南苏丹Melut盆地Ruman潜山构造演化及其对油气成藏的控制作用

Tectonic evolution and its influence on hydrocarbon accumulation of Ruman buried hill in Melut Basin,South Sudan

Melut盆地Ruman潜山经历了多期构造演化,导致该区油气成藏规律复杂。为落实Ruman潜山构造演化对油气成藏的控制作用,进一步探索油气勘探潜力,综合利用地震、钻井及区域构造资料,开展基于平衡剖面技术的构造演化分析,并结合烃源岩生排烃史,对Ruman潜山周缘油藏动态成藏过程进行剖析。结果表明:Ruman潜山自白垩纪以来经历了2期规模较大的翘倾抬升;白垩纪末期的翘倾抬升有利于潜山周缘地层-岩性圈闭的形成,古近纪末期的翘倾抬升导致潜山暴露,先期成藏的原生油藏遭受破坏,形成次生型稠油油藏;新近纪以来构造活动弱,围绕Ruman潜山形成晚期成藏型白垩系Galhak组地层-岩性稠油油藏以及新近系Jimidi组构造-岩性稠油油藏,二者均具有较大的勘探潜力。

The Ruman buried hill in the Melut Basin has experienced multi-stage tectonic evolution,resulting in complex hydrocarbon accumulation modes in this area.To reveal the role of the tectonic evolution of the Ruman buried hill in controlling hydrocarbon accumulation and further explore the exploration potential in this area,this paper combined seismic,drilling,and regional tectonic data for structural evolution analysis based on the balanced cross-section technique.Moreover,based on the hydrocarbon generation and expulsion history of source rocks,the dynamic accumulation process of reservoirs around the Ruman buried hill was analyzed.The results show that the Ruman buried hill has experienced two largescale tilting uplift activities since the Cretaceous.The tilting uplift in the late Cretaceous was beneficial to the stratigraphiclithologic traps around the buried hill,and those in the late Paleogene led to the exposure of buried hills,which destroyed the primary reservoirs that formed earlier,leading to secondary heavy oil reservoirs.In addition,the tectonic activity has been weak since the Neogene.It results in the stratigraphic-lithologic heavy oil reservoirs of the Cretaceous Galhak Formation and the structural-lithologic heavy oil reservoirs of the Neogene Jimidi Formation in the late accumulation around the Ruman buried hill,and both the reservoirs show great exploration potential.