Estimasi Cadangan Hidrokarbon Berbasis Analisis Petrofisika dan Static Reservoir Modelling di Lapangan Koma, Formasi Talang Akar, Subcekungan Palembang Selatan

Putri Septyaningsih, Dr. Ir. T. Marwan Irnaka, S.Si., M.Sc.; Ir. M. Destrayuda Trisna, S.T., M.Eng.

2026 | Skripsi | GEOFISIKA

Peningkatan konsumsi energi nasional serta penurunan produksi minyak nasional rata-rata 3,5% per tahun sejak 2010 mendorong kebutuhan pengembangan cadangan hidrokarbon pada cekungan sedimen yang masih prospektif. Penelitian ini dilakukan di Lapangan Koma, Formasi Talang Akar, Subcekungan Palembang Selatan, yang telah terbukti mengandung hidrokarbon namun masih memiliki ketidakpastian terkait distribusi reservoir dan karakteristik petrofisikanya. Penelitian ini bertujuan untuk menentukan karakteristik petrofisika, memodelkan distribusi spasial fasies dan properti petrofisika secara tiga dimensi, serta menghitung estimasi cadangan hidrokarbon. Analisis menggunakan data empat sumur dan seismik 3D PSTM. Petrofisika dihitung secara deterministik meliputi volume shale (metode linier), porositas efektif (metode densitas-neutron), dan saturasi air (Persamaan Indonesia), dengan cut-off  Vsh ? 0,40, porositas ? 0,10, dan Sw ? 0,55. Static reservoir modelling tiga dimensi dilakukan menggunakan Sequential Indicator Simulation (SIS) untuk fasies dan Sequential Gaussian Simulation (SGS) untuk properti petrofisika, dikontrol oleh atribut RMS amplitudo seismik. Estimasi cadangan dihitung secara probabilistik melalui tiga skenario batas kontak fluida, yaitu low case, base case, dan high case. Hasil menunjukkan kualitas reservoir dengan rata-rata porositas efektif 14,36%, saturasi air 40%, dan net to gross 18,28%. Fasies batupasir berkembang berarah NE–SW dengan kualitas terbaik pada bagian interval bawah formasi. Estimasi cadangan menghasilkan STOIIP secara probabilistik P90 19,58 MMSTB, P50 48,24 MMSTB, dan P10 79,93 MMSTB.

The increase in national energy consumption and the decline in national oil production by an average of 3.5% per year since 2010 have driven the need to develop hydrocarbon reserves in sedimentary basins that remain prospective. This study was conducted at the Koma Field, Talang Akar Formation, South Palembang Subbasin, which has been proven to contain hydrocarbons but still has uncertainties regarding reservoir distribution and petrophysical characteristics. The objective of this study is to determine petrophysical characteristics, model the three-dimensional spatial distribution of facies and petrophysical properties, and estimate hydrocarbon reserves. The analysis utilized data from four wells and 3D PSTM seismic data. Deterministic petrophysical calculations included shale volume (linear method), effective porosity (neutron Densitas method), and water saturation (Indonesian Equation), with cut-off values of Vsh ? 0,40, porosity ? 0,10, and Sw ? 0,55. Three-dimensional static modeling was performed using Sequential Indicator Simulation (SIS) for facies and Sequential Gaussian Simulation (SGS) for petrophysical properties, controlled by the RMS seismic amplitude attribute. Reserve estimates were calculated probabilistically using three fluid contact boundary scenarios: low case, base case, and high case. The results indicate reservoir quality with an average effective porosity of 14,36%, water saturation of 40%, and a net-to-gross ratio of 18,28%. The sandstone facies extends in a NE–SW direction, with the best quality observed in the lower interval of the formation. The reserve estimates yield probabilistic STOIIP values of P90 19,58 MMSTB, P50 48,24 MMSTB, and P10 79,93 MMSTB.

Kata Kunci : Formasi Talang Akar, petrofisika, sequential indicator simulation, sequential gaussian simulation, static reservoir modelling, estimasi cadangan