Facies-3D – a computer simulation model for reconstruction of sedimentary processes: a case study for Miocene carbonate reservoirs

Abstract

Abstract A computer simulation model for the reconstruction of sedimentary processes for carbonates and siliciclastics (Facies-3D) has been developed by Japan National Oil Corporation. The Facies-3D carbonate model describes carbonate facies in each grid in three dimensions based on water depth and current velocity in conjunction with estimated paleo-topography. The Facies-3D model also contains a module for evaluation of porosity changes in meteoric diagenetic environments. Output data at each step are facies, thickness, and porosity for each grid. The above-mentioned calculations are made at each step for the simulation period. A simulation case study was conducted using the depositional and diagenetic model of the Upper Miocene reefal carbonate reservoirs of the Kais Formation in the Walio Field in the Salawati Basin. Events R, Q, P, O, N, M-2, L-2, and K (in an ascending order), which were correlated with sequence boundaries of a third order or a higher order cycle, were recognized in the upper Kais Formation, which was subdivided into seven cycles (Q/R, P/Q, O/P, N/O, M-2/N, L-2/M-2 and K/L-2 cycles) by these events. A flooding event is present above a sequence boundary in each cycle, and is followed by a shallowing upward sequence. The Kais reef was drowned after the Event K, and was covered by Klasafet claystones. Kais reservoirs are interpreted to have been affected by meteoric diagenesis. The upper part of the O/P cycle, and N/O and N-2/N cycles were simulated in the case study. Results of the simulation show that the Facies-3D approximated to a high degree, the distribution of facies and occurrence of porous intervals.