Sequence Stratigraphic Analysis And Reservoir Prediction In Qianjiang Sag, Jianghan Basin, Eastern Center Of China

The sequence stratigraphic analysis based on 3D seismic patterns and the interaction of some well-logs correlation in Qianjiang depression in Jianghan Basin will be done.The saline lacustrine Jianghan basin is a famous basin in Eastern China, where abundant oil and gas reserves have been discovered and still exploited.It is a Mesozoic to Cenozoic multi-cycle sedimentary basin that developed after the Yanshanian structural movement into multiple depressions and uplifts;whereas Qianjiang sag is the most important oil and gas field in the basin.Hence it has a great number of studies.Sequence stratigraphic analysis has come of age,and it is a tool every explorationist must master.Among the proxies used as sequence stratigraphic features interpretation,sedimentary facies determination and the depositional environments subdivision;3D seismic sections and well-logs correlation have made a great contribution to this study.3D seismic data composed of four seismic sections(xg₃05,xnbhlp₇15, xnbhlp₃15,and xplp₂79),will be used in here to identify the depositional sequences(stratigraphic units of relatively conformable succession of genetically related strata),and their related unconformities.Boundaries will be recognized based on lateral terminations of strata using the seismic patterns of Mitchum et al.1977a (onlap,toplap,downlap,and offlap);to analyze the configurations of reflections within depositional sequences(seismic facies),in order to determine environmental settings and to estimate the lithology.Age determination of different sequences is based on geologic reports of Jianghan oilfield(SINOPEC),so that sequences can be tied into the standard Chronostratigraphic framework.To provide the link between lithology and seismic reflections and stratigraphic calibrations of seismic-sequence boundaries,extract the depositional environment;four well logs were used:Zhang 25,Zhong 64,Tan 16, and Xi 2.These wells are provided by both of gamma-ray and resistivity patterns.The well logs:Gao 53,Hao 3,Hao 53,Guang 20,Guang 18,Wang 31,and Ze 9 are used to make the stratigraphic cross section model,in order to make a reservoir prediction.Most of the sand bodies occur in the northem part of the depression.The predicted sand bodies are mainly:bar sand bodies,fan sand bodies,fan-delta sand bodies,and gravity flow and turbidity-current sand bodies.