Although the genetic algorithm （GA） for structural optimization is very robust, it is very computationally intensive and hence slower than optimality criteria and mathematical programming methods. To speed up the de...Although the genetic algorithm （GA） for structural optimization is very robust, it is very computationally intensive and hence slower than optimality criteria and mathematical programming methods. To speed up the design process, the authors present an adaptive reanalysis method for GA and its applications in the optimal design of trusses. This reanalysis technique is primarily derived from the Kirsch＇s combined approximations method. An iteration scheme is adopted to adaptively determine the number of basis vectors at every generation. In order to illustrate this method, three classical examples of optimal truss design are used to validate the proposed reanalysis-based design procedure. The presented numerical results demonstrate that the adaptive reanalysis technique affects very slightly the accuracy of the optimal solutions and does accelerate the design process, especially for large-scale structures.展开更多
Classical multi-channel technology can significantly reduce the pre-stack seismic inversion uncertainty, especially for complex geology such as high dipping structures. However, due to the consideration of complex str...Classical multi-channel technology can significantly reduce the pre-stack seismic inversion uncertainty, especially for complex geology such as high dipping structures. However, due to the consideration of complex structure or reflection features, the existing multi-channel inversion methods have to adopt the highly time-consuming strategy of arranging seismic data trace-by-trace, limiting its wide application in pre-stack inversion. A fast pre-stack multi-channel inversion constrained by seismic reflection features has been proposed to address this issue. The key to our method is to re-characterize the reflection features to directly constrain the pre-stack inversion through a Hadamard product operator without rearranging the seismic data. The seismic reflection features can reflect the distribution of the stratum reflection interface, and we obtained them from the post-stack profile by searching the shortest local Euclidean distance between adjacent seismic traces. Instead of directly constructing a large-size reflection features constraint operator advocated by the conventional methods, through decomposing the reflection features along the vertical and horizontal direction at a particular sampling point, we have constructed a computationally well-behaved constraint operator represented by the vertical and horizontal partial derivatives. Based on the Alternating Direction Method of Multipliers (ADMM) optimization, we have derived a fast algorithm for solving the objective function, including Hadamard product operators. Compared with the conventional reflection features constrained inversion, the proposed method is more efficient and accurate, proved on the Overthrust model and a field data set.展开更多
With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter ...With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter switching frequency of the inverter is one of the impacting factors.At the same time,the control accuracy of the system also needs to be considered,and the torque ripple and flux ripple are usually considered to be its important indexes.This paper proposes a three-stage series Model Predictive Torque and Flux Control system(three-stage series MPTFC)based on fast optimal voltage vector selection to reduce switching frequency and suppress torque ripple and flux ripple.Firstly,the analytical model of the PMSM is established and the multi-stage series control method is used to reduce the switching frequency.Secondly,selectable voltage vectors are extended from 8 to 26 and a fast selection method for optimal voltage vector sectors is designed based on the hysteresis comparator,which can suppress the torque ripple and flux ripple to improve the control accuracy.Thirdly,a three-stage series control is obtained by expanding the two-stage series control using the P-Q torque decomposition theory.Finally,a model predictive torque and flux control experimental platform is built,and the feasibility and effectiveness of this method are verified through comparison experiments.展开更多
