Combined synchronous simulation of discrete and continuous variables under high net-to-gross ratio reservoir

Abstract

The Triassic TIII oil group in the Sangtamu oil field in the Tarim Basin is formed by multiple phases of channels cutting and superimposing one another, and the net-to-gross (NTG) ratio can exceed 90%. Strong heterogeneity exists in the spatial storage and seepage features of the sand body within the channel, causing significant uncertainty in the 3D geological modeling of the reservoir. In order to delicately characterize the reservoir heterogeneity within the channel in its various phases, this paper proposes a facies modeling method based on the deposition process. It includes a strategy of joint synchronous simulation of discrete facies and continuous physical property variables, fused trend body-constrained modeling established by the internal variation characteristics of single-phase channel sand, and an increase in channel phases to meet high NTG ratio reservoir conditions. In this process, the object-based method and sequential gaussian simulation method are both used to simulate step-by-step the 3D geological model of the facies and physical properties of different phase channels, respectively. The results show that 61 small sand bodies compose the results of the established 3D geological model, and the physical simulation results reflect the characteristics of physical changes inside the channel at different phases. The model has been verified by vacuate wells validation with a compliance rate of 97.4%, and the method reduces the model's multiple solutions and uncertainties while offering a new practical method for modeling complex fluvial facies reservoirs.