Publications

The MDC-1 exploration well, drilled in the MEDCOENERGI’s North Sumatra Block A during late 2012 and early 2013, discovered gas in a seismic supported the Early Miocene carbonate prospect. The well tested around 25 million cubic feet gas per day within an interval of the carbonate reservoir. Results at the MDC-1 well are different from the earlier exploration in the area tested only a few million cubic feet gas per day. Severe drilling fluid losses occurred within the interpreted carbonate reservoir interval during the drilling operation. These losses resulted in a premature TD before the entire reservoir interval was penetrated. Only about 100 feet of reservoir out of an expected 400 feet was encountered before the well was reaching a TD. As a result of total loss drilling, no cuttings samples were recovered to help substantiate detailed reservoir lithology and properties. However, seismic stratigraphic correlation from offset wells, along with petrophysical log analysis and testing results support the carbonate reservoir interpretation. Biostratigraphic data above obtained from the tested interval suggests that this carbonate reservoir is older than N6 age, thus we assign an age of N5-N4 (Early Miocene). Unlike other carbonate prospects in the Block A, where this carbonate is more typically deposited on a paleo-high, the carbonate interval at the MDC-1 appears to have been deposited off a paleo-high. Based on lithological descriptions from other exploration wells that penetrated this stratigraphic interval based on seismic correlations, the carbonate appears to have been deposited in a shelfal environment and had the potential to develop enhanced porosity during sea level drops (subaerial exposured). In addition to primary and/or secondary porosities and permeability enhancement inferred by the significant drilling losses, DST results suggest the reservoir also contains fractures. The MDC-1 exploration success highlights the likelihood of similar exploration opportunities in the Block A and may offer for a new play concept for the region.