珠江口盆地惠州地区珠江组控砂机制及地层-岩性圈闭发育模式

惠州地区是目前珠江口盆地勘探程度最高的地区,珠江组作为主力产油层段,具有寻找地层岩性圈闭的有利条件。通过对惠州地区珠江组砂岩发育的控制因素分析,认为盆地转换期的古地貌特征、层序地层发育特征、以三角洲为主体的沉积体系展布、海陆过渡相区的水动力条件和后期构造运动都对砂体的形成和展布具有重要的影响;其中沉积相决定了砂体的宏观展布,层序结构影响砂体在不同体系域平面上的分布和纵向上的发育程度及叠置样式,二者是控砂的主要因素。在对控砂机制分析的基础上,结合对已发现岩性圈闭油气藏的解剖分析,建立了惠州地区珠江组地层岩性圈闭的发育模式,分析了有利地层岩性圈闭区带和类型,认为沉积坡折附近和海进体系域退积砂岩岩性尖灭圈闭是惠州地区珠江组最为有利的地层岩性圈闭类型。

Factors controlling sandbody development and models of stratigraphic-lithologic traps of Zhujiang Formation in Huizhou area,Pearl River Mouth Basin

Huizhou is an area with the highest exploration maturity in Pearl River Mouth Basin,wherein the Zhujiang Formation is the primary oil-producing layer and has the potential of finding stratigraphic-lithologic traps.Through analyses on the factors controlling sandbody distribution of the Zhujiang Formation in Huizhou area,this paper concludes that various factors including palaeogeomorphology,sequence stratigraphy,delta-dominated sedimentary facies distribution and hydrodynamics in transitional zone during basin transformation and subsequent tectonic movements all have important influences on the formation and distribution of sandstones.Sedimentary facies determines the macroscopic distribution of sandbodies,and sequence structure influences the lateral and vertical sandbody development and sandbody stacking patterns in different system tracts.Sedimentary facies and sequence structure are the two main controlling factors.Based on the study of the controlling factors and the discovered lithologic hydrocarbon reservoirs,this paper establishes development models of stratigraphic-lithologic traps of Zhujiang Formation in Huizhou area,and analyzes the favorable area and types of stratigraphic-lithologic traps.We believe that the lithologic pinchout traps around sedimentary slope-break and / or within transgressive system tracts are the best ones for hydrocarbon accumulation.