阿曼前陆盆地构造-沉积特征及其对油气成藏的控制

Structural and sedimentary features of Oman foreland basins and its influences on hydrocarbon accumulation

晚白垩世阿曼造山运动影响了被动陆缘和主动陆缘两种沉积体系,控制了周缘鲁卜哈利和阿曼盆地的油气富集。为明确阿曼造山构造全过程与周缘地区沉积-成藏条件的作用关系,通过构建区域地质-地震剖面,细化阿曼山构造演化阶段和时空差异,梳理前陆盆地不同构造单元的沉积耦合特征;基于岩心、薄片、微米CT和地球化学、地震资料,总结了阿曼造山运动对白垩系关键地质要素和多类型岩性圈闭的控制作用。研究表明,阿曼山所处的阿拉伯板块东北缘在白垩纪至古近纪经历了被动陆缘晚期、洋壳仰冲、前陆造山三个演化阶段,垂向构造体系经历了断垒向压扭或逆冲断层的演化,空间应变具由北东向南西逐渐减弱的特征。阿曼前陆盆-山体系主要影响了Lekhwair隆起带周缘的前渊-斜坡及隆后单元的构造-沉积过程,白垩系垂向上记录了被动陆缘稳定沉降、主动大陆边缘挠曲剥蚀和稳定沉降等三期沉积建造。晚白垩世挤压应力控制了两阿(阿联酋、阿曼)优质储层进一步改造和礁滩、断块、岩溶及不整合等多类型圈闭的定型。研究工作系统梳理了阿曼造山运动控制下的白垩系沉积-成藏特征,为多类型岩性圈闭机理研究和精细勘探提供启示。

Oman orogeny that occurred at Late Cretaceous affected both passive and active continental margin depositional systems,and controlled the hydrocarbon enrichment in the Rub Al-Khali Basin and Oman Basin.In order to clarify the relationships among the Oman orogeny,deposition and hydrocarbon accumulation conditions,we summarized the tectonic evolution stages and differences,and refined the sedimentary coupling characteristics of different structural units according to the balanced cross-section recovery in several regional geological-seismic data.By analyzing cores,thin sections,Micro-CT,geochemical and seismic data,the controls of Oman orogeny on key geological elements and multi-type lithologic traps of the Cretaceous were summarized.It is concluded that,the Oman Mountains located at the northeastern margin of the Arabian Plate and evolved three stages from the Cretaceous to the Paleogene,including the late passive continental margin,the oceanic crust over-thrust,and the foreland orogeny.The tectonic system has undergone the evolution from the fault-horst to compression-torsion or thrust faults,and the strain intensity has the characteristics of weakening from north to south.The Oman foreland basin mainly affects the tectonic-sedimentation process of the foredeep-slope and backbulge zones around the Lekhwair uplift.The Cretaceous strata recorded the sedimentations of passive continental margin,active continental margin denudation,and stable subsidence.Late Cretaceous compressive stress controlled the high-quality reservoirs in the UAE and Oman and the final shaping of multiple types of traps such as reef-shoals,fault blocks,karsts and unconformities.The research work systematically sorts out the sedimentary and hydrocarbon accumulation characteristics and provides the inspiration for the forming mechanism and fine exploration of multi-types of lithologic traps.