渤中凹陷西斜坡东营组储层特征及其控制因素

Characteristics and controls of the reservoir sandstones from the Dongying Formation on the western slope of the Bozhong depression

通过岩心、薄片、扫描电镜等资料,对渤中凹陷西斜坡东营组储层进行了详细的研究。结果表明,该研究区东营组储集砂体主要以长石砂岩、岩屑长石砂岩为主,含少量长石岩屑砂岩。孔隙类型主要包括粒间孔隙、粒内溶蚀孔隙以及微裂缝,为中孔-中低渗储层。储层的发育程度对油气成藏具有重要的控制作用。沉积作用宏观上控制储层的发育;成岩作用在微观上影响储层内部结构的变化;深层的超压作用对次生孔隙的保护起着重要的作用,但过大的地层压力对储层的物性也会带来不利的影响。

With the aid of the cores, thin sections and SEM examination, the present paper gives a detailed study of the reservoir sandstones from the Dongying Formation on the western slope of the Bozhong depression. The reservoir sandstones in the Dongying Formation consist mainly of arkose and lithic arkose, with subordinately feldspathic litharenite. The porosity types comprise intergranular and intragranular solution openings and microfissures, suggesting the mesopores and low- to medium-permeability reservoir sandstones. The controlling factors include the deposition influencing the development of the reservoir sandstones and diagenesis exercising a major control on the internal structures of the reservoir sandstones. The deep-seated overpressure may be favourahle for the preservation of the secondary porosity. However, the overloaded formation pressure may bring about the velocity sensitivity and decrease the oil productivity of the low-permeability reservoir sandstones.