Solid Expandable Tubulars Slim Well Design and Isolate Zones for Brownfield Redevelopment in Oman
The Fahud water flood project is a major brownfield redevelopment project and a key component to PDO’s future production plan. Key value drivers for the successful project delivery are selecting the right recovery mechanisms for the target reservoirs and achieving low-cost well delivery through standardization and technological innovations. The pilot program, which consists of drilling 39 vertical wells in PDO’s Fahud field, commenced in April 2004 to gather data on four Natih target reservoirs. The data will be used to identify applicable recovery mechanisms for future field development. The recovery methods under review include the following: • Water flood • Gas-oil gravity drainage (GOGD) • Combination GOGD and water flood • Combination GOGD and depletion • Combination GOGD and gas flood Natih is a stacked layered reservoir. Natih A and C were developed by water floods in 1972-1980. These wells were unsuccessful due to early water breakthrough through fractures and karst parts of the reservoir. From 1984 to 1998 certain reservoir sections were developed by GOGD with 200+ development wells drilled. Since 1997, water flooding has been used to produce different zones in the Natih reservoir. Most of the drilling during this time consisted of horizontal wells with single or dual laterals. Although horizontal wells, in particular dual-lateral wells, provide excellent area data coverage, they also • Provide ambiguous production data from single zones. • Do not allow observation of reservoir behaviour in overand underlying zones. • Are costly to enter (hoist/coiled tubing). • Present a challenge to manage flow profiles. These issues led to the consideration of implementing alternative well designs. This paper will discuss the well planning, wellbore preparation and successful application of solid expandable tubular technology. These systems, combined with swelling elastomers, slim the well design and provide reliable isolation of the Natih sub-units to allow independent testing of the zones. The paper also presents the completion design planned for the test program and long term production.