苏丹Rawat盆地构造特征及成藏主控因素

Analysis of tectonic characteristics and main controlling factors of hydrocarbon accumulation in Rawat Basin,Sudan

苏丹Rawat盆地是在中非剪切带斜向张裂作用诱导下发育起来的中生代—新生代陆内裂谷盆地,目前仅在盆地中部获得油气发现,成藏主控因素尚不明确。为此,梳理了Rawat盆地构造特征,完成了构造单元划分,明确了构造演化阶段,探讨了各次盆油气成藏主控因素。研究认为:在持续强烈的拉张应力作用下,Rawat盆地形成5个次盆,即中央次盆、北次盆、东次盆、西次盆和东南次盆;自白垩纪以来,主要经历了晚白垩世到始新世的第一期断陷期,渐新世的第二期断陷期以及中新世以来的拗陷期共三个构造演化阶段;受控于构造演化过程,各次盆具不同结构和沉积特征,导致了油气分布的差异;油气成藏的主控因素为烃源岩质量;中央次盆具备较大的油气勘探潜力,西次盆次之,其他次盆勘探潜力有限。

The Rawat Basin in Sudan is a Mesozoic-Cenozoic intracontinental rift basin developed under the induction of oblique rifting of the Central African shear zone.Currently,hydrocarbon has been discovered only in the central part of the basin,and the main controlling factors for hydrocarbon accumulation are still unclear.Thus,this paper sorts out the tectonic characteristics of Rawat Basin,completes the tectonic unit division,and clarifies the tectonic evolution stages,with the main controlling factors of hydrocarbon accumulation in each sub-basin discussed.The research shows that under continuous and strong tensile stress,the Rawat Basin develops into five sub-basins,including the central,northern,eastern,western,and southeastern sub-basins.Since the Cretaceous,it has mainly experienced three tectonic evolution stages,containing the first rifting period from the Late Cretaceous to the Eocene,the second rifting period from the Oligocene,and the depression period since the Miocene.Controlled by tectonic evolution,each sub-basin has different structures and sedimentary features,resulting in differences in hydrocarbon distribution.The main controlling factor of hydrocarbon accumulation is the quality of source rocks.The central sub-basin has great exploration potential followed by the western sub-basin,and the other sub-basins have limited potential.