塔里木盆地富满油田凝析气藏成因

Origin of gas condensate reservoir in Fuman Oilfield,Tarim Basin,NW China

基于塔里木盆地FD1井及周围主干走滑断裂钻探成果,从沉积-层序、台内滩储集层和油气成因等方面分析,以揭示超深主干走滑断裂带间中—上奥陶统台内滩储集性能及成藏条件。取得以下地质研究成果和认识:主干走滑断裂带间鹰山组台内滩叠加低序次断裂带构成一种新的成藏组合类型,下寒武统玉尔吐斯组烃源岩生成的油气首先由主干走滑断裂带垂向输导运移至鹰山组2段,然后发生侧向运聚成藏;FD1井少量原油是玉尔吐斯组成熟阶段生成的,而大量的天然气主要为超深油藏原油裂解气,从而形成高气油比的干气(干燥系数为0.970)和混合型次生凝析气藏。这种“台内滩+低序次断裂带”成藏组合新类型预示富满地区有望形成含油气连片局面并将进一步横向拓展富满油田超深领域的油气勘探空间。

To understand the reservoir property and hydrocarbon accumulation conditions of the Middle and Upper Ordovician intraplatform shoal between ultra-deep main strike-slip faults in Fuman Oilfield of the Tarim Basin,China,the main strike-slip faults in and around Well FD1 in the basin were analyzed in terms of sedimentary facies,sequence stratigraphy,intraplatform shoal reservoir property,and oil and gas origins,based on drilling data.The Yingshan Formation intraplatform shoal between the main strike-slip faults is superimposed with low-order faults to form a new type of hydrocarbon play.Hydrocarbons generated from the Lower Cambrian Yuertusi Formation source rocks were firstly transported through the main strike-slip faults vertically to the second member of Yingshan Formation,and then migrated laterally until they were accumulated.In Well FD1,a small amount of oil came from the Yuertusi Formation source rocks in the mature stage,and a large amount of gas was cracked from oil in the ultra-deep reservoir.Therefore,the secondary gas condensate reservoir in Well FD1 is characterized by high gas to oil ratio,dry gas(dryness coefficient being 0.970)and hybrid origin.This new type of hydrocarbon play consisting of intraplatform shoal and low-order fault suggests a prospect of continuous hydrocarbon-bearing area in Fuman Oilfield,which will expand the ultrap-deep oil and gas exploration in the oilfield.