珠一坳陷油气成藏组合划分及有利成藏组合预测

    Division of hydrocarbon accumulation assemblage and prediction of favorable accumulation assemblage in ZhuⅠDepression

    • 摘要: 针对珠江口盆地(东部)寻找接替勘探领域、降低勘探风险的需要,采用成藏组合分析方法,从油气充注条件分析入手,研究珠一坳陷不同成藏组合油气优势运移聚集方向,研究表明:区域盖层的岩性组合与断裂活动强度共同决定了珠一坳陷油气在不同成藏组合间的分配与富集,恩平组砂地比在50%以上,且断层断距在140 m以上时,油气主要在T70界面之上的珠海-粤海组成藏组合富集,反之则主要在T70界面之下的成藏组合富集。长期活动型及叠加复合A型洼陷,油气以垂向运移为主,主力成藏组合及成藏带多位于烃源灶之上;早期活动型及叠加复合B型洼陷,油气以侧向运移为主,源内和近源的成藏组合最为有利,远源的珠海-粤海组成藏组合,其有利成藏带通常位于洼陷边缘及隆起区。

       

      Abstract: In order to find the further exploration target and reduce the exploration risk in the eastern Pearl River Mouth Basin, this paper analyzed hydrocarbon accumulation assemblage and hydrocarbon charging conditions to study the dominant migration and accumulation direction of oil and gas in different hydrocarbon accumulation assemblages in the ZhuⅠDepression. According to the study, the lithologic combination of the regional caprock and fault activity intensity control the distribution and enrichment of oil and gas. Oil and gas mainly accumulate in strata above the Enping Formation, when the sand/formation ratio of the direct caprock on the source, is greater than 50% and the fault displacement is greater than 140 m; The main hydrocarbon accumulation assemblage and accumulation zones are usually located above the source-kitchen in sags with long-term fault activities and superimposed activities of multi-episodic fault where oil and gas is mainly migrated vertically; for the sags where the faults are only active in the early stage and the degree of fault superimposition in different periods is low, the hydrocarbon accumulation assemblage in source and near source is more favorable, the favorable accumulation zones are usually located at the edge of depressions and uplifted areas in Zhuhai-Yuehai Formation accumulation assemblage where is far away from the source rock.

       

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