ANALISIS STRUKTUR BAWAH PERMUKAAN LAPANGAN “S” RIAU BERDASARKAN DATA GRAVITASI; SUBSURFACE STRUCTURAL ANALYSIS OF “S” FIELD AT RIAU BASED ON GRAVITY DATA

Irjayanto, Dedy, Sismanto

2015 | Disertasi | FMIPA

"S” field is the largest hydrocarbon producer that is located in the central Sumatera Basin, Indonesia. Analysis of subsurface structures are calculated by using gravity method. This method is based on the Earth’s gravitational field variations due to differences of mass density between rocks which are closely related to the subsurface geological structure. Data processing is done by reducing gravity data observation until complete Bouguer anomaly values obtained in the topography. The complete Bouguer anomaly was transformed into a horizontal plane based on Dampney method by the depth of mass is 550 m. The regional and residual anomalies were separated by using upward continuation methods with the height is 850 m. The rock density of subsurfaces were calculated by using Nettleton method. The results shows that the density is 2.4 g/cm3. 3D modeling was performed on regional anomaly by using Grablox and Bloxer software, while 2.5D modeling was performed on residual anomaly by using Geosoft software. The result of modeling showed that the subsurface geological structure of the research area is complex enough. It can be seen from the structures variation of rock at models. The Kelesa formation identified as a hydrocarbon reservoir rocks with a densitiy of 2.5 g/cm3 which located at a depth of 600 m.

Kata Kunci : Gravity Anomaly; Kelesa Formation; 2.5D and 3D Modelling