Fumiaki Matsuda¹, M. Saito¹, R. Iwahashi¹, H. Oda¹, Y. Tsuji¹
(1) Japan National Oil Corporation, Chiba-shi, Chiba, Japan

Abstract: Computer simulation of carbonate sedimentary and shallow diagenetic processes

A computer simulation model Facies-3D carbonate, developed by Japan National Oil Corporation, describes three-dimensional carbonate facies based on water depth and current velocity in conjunction with paleo-topography. The Facies-3D also describes porosity changes by meteoric diagenesis. Output data are facies, thickness, and porosity for each grid for simulation period. The following two simulation case studies were conducted.

In the Pleistocene Ryukyu Limestone in the Irabu Island, Southwest Japan, the shallow shelf coral limestone facies in the eastern part of the island changes into the deeper shelf rhodolith limestone facies in the western part. Enhancement of porosity was observed beneath subaerial exposure surfaces. Simulation parameters were extracted from not only the Ryukyu Limestone but also modern carbonates off the Irabu Island with the same depositional setting as the Ryukyu Limestone.

The Miocene Kais carbonate reservoirs in the eastern Walio field in Indonesia were subdivided into seven shallowing upward cycles. The back reef facies in the western and central area changes into the reef /fore reef facies in the eastern margin. Three shallowing upward cycles with porosity enhancement by meteoric diagenesis in the uppermost part of each cycle were simulated. Simulation parameters were extracted from the modern and Pleistocene carbonates in the Irabu Island area in conjunction with the Kais carbonates. Results of the two simulation case studies show that the Facies-3D carbonate model approximated to a high degree, the distributions of facies and porous intervals.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana