Affiliation:
1. PT. Pertamina Hulu Rokan
Abstract
Abstract
KILAU Field is a mature field that produced through primary recovery. Managing mature field to keep performance in existing wells has many challenges, especially in performing workover activity. With limited data to knowing current subsurface condition, it has a high level of uncertainty in achieving a success rate in workover activity.
In 2021, 10 workover programs were executed but success rate was only 30%. Five jobs were failed with no oil gain and others only delivered average 19 BOPD/well. Part of improvement process, it conducted lookback to find the root cause. The result observed that if the well was produced from A-1 sand, it would have failed. The type of well completion, both even produced with commingled completion or single completion were failed since producing the A-1 sand.
Detailed subsurface review as part of lookback process was carried out. It turns out that the A-1 sand, based on log data from new wells (which were drilled in Q3-2021 until Q1-2022), shown that the level of OWC (Oil water contact) has clearly raised, or the oil already drained. So, if the well was perforated or produced from A-1 sand, then the production of the well will experience high water (high WC).
Another analysis result obtained from information of new wells was a high oil opportunity in sand of A-3, A-5, & C-1. So, the new wells log data told the mystery of the current condition of the subsurface. This very meaningful information enabled revised strategy to optimize existing old wells.
This paper discusses how to utilize new wells data to improve success rate of doing workover job by integrating updated subsurface information and production data though well log correlation and mimicking the completion of high production wells. The improvement process has been carried out in 7 wells through workover programs, which targeted reservoir A-3, A-5, & C-1 and to avoid producing sand A-1. It was obtaining a 100% success ratio with total oil gain of 966 BOPD.