Petroleum prospect analysis and new gas horizon detection at Fenchuganj Gas Field in the Surma Basin, Bangladesh: An application of sequence stratigraphic concept

Abstract

Abstract The biggest question in the present gas crisis is where to find gas in the onshore of Bangladesh. The exploration strategies so far taken over the Surma Basin give importance only to the structural traps (fault-bounded anticlines). Already most of the anticlinal structures have been drilled and now they are at nearly matured stage. Therefore, most sustainable solutions are revising all the gas fields with sequence stratigraphic concept and find out the hidden possibilities of stratigraphic traps that are being still neglected. In this paper, interpretation of available logs and seismic has revealed the sequence stratigraphic concept of the reservoirs as well as new exploration prospect in the portion of Fenchuganj Gas field. The study reveals seven prospective reservoir zones, PR-1 to PR-7 from older to younger in studied area. Prospective reservoir PR-1 and PR-4 are belong to highstand system tract whereas PR-2, PR-3 and PR-5 are in the lowstand system tract. Upper two reservoirs PR-6 and PR-7 are located within the sand facies of transgressive system tract. Analysis of seismic attribute and log response has yield a prospective future drilling target in the erosional remnant of a highstand system tract truncated against lowstand-incised valley and capped by transgressive shale. Based on the seismic amplitude (bright spot), two exploration prospects were also identified in the stratigraphic traps located on the flank of the Fenchuganj structure. One is highstand sand truncated against shale-filled valley and the other one is lowstand channel sand sealed by transgressive shale, which demand further investigation. Thus, this approach provides new insights for local and international oil companies that there are huge possibilities of finding stratigraphic traps in the tidal deposits of regressive shelves that are yet to be well documented.