关键词: 碳酸盐岩油藏, 分类评价, 主成分分析, K-均值聚类, 注水开发对策, 中东地区

Abstract: In view of the fact that there is no guidance for the classified development mode of complex and diverse carbonate reservoirs in the Middle East, a classified evaluation method of oil reservoirs was proposed based on principal component biplot and K-means clustering diagram. Through the combination of qualitative analysis and multivariate statistical analysis, 8 reservoir characteristic parameters that can reflect petrology, structure and physical properties of carbonate reservoir, interlayers, fluid properties and heterogeneity were selected from 16 typical carbonate reservoirs, based on which a data matrix was constructed. Later, principal component analysis was achieved by the singular value decomposition of covariance matrix, and then the principal component biplot was constructed for the graphic analysis of reservoirs, reservoir characteristic parameters and the relationship between the both. Finally, the classified evaluation of reservoirs was conducted using the K-means clustering method. The results show that key parameters such as micro-pore structure, reservoir thickness and heterogeneity have a strong ability to distinguish the reservoirs, so that the carbonate reservoirs in the Middle East can be divided into 3 types accordingly. The irregular distribution of thief layers in thin reservoirs has led to serious water-out performance in horizontal wells. The great difference in vertical physical properties of thick layered reservoirs has an adverse influence on the degree of reserve utilization. The super-thick massive reservoirs are characterized by a complex micro-pore system, subtle interlayers, and strong heterogeneity, which have intensified the contradiction in the general development of commingled water injection. Based on this, the paper proposes the development strategies including bottom interval injection and top interval production with horizontal well patterns for thin reservoirs, progressive peripheral water injection for thick layered reservoirs, and separated layer water injection with hidden baffles and barriers for super-thick massive reservoirs, thus providing technical support for the efficient waterflood development of carbonate reservoirs in the Middle East.

Key words: carbonate reservoirs, classified evaluation, principal component analysis, K-means clustering, waterflood development strategies, Middle East