The Sinian Dengying Formation gas reservoir in the Anyue gas field of the Sichuan Basin is an ultra-deep ancient dolomite karst gas reservoir,whose development is of high difficulty,for the reservoir is thin and scatt...The Sinian Dengying Formation gas reservoir in the Anyue gas field of the Sichuan Basin is an ultra-deep ancient dolomite karst gas reservoir,whose development is of high difficulty,for the reservoir is thin and scattered with strong heterogeneity and is overall characterized by low porosity and low permeability.In order to provide support for the large-scale productivity construction of the gas reservoir of the fourth member of Dengying Formation(Deng 4 Member)in the marginal platform belt of the Anyue gas field,this paper carries out multi-discipline comprehensive researches on the technical bottlenecks based on the geological characteristics of the gas reservoir.In addition,the targeted key technologies for the efficient development of gas reservoirs were developed in the mode of“simultaneous research,application and improvement”.And the following research results are obtained.First,based on the modeling technology of fracturedevuggy dolomite karst reservoirs,accurate modeling of karst reservoirs is realized.Late actual drilling results show that the model's coincidence rate is increased from 63.0% to 90.7% and the“transparency”of gas reservoirs is achieved.Second,based on the reserve mobility evaluation technology of lowporosity and highly-heterogeneous karst reservoirs,the recovery factors of different reservoirs are determined.And consequently,the lower limit of well-controlled reserves and radius for the efficient development of different reservoirs are obtained and type Ⅰ and Ⅱ reservoirs are selected as the main development targets.Third,based on the development optimization design technology of highly-heterogeneous karst gas reservoirs,it is recommended to apply highly-deviated wells(the maximum deviation angle of 75°-84°)in the situations with multiple reservoirs crossed and superimposed.If type Ⅰ and Ⅱ reservoirs are developed intensively,it is recommended to adopt horizontal well drilling with a horizontal section of 800-1100 m.What's more,the reasonable well spacing in type Ⅰ and Ⅱ reservoirs shall be 1.6-3.3 km and 0.9-1.4 km,respectively.Fourth,based on the distinguished drilling technology of highly-deviated wells/horizontal wells in deep carbonate rocks,the fault complexity ratio is decreased from 20.7% to 4.9%,so safe and fast drilling and completion of highly-deviated wells/horizontal wells is realized and well control risks are diminished.What's more,the drilling rates of type Ⅰ and Ⅱ reservoirs are increased from 24.2% to 87.3%,indicating an effective improvement of reservoir drilling rates.Fifth,based on the open-hole segmented accurate acid fracturing technology of highly-deviated and horizontal wells,the difficulty in the highly-heterogeneous reservoir stimulation by horizontal well drilling is solved by conducting the differentiated acid fracturing process of“one segment,one strategy”.Based on the application of these innovative development technologies in the Deng 4 Member gas reservoir in the marginal platform belt of the Anyue gas field,the annual natural gas production capacity and cumulative natural gas production by the end of December 2020 are 60×10^(8) m^(3) and 103×10^(8) m^(3),respectively.In this way,the Sinian Dengying Formation gas reservoir of the Anyue gas field,the economic benefit of which is close to the marginal benefit,becomes the main force of conventional natural gas production increase.展开更多
Normal-pressure shale gas is an important object of shale gas reserves and production increasewith broad resource prospects in China,but its large-scale benefit development is still confronted with technical bottlenec...Normal-pressure shale gas is an important object of shale gas reserves and production increasewith broad resource prospects in China,but its large-scale benefit development is still confronted with technical bottlenecks.To promote the large-scale benefit development of normal-pressure shale gas,this paper systematically sorts out and summarizes the research achievements and technological progresses related to normal-pressure shale gas from the aspects of accumulation mechanism,enrichment theory,percolation mechanism,development technology,and low-cost engineering technology,and points out the difficulties and challenges to the benefit development of normal-pressure shale gas in the complex structure zones of southern China,by taking the shale gas in the Southeast Chongqing Area of the Sichuan Basin as the research object.In addition,the research direction of normal-pressure shale gas exploration and development is discussed in terms of sweet spot selection,development technology policy,low-cost drilling technology and high-efficiency fracturing technology.And the following research results are obtained.First,the accumulation mechanism of normal-pressure shale gas is clarified from the perspective of geological exploration theory;the hydrocarbon accumulation model of generation,expulsion,retention and accumulation is established;the enrichment theory of“three-factor controlling reservoir”is put forward;and the comprehensive sweetspot target evaluation system is formed.Second,as for development