Publications

C A-04 is a development well in the C field, drilled in 1971 with a cased-hole perforated completion and ESP. Initial production was from the Talang Akar Formation (TAF) and Baturaja Formation (BRF). In 1978, the BRF was isolated, and this well has produced only from the TAF sands 1B2, 1B3, and 2A. Cumulative oil production from this well is 10.48 MMBO. In 2009, the ESP failed. A workover job was performed to replace and up-size the ESP, as the Inflow Performance Relationship (IPR) suggested this well could produce more than 10,000 BFPD. Some time after the workover, the ESP failed again, as sand had buried the pump. In 2011, a heavy workover cut the free tubing, cleaned out sand from both inside and outside the work string, fished the string, re-perforated, frac-packed and installed an expandable sand screen (ESS). After one month of production, the sand returned. Plentiful sand was found inside the ESS, which could not be bailed, so we considered to plug and abandon and well. Later in 2011, more in-depth evaluation of the well showed it still had potential to recover an additional 640 MBO, so it was decided to reactivate the well by way of sidetrack drilling. The kick-off point was close to the old perforation interval, so the side-track would twin the existing productive zone. A 9-5/8" whip-stock and milling assembly were used to exit the casing, and a Gyro was used for orientation. An 8-½" hole was drilled to TD, and the well was completed. Before drill the sitetrack, a sand control study was performed, including critical rate calculation to prevent sand production, sieve analysis, sand distribution analysis and sand control design. Completion equipment selection was very important because the well was prone to losses as reservoir pressure had depleted to 500 psi and the well was prone to severe sand production. Based on the results of the study it was decided to use an open-hole completion system with stand-alone metal mesh screens and swell packers for zone isolation. The selection of open hole completion was done to minimize skin and the drawdown due to mud and cement invasion into the production zone. Mitigation against sand was to install 5-½" standalone metal mesh screens, which required additional equipment in the form of a 9-5/8" permanent packer, 7 "blank pipe and 7" swell packers. Metal mesh screen was selected because it is suitable for TAF sand which has medium grain size (from particle size distribution curve). Swell packers were used to isolate the oil zone from the underlying water zone. Hybrid swell packers were used because of the predicted high water cut of around 80%. From December 2011 to 31 April 2013, C A-04ST has experienced ESP replacement three times, with ESP run life between 95-145 days. During the first installation, sand fines were still produced and jammed the ESP. In the second installation, the ESP died due to electrical problems. In the third installation, the ESP has run smoothly and is capable of producing large fluid rates. The C A-04ST project has returned a very good NPV. Keywords : Open Hole , Sidetrack, Swell Packer, Sand Problem, Sand Control.