河道砂体内部夹层岩性与遮挡性识别

河道砂体内部夹层作为储层构型界面,厚度较薄,岩性、遮挡性存在差异,对河道砂体内流体渗流及剩余油分布的影响不尽相同。本文以大庆油田萨北二区为例,利用密闭取芯井岩芯和纵向分辨率较高的微电极测井曲线等资料,以岩芯识别夹层岩性为基础,通过对测井曲线幅值、幅差、回返率交汇分析,优选出微电位回返最低值和微梯度回返率作为夹层岩性判别标准,夹层岩性识别符合率达82%;并以夹层含油性为依据,将夹层按遮挡性分为完全阻流型、强限流型、弱限流型等三种类型;分析密闭取芯井河道砂体内部夹层岩性与遮挡性对应关系,建立了非取芯井河道砂体内部夹层遮挡性的岩性解释法,夹层遮挡性识别符合率达72%。以此为深入研究地下河道砂体内部构型对注入剂驱替路径及剩余油分布的影响奠定基础。

The Identification of Lithology and Shielding of Interlayer inside Channel Sand Body

The interlayer taken as architecture interface inside channel sand body was thin. There were differences in lithology and shielding of interlayer which shielded the flow of fluid and influenced the distribution of remaining oil. This paper took North Second Area of Daqing Oilfield as an example. The core of sealed coring wells and vertical high resolution microelectrode logging data were used in this study. The lithology of interlayer was analyzed by using the intersection of amplitude values, amplitude difference and the rate of return of well logging curves on the basis of core identification. The lowest value of RMN (resistivity of micro normal) and the rate of return of RMG (resistivity of micro gradient) were selected as criteria of interlayer lithology identification. The identification rate of interlayer lithology was up to 82%.Taking oil bearing interlayer as basis, the interlayer was divided into three types: complete block interlayer, strong limit interlayer and weak limit interlayer. Considering the relationship of lithology and shielding, the lithologic interpretation method of the interlayer shielding inside channel sand body was established. The identification rate of interlayer shielding was up to 72%. Therefore, this paper laid the foundations for the deep study that the architecture influenced the displacement path of injection and the distribution of remaining oil in underground channel sand body.