described.These aforementioned evolutions of the flow field are shown to arise from the nozzling effects associated with the particle-scale variations in the volume fraction.展开更多
To elucidate the formation and evolution of overpressure in the Yinggehai Basin,numerical basin modeling and fluid inclusion trapping pressure calculations were conducted to reconstruct the evolution of formation pres...To elucidate the formation and evolution of overpressure in the Yinggehai Basin,numerical basin modeling and fluid inclusion trapping pressure calculations were conducted to reconstruct the evolution of formation pressure and to investigate the controlling effects of overpressure on natural gas accumulation.The study reveals that the Yinggehai Basin generally exhibits a characteristic of rapid late-stage pressurization,with differences in the overpressure evolution processes between the northern and southern parts of the basin.In the northern Dongfang area,overpressure developed earlier(5.5 Ma)but increased slowly in the later stages,whereas in the southern Ledong area,overpressure developed later(2.5 Ma)but increased rapidly and to a higher degree in the later stages.The formation of overpressure is attributed to two main factors:First,the rapid development of undercompaction overpressure in mudstones under high sedimentation rates;second,the rapid burial and heating of source rocks,leading to the rapid maturation of organic matter and the onset of hydrocarbon generation and expulsion,which enhances the contribution of hydrocarbon generation to overpressure.Since the deposition of the Pliocene strata,the sedimentation rate has been higher in the south than in the north,which is highly consistent with the overpressure evolution process,indicating that the development of overpressure in the basin is controlled by changes in sedimentation rates.Overpressure is a key factor controlling natural gas accumulation in the Yinggehai Basin:(1)The high-temperature and high-pressure environment plays a controlling role in the preservation of high-quality reservoirs;(2)strong overpressure controls the development of efficient conduits such as diapirs,faults,and hydraulic fractures,which are crucial for natural gas accumulation in the middle and deep layers;(3)the development of overpressure controls the periodic accumulation and release of fluids,which is closely related to episodic hydrocarbon charging and rapid natural gas accumulation,serving as an important dynamic source for natural gas accumulation.展开更多
The Damintun depression is one of the four depressions in the Liaohe basin in northern China, and is a rift basin developed in the Paleogene. This paper discusses in detail the characteristics of pressure and fluid po...The Damintun depression is one of the four depressions in the Liaohe basin in northern China, and is a rift basin developed in the Paleogene. This paper discusses in detail the characteristics of pressure and fluid potential of the Damintun depression based on a synthesis of the data from boreholes, well tests and seismic surveys. Data from sonic logs, well tests and seismic velocity measurements are used to study the pressure characteristics of the areas. From the sonic log data, shales can be characterized as normally pressured, slightly overpressured or highly overpressured; from the well test data, the pressure-depth gradient in oil-producing intervals implies hydrostatic pressure in general. Most seismic profiles in the Damintun depression are of sufficiently high quality for seismic velocities to be measured. The fluid pressures, excess pressures and pressure coefficients in 47 representative seismic profiles are predicted using formula calculation methods, and further transformed to fluid potenti展开更多
The Damintun sub-basin is one of the four sub-basins in the Liaohe basin in North China, and regarded as a rift basin initiated in the Paleogene. Synthesizing the data from boreholes, well tests and seismic surveys, t...The Damintun sub-basin is one of the four sub-basins in the Liaohe basin in North China, and regarded as a rift basin initiated in the Paleogene. Synthesizing the data from boreholes, well tests and seismic surveys, the characteristics of pressure of the Damintun sub-basin are discussed in detail. From the data of sonic logs in 57 wells, shale in the Damintun sub-basin could be of normally pressured, overpressured or highly overpressured characteristics. From 391 pres-sure measurements from 152 wells, pressure-depth gradient in oil-producing intervals is near to unity in general. The fluid-pressures, excess pressures and pressure coefficients in 47 representative seismic profiles were predicted using seismic methods. The resultant pressure profiles showed normal pressure, slight overpressure and intense overpressure increasing with depth. Using the basic principles of fluid pressure evolution and data from drilling, lithology and well tests,the pres-sure evolution in profiles was restored. It showed that the pressure evolution can be divided into three stages of initial over-pressure accumulation, partly overpressure dissipation and overpressure re- accumulation. The intensities of abnormal pres-sures in the Damintun sub-basin were less than those in other areas in the Bohai Bay basin.展开更多
