Image Analysis of Reservoir Pore Systems: State of the Art in Solving Problems Related to Reservoir Quality

Abstract

Abstract Image analysis is rapidly emerging as a promising new technology for the quantification of pore geometry. This paper presents reservoir-oriented applications of pore geometry analysis with particular emphasis on reservoir quality (porosity and permeability). Image analysis consists of a computer-based, systematic procedure which quantifies those aspects of porosity that are visible using a 2 dimensional image (thin section or SEM image). This allows for identification and quantification of the size, shape, distribution and volume proportions of different pore types (pore geometry). In terms of producibility, pore geometry can be more important than total porosity particularly in rocks with less than 25% porosity. Two examples are presented that demonstrate the application of image analysis of reservoir pore systems to problems related to formation damage and reservoir quality. In the first example, pore geometry derived from sidewall cores is related to test results in an offshore well. There is a direct relationship between pore geometry and flow rates. Zones that under-produce their pore system are identified as potentially damaged zones. In the second example, pore geometry is related to test results, routine core analysis and log response (specifically deep induction and sonic travel time). A rock-based log model is developed to identify Rock Type units on a foot-by-foot basis in cored and non-cored intervals.