Tectonic Characteristics And Oil-Gas Exploration Potential In ZhangWu Basin

Zhangwu basin lies in North Liaoning Province,East Neimenggu Province and West Jilin Province.It is a fault basin,formed from Early Cretaceous Epoch. By the control of Palaeotectonic and Tectonic movement,sediments rapidly accumulated near source areas in Depressions of the basin.steep slopes of Depressions mainly develope the alluvial fans,near-bank underwater fans,turbidite fans and fan Deltas,gradual slopes with adequate sources supply develope fan deltas and braided river deltas; gradual slopes which are lack of sources supply develope shore-shallow lacustrine facies.There are three sets of source rocks in basin,which are Jiufotang Formation,Shahai Formation and Fuxin Formation.In Plane, Zhang Qiang Depression is best,Ganjika depression is better,Daliujiazi Depression is worse,Daleng Depression is worst.On the horizon,the main source rocks in the eastern region are best in Shahai Formation,and better in Jiufotang Formation,the main source rocks in the western region are best in Jiufotang Formation,and better in Shahai Formation. source rocks in Fuxin Formation are the same in all depressions,with low organic abundance,which are poor-no source rocks.Poor reservoir performance in all Later Cretaceous Epoch formations is the key conditions to control the oil and gas exploration.Reservoir evaluation showed that,this area is ultra-low Porosity and permeability reservoir,the pore structure are the ultra-small throats and micro-small throats,which affect the production and exploitation of the oil and gas.But in good sedimentary facies,there are still good reservoir Layers,such as sandbodies in underwater tributary channels in fan-deltas and fluvial channels. From a reservoir perspective,future exploration work should focus on the edge of the lake zones.According to the analysis of petroleum geology of the basin,the comprehensive evaluation of all depressions shows that, ganqika Depression is the most favourable oil-bearing Depression in Zhangwu Basin,Xidala Depression,Yemaotai Depression and Daliujiazi Depression are poorer oil-bearing Depressions.Hulesinuoer Depression,wuritutala Depression and Houmenggundaba Depression are worse oil-bearing Depressions.Therefore,at present,evaluation and exploration should be strengthened in ganqika Depression,baogetu Depression,Zhalan yingzi Depression and daleng Depression,particularly ganqika depression should be placed on the first.