塔东地区下古生界天然气成藏主控因素及勘探领域

Conditions for Gas Accumulation and Potential Areas in Lower Paleozoic Eastern Tarim Basin

利用岩心、分析化验及地球物理资料对塔东地区下古生界烃源岩和储集层进行了综合分析。研究认为寒武系—奥陶系烃源岩已处于高—过成熟阶段,原油裂解气是主要气源,并圈定裂解气有效供气范围主要集中在古城以北的地区。储层主要为颗粒灰岩和白云岩,颗粒灰岩的孔隙类型主要为裂缝及与之伴生的溶蚀孔洞,分布在古城台地边缘带和罗西台地边缘带的奥陶系中;白云岩主要发育溶蚀孔,在塔东地区广泛分布。结合区域构造演化史分析,指出古城鼻隆及其西北地区是最有利的勘探区带,其次为英东构造带及满加尔凹陷、英吉苏凹陷内的其他隆起区。

By means of drilling core and analysis data,as well as logging data and seismic data,the source rock and reservoir rock of the Lower Paleozoic in eastern Tarim Basin are comprehensively evaluated.It is indicated that,the source rock within the Lower Paleozoic from Cambrian to Ordovician is in high and over mature stage,therefore providing hydrocarbon in the form of oil-cracking gas.It is pointed out that the effective cracking gas-bearing targets are concentrated in the northern Gucheng area.The primary reservoir is in two forms as follows:The granular limestone with fracture and dissolution pores mainly distributed in the west platform edge of Gucheng and in the east Luoxi platform;The dolomite with dissolution pores mainly distributed in the platform of eastern Tarim Basin.Combined with the analysis of regional tectonic evolution history,it is proposed that the nose structure of Gucheng and its north-west area are the most favorable areas,and Yingdong structure belt and other uplifts in the sag are the secondary favorable areas.