technology,the development technology policies of“multiple series of strata,variable well spacing,long horizontal section,small included angle,low elevation difference,strong stimulation and pressure difference controlling”are formulated.Third,as for drilling engineering,the optimal fast drilling and completion technology with“secondary structureþradical parameterþintegrated guidanceþunpressured leak-proof cementing”as the core is formed.Fourth,as for fracturing engineering,the low-cost and high-efficiency fracturing technology with“multi-cluster small-stageþlimited-entry perforatingþdouble temporary blockingþhigh-intensity sand injectionþfully electric”as the core is formed.Fifth,normal-pressure shale gas is characterized by complex geological conditions,low pressure coefficient and gas content,poor resource endowment and so on,but its resource utilization still faces a series of challenges,such as uncertain productivity construction positions,low single-well productivity and ultimate recoverable reserve,high investment cost and poor economic benefit.In conclusion,the key research directions to realize the large-scale benefit development of low-grade normal-pressure shale gas are to deepen the research on the enrichment and high yield mechanism and sweet spot selection of normal-pressure shale gas,strengthen the research on the benefit development technology policy based on percolation mechanism and the key technologies for low-cost drilling,accelerate the research and devel-opment of the key technologies for low-cost and high-efficiency fracturing,and implement cost reduction and efficiency improvement continuously.展开更多
A novel real-time predictive control strategy is proposed for path following(PF)and vehicle stability of autonomous electric vehicles under extreme drive conditions.The investigated vehicle configuration is a distribu...A novel real-time predictive control strategy is proposed for path following(PF)and vehicle stability of autonomous electric vehicles under extreme drive conditions.The investigated vehicle configuration is a distributed drive electric vehicle,which allows to independently control the torques of each in-wheel motor(IWM)for superior stability,but bringing control com-plexities.The control-oriented model is established by the Magic Formula tire function and the single-track vehicle model.For PF and direct yaw moment control,the nonlinear model predictive control(NMPC)strategy is developed to minimize PF tracking error and stabilize vehicle,outputting front tires’lateral force and external yaw moment.To mitigate the calcu-lation burdens,the continuation/general minimal residual algorithm is proposed for real-time optimization in NMPC.The relaxation function method is adopted to handle the inequality constraints.To prevent vehicle instability and improve steering capacity,the lateral velocity differential of the vehicle is considered in phase plane analysis,and the novel stable bounds of lateral forces are developed and online applied in the proposed NMPC controller.Additionally,the Lyapunov-based constraint is proposed to guarantee the closed-loop stability for the PF issue,and sufficient conditions regarding recursive feasibility and closed-loop stability are provided analytically.The target lateral force is transformed as front steering angle command by the inversive tire model,and the external yaw moment and total traction torque are distributed as the torque commands of IWMs by optimization.The validations prove the effectiveness of the proposed strategy in improved steering capacity,desirable PF effects,vehicle stabilization,and real-time applicability.展开更多
Though diabetes is common worldwide, the proportion of cases diagnosed is not high. Nearly fifty percent of patients with diabetes mellitus (DM) in US are undiagnosed.~1 The ratio might be higher in China. It has been...Though diabetes is common worldwide, the proportion of cases diagnosed is not high. Nearly fifty percent of patients with diabetes mellitus (DM) in US are undiagnosed.~1 The ratio might be higher in China. It has been suggested that diabetes may be present 4 to 7 years before diagnosis.~2 (Many of) the complications appear to be present at the time of diagnosis of the diabetic status.~1 (Screening for) diabetes in early stage of diabetes is thus a worthwhile exercise.展开更多
