Application of Passive Seismic to Minimize Subsurface Uncertainties in Exploration, A Case History Selong & Akatara Prospects, Jambi



Selong and Akatara Prospects that divided by faults are located at Lemang Exploration block, Jambi sub-basin, South Sumatera
Basin adjacent to Jabung Block. 2D seismic data and several existing exploration wells become the main data for geological
interpretation.  The application of the Passive Seismic phenomenon is an opportunity for a direct hydrocarbon exploration and use to minimize subsurface uncertainties. The technique has already  been successfully applied as reconnaissance tool and complementary method to the existing geophysical data,especially to validate presence of the hydrocarbon in Selong and Akatara prospects, and minimize the drilling risk of Selong-1 and Akatara-1 proposed wells. Passive Seismic acquisition was conducted in 2011. The calibrated measurement has been done to get the amplitude spectrum signature of several wells condition (gas, oil and dry). These spectrums are usedhave been used to determine frequency value cutoff and appliedto specify frequency anomaly from all the measurements. 17 measurements points are interpreted as various possibilities in presence of hydrocarbon and indicated mainly in Talang Akar Formation. Frequency anomalous of 2-6 Hz has average amplitude range value of 20 – 30 x 10-5 at Selong-1 and 20 x 10-5 at Akatara-1. According to calibration result, these proposed wells are feasible to be drilled. The frequency anomaly from other points near Selong-1 and Akatara-1 would be useful to support Selong and Akatara delineation prospects. Selong-1 drilling campaign was completed on December 2012 and delivered 790 BOPD from DST in LTAF interval and 16.8 MMSCFDwet gas from Upper Talang Akar(32/64” choke size), while Akatara-1 was completed with encouraging DST result of 11,02 MMCFD and 379 BCPD from UTAF (48/64” choke size) and oil from LTAF interval but formation damage.

Keywords: Exploration, Passive Seismic, and Discovery.


Authors : A. Rahman, L. Fransisco