Publications

All of the eleven (11) producing oil fields in P.T. Stanvacs Central Sumatra Kampar Block are structural traps with, in some cases, associated fault dependent closure. However, in the Parum Field the transgressive Lakat Formation (24 MYBP sequence) sands onlap the irregular pre-existing topography of the Kelesa Formation (29 MYBP sequence) and depositional pinchouts are the major trapping mechanism for most of the oil. Structurally trapped oil in the Tualang Formation constitutes only a small proportion of the reserves.Parum is a northwest-southeast oriented anticlinal feature located on the high side of a major NW-SE trending reverse fault. The wildcat well was located to test the crest of what at the time was being interpreted as. clearly a structural play. However, this first well encountered only five feet of net oil sand. It was decided to continue to assess the fields potential by drilling on the flanks of the structure anticipating the development of thicker potential reservoir sands. After the drilling of the early wells it became quite apparent that the development effort had to be focused more from a stratigraphic point of view. Subsequent drilling efforts have now proven that oil exists in eight separate reservoirs.The fluvial-tidal dominated shoreline systems of the Late Oligocene Early Miocene Lakat Formation have been divided into two groups (L1 to L4 and L5 and below) based on lithologic descriptions and log criteria. Variations in dipmeter plot data, changes in the resistivity of the shale zones, variations in porosiiy values and an abrupt change in the sonic transit time values are some of the log observed criteria which support the subdivision. Data which have been acquired during the early development stage of the field have been studied and a geologic model developed. This paper will present the reservoir, source and seal framework as well as the stratigraphy and depositional environments as interpreted from seismic, well log and core data.