Declustering Effect of Geology Data

The various complex geological processes result in the reservoir heterogeneity. Wells are always drilled in areas with a greater probability of good reservoir quality. Core measurements are taken preferentially from good quality reservoir rock. The data from these sources distribute asymmetrically in the interesting area. Usually, some data are spatially clustered. It needs to correct this preferential clustering before making statistic. Two methods are introduced to obtain a representative statistic of the entire area of interest: one is cell declustering, and the other is polygonal declustering. The basic idea of the two methods is to assign lesser weights to closely spaced data and to assign greater weights to widely spaced data. A case study in Shi Nan oil field is presented. The research result shows that the statistic results using these two declustering methods are more reliable.