Large numbers of gas reservoirs have been discovered in overpressure basins.Fluid charging has a close relationship with paleo-pressure evolution,affecting the migration of gas reservoirs.To study fluid charging and t...Large numbers of gas reservoirs have been discovered in overpressure basins.Fluid charging has a close relationship with paleo-pressure evolution,affecting the migration of gas reservoirs.To study fluid charging and the related pressure system,we analyzed burial histories and fluid inclusion(PVTx)simulations and conducted basin modeling of the Ledong Slope Zone in the Yinggehai Basin as an example.On the basis of fluid-inclusion assemblages(FIAs),homogenization temperature(Th),final melting temperature(Tm,ice)and Raman spectroscopy in fluid inclusions,there are three stages of fluid charging:during the first and second stage,methane-dominated fluid was charged at 2.2–1.7 Ma and 1.7–0.9 Ma,respectively.In the third stage,CO_(2)-rich hydrothermal fluid was charged since 0.9 Ma.It could be concluded from the well-logging data that the disequilibrium compaction in the Yinggehai Fm.,along with the fluid expansion and clay diagenesis in the Huangliu and Meishan formations,resulted in the overpressure in the Ledong slope zone.The evolution of paleo-pressure was affected by the sedimentation rate of the Yinggehai Fm.,as well as the hydrocarbon generation rate.Additionally,the Ledong Slope Zone is less affected by diapir activity than the nearby diapir area.Based on fluid inclusions,paleo-pressure,basin modeling and geological background,the gas migration history of the Ledong Slope Zone can be divided into four stages:in the first stage,excess pressure was formed around 5 Ma;from 2.2 to 1.7 Ma,there was a reduction in the charging of hydrocarbon fluid and steadily increasing excess pressure;during the 1.7–0.9 Ma period a large amount of hydrocarbon was generated,excess pressure increasing significantly and hydraulic fractures forming in mudstones,With gas reservoirs developing in structural highs;since 0.9 Ma,CO_(2)-rich hydrothermal fluid accumulated in reservoirs adjacent to faults and the pressure coefficient remained stable.The research results are helpful in the study of fluid migration and accumulation mechanisms in overpressure basins.展开更多
The Ledong-30 area is located in the southern part of the central depression of the Yinggehai basin, where the exploration activity aims to gas in the middle and deep strata is started lately. The previous studies on ...The Ledong-30 area is located in the southern part of the central depression of the Yinggehai basin, where the exploration activity aims to gas in the middle and deep strata is started lately. The previous studies on the sedimentary system and main controlling factors of reservoir formation are mainly focused on the middle and shallow strata above the Huangliu Formation. Based on a fine interpretation of seismic data, the sedimentary characteristics, internal structures, and distribution rules of submarine fans and gravity flow channels in the Ledong-30 area are analyzed in this paper. In addition, the dynamic migration processes of their planar distribution and the vertical evolution law (vertical sequence combinations and superposition features of turbidity events) are also addressed. At last, the internal structural characteristics of the gravity flow system and comprehensive formation mechanisms of the large-scale gravity flow sediments (turbidities fans) are also been analyzed, which is helpful for the prediction of favorable reservoir distribution. The results can be used directly to guide oil and gas exploration in the Ledong area of the Yinggehai basin.展开更多
Objectives:The sedimentary distribution of Ledong formation in Yinggehai basin is not clear.The combination of seismic data and seismic forward modeling can clarify the sedimentary distribution in this area.Methods:Th...Objectives:The sedimentary distribution of Ledong formation in Yinggehai basin is not clear.The combination of seismic data and seismic forward modeling can clarify the sedimentary distribution in this area.Methods:The seismic facies boundary is characterized by seismic configuration,and the seismic subfacies boundary is characterized by seismic attribute structure.The sand body thickness of Ledong formation is characterized by seismic forward modeling and well logging sand body statistics of relevant well sections.Finally,the plane distribution of sedimentary facies is summarized.Results and conclusions:(1)The overall seismic attributes of the Ledong Formation in the Yinggehai Basin are favorable,characterized primarily by moderate to strong reflections on both sides.However,the middle section is severely disrupted by faults,exhibiting weak reflection characteristics.(2)The Ledong Formation represents a shallow marine beach-dam depositional environment,with extensive sand body development.A significant beach-dam complex is developed in the central part of the study area.The core of the sand bodies is relatively pure in texture and possesses excellent physical properties,making it a promising reservoir for oil and gas.(3)Based on seismic facies,two gas-water models are summarized:sheet sand bodies and multiple sets of sand bodies.展开更多
