To solve the problems in restoring sedimentary facies and predicting reservoirs in loose gas-bearing sediment,based on seismic sedimentologic analysis of the first 9-component S-wave 3D seismic dataset of China,a four...To solve the problems in restoring sedimentary facies and predicting reservoirs in loose gas-bearing sediment,based on seismic sedimentologic analysis of the first 9-component S-wave 3D seismic dataset of China,a fourth-order isochronous stratigraphic framework was set up and then sedimentary facies and reservoirs in the Pleistocene Qigequan Formation in Taidong area of Qaidam Basin were studied by seismic geomorphology and seismic lithology.The study method and thought are as following.Firstly,techniques of phase rotation,frequency decomposition and fusion,and stratal slicing were applied to the 9-component S-wave seismic data to restore sedimentary facies of major marker beds based on sedimentary models reflected by satellite images.Then,techniques of seismic attribute extraction,principal component analysis,and random fitting were applied to calculate the reservoir thickness and physical parameters of a key sandbody,and the results are satisfactory and confirmed by blind testing wells.Study results reveal that the dominant sedimentary facies in the Qigequan Formation within the study area are delta front and shallow lake.The RGB fused slices indicate that there are two cycles with three sets of underwater distributary channel systems in one period.Among them,sandstones in the distributary channels of middle-low Qigequan Formation are thick and broad with superior physical properties,which are favorable reservoirs.The reservoir permeability is also affected by diagenesis.Distributary channel sandstone reservoirs extend further to the west of Sebei-1 gas field,which provides a basis to expand exploration to the western peripheral area.展开更多
A correct understanding of organic matter abundance is key to understanding the conditions necessary for generating biogenic gas,seeking favorable exploration intervals and fields and evaluating resources correctly.Th...A correct understanding of organic matter abundance is key to understanding the conditions necessary for generating biogenic gas,seeking favorable exploration intervals and fields and evaluating resources correctly.The Qigequan Formation shale of the Quaternary in the Sanhu Depression of the Qaidam Basin is taken as the research object.The abundance of dissolved organic matter was determined through total carbon,pyrolysis and other experiments.The evaluation criteria were established and applied.The resource quality is calculated.The results are as follows.(1)Dissolved organic matter is the basis for biogenic gas generation and should be emphasized in the evaluation.(2)The shale has a relatively high dissolved organic carbon(DOC)content,with an average of 2.48 times that of insoluble organic carbon.(3)The DOC of the good source rock is more than 0.60%,that of the medium is 0.25~0.60%,and that of the poor is less than 0.25%.(4)The distribution of good source rocks is influenced by the position and depth of the water column and the paleoclimate.Favorable intervals are mainly in the upper sections of K10,K9 and K8 and the middle section of K7.The favorable areas are mainly the Tainan,Sebei and Sedong areas.展开更多
基金Supported by the CNPC Science and Technology Projects(2022-N/G-47808,2023-N/G-67014)RIPED International Cooperation Project(19HTY5000008).
文摘To solve the problems in restoring sedimentary facies and predicting reservoirs in loose gas-bearing sediment,based on seismic sedimentologic analysis of the first 9-component S-wave 3D seismic dataset of China,a fourth-order isochronous stratigraphic framework was set up and then sedimentary facies and reservoirs in the Pleistocene Qigequan Formation in Taidong area of Qaidam Basin were studied by seismic geomorphology and seismic lithology.The study method and thought are as following.Firstly,techniques of phase rotation,frequency decomposition and fusion,and stratal slicing were applied to the 9-component S-wave seismic data to restore sedimentary facies of major marker beds based on sedimentary models reflected by satellite images.Then,techniques of seismic attribute extraction,principal component analysis,and random fitting were applied to calculate the reservoir thickness and physical parameters of a key sandbody,and the results are satisfactory and confirmed by blind testing wells.Study results reveal that the dominant sedimentary facies in the Qigequan Formation within the study area are delta front and shallow lake.The RGB fused slices indicate that there are two cycles with three sets of underwater distributary channel systems in one period.Among them,sandstones in the distributary channels of middle-low Qigequan Formation are thick and broad with superior physical properties,which are favorable reservoirs.The reservoir permeability is also affected by diagenesis.Distributary channel sandstone reservoirs extend further to the west of Sebei-1 gas field,which provides a basis to expand exploration to the western peripheral area.
基金supported by the Natural Science Foundation of China(No.41872135)the China Scholarship Council.
文摘A correct understanding of organic matter abundance is key to understanding the conditions necessary for generating biogenic gas,seeking favorable exploration intervals and fields and evaluating resources correctly.The Qigequan Formation shale of the Quaternary in the Sanhu Depression of the Qaidam Basin is taken as the research object.The abundance of dissolved organic matter was determined through total carbon,pyrolysis and other experiments.The evaluation criteria were established and applied.The resource quality is calculated.The results are as follows.(1)Dissolved organic matter is the basis for biogenic gas generation and should be emphasized in the evaluation.(2)The shale has a relatively high dissolved organic carbon(DOC)content,with an average of 2.48 times that of insoluble organic carbon.(3)The DOC of the good source rock is more than 0.60%,that of the medium is 0.25~0.60%,and that of the poor is less than 0.25%.(4)The distribution of good source rocks is influenced by the position and depth of the water column and the paleoclimate.Favorable intervals are mainly in the upper sections of K10,K9 and K8 and the middle section of K7.The favorable areas are mainly the Tainan,Sebei and Sedong areas.
