Sinian rift valley development characteristics in Tarim basin and its guidance on hydrocarbon exploration

Based on the former research of deep formations in Tarim basin,by using drilling and seismic data for the first time,the fine description of Sinian rift valley development characteristics in Tarim basin has been made.It is believed that the Tarim basin in Sinian was controlled by Tianshan Ocean and Kunlun Ocean rifting,three aulacogens(Maigaiti,Manjiaer,and Awati)and three big ancient lands(northern Tarim,Bachu- mid Tarim and Hetian)were developed.The sedimentation of Sinian was divided into chasmic and depression stages.In this article,the guidance of Sinian on hydrocarbon exploration has been analyzed:the first one is that the direct control of Sinian rifting and its successive subsidence on Sinian period itself and the sourcerock of the lower Cambrian Yuertusi formation in Tarim Basin,the second one is that the control of subsidence marginal of successive rifting in Sinian on marginal facies belt of lower Cambrian platform,the successive ancient land on the distribution of the lower Cambrian platform,the third one is that the common control of Sinian ancient land and successive rifting margin on the distribution of Plaster gypsum in Middle Cambrian,and the fourth one is the favorable exploration zone,namely Cambrian pre-salt structure of mid-Tarim basin,while Bachu and Madong are the most favorable area for Cambrian pre-salt exploration.