Study On Characteristics Of Hydrocarbon Conduit System In The West Of Baiyun Sag, Pearl River Mouth Basin, South China Sea

At present,the study of Baiyun Sag is mainly concentrated in the central and eastern of Baiyun Sag,while little word is in the west of Baiyun Sag.Based on systematic analysis of static elements of hydrocarbon migration and accumulation,such as source rock,reservoir,cap rock,trap,this paper used the comprehensive research ideas and methods,static description and dynamic simulation,macro and micro features,qualitative and quantitative analysis to study the characteristics of hydrocarbon conduit system,accumulation times and moment of the west of Baiyun Sag deeply and evaluate the effectiveness and set up the model of hydrocarbon conduit system.They can provide the basis for decision-making and reserve discovery of hydrocarbon exploration in the next step,so as to effectively guide hydrocarbon exploration and development in the west of Baiyun Sag and even the Pearl River Mouth Basin.The sand body carrier layer of Zhuhai formation and Zhujiang formation is the main channel for lateral migration of hydrocarbon,and hydrocarbon migration mainly along the central tectonic ridge and the southwest tectonic ridge.The sand body thickness of Zhuhai formation is 180 ~ 330 m,the sand ratio is 0.2 ~ 0.6,the GOI value is 1% ~ 5%,so the geometric connectivity and fluid connectivity of the sand body of Zhuhai formation are good.And the sand body thickness of Zhujiang formation is 200 ~ 400 m,the sand ratio is 0.2 ~ 0.4,the GOI value is between 1% ~ 5%,QGF index less than 4,QGF-E less than 40 pc,so the geometric connectivity and fluid connectivity of the sand body of Zhujiang formation are good.In this study area,the fault density is high and normal faults are the main type,and the boundary fault of each sag is inherited.A single fault can be divided into planing,listric and sloping style,and the combination of multiple faults can be divided into flower,Y,X and ladder shape.Fault dip is mainly distributed between 20 and 60 degrees,the SGR values are mostly less than 15%,so the lateral side of the fault is not blocked in the west of Baiyun Sag.What's more,the maximum velocity of fault activity was 19.1 m/Ma between 10~2.59 Ma.The T80 and T70 unconformities of the west of Baiyun Sag are identified by seismic reflection profile,well logging and geochemical data,and the vertical structure of unconformity is identified by lithology and logging curves.Then,the vertical structure of unconformity be divided into basal conglomerate,water-transgression sandstone and weathering clay bed.The unconformity of the west of Baiyun Sag is distributed throughout the region,so it can effectively transport oil and gas.The hydrocarbon generated early and lasted for a long time,fault activity was later,traps formed earlier than hydrocarbon migrating and accumulating.Therefore,the hydrocarbon conduit system of the Baiyun Sag has good matching with source rocks,reservoirs and traps in time and space,and can effectively transport oil and gas.