Publications

Weight drop seismic acquisition has been shown to be an efficient and cost effective method of acquiring seismic data in frontier onshore areas where conventional seismic data (using dynamite) is difficult, expensive or takes a long time to acquire. In the Central Kalimantan Palangkaraya PSC, ConocoPhillips Indonesia acquired 126 kilometers of weight drop 2D seismic reflection data as part of their exploration program. In this area, the weight drop seismic is operationally superior to conventional to 2D since it was quick to acquire, relatively inexpensive and did not require permitting, extensive logistics or socialization studies. The results from this seismic data made it possible to de-risk the presence of the very thin Tertiary cover and map key stratigraphic events including the Pre-Tertiary basement. The weight drop survey design consisted of a single land geophone array of about 4 km. For each shot point station, 4-8 shots were taken (multiple thumps per shot point) and then summed together to enhance coherent signal and reduce random noise. An industry standard seismic processing workflow including Kirchhoff Pre Stack Time Migration was applied to process the data. The resulting seismic data produced excellent image quality to about 1 second TWT, proving to be better in many ways than the offset vintage seismic data in the same interval. Using this data, the acoustic basement is interpreted to be located at about 0.6 to 1 second TWT over Palangkaraya PSC. In addition, the seismic data made it possible to interpret Miocene Warukin, Oligocene Berai and Eocene Tanjung equivalent Formations across the block. The data also indicate the presence of buried hills interpreted to be Late Cretaceous granitic plutons and confirm recent structural movement on the block. The weight drop seismic proved to be an effective tool to quickly and efficiently map key areas of the Palangkaraya Block. This data has been instrumental for the depth and lithology prognosis in the Nangka-1 exploration well as well as casing point locations. In addition, this seismic data has made it possible to successfully distinguish different lithostratigraphic units in the area.