Shaanxi Key Laboratory of Exploration and Comprehensive Utilization of Mineral Resources, Xi'an 710054, China
2 State Key Laboratory of Continental Dynamics, Northwest University, Xi'an 710069, China
3 Department of Geology, Northwest University, Xi'an 710069, China
Three-dimensional geological modeling of reservoirs is not only the key factor for reservoir description and prediction of oil reserves but also an important means of quantitative characterization of reservoir geometry and heterogeneity in three dimensional spaces. The aim of this paper is to establish prediction model for sandstone classification and reservoir petrophysical properties.
Sand body prediction model was built by using stochastic simulation of discrete variables. Gauss model and sequential Gauss simulation method were selected to build porosity, permeability and oil saturation models.
The Chang 812 layer includes three sedimentary microfacies: distributary channel, inter-distributary bay and swamp. The dominant thickness of Chang 812 layer ranges from 15 to 20m. Three other classes of thickness (5-10 m, 10-15 m and 0-5 m) are subsequently less present. The major porosity of Chang 812 layer ranges from 5 to 15%, the major permeability ranges from 0.1 to 2×10-3μm2 and the major oil saturation ranges from 55 to 70%.
The Chang 812 layer of Triassic Yanchang Formation mainly formed in braided delta plain depositional environment. The truncated Gauss simulation of sand body was applied in simulation. The thickness of the sand body is relatively greater than the porosity, permeability and oil saturation values.
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