基金supported by the‘Research on Exploration and Development Technology and New Exploration Fields of high Temperature and High-pressure Gas Reservoirs in the West of the South China Sea’,a subject of the key technology projects of the CNOOC‘Key Technologies for Producing 20 million m~3 of Oil in the Western South China Sea Oilfield’(No.CNOOC-KJ 135 ZDXM 38 ZJ 02 ZJ)The financial support from CNOOC(Hainan)。
文摘Large numbers of gas reservoirs have been discovered in overpressure basins.Fluid charging has a close relationship with paleo-pressure evolution,affecting the migration of gas reservoirs.To study fluid charging and the related pressure system,we analyzed burial histories and fluid inclusion(PVTx)simulations and conducted basin modeling of the Ledong Slope Zone in the Yinggehai Basin as an example.On the basis of fluid-inclusion assemblages(FIAs),homogenization temperature(Th),final melting temperature(Tm,ice)and Raman spectroscopy in fluid inclusions,there are three stages of fluid charging:during the first and second stage,methane-dominated fluid was charged at 2.2–1.7 Ma and 1.7–0.9 Ma,respectively.In the third stage,CO_(2)-rich hydrothermal fluid was charged since 0.9 Ma.It could be concluded from the well-logging data that the disequilibrium compaction in the Yinggehai Fm.,along with the fluid expansion and clay diagenesis in the Huangliu and Meishan formations,resulted in the overpressure in the Ledong slope zone.The evolution of paleo-pressure was affected by the sedimentation rate of the Yinggehai Fm.,as well as the hydrocarbon generation rate.Additionally,the Ledong Slope Zone is less affected by diapir activity than the nearby diapir area.Based on fluid inclusions,paleo-pressure,basin modeling and geological background,the gas migration history of the Ledong Slope Zone can be divided into four stages:in the first stage,excess pressure was formed around 5 Ma;from 2.2 to 1.7 Ma,there was a reduction in the charging of hydrocarbon fluid and steadily increasing excess pressure;during the 1.7–0.9 Ma period a large amount of hydrocarbon was generated,excess pressure increasing significantly and hydraulic fractures forming in mudstones,With gas reservoirs developing in structural highs;since 0.9 Ma,CO_(2)-rich hydrothermal fluid accumulated in reservoirs adjacent to faults and the pressure coefficient remained stable.The research results are helpful in the study of fluid migration and accumulation mechanisms in overpressure basins.
文摘The Ledong-30 area is located in the southern part of the central depression of the Yinggehai basin, where the exploration activity aims to gas in the middle and deep strata is started lately. The previous studies on the sedimentary system and main controlling factors of reservoir formation are mainly focused on the middle and shallow strata above the Huangliu Formation. Based on a fine interpretation of seismic data, the sedimentary characteristics, internal structures, and distribution rules of submarine fans and gravity flow channels in the Ledong-30 area are analyzed in this paper. In addition, the dynamic migration processes of their planar distribution and the vertical evolution law (vertical sequence combinations and superposition features of turbidity events) are also addressed. At last, the internal structural characteristics of the gravity flow system and comprehensive formation mechanisms of the large-scale gravity flow sediments (turbidities fans) are also been analyzed, which is helpful for the prediction of favorable reservoir distribution. The results can be used directly to guide oil and gas exploration in the Ledong area of the Yinggehai basin.
文摘Objectives:The sedimentary distribution of Ledong formation in Yinggehai basin is not clear.The combination of seismic data and seismic forward modeling can clarify the sedimentary distribution in this area.Methods:The seismic facies boundary is characterized by seismic configuration,and the seismic subfacies boundary is characterized by seismic attribute structure.The sand body thickness of Ledong formation is characterized by seismic forward modeling and well logging sand body statistics of relevant well sections.Finally,the plane distribution of sedimentary facies is summarized.Results and conclusions:(1)The overall seismic attributes of the Ledong Formation in the Yinggehai Basin are favorable,characterized primarily by moderate to strong reflections on both sides.However,the middle section is severely disrupted by faults,exhibiting weak reflection characteristics.(2)The Ledong Formation represents a shallow marine beach-dam depositional environment,with extensive sand body development.A significant beach-dam complex is developed in the central part of the study area.The core of the sand bodies is relatively pure in texture and possesses excellent physical properties,making it a promising reservoir for oil and gas.(3)Based on seismic facies,two gas-water models are summarized:sheet sand bodies and multiple sets of sand bodies.
