Sandstone Facies Model Producing Hydrocarbon in Lower Keutapang, Paluh Tabuhan Timur Area, North Sumatra Basin, Indonesia

Sadjati, Ory, Ari Samodra, Rusalida Raguwanti, Pertamina Upstream, Jakarta, Indonesia

The Paluh Tabuhan Timur (PTT) area, North Sumatra Basin is located in the North West of the PTD (Paluh Tabuhan Dalam) field area with the Lower Keutapang Formation as the hydrocarbon producer. The discovery of 7 dry wells in this study area is important to know the lateral changes of stratigraphy and the facies model of the sandstone that producing hydrocarbon.

To understand the facies model of sandstone in Lower Keutapang Formation, the inter­esting layers with maximum amplitude were mapped. The 3D Seismic data in this area can be interpreted by using 3D interpretation software. The RMS amplitude and the instanta­neous frequency were used to detect the lateral changes in stratigraphy, focus the window on the specific sequence interval of interest. These seismic facies have been integration with the geological data to construct a depositional model for the field.

Two distinct facies could be identified on the seismic data, layer1 and layer 2 of the Lower Keutapang Formation are interpreted as the part of the sand distribution pattern from the complex of delta. Combined between high amplitude and low frequency correspond to the gas absorption effects within the reservoir.

In summary, this interpretation can give better play of hydrocarbon trapping in the Lower Keutapang Formation and a strategy for the next drilling. The presences of dry holes in the top structure and in the center area can be evaluated, and we can avoid another of dry holes with this interpretation.