This paper discusses the exploration and development history and lessons of the large ultra-deep biogenic reef gas field in Yuanba area,where the previous“Kaijiang-Liangping shelf”model provides an insight for the d...This paper discusses the exploration and development history and lessons of the large ultra-deep biogenic reef gas field in Yuanba area,where the previous“Kaijiang-Liangping shelf”model provides an insight for the discovery of the biological reef and bank on the platform margin.Systematic analysis of key geological conditions for hydrocarbon accumulation shows that the reef and bank reservoirs in Yuanba area are characterized by row and zonal distribution along“Kaijiang-Liangping shelf”,the bank in early and the reef in late,the reef in the front and the bank in the back,and dominated by lateral accretion and progradation.The major exploration target of high-quality reef-bank reservoirs are developed in Changxing Formation instead of in Feixianguan Formation,Three stages of fractures and dissolution,and dolomitization control the development of the high-quality reservoirs.Two sets of effective source rocks(Permian Dalong Formation and Wujiaping Formation)provide sufficient gas source for the large gas field.Three dimensional migration pathway system composed of micro-faults,micro-fractures and interlayer fissures facilitates the hydrocarbon migration and accumulation.The accumulation model of Yuanba gas field is characterized by the near-source accumulation,three-micro migration pathway system,lithological-stratigraphic reservoirs and tectonics controlling enrichment.According to the complex geological conditions such as ultra-deep reservoirs and multiple pressure systems in Yuanba gas field,several key technologies are developed during hydrocarbon exploration and development,including fine prediction of ultra-deep reef-bank reservoirs and identification of gas and water,fine-scale reservoir description and characterization of complex thin and small reef gas reservoirs,optimal&fast drilling of ultra-deep horizontal well,geo-steering of ultra-deep horizontal well for complex reef and bank.All these technologies resulted in the efficient exploration and development of Yuanba gas field and accelerated the innovation of theoretical technology and methods for ultra-deep reservoirs.展开更多
基金supported by the National Natural Science Foundation of China(50975121)the Project 2009-2007 of the Graduate Innovation Fund of Jilin University
文摘Although the genetic algorithm （GA） for structural optimization is very robust, it is very computationally intensive and hence slower than optimality criteria and mathematical programming methods. To speed up the design process, the authors present an adaptive reanalysis method for GA and its applications in the optimal design of trusses. This reanalysis technique is primarily derived from the Kirsch＇s combined approximations method. An iteration scheme is adopted to adaptively determine the number of basis vectors at every generation. In order to illustrate this method, three classical examples of optimal truss design are used to validate the proposed reanalysis-based design procedure. The presented numerical results demonstrate that the adaptive reanalysis technique affects very slightly the accuracy of the optimal solutions and does accelerate the design process, especially for large-scale structures.
基金We would like to acknowledge the sponsorship of the National Natural Science Foundation of China(42004092,42030103,41974119)Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(Grant No.2021QNLM020001-6)Young Elite Scientists Sponsorship Program by CAST(2021QNRC001).
文摘Classical multi-channel technology can significantly reduce the pre-stack seismic inversion uncertainty, especially for complex geology such as high dipping structures. However, due to the consideration of complex structure or reflection features, the existing multi-channel inversion methods have to adopt the highly time-consuming strategy of arranging seismic data trace-by-trace, limiting its wide application in pre-stack inversion. A fast pre-stack multi-channel inversion constrained by seismic reflection features has been proposed to address this issue. The key to our method is to re-characterize the reflection features to directly constrain the pre-stack inversion through a Hadamard product operator without rearranging the seismic data. The seismic reflection features can reflect the distribution of the stratum reflection interface, and we obtained them from the post-stack profile by searching the shortest local Euclidean distance between adjacent seismic traces. Instead of directly constructing a large-size reflection features constraint operator advocated by the conventional methods, through decomposing the reflection features along the vertical and horizontal direction at a particular sampling point, we have constructed a computationally well-behaved constraint operator represented by the vertical and horizontal partial derivatives. Based on the Alternating Direction Method of Multipliers (ADMM) optimization, we have derived a fast algorithm for solving the objective function, including Hadamard product operators. Compared with the conventional reflection features constrained inversion, the proposed method is more efficient and accurate, proved on the Overthrust model and a field data set.
