Comprehensive Classification of Low and Ultra-Low Permeability Sandstone Reservoirs in Jidong Oilfield, China

Abstract

Reservoir classification is an important content of reservoir evaluation, and has significance for the optimization of favorable areas and the formulation of development plans. Aiming at the characteristics of low and ultra-low permeability sandstone reservoirs in Jidong Oilfield, this paper selects sedimentary facies, sand body width, mean effective radius and effective percolation coefficient as evaluation parameters. Through conducting the macro qualitative analysis and microscopic quantitative evaluation, the classification boundary is determined by cluster analysis, a comprehensive evaluation system of low and ultra-low permeability sandstone reservoirs is established. The reservoirs are divided into four types, the physical properties get worse in turn of type I to III, and type IV is small sand body. The sedimentary facies of type I to III reservoirs are mainly bar host and fluvial channels, the inner edge of the bar, the outer edge of the bar and shoal in turn. The sand body width of type I to III is more than 300 m,and it is less than 300 m of type IV reservoirs. Based on the classification results, the feasibility analysis of water injection was carried out, and corresponding development policy recommendations are put forward for four types of reservoirs.