Improved Hydrocarbon Recovery of a Lean Retrograde Gas Reservoir under Propane Injection

In most cases, retrograde gas reservoir in N Field which is located at the north of Malay Basin achieved 40-70% of recovery factor (RF) compared to dry gas reservoir, 80-90% of RF. Reservoir K, a lean retrograde gas reservoir of the N Field drained by Well 5 experience reduction in recovery (about 60% of RF) that is caused by a significant productivity loss, suspected due to condensate banking effect. Condensate banking phenomenon (observed as skin) around the perforation zone restrict the flow of gas after the flowing bottom hole pressure falls below the dew point pressure. Therefore, the reduction in gas Inflow Performance Relationship (IPR) limits the Estimated Ultimate Recovery (EUR) of Reservoir K that is produced from 2008 to 2013. Miscible propane stimulated injection is proposed at mid of 2012 (where skin start increasing) to improve the IPR, well deliverability and hence reservoir recovery. The retrograde gas reservoir model is integrated between E300, IPM PROSPER (well model) and IPM MBAL (reservoir model) software in reservoir performance prediction and forecasting study. Results show that there is 4% increment in gas recovery and 6% increment in condensate recovery after injection of propane to Reservoir K. There are about 4.2 million USD increment in revenue upon propane injection development. As conclusion, propane injection could minimize the condensate saturation that improves reservoir IPR and hydrocarbon recovery for both gas and condensate.