基金co-supported by the National Natural Science Foundation of China(No.52477063)the National Key Research and Development Program of China(No.2023YFF0719100)。
文摘With the development of More Electric Aircraft(MEA),the Permanent Magnet Synchronous Motor(PMSM)is widely used in the MEA field.The PMSM control system of MEA needs to consider the system reliability,and the inverter switching frequency of the inverter is one of the impacting factors.At the same time,the control accuracy of the system also needs to be considered,and the torque ripple and flux ripple are usually considered to be its important indexes.This paper proposes a three-stage series Model Predictive Torque and Flux Control system(three-stage series MPTFC)based on fast optimal voltage vector selection to reduce switching frequency and suppress torque ripple and flux ripple.Firstly,the analytical model of the PMSM is established and the multi-stage series control method is used to reduce the switching frequency.Secondly,selectable voltage vectors are extended from 8 to 26 and a fast selection method for optimal voltage vector sectors is designed based on the hysteresis comparator,which can suppress the torque ripple and flux ripple to improve the control accuracy.Thirdly,a three-stage series control is obtained by expanding the two-stage series control using the P-Q torque decomposition theory.Finally,a model predictive torque and flux control experimental platform is built,and the feasibility and effectiveness of this method are verified through comparison experiments.
基金Project supported by the National Science and Technology Major Project“Demonstration Project of Giant Carbonate Gas Field Development in Sichuan Basin”(No.2016ZX05052)the PetroChina Major Technology Special Project“Research and Application of Key Technology for Large-scale Efficient Development of the Fourth Member of Dengying Formation in Central Sichuan”(No.:2016E-0606).
文摘The Sinian Dengying Formation gas reservoir in the Anyue gas field of the Sichuan Basin is an ultra-deep ancient dolomite karst gas reservoir,whose development is of high difficulty,for the reservoir is thin and scattered with strong heterogeneity and is overall characterized by low porosity and low permeability.In order to provide support for the large-scale productivity construction of the gas reservoir of the fourth member of Dengying Formation(Deng 4 Member)in the marginal platform belt of the Anyue gas field,this paper carries out multi-discipline comprehensive researches on the technical bottlenecks based on the geological characteristics of the gas reservoir.In addition,the targeted key technologies for the efficient development of gas reservoirs were developed in the mode of“simultaneous research,application and improvement”.And the following research results are obtained.First,based on the modeling technology of fracturedevuggy dolomite karst reservoirs,accurate modeling of karst reservoirs is realized.Late actual drilling results show that the model's coincidence rate is increased from 63.0% to 90.7% and the“transparency”of gas reservoirs is achieved.Second,based on the reserve mobility evaluation technology of lowporosity and highly-heterogeneous karst reservoirs,the recovery factors of different reservoirs are determined.And consequently,the lower limit of well-controlled reserves and radius for the efficient development of different reservoirs are obtained and type Ⅰ and Ⅱ reservoirs are selected as the main development targets.Third,based on the development optimization design technology of highly-heterogeneous karst gas reservoirs,it is recommended to apply highly-deviated wells(the maximum deviation angle of 75°-84°)in the situations with multiple reservoirs crossed and superimposed.If type Ⅰ and Ⅱ reservoirs are developed intensively,it is recommended to adopt horizontal well drilling with a horizontal section of 800-1100 m.What's more,the reasonable well spacing in type Ⅰ and Ⅱ reservoirs shall be 1.6-3.3 km and 0.9-1.4 km,respectively.Fourth,based on the distinguished drilling technology of highly-deviated wells/horizontal wells in deep carbonate rocks,the fault complexity ratio is decreased from 20.7% to 4.9%,so safe and fast drilling and completion of highly-deviated wells/horizontal wells is realized and well control risks are diminished.What's more,the drilling rates of type Ⅰ and Ⅱ reservoirs are increased from 24.2% to 87.3%,indicating an effective improvement of reservoir drilling rates.Fifth,based on the open-hole segmented accurate acid fracturing technology of highly-deviated and horizontal wells,the difficulty in the highly-heterogeneous reservoir stimulation by horizontal well drilling is solved by conducting the differentiated acid fracturing process of“one segment,one strategy”.Based on the application of these innovative development technologies in the Deng 4 Member gas reservoir in the marginal platform belt of the Anyue gas field,the annual natural gas production capacity and cumulative natural gas production by the end of December 2020 are 60×10^(8) m^(3) and 103×10^(8) m^(3),respectively.In this way,the Sinian Dengying Formation gas reservoir of the Anyue gas field,the economic benefit of which is close to the marginal benefit,becomes the main force of conventional natural gas production increase.
