Pemodelan geologi untuk karakterisasi reservoir karbonat formasi batu raja, lapangan Wintora, cekungan Sumatera Selatan
D aerah penelitian terletak di sebelah selatan kota Prabumulih, Cekungan Sumatera Selatan. Secara geografis daerah penelitian terletak pada 104° 10' 4.16" BT-104° 12' 53.49" BT dan 3° 50' 52.55" LS - 3° 54' 24.49" LS dengan luas dengan luas 19 . Target utama reservoarnya adalah Formasi Baturaja dengan litologi penyusunnya adalah batugamping. Penelitian bertujuan mengetahui distribusi fasies, rock type dan distribusi properti reservoar. Metoda penelitian dilakukan degan mengintegrasikan data seismik, core, dan well log untuk didistribusikan menjadi 3D model: fasies, rock type, porositas, permeabilitas, dan saturasi air menggunakan metoda geostatistik. Atribute seismik membantu dalam penyebaran fasies dan porositas, dengan menggunakan Akustik Impedansi. Fasies didefinisikan sebagai fasies reef, near reef, dan inner lagoon yang terendapkan pada middle shelf dengan tipe isolated platform. Besaran properti reservoar dipengaruhi oleh proses diagenesa, yaitu berupa pelarutan, dimana semakin keatas banyak mengandung organik karbonat dan membentuk porositas sekunder yanglebih tinggi. Rock type dikelompokkan berdasarkan nilai densitas dan porositasberdasarkan metoda Lucia. Rock type ini dibagi menjadi rock type baik, buruk dansedang yang digunakan dalam perhitungan saturasi air dan permeabilitas. Rocktype yang baik memiliki nilai densitas, porositas, dan permeabilitas tinggi yangberasosiasi dengan fasies reef dan near reef. Kemudian saturasi air dihitungmenggunakan J-function berdasarkan rock type.
T he study area is located in the south Sumatera Basin at south Prabumulih, south Sumatera Basin. Geographically, the area is located in coordinate 104° 10' 4.16" to 104° 12' 53.49" Meridian and -3° 50' 52.55" to -3° 54' 24.49" Equator. Width of area is about 19 The interested reservoir is Baturaja Formation as reservoir that be limestone. The research purposes is to know facies, rock type, reservoir property distributions. The research method is done by integrating seismic, core, and well log data for distributing to be 3D models; facies, rock type, porosity, permeability, and water saturation bygeostatistical method. Seismic attribute is as trend for facies and porosity distributions by using acoustic impedance. Facies is defined such as: reef, near reef, and inner lagoon that they are deposited at middle shelf in isolated platform. Reservoir property value is affected by diagenesa process, such as dissolution. Vertically upward the carbonate consist of organic carbonate and generated more secondary porosity. Rock type is grouped according to porosity and density by Lucia method. The rock type is classificated as following: good, middle, and poor qualities. The good rock type have high density, porosity, and permeability which associated with facies of reef and near reef. They are used in calculating water saturation and permeability. Subsequently, water saturation is determined by J-function method based on rock types.