Successfully Deploying & Retrieving 6,200ft of Perforating Guns Over Six Challenging HPHT Wells

Abstract

A six wells campaign to single-run perforate long completion intervals was undertaken in Brunei. The offshore field presented inherent challenges due to high pressure, temperature and long perforating intervals. A major challenge was to perforate underbalance to reduce potential permanent formation damage. The solution proposed for this high pressure and high temperature (HPHT) perforation was to use a high grade of coiled tubing (CT) with live-well gun deployment and retrieval system. The live-well gun deployment system utilizes perforating connections designed to support the gun weight, firing shock loads and ballistic transfer. The connection and break-out are facilitated via specialized rams in a dedicated BOP body in live well conditions. A 130-ksi yield strength CT string was engineered to withstand high tensile forces from running up to 1,150-ft of guns to depths of 18,000-ft in near vertical wells and provide a suitable safety margin when high collapse pressures were present. However, when perforating with long gun lengths, high dynamic shock loads will be experienced by the CT string. Thus, for all the wells, two software systems were used, traditional CT force analysis program and a gun force software for the short duration transients present during perforating. There were numerous continual improvements implemented during the duration of the campaign and one of them was maximizing the underbalance perforation up to 5,500-psi. Although such high underbalance was not a standard practice in the industry with CT, it was carried out after a comprehensive study and review to perform the operation safely and efficiently. There were no recordable safety issue throughout the two years campaign where more than 6,230-ft of guns were ran and live-well reverse deployed. The campaign was successful and operator expectations met. This paper outlines the characteristics of this campaign from the planning stage up to operational execution and efficiencies recorded over the six wells campaign. Well control mitigation practices and general contingencies will be detailed. This paper will act as a suitable reference for future operations.