The permeability evolution of rock during the progressive failure process is described. In combination with the strength degradation index, the degradation formulas of s and a, which are dependent on the plastic confi...The permeability evolution of rock during the progressive failure process is described. In combination with the strength degradation index, the degradation formulas of s and a, which are dependent on the plastic confining strain component, the material constants of Hock-Brown failure criterion are presented, and a modified elemental scale elastic-brittle-plastic constitutive model of rock is established. The rela- tionship between volumetric strain and permeability through tri-axial compression is investigated. Based on the above, a permeability evolution model is established. The model incorporates confining pressure- dependent degradation of strength, dilatancy and corresponding permeability evolution. The model is implemented in FLAC by the FISH function method. The permeability evolution behavior of rock is inves-tigated during the progressive failure process in a numerical case. The results show that the model is cap- able of reproducing, and allowing visualization of a range of hydro-mechanical responses of rock. The effects of confining pressure on degradation of strength, dilatancy and permeability evolution are also reflected.展开更多
Due to the limited permeability and high methane content of the majority of China’s coal seams,significant coal mining gas disasters frequently occur.There is an urgent need to artificially improve the permeability o...Due to the limited permeability and high methane content of the majority of China’s coal seams,significant coal mining gas disasters frequently occur.There is an urgent need to artificially improve the permeability of coalbed methane(CBM)reservoirs,enhance the recovery efficiency of CBM and prevent mine gas accidents.As a novel coal rock fracture technology,the CO_(2) phase transition jet(CPTJ)has been widely used due to its advantages of safety and high fragmentation efficiency.In this study,to ascertain the effects of the pressure of CPTJ fracturing,the influence of its jet pressure on cracked coal rock was revealed,and its effect on CBM extraction was clarified.In this research,the law of CPTJ pressure decay with time was investigated using experimental and theoretical methods.Based on the results,the displacement and discrete fracture network law of CPTJ fracturing coal rock under different jet pressure conditions were studied using particle flow code numerical simulation.Finally,field experiments were conducted at the Shamushu coal mine to assess the efficiency of CPTJ in enhancing CBM drainage.The results showed that the pressure of the CPTJ decreased exponentially with time and significantly influenced the number and expansion size of cracks that broke coal rock but not their direction of development.CPTJ technology can effectively increase the number of connected microscopic pores and fractures in CBM reservoirs,strongly increase the CBM drainage flow rate by between 5.2 and 9.8 times,and significantly reduce the CBM drainage decay coefficient by between 73.58%and 88.24%.展开更多
基金supported by the National Natural Science Foundation of China (No. 40172051)the Jilin Oil Field Scientific Project of China National Petroleum Corporation (No. 2006026157)the Special Fund for Basic Scientific Research of Central Colleges, China University of Geosciences (Wuhan) (Nos. 2010029056, CUGL10024)
文摘The Yitong（伊通） basin is a Late Mesozoic and Cenozoic continental sedimentary basin in Northeast China.On the basis of well tests and seismic data,we use the 2D modeling technique to rebuild the pressure evolution and hydrocarbon migration in the Moliqing（莫里青） fault depression of the Yitong basin.Based on the modeling results,four conclusions are drawn as follows.（1） The Eocene Shuangyang（双阳） Formation within the Moliqing fault depression had entirely undergone three epi-sodic cycles of pressure accumulation and release in geological history,and the three tectonic move-ments since the Middle Eocene played important roles in the episodic changes of excess pressure.（2） The present formation pressure distribution is characterized by normal pressure in almost the entire fault depression with some residual overpressure.The differential distribution of pressure results mainly from the difference in rock facies,sedimentation rate,hydrocarbon generation,and fault activi-ties.（3） The hydrocarbon migration is more active during the release of pressure in the Moliqing fault depression,which happened mainly in the Middle-Late Oligocene and provided the driving force for hydrocarbon migration.（4） The hydrocarbon migration was mostly directed to the Shuangyang For-mation within the Jianshan（尖山） uplift and the Kaoshan（靠山） sag.With the superior condition ofhydrocarbon accumulation and the higher de-gree of hydrocarbon concentration,the north-west part of Kaoshan sag is considered a favor-able area for oil and gas exploration in the Moliqing fault depression.
