基于主成分分析技术计算蚀变地层孔隙度的新方法

摘要

According to the thin rock slices and log response characteristics, Xiazijie formation of X1, X2 well areas in the Junggar Basin exists altered formation of hydrothermal origin. Altered sandstone and sandy conglomerate are the main lithology of altered formation. With the altered type and extent of changes, it is hard to choose rock matrix parameters and difficult to calculate the porosity. For calculating porosity of altered formation quickly and accurately, this paper presents a new porosity calculation method based on rock matrix parameters extracted by principal component analytical(PCA) technology. The thin rock slices data display the mineralogy features of the hydrothermal altered formation. The principle components (such as Ec, △φ and N) of dolomites, limestones, sandstones, typical mudstones and continous hydrothermal altered formation are analysed with the PCA technology so to extract the rock matrix parameters. Actual data application results show that the porosity calculated by the new method coincides well with porosity obtained from core analysis, which can meet the requirements of calculation accuracy.%根据岩石薄片和测井响应特征发现准噶尔盆地X1、X2等井区夏子街组存在热液成因的蚀变地层.提出基于主成分分析技术提取岩石骨架参数计算地层孔隙度的新方法.通过薄片分析资料,基本掌握热液蚀变地层矿物学总体特征,将白云岩、石灰岩、砂岩、典型泥岩段和连续热液蚀变地层的等效弹性模量、中子—密度视石灰岩孔隙度差异值和骨架中子值经主成分分析技术可有效提取岩石骨架参数.在此基础上,应用补偿岩性和流体的孔隙度计算方程能提高计算精度,避免了区分岩性后再分别建立孔隙度模型的繁琐步骤.