Answering The Challenges For Improving Gas And Condensate Production In Mature Field. Case Study: Wet Gas Limited Reservoir

Abstract

Strong hydrocarbon demand and rise in oil prices have challenged petroleum industry to increase production. Pertamina EP as a giant hydrocarbon producer in Indonesia was one amongst hundred that was challenged to improve production through the mature assets reactivation.
Anya Field is one of the mature fields operated by Pertamina EP Asset 2, located at 25 km North-West of Prabumulih, South Sumatera. It was discovered in March 1941 from Sandstone Talang Akar Formation (TAF) producing gas and condensate. Peak production was achieved in December 1984 with 3189 BOPD of condensates and 80 MMSCFD of gas from 28 production wells. Afterwards, production decline was continued until December 2016 with 17 BOPD from 1 production well. Currently 47 wells are idle in Anya Field.
The challenges were on the reservoir boundary and uncertainties, the absence of flow line installation due to suspended wells and no gas compressor installation at gathering station. Because of this, wellhead pressure must be within 400-450 psi that was higher than pipeline pressure.
Steps to attain production enhancement was including potential reserves by layer identification based on geological and reservoir study, well selection for workover candidates, data acquisition including welltest, hydrocarbon volume estimation using Material Balance Model, field life estimation and economic evaluation.
The study has positive outcome in production and economic aspects. Therefore, production line was installed from well to gas gathering station. Production and pressure monitoring were periodically performed to evaluate and update Material Balance Model. As the result, Anya Field production was increased by 537 BOPD and 7.5 MMSCFD from 6 production wells. In addition, new reservoir was discovered for future drilling opportunity.