基金supported by the National Science and Technology Major Project of China"Demonstrative project of normal-pressure shale gas exploration and development in the Pengshui area"(No.2016ZX05061)the Sinopec Scientific Research Projects"Evaluation of normal-pressure shale gas enrichment and production mechanisms and targets in Nan-chuan-Wulong"(No.P21087-6)"Evaluation of shale gas enrichment and targets in the East China exploration area in Sichuan Basin and its periphery"(No.P20059-6).
文摘Normal-pressure shale gas is an important object of shale gas reserves and production increasewith broad resource prospects in China,but its large-scale benefit development is still confronted with technical bottlenecks.To promote the large-scale benefit development of normal-pressure shale gas,this paper systematically sorts out and summarizes the research achievements and technological progresses related to normal-pressure shale gas from the aspects of accumulation mechanism,enrichment theory,percolation mechanism,development technology,and low-cost engineering technology,and points out the difficulties and challenges to the benefit development of normal-pressure shale gas in the complex structure zones of southern China,by taking the shale gas in the Southeast Chongqing Area of the Sichuan Basin as the research object.In addition,the research direction of normal-pressure shale gas exploration and development is discussed in terms of sweet spot selection,development technology policy,low-cost drilling technology and high-efficiency fracturing technology.And the following research results are obtained.First,the accumulation mechanism of normal-pressure shale gas is clarified from the perspective of geological exploration theory;the hydrocarbon accumulation model of generation,expulsion,retention and accumulation is established;the enrichment theory of“three-factor controlling reservoir”is put forward;and the comprehensive sweetspot target evaluation system is formed.Second,as for development technology,the development technology policies of“multiple series of strata,variable well spacing,long horizontal section,small included angle,low elevation difference,strong stimulation and pressure difference controlling”are formulated.Third,as for drilling engineering,the optimal fast drilling and completion technology with“secondary structureþradical parameterþintegrated guidanceþunpressured leak-proof cementing”as the core is formed.Fourth,as for fracturing engineering,the low-cost and high-efficiency fracturing technology with“multi-cluster small-stageþlimited-entry perforatingþdouble temporary blockingþhigh-intensity sand injectionþfully electric”as the core is formed.Fifth,normal-pressure shale gas is characterized by complex geological conditions,low pressure coefficient and gas content,poor resource endowment and so on,but its resource utilization still faces a series of challenges,such as uncertain productivity construction positions,low single-well productivity and ultimate recoverable reserve,high investment cost and poor economic benefit.In conclusion,the key research directions to realize the large-scale benefit development of low-grade normal-pressure shale gas are to deepen the research on the enrichment and high yield mechanism and sweet spot selection of normal-pressure shale gas,strengthen the research on the benefit development technology policy based on percolation mechanism and the key technologies for low-cost drilling,accelerate the research and devel-opment of the key technologies for low-cost and high-efficiency fracturing,and implement cost reduction and efficiency improvement continuously.
