Publications

Application of acoustic impedance (AI) is commonly used as a lithology indicator using impedance separation between two lithologies or more. AI is usually used to identify lithology based on the distribution of the AI inversion results. Unfortunately, it does not work occasionally if some lithology has the same impedance value as another lithology. To improve the differentiation of lithology in impedance domain, we include gradient impedance (GI) in our analysis. The combination of acoustic impedance and gradient impedance (AIGI) into a crossplot will maximize the separation of lithology and fluid impedance using a projection line and rotation angle that can help AI to maximize lithology and fluid identification. The E3140 reservoir on the B6 well is a sandstone reservoir located in the crest of anticlinal structure in the Kutai Basin that contains hydrocarbon and was used to apply the AIGI method for hydrocarbon identification. The crossplot between AI and GR on B6 well shows an impedance overlap between the sand and shale. The AIGI crossplot result on the B6 well shows a good impedance population, with the hydrocarbon sand especially showing good separation at rotation angle of 15. The impedance characters of hydrocarbon sand at this angle are low AI, low GI, separately with another lithology and fluid. It means that the inversion method can be applied to generate the AIGI volume to identify the distribution of hydrocarbon sand. The AIGI inversion uses seismic angle stack, sonic logs (P and S) and density log. The final result of the AIGI inversion shows a good correlation between AI sections and hydrocarbon sand impedance on the E3140 reservoir. Based on this inversion result, the distribution of hydrocarbon sand probability tends to the south from B6 well. It means this method will give the advantage for lithology, reservoir delineation, and hydrocarbon potential identification. The main point of this paper is how to maximize seismic data combined with log data using different strategies to obtain the powerful reservoir information, especially in identifying hydrocarbons. Keywords: Seismic Inversion, AIGI Inversion, Sandstone Reservoir, Hydrocarbon Reservoir.