Publications

The P field is a big sandstone dry-gas field in the Kangean PSC, located under and around Pagerungan Island, north of Bali. First production was in 1994 from a total of 14 wells: 6 onshore wells and 8 subsea wells (the first in Indonesia). Cumulative production until October 2016 is 1.2 tcf. Extensive production and reservoir pressure data was collected in the first 8 years of production, and traditional material balance techniques were applied to estimate gas-in-place and to investigate potential compartmentalization both laterally and vertically. These measurements were limited to the onshore wells since the offshore wells were designed as zero intervention wells, therefore the reservoir pressures were estimated from the well head pressures. In the later years, downhole reservoir pressure measurements became less common especially in the offshore wells due to failure of wellhead pressure meters and also water breakthrough that added significant uncertainty to conversion of wellhead pressures to bottomhole pressures. In order to fill in this gap in downhole data, the team applied modern rate transient analysis, which uses wellhead pressure and rate data to estimate downhole wellbore and reservoir pressures. This provided a fresh look at reservoir characterization and gas-in-place. The results from this new approach were compared to those from the existing traditional analysis. The team found that estimates of 1.4 TCF Gas in place from modern rate transient analysis was consistent with the static traditional approach. This insight increases confidence to apply rate transient analysis for production management amongst other Kangean gas fields, where regular downhole pressure data surveillance will not be practically feasible.