Abstract
A computer model “Facies-3D” has been developed to simulate the sediment distribution in deltaic and carbonate sedimentary environments. Three-dimentional sediment distribution is reconstructed on the basis of modeling of the sedimentary processes in these environments. In the simulation model, therefore, the emphasis is laid basically upon the understandings of the processes operating in the recent/ancient sedimentary environments and upon the numerical modeling of them.
A case study of the Pleistocene carbonates from the Ryukyu Group distributed in Irabu Island in the southwestern tip of Japan is presented in this paper. The cyclic sedimentation of coral reef-dominant and rhodolith-dominant limestones found in the group is considered to reflect the relative sea-level change induced by glacio-eustasy, ranging over tens of meters during the Quaternary time. Taking these geological backgrounds into account, a series of simulation studies was conducted. The results successfully approximate the actual facies distribution if the tilting of the basement toward the west-southwest is assumed as the tectonic subsidence data. Significant control of tectonism, together with eustasy, on carbonate sedimentation was revealed and evaluated quantitatively through the simulation study.
Another study has been conducted to simulate the sedimentary processes of the Miocene carbonate reservoir in the Walio Field in Indonesia. Preliminary results indicate that the model would be a useful tool for hydrocarbon exploration and exploitation, for understanding the geological settings and for reconstructing the sediment distribution in an area of interest, although several improvements are still necessary.
