Study On Hydrocarbon Accumulation Condition In Northern Depression Of DaYangshu Basin

By using seism,well logging,core, gravity and magnetic, production test and the other allied data,this paper have researched the lithology character of slag,the rock facies types and characters and the change regulation of stratum thick.The regulation of the thick of sendimentary rock and volcanics and the habitates of lithology facies was cleared,the cause mode of the habitates of lithology facies was buite.This paper indicated that the emposieu and the fracture was the main reservoir of Dayangshu basin.The surce rock-reservoir-cap bed group was also analysed in this paper.The volcanics developed in the vast of the basin particularly in the time of Ganhe group sendimented, in that time,the whole basin was capped by volcanics, while in the time of Longjiang and Jiufengshan group sendimented, the volcanics and sendimentary rocks developed alternately.Many types of volcanics pore and the fracture formed the beneficial hydrocarbon reservoir, while the dense slag, volcanic tuff and pelitic siltstone could be well cap bed. The volcanics lithology types were overflow face, the burst face the burst sendimentary face(including alluvion face and lacustrine bog face) and the pass through types. The burst face was composed by auto brecciated lava and and lava and habitated around the center of volcanic.The overflow face was mainly composed by the lava, including rhyolite, trachydacit and mixpah. The volcanics sendimentary face was composed by tuffaceous sandstone and tuffaceous mud and habitated by the edge of volcanics. The rocks of buest face, caused by the power of burst, could broke the cap rock and the surrounding rock and then buite vast fractures, at the same time, the auto brecciated lava and the lava were formed. The hole developed in the auto brecciated lava which was the beneficial reservoir.This paper forecased the beneficial area of northern Dayangshu basin by using the structural trap condition, the sorce rock, reservoir, cap bed condition and there matching condition.The lake face sendimentary rock was the main sorce rock in the northern depression in Dayangshu basin and it habitated mainly in the deep depression area. The hydrocarbon formed migrated up to the traps with well rseserve condition by using the fault as aisle. Because the bottom Ganhe group capped the upper Jiufengshan group sorce rock, the bottom Jiufengshan group had a well sorce-reservoir-cap combined condition. So, the traps in Jiufengshan group and the bottom Ganhe group had the priority to pray hydrocarbon and was the beneficial hydrocarbon assemble area. The lithology and structure traps habitated in the center of depression was the best trap. By synthesize analyse, the middle fault depression belt was the best exploration area.