基金supported by National Natural Science Foundation of China(Grants No.11972088,No.12122203).
文摘The pressure evolution associated with the transient shock-induced infiltration of gas flow through granular media consisting of mobile particles is numerically investigated using a coupled Eulerian–Lagrangian approach.The coupling between shock compaction and interstitial flow has been revealed.A distinctive two-stage diffusing pressure field with deflection occurring at the tail of the compaction front is found,with corresponding spikes in both gaseous velocity and temperature profiles emerging within the width of the compaction front.The compaction front,together with the deflection pressure,reaches a steady state during the later period.An analytical prediction of the steady deflection pressure that considers the contributions of porosity and the non-isothermal effect is proposed.The isothermal single-phase method we developed,combining the porosity jump condition across the compaction front,shows consistent pressure evolution with the non-isothermal CMP-PIC one under weak shock strength and low column permeability.Lastly,the microscale mechanism governing the formation of not only pressure deflection but also gaseous velocity and temperature spikes within the width of the compaction front has been described.These aforementioned evolutions of the flow field are shown to arise from the nozzling effects associated with the particle-scale variations in the volume fraction.
基金supported by the Science and Technology Innovation Program of the Laoshan Laboratory(Grant No.LSKJ202203403)the National Natural Science Foundation of China(Grant No.42488101)the Hainan Branch of the China National Offshore Oil Corporation(CNOOC)(Grant No.KJZH-2021-0003-00)。
文摘To elucidate the formation and evolution of overpressure in the Yinggehai Basin,numerical basin modeling and fluid inclusion trapping pressure calculations were conducted to reconstruct the evolution of formation pressure and to investigate the controlling effects of overpressure on natural gas accumulation.The study reveals that the Yinggehai Basin generally exhibits a characteristic of rapid late-stage pressurization,with differences in the overpressure evolution processes between the northern and southern parts of the basin.In the northern Dongfang area,overpressure developed earlier(5.5 Ma)but increased slowly in the later stages,whereas in the southern Ledong area,overpressure developed later(2.5 Ma)but increased rapidly and to a higher degree in the later stages.The formation of overpressure is attributed to two main factors:First,the rapid development of undercompaction overpressure in mudstones under high sedimentation rates;second,the rapid burial and heating of source rocks,leading to the rapid maturation of organic matter and the onset of hydrocarbon generation and expulsion,which enhances the contribution of hydrocarbon generation to overpressure.Since the deposition of the Pliocene strata,the sedimentation rate has been higher in the south than in the north,which is highly consistent with the overpressure evolution process,indicating that the development of overpressure in the basin is controlled by changes in sedimentation rates.Overpressure is a key factor controlling natural gas accumulation in the Yinggehai Basin:(1)The high-temperature and high-pressure environment plays a controlling role in the preservation of high-quality reservoirs;(2)strong overpressure controls the development of efficient conduits such as diapirs,faults,and hydraulic fractures,which are crucial for natural gas accumulation in the middle and deep layers;(3)the development of overpressure controls the periodic accumulation and release of fluids,which is closely related to episodic hydrocarbon charging and rapid natural gas accumulation,serving as an important dynamic source for natural gas accumulation.
基金supported by the National Natural Science Foundation of China(Grant No.40172051)the Foundation for University Key Teachers by the Ministry of Education of China(No.GG-70-0491-1460)conducted as part of a study on petroleam system in the Damintun depression in 1997-1998 by the Department of Petroleum Geology,China University of Geosciences,which was supported by a grant from the Bureau of Liaohe Petroleam Exploration,CNPC.
