Hydrocarbon Migration And Accumulation Characteristics In Baiyun Sag,Pearl River Mouth Basin

Petroleum migration and accumulation characteristics in Baiyun Sag in Pearl River Mouth Basin were studied from the following aspects: the source of crude oil,sedimentary environment and maturity parameters,oil source correlation analysis,oil and gas transporting and geological logging characteristics,qualitative and quantitative analysis of secondary reservoir reformation,etc.Geochromatographic layer effects of maturity parameters indicates hydrocarbon migration and traces hydrocarbon migration path;Multipling the study area's sedimentary environment,tectonic background,and using gas washing effect,to indicate hydrocarbon charging times,to carry out the research of petroleum characteristics in Baiyun Sag.Experimental samples' laboratory analysis and comprehensive study make it clear that the northern and eastern regional crude oil of the Panyu Low Uplift and the Liwan-Liuhua structure in Baiyun Sag have different characteristics of sources and maturity and the northern crude oil has a higher maturity.Combinating GC-MS,GC-MSMS with the whole oil and single molecule carbon isotope,to select the effective biogenic parameters applied to this area(full oil carbon isotope,tricyclic terpane / hopanes,1,2,5 / 1,3,6-trimethyl-naphthalene,steranes / hopane,etc.)and the maturity parameters(methyl naphthalene ratio,ethyl naphthalene ratio,methylphenanthrene index,methylphenanthrene ratio,dimethyl phenanthrene index,4-MDBT / 1-MDBT,double adamantane index,etc.).Oil-source correlation shows that Enping source rock is the main source rock of Baiyun Sag,Northern crude oil is mixed with Wenchang source rock,Eastern crude oil is mixed with Zhuhai source rock.Maturity parameters used to trace Hydrocarbon migration path has a good similarity to each other and they can be compared perfectly.Combinating these parameters tracing migration path,they indicate the direction of hydrocarbon migration is along the main transport depression center to the surrounding and near Panyu low uplift,migration direction is from west to east,namely along the maturity descending direction migration.The main eastern deepwater reservoirs in Baiyun Sag has two times accumulation,early gathering oil and late gathering gas and condensate.the main accumulation period is Yuehai-Nowadays.The typical eastern accumulation reservoir characteristics is divided into three parts,namely LW3-1 structure,LH34-2 structure-LH29-1 structure,LH16-2 structure.Oil-source problem of Baiyun Sag,complex pathway system types and different accumulation characteristics make the study hard.In order to better distinguish between oil and source,deepen the study of hydrocarbon migration and accumulation characteristics for guiding practice exploration,it has become particularly necessary.Studing the present situation,the macro analysis of regional tectonic oil-source is extremely difficult,it can not resolve one be one well as a unit.This paper will systematicly research from providing petroleum hydrocarbon layers,dominant migration paths to gathering into reservoirs,namely the "source-migration-gathering".The study will start from the macro oil-source analysis,migration direction and microscopic focusing on showing trace hydrocarbon migration paths,dissecting typical hydrocarbon accumulation features.This paper is intended to clear hydrocarbon migration paths,dominant migration channels of the work area,the study of hydrocarbon accumulation times and dividing typical accumulation area.This paper reaserch is for oil and gas exploration to provide certain guidance and reference in Baiyun Sag in Pearl River Mouth Basin.