Publications

Lawang Field is a field that has been on waterflood since 1974 - or as early as 3 years after its first POP- thus categorized as a mature waterflooded field. Finding remaining oil locations is particularly challenging. A new technique is needed to confirm areas with oil potential to support workover jobs in Asset Optimization Team. One reservoir management surveillance in oil industry is by fingerprinting. Fingerprinting analysis has been widely used to determine oil allocation among sands in commingled completion. In Lawang Field, this technique was one key factor of success in low quality Abu sand Waterflood project initiated back in 2017 and any other workover jobs since 2018. It has the ability to differentiate oil composition from different reservoirs, depending on oil characteristics. The surveillance involves lab analysis using gas chromatography to analyse the hydrocarbon chemistry by separating and analysing compounds that can be vaporized without decomposition. By understanding the reservoir characteristics and where the oil is potentially produced from, ES or PE can determine oil characteristics from each reservoir (called end-member). The gas chromatography analysis is conducted for each end-member and followed by the analysis for mixtures from two end-members (25:75, 50:50, 75:25). Using Malcom software, the oil samples from targeted wells (unknown oil allocation) are being analysed and compared with the end-member results to determine the oil allocation The advantage of oil fingerprinting technique over conventional production logging methods are cost-effective, reliable and no well intervention needed. The analysis is also applicable for high or low-rate production. However, some challenges may be faced especially for highly commingled wells due to software limitation. This technique has successfully supported a number of workover programs in Lawang Field such as size up, new perforations, reactivation, and fracturing. 30-day-oil gain from those programs has been 680 BOPD from 11 wells.