GAG Condensate 3D Geological Model Study

GAG gas condensate field is located within the Jabung block of South Sumatra in Indonesia, and is a smooth single west tilt incline structure with complicated faults. Main reservoir is sand-shale strata of the Lower Talang Akar formation of Tertiary Oligocene. As reservoir have complex faults, multiple sedimentary facies types, different CQ content, and complicated oil-gas-water relationship, it needs to be described comprehensively and detailedly, and analyze its character of distribution and variation in 2D and 3D. This study using Carbonsoft, Geomap, Geolog, Petrel, and guided by the Sequence stratigraphy, seismic exploration, geophysics, computer technology Theory, and combined with core, logging, master log, CQ content, DST, production data, etc., the Lower Talang Akar Formation is divided into Simpang, Lower Lumut, Middle Lumut and Upper Lumut sub-segments and 12 layers from bottom to top by well seismic calibration. Crossborehole sand and facies distribution is by methods of logging sedimentary facies and seismic attributes analysis. Main reservoirs of oil&gas accumulation are braided and distributary channels sand which is the deposition of braided river and braided delta. Fine logging interpretation model and reservoir parameters cut-off are built by studying four property relationships (lithology, electric, physical and hydrocarbon), the gas and oil porosity cut-off are respectively 10% and 12%. Based on oil-gas-water contact analysis, there are 65 oil-gas-water systems in GAG field that is subject to layer reservoir type with edge and bottom water. Stucture modeling is built under controlling of the seismic interpretat, faults modeling and well tops by intrapolated and extrapolated methods. Facies modeling is built using Sequential Indicator Simulation method with seismic attribute trend. Porosity modeling is based on the facies model using SGS method. Permeability modeling is based on the porosity model using collocated-cokriging. Building of 3D geological modeling is built. Based on above study results, three types favourable-region are forecasted. Above are provided with reliable base geological data for development program study of gas field.