Publications

Sungai Gelam structure is one of the backbone brownfield structures supporting Jambi field oil and gas productions. Both Air Benakat and Talang Akar Formations which have been known as prolific reservoirs in South Sumatra Basin are the main producers in this field. There are total 26 wells in Sungai Gelam penetrate the Air Benakat Formation, some extend through the Talang Akar Formation. As part of a pressure maintenance strategy in 2017, a water injection S-24 well was drilled in the western flank of the Sungai Gelam structure. The main targeted sand was found shallower than expected, and later on produces 110 BOPD. Depth and sand distribution uncertainties from S-24 well drilling prompt re-evaluation of the field; geological model. New model shows much larger closure prolongs the western area of the field. It suggests potential new closure to be drained by a number of additional wells in the future, including a step-out deep well to prove the existence of Baturaja Formation as a new concept. The western expansion plan however has been problematic, because there is no valid velocity control as the only one checkshot data located in the eastern side of the field. Seismic datum and its velocity inconsistencies further degrade the depth conversion effort. In 2018, amid the known problems two wells have been drilled and indeed have depth discrepancies. The two wells however register higher formation pressure than the existing producing sands. The results may be subjected to new reservoir compartments which have not been characterized before. New development planning has been exercised with the newly acquired well data and fresh understanding of the uncertainty. Post mortem of the recent wells are reported as lessons learned to continue the undertaking of Sungai Gelam step-out drilling campaign and the future waterflood management.