PENGARUH STRUKTUR DAN TEKTONIK DALAM PREDIKSI POTENSI COALBED METHANE SEAM PANGADANG-A, DI LAPANGAN “DIPA”, CEKUNGAN SUMATERA SELATAN, KABUPATEN MUSI BANYUASIN, PROVINSI SUMATERA SELATAN

Abstract

The increasing of oil and gas and energy crisis nowadays has been causing the explorationist look for the new energy sources such as gas in shale and coal which more environmentally friendly. South Sumatera Basin is one of Indonesian Basin which has a large potency with 183 tcf. Methane gas is stored in natural fracture of coalbeds called cleat. Cleat was produced during coalification and tectonism process. The aim of this study is to evaluate the influence of structures and tectonism processes towards the CBM potency in an area. The CBM potency is done by evaluating several parameters, such as geologic structures which control the secondary permeability of coal formed by fracture, thickness, and depth of coal seam. Structural geology analysis is used to understand the primary orientation trends which configure geologic structures in study area to understand the cleat orientation. The research methods were done by desciptive and analysis methods. Descriptive method was done by describing secondary data which contain rock mass data, and analyzing method was done by analyzing subsurface data consist of seismic and wireline log. Those data were used to determine the sweetspot area and calculate gas in place in target zone of CBM. Based on geologic structure analysis, primary orientation trends which configure geologic structures is northeast-southwest, it is a Compression Phase of Miocene-Recent. This stress configured sincline, sinistral strike-slip fault, and normal faults in tensional phase. The interesting area of CBM exploration or sweetspot area located in the northeast area, with normal faults which control fracture permeability reach 12,22 mD, high thickness reach 14 – 18 feet (4,7 – 6 meter), and CBM target depth of < 6000 feet (2000 meter), and gas in place calculation reach 0,742 tcf. Completion techniques for CBM target in study area with relatively low permability are hydraulic fracturing completion and horizontal well with direction of well is relatively northeast-southwest which perpendicular with face cleat. Keywords : coalbed methane, secondary permeability, sweetspot area