Carbonate reservoir characterization: an integrated approach

TLDR

Estimating fluid and rock properties in heterogeneous carbonate reservoirs is difficult, and conventional petrophysical logs, laboratory tests, geostatistics, outcrop data, borehole scans, and fractal fracture networks provide only static, limited descriptions. This study introduces a dynamic procedure to improve conventional reservoir characterization. The approach integrates production data over time with rock and fluid properties to estimate well drainage radius, matrix block dimensions, porosity, and fracture width. Applied to a real reservoir, the method produces spatial maps of matrix block size, fracture width, and porosity, and can assess the effectiveness of acid or hydraulic fracturing.

Abstract

Abstract Estimation of fluid and rock properties of a hydrocarbon reservoir is always a challenging matter; especially, it is true for heterogeneous carbonate reservoirs. Petrophysical logs and laboratory activities are common methods for characterizing a hydrocarbon reservoir. This method in conjunction with geostatistical methods is applied to relatively homogeneous sandstone reservoirs or matrix media of dual-porosity heterogeneous carbonate reservoirs. To estimate properties of fracture system of a dual-media carbonate reservoir, outcrop properties, electrical borehole scans, fractal discrete fracture network and analogy with other reservoirs are common methods. Results which obtained from these methods describe the reservoir in a static way and could be relied on them for very small portion of the reservoir. In this paper, a dynamic procedure for describing reservoir features is proposed in order to enhance the conventional reservoir characterization methods. This method utilizes the reported production data for a specific period of time in conjunction with rock and fluid properties to estimate drainage radius of the well and matrix block height, porosity and width of fracture in the estimated drainage radius. The presented method is elaborated through its application in a real case. By this method, one can generate maps of matrix block size and fracture width and porosity throughout the reservoir. Also, it could be a powerful tool for estimation of effectiveness of acid/hydraulic fracturing activity.