Study On The Migration Of Oil And Gas And Transmission System In The Middle Shallow Layer Of NanPu Sag

In this paper,the No.1 structure of Nanpu Sag is selected as the research area.Based on the integration of geochemical parameters,seismic data,well logging data,formation water data and pressure data,the geological comprehensive research method and geochemical parameter tracing method are used to systematic analyze the source,migration direction and migration characteristics.These researches also provide support for fine exploration in the Bohai Bay Basin.In the Nanpu Sag No.1 structural area,the migration system consists of faults and sand bodies.The faults,which connect deeper hydrocarbon source rocks and shallower sandstone reservoirs,are vertical migration routes for oil and gas.Nanpu-1 fault is the main fault in our work area.On the two sides of this fault,there are two obviously different faults distribution systems: at the zone in the south of Nanpu-1 fault,the middle-shallow faults are well developed and break through the overburden rock;at the zone in the north of Nanpu-1 fault,middle-shallow faults are not developed.Crude oil moved laterally along the sand body after moving to shalow layers.The physical properties of reservoir sandstones in the study area are generally good,and are not the key factors restricting oil and gas migration.In Ng group of the No.1 tectonic of NanPu Sag,a mass volcanic cap rock which different from other structures is developed.At the zone in the south of No.1 fracture of NanPu Sag,faults break through the overlying volcanic cap rocks.At the zone in the north of No.1 fracture of NanPu Sag,faults are barely developed,volcanic cap rocks continuously distributed.Faults and cap rocks are the most important elements of reservoir forming in the study area.Different distribution characteristics of fractures and cap rocks lead to different parameters distribution on each sides of the No.1 fracture of NanPu Sag,.Parameters such as pressure characteristics,formation water parameters,oil-bearing areas,crude oil physical properties,biomarker compound parameters and hydrocarbon migration modes are totally different.