Enhanced Coiled Tubing Improves Well Intervention Offshore Malaysia

The Angsi field is a significant priority in terms of oil and gas production for Petronas Carigali Sdn. Bhd., a subsidiary of Malaysia’s national oil company. Exploration in the field began in 1974, with first oil and gas production in 2001 and 2002 respectively. In 2004, Well A-33, which penetrated three pay zones, was drilled and completed with dual 3 1/2-in oil and gas production tubing. In mid-2008 the well ceased production due to low flow-tubing-head pressure. In 2009 and 2010 the string was again put onstream to assess its potential. Three well tests were carried out. The average gas rate obtained was less than 5 MMcf/d. Because of the production decline, it was decided to restore potential by adding perforations via coiled tubing. Adding perforations is challenging because of complexities such as on-depth perforation, depth accuracy of coiled tubing, and uncertainty of depth correlation prior to detonation.