文摘The Damintun depression is one of the four depressions in the Liaohe basin in northern China, and is a rift basin developed in the Paleogene. This paper discusses in detail the characteristics of pressure and fluid potential of the Damintun depression based on a synthesis of the data from boreholes, well tests and seismic surveys. Data from sonic logs, well tests and seismic velocity measurements are used to study the pressure characteristics of the areas. From the sonic log data, shales can be characterized as normally pressured, slightly overpressured or highly overpressured; from the well test data, the pressure-depth gradient in oil-producing intervals implies hydrostatic pressure in general. Most seismic profiles in the Damintun depression are of sufficiently high quality for seismic velocities to be measured. The fluid pressures, excess pressures and pressure coefficients in 47 representative seismic profiles are predicted using formula calculation methods, and further transformed to fluid potenti
基金supported by the National Natural Science Foundationof China(No.40172051)the Foundation for University KeyTeacher by the Ministry of Education in China(No.GG-170-10491-1460)
文摘The Damintun sub-basin is one of the four sub-basins in the Liaohe basin in North China, and regarded as a rift basin initiated in the Paleogene. Synthesizing the data from boreholes, well tests and seismic surveys, the characteristics of pressure of the Damintun sub-basin are discussed in detail. From the data of sonic logs in 57 wells, shale in the Damintun sub-basin could be of normally pressured, overpressured or highly overpressured characteristics. From 391 pres-sure measurements from 152 wells, pressure-depth gradient in oil-producing intervals is near to unity in general. The fluid-pressures, excess pressures and pressure coefficients in 47 representative seismic profiles were predicted using seismic methods. The resultant pressure profiles showed normal pressure, slight overpressure and intense overpressure increasing with depth. Using the basic principles of fluid pressure evolution and data from drilling, lithology and well tests,the pres-sure evolution in profiles was restored. It showed that the pressure evolution can be divided into three stages of initial over-pressure accumulation, partly overpressure dissipation and overpressure re- accumulation. The intensities of abnormal pres-sures in the Damintun sub-basin were less than those in other areas in the Bohai Bay basin.
基金the National Natural Science Foundation of China (Nos.51274079,51274110 and 51574139)the Natural Science Foundation of Hebei Province (No.E2013208148)
文摘The permeability evolution of rock during the progressive failure process is described. In combination with the strength degradation index, the degradation formulas of s and a, which are dependent on the plastic confining strain component, the material constants of Hock-Brown failure criterion are presented, and a modified elemental scale elastic-brittle-plastic constitutive model of rock is established. The rela- tionship between volumetric strain and permeability through tri-axial compression is investigated. Based on the above, a permeability evolution model is established. The model incorporates confining pressure- dependent degradation of strength, dilatancy and corresponding permeability evolution. The model is implemented in FLAC by the FISH function method. The permeability evolution behavior of rock is inves-tigated during the progressive failure process in a numerical case. The results show that the model is cap- able of reproducing, and allowing visualization of a range of hydro-mechanical responses of rock. The effects of confining pressure on degradation of strength, dilatancy and permeability evolution are also reflected.
基金the National Natural Science Foundation of China(Grant Nos.52204095,51974163,52274127 and 52174174)the National Key Research and Development Program of China(No.2021YFC2902104)+3 种基金the Natural Science Foundation of Hunan Province,China(No.2023JJ30509)the Key Laboratory of Safety and High-efficiency Coal Mining of Ministry of Education(No.JYBSYS2020204)the Special Program for Basic Research of Key Scientific Research Projects of Colleges and Universities in Henan Province of China(No.21ZX004)the Innovative Scientific Research Team of Henan Polytechnic University in China(No.T2022-1).
文摘Due to the limited permeability and high methane content of the majority of China’s coal seams,significant coal mining gas disasters frequently occur.There is an urgent need to artificially improve the permeability of coalbed methane(CBM)reservoirs,enhance the recovery efficiency of CBM and prevent mine gas accidents.As a novel coal rock fracture technology,the CO_(2) phase transition jet(CPTJ)has been widely used due to its advantages of safety and high fragmentation efficiency.In this study,to ascertain the effects of the pressure of CPTJ fracturing,the influence of its jet pressure on cracked coal rock was revealed,and its effect on CBM extraction was clarified.In this research,the law of CPTJ pressure decay with time was investigated using experimental and theoretical methods.Based on the results,the displacement and discrete fracture network law of CPTJ fracturing coal rock under different jet pressure conditions were studied using particle flow code numerical simulation.Finally,field experiments were conducted at the Shamushu coal mine to assess the efficiency of CPTJ in enhancing CBM drainage.The results showed that the pressure of the CPTJ decreased exponentially with time and significantly influenced the number and expansion size of cracks that broke coal rock but not their direction of development.CPTJ technology can effectively increase the number of connected microscopic pores and fractures in CBM reservoirs,strongly increase the CBM drainage flow rate by between 5.2 and 9.8 times,and significantly reduce the CBM drainage decay coefficient by between 73.58%and 88.24%.
