Abstract
The Enfield development was the first oil field to