Fractured Sandstone Reservoir Characterization Study

With the development of water flooding process in fractured sandstone reservoirs, severe heterogeneities both in vertical and in areal result in a poor swept efficiency. As a result, establishing a precise geological model to character fractures and matrixes plays important roles in predicting residual oil saturation and enhancing oil recovery in water flooding process in fractured sandstone reservoir.In this paper, with the help of advanced geology, geological statistics, random and fractal geometry, fractal simulation has been applied to establish a precise geological model of fractured sandstone reservoir. The simulation result indicated that the H2 Grope in HuoShaoShan reservoir is a deposition fan delta during the datum level drops. Reservoir deposition is the fan delta underwater distributor channel and the bar sandstone.During the reservoir matrixes description, the geological, srismic and well logging data, and the high-resolution preface and deposit microfacies analysis results were applied in the simulation to determine the distribution of the matrix parameters in fractured reservoirs. A three-dimension reservoir parameter distribution model before and after water flooding process was established by using the core analysis and the well logging materials.In discerning and simulation of the constructed fractures, well logging materials, fractal discerning and routine distinguished method were used to describe the development of the reservoir fractures, a three-dimension reservoir fractures distribution model was established. The coincidence is more than 90%. Simulation results showed that the fractured reservoir is a specially low permeability sandstone reservoir, the distribution of the matrices in reservoir rely on the form of lens, the fracture is relatively developed, and the fractures are divided into three different position (ie NE-SW, nearly S-N and NW-SE). After the water flooding process in the fractured reservoir, the reservoir parameters permeability increased because of the influence of the water flushing.The investigation results indicated that the most important factor influencing sedimentary microfacies model is the high-resolution sequence stratigraphy. The primary basis to describe the hierarchical of internal /interlayer is the well logging treating of the reservoir-characteristics. The fractures are the master control factor of the residual oil in the fractured sandstone reservoir during water flooding. Three dimensional fractures grid simulation became the key technology to enhance oil recovery. The method ofthe fractal geometry is the effective way to describe the fractured sandstone reservoir during water flooding. The dynamic change models before or after water flood become important tools to get the accurate information from the fracture reservoirs and to adjust production scheme to improve oil recovery.