基金supported by the Natural Science Foundation of Beijing(Grant No.3212013)by the National Natural Science Foundation of China(Grant No.51805030)in part by the National Natural Science Foundation of China(Grant No.51775039).
文摘A novel real-time predictive control strategy is proposed for path following(PF)and vehicle stability of autonomous electric vehicles under extreme drive conditions.The investigated vehicle configuration is a distributed drive electric vehicle,which allows to independently control the torques of each in-wheel motor(IWM)for superior stability,but bringing control com-plexities.The control-oriented model is established by the Magic Formula tire function and the single-track vehicle model.For PF and direct yaw moment control,the nonlinear model predictive control(NMPC)strategy is developed to minimize PF tracking error and stabilize vehicle,outputting front tires’lateral force and external yaw moment.To mitigate the calcu-lation burdens,the continuation/general minimal residual algorithm is proposed for real-time optimization in NMPC.The relaxation function method is adopted to handle the inequality constraints.To prevent vehicle instability and improve steering capacity,the lateral velocity differential of the vehicle is considered in phase plane analysis,and the novel stable bounds of lateral forces are developed and online applied in the proposed NMPC controller.Additionally,the Lyapunov-based constraint is proposed to guarantee the closed-loop stability for the PF issue,and sufficient conditions regarding recursive feasibility and closed-loop stability are provided analytically.The target lateral force is transformed as front steering angle command by the inversive tire model,and the external yaw moment and total traction torque are distributed as the torque commands of IWMs by optimization.The validations prove the effectiveness of the proposed strategy in improved steering capacity,desirable PF effects,vehicle stabilization,and real-time applicability.
文摘Though diabetes is common worldwide, the proportion of cases diagnosed is not high. Nearly fifty percent of patients with diabetes mellitus (DM) in US are undiagnosed.~1 The ratio might be higher in China. It has been suggested that diabetes may be present 4 to 7 years before diagnosis.~2 (Many of) the complications appear to be present at the time of diagnosis of the diabetic status.~1 (Screening for) diabetes in early stage of diabetes is thus a worthwhile exercise.
基金The work was supported by the National Science and Technology Major Project of China(No.2011ZX05005-003).
文摘This paper discusses the exploration and development history and lessons of the large ultra-deep biogenic reef gas field in Yuanba area,where the previous“Kaijiang-Liangping shelf”model provides an insight for the discovery of the biological reef and bank on the platform margin.Systematic analysis of key geological conditions for hydrocarbon accumulation shows that the reef and bank reservoirs in Yuanba area are characterized by row and zonal distribution along“Kaijiang-Liangping shelf”,the bank in early and the reef in late,the reef in the front and the bank in the back,and dominated by lateral accretion and progradation.The major exploration target of high-quality reef-bank reservoirs are developed in Changxing Formation instead of in Feixianguan Formation,Three stages of fractures and dissolution,and dolomitization control the development of the high-quality reservoirs.Two sets of effective source rocks(Permian Dalong Formation and Wujiaping Formation)provide sufficient gas source for the large gas field.Three dimensional migration pathway system composed of micro-faults,micro-fractures and interlayer fissures facilitates the hydrocarbon migration and accumulation.The accumulation model of Yuanba gas field is characterized by the near-source accumulation,three-micro migration pathway system,lithological-stratigraphic reservoirs and tectonics controlling enrichment.According to the complex geological conditions such as ultra-deep reservoirs and multiple pressure systems in Yuanba gas field,several key technologies are developed during hydrocarbon exploration and development,including fine prediction of ultra-deep reef-bank reservoirs and identification of gas and water,fine-scale reservoir description and characterization of complex thin and small reef gas reservoirs,optimal&fast drilling of ultra-deep horizontal well,geo-steering of ultra-deep horizontal well for complex reef and bank.All these technologies resulted in the efficient exploration and development of Yuanba gas field and accelerated the innovation of theoretical technology and methods for ultra-deep reservoirs.
