Abstract

In an effort to reduce risk and improve the potential of drilling a successful well, Mobil Oil Indonesia applied leading edge technologies in the Makassar area to better quantify the prospect potential in the block. The geophysical methods that were found useful and are the focus of this paper include rock physics modeling, poststack seismic inversion and AVO (Amplitude Versus Offset). The application of these technologies in Makassar are unique to Indonesia in several respects. The unique aspects include deep water, a slope rather than shelf environment and structural complexity. Rock physics was used to quantify the effects of fluids on seismic responses, inversion was used to help verify the presence of reservoir rock and AVO was used to detect the presence of hydrocarbons at the Perintis-1 well location. Based on drilling, the inversion results correctly predicted the presence of low acustic impedance layers, where hydrocarbon bearing sands were encountered. AVO also correctly showed positive anomalies associated with the low acoustic impedance gas bearing reservoirs. At the first seismic anomaly, which had a positive AVO response, the depth predicted by the inversion was 1581 m. Drilling encountered a low acoustic impedance gas bearing sand at 1577 m. This result is in error by 4 m or within the error limits of the technique. When applied properly, in an integrated approach, the rock physics inversion and AVO technologies can extract additional useful information from available data that can help answer exploration questions. Work currently under way suggests that information gained from the application of rock physics, inversion and AVO will continue to contribute to future successes in the Makassar Block, and have the potential to help in other areas of Indonesia.