3D Geological Modeling of Fluvial Facies Reservoir: A Case Study of Sulige Gasfield in China

Abstract

Sulige gasfield in China is a typical fluvial tight sandstone gas reservoir. Because of its strong heterogeneity it is not easy to establish satisfactory sedimentary facies model and effective reservoir model by conventional deterministic methods or stochastic geological methods. Taking Sulige gas field as an example, a new 3D geological modeling method combining with both static and dynamic constraints for fluvial facies reservoir was built. First, through the distribution scale measurement of 77 major rivers in the world, the configuration and distribution of the main sand bodies in the fluvial facies were quantitatively characterized. Under the constraint of quantitative geological knowledge, a series of more accurate sedimentary facies distribution figures were mapped by the comparison of microfacies between wells. Second, combining the advantages of deterministic modeling and stochastic modeling methods, facies model was established by using the multi-step facies modeling method. Compared with conventional sedimentary facies modeling, the facies model can better reflect the distribution of sedimentary facies and the reservoir heterogeneity both horizontal and vertical. Finally, under the control of the facies model and production dynamics, the effective reservoir was simulated randomly. Facies model was mainly used to control the boundary and direction of the effective reservoir, and the well drainage radius obtained from production dynamic analysis was used to limit the distribution size of effective reservoir. By synthesizing the advantages of traditional modeling methods, the accuracy of the model can be improved significantly under the constraints of dynamic and static. Based on this model, the history matching coincidence rate is improved to 52.4%, which indicates that the new method can model the actual situation of the reservoir well.