Reservoir Prediction And The Characters Of Oil Accumulation In The Lower Cretaceous, Northwestern Beier Depression, Hailaer Basin

The northwestern Beier depression is one of the most important petroleum exploration regions in Hailaer basin. Based on the interpretation and inversion of seismic data and well logs,classification of system tracts and sedimentary facieses, this dissertation discussed the essential factors controlling the generation,migration, accumulation and distribution of oil and gas in the area. As a conclusion,the author believed that:The Tongbomiao Fm can be divided in a lowstand system (LST) and a transgressive system tract (TST) in the area. The 1st member of Nantun Fm can be divided into a LST, a TST and a highstand system tract (HST),and a TST and HST in the 2nd member of the formation,respectively. The sequence stratigraphy frame work established in the dissertation can be used to the analyses of the factors controlling the foundation of reservoir and reserve distribution in the NW Beier area,from the upper Nantun Fm,to the middle Damuguaihe Fm and the lower Tongbomiao Fm.The faults in the area can be compartmentalized into 3 types,the early stage developed fault,the later stage developed fault and the long term developed fault, among which,the early stage and the long term developed faults are the most important faults controlling the migration and distribution of oil and gas in the area. And moreover,the long term faults controlled the structural framework,the Slope Break location and the paleotopography of the Beier depression. Integrated seismic data interpretation revealed the distribution and occurrence of these kinds of faults in the area.The sedimentary facies of the Cretaceous in the area include fan delta, fluvial fan,river delta,lake and underwater fan. And the distribution of sedimentary systems was clearly controlled by the basin framework and the tectonic activities. The main successional sinking and sedimentary center is located at the western Beier sub-depression,in which the deep-lake,sub-deep lake and turbid sediments were developed. By comparison,various types of terrestrial coarse clastics of fan systems were mainly occurred at the two slopes of the sag.Three source-reservoir-cap rock associations were identified in the Cretaceous in the area. The migration and accumulation model of oil and gas in the area can be concluded in 2 types,the T-shape and S-shape.Three major factors controlled the occurrence of oil and gas in the area, i.e., rich oil and gas source kitchen,favorable sedimentary facies and the faults or unconformity connecting the source kitchen to the reservoirs.