Publications

The Talangjimar Field is known as a mature oilfield and has been producing hydrocarbons for the Royal Dutch Company since its discovery in 1937. Geologically, it is located on the South Sumatra Basin and is part of the Limau – Pendopo NW–SE anticlinal system. The Talangjimar Field is identified as shallow gas and as a drilling hazard and potential reservoir. Bubble gas from many areas are exposed to the surface due to a minor fault on the seismic imaging. A blowout accident on TLJ-240 (development well) probably indicated the 30 Mmscf of shallow gas kicked when drilling operations took place in March 2013. The concern of this well is based on previous wells (TLJ-157, TLJ-237 TLJ-154, and TLJ-243) that have been drilled around TLJ-240. Integrated geology, geochemistry, and geophysical aspects have been conducted in detail, and consist of well log and seismic interpretation, flowpoint rapid response, and carbon isotope C-13 analysis, until reserve estimation. Subsurface aspects identify the origin, source, and lateral continuity of the shallow gas for further development of the Talangjimar Field. Shallow gas on the TLJ-240 well occurs from the sandstone layer of the Muara Enim Formation at 310 m in depth. The layer is characterized by fining upward, with an average thickness of 80 m. The geometry of the Sand ME1 layer is widespread throughout the Talangjimar Field with approximately 53,322 Mmscf. Carbon isotope C-13 analysis on the TLJ-157 well showed thermogenic type (–41.89). In addition, the measurement of bubble gas on the surface (Lower Explosive Limit) indicated a concentration of 5.0 (biogenic methane). This could be caused by the gas hydrate drying effect (confirmed by the overcooling effect of temperature gradient using Flowpoint Rapid Response), a mixture of biogenic and thermogenic gas in the Bernard Diagram (Bernard et al., 1978), and the biogenic component existing in the trap prior to the influx of thermogenic gas. From 2D seismic data, reactivation of Lembak Normal Fault (Pliocene-Pleistocene) may influence hydrocarbon accumulation in the shallow formation (Muara Enim Formation).