Publications

The Lower and Middle Miocene sediments in the Central Sumatra Basin are comprised of several lithological units which are related laterally by facies changes. The Telisa Formation, which is recognized as top seal in the petroleum system of the Basin, was deposited in various depositional environments ranging from outer neritic to inter tidal in the Central Sumatra Basin contrary to the previous belief that it was deposited only as deep marine sediments. Tectonics in the Central Sumatra Basin during Lower and Middle Miocene, had continuous subsidence which was accompanied by the deposition of the Sihapas Group as a transgressive sequence of which the Telisa is mainly a shally facies. The Telisa Formation has a wide variety of vertical thicknesses. In the northern area of the basin, such as in the Pinang Field, the formation is 500 feet and thickens to the south, toward Lindai, up to 650 feet. As the Lower and Middle Miocene Basin filled, it was transgressed toward the north and northeastern directions. This opens the possibility of finding multiple sand depositional environments, ranging from deep marine to shallow marine sediments. Pertinent well logs, cores and seismic data were gathered from existing fields and were used to review their correlations. Then ensued a re-mapping of the sand and shale units in order to characterize the regional deposition of the Telisa using a sequence stratigraphic approach. The correlations were validated with biostratigraphic analyses. This depositional facies model provides a better prediction of the sandy facies distribution within the Telisa which potentially could add significant reserves and production.