塔里木盆地西南坳陷二叠系页岩油气地质条件分析

Analysis of Geological Conditions of Permian Shale Oil and Gas in the Southwestern Depression of the Tarim Basin,Northwest China

二叠系泥页岩是塔里木盆地西南坳陷重要的烃源岩层系,阿克莫木、柯克亚、柯东1、杜瓦等地区或钻井的油气均源自二叠系,然而其页岩油气地质条件研究鲜见报道。笔者在分析研究区构造和沉积发育及其演化特征的基础上,重点研究了二叠系泥页岩的厚度、分布、地球化学和储层特征等页岩油气地质条件,探讨了构造、沉积与泥页岩生烃之间的演化关系,研究结果表明:①塔西南坳陷二叠系泥页岩累计厚度介于50~400 m,主要分布在叶城凹陷和和田凹陷,沉积环境以浅海陆棚相和海陆过渡相为主,第四纪喜山运动对二叠系泥页岩的生烃演化具有重要的促进作用。②塔西南坳陷二叠系泥页岩具有良好的页岩气生成和储集条件,是塔里木盆地页岩气勘查的潜在层系;叶城凹陷和和田凹陷是塔西南坳陷页岩油气勘查的有利区,需进一步加强钻探验证工作。

Permian shale is an important source rock in the depression of southwestern Tarim Basin.Oil and gas from such fields as Akemomu,Kekeya,Kedong1 and Duwa1 are originated from the Permian system,while research on its shale geological conditions is rarely reported.Based on the comprehensive analysis of the tectonic and sedimentary development and its evolution characteristics,the authors focused on the thickness,distribution,geochemistry and reservoir characteristics of the Permian shale,and also discussed the coupling relationship between evolution of tectonic,sedimentary and hydrocarbon generation.The results show that the accumulated thickness of Permian shale is between 50 and 400 m,mainly distributed in Yecheng sag and Hetian sag with shallow sea shelf facies and sea-land transitional facies.The Quaternary Himalayan movement plays an important role in promoting the hydrocarbon generation of the Permian shale.Comprehensive analysis suggests that the Permian shale in the southwestern Tarim depression has good conditions of shale gas generation and reservoir,and is the potential stratum shale gas exploration.The Yecheng sag and Hetian sag are favorable for shale oil and gas exploration,which needs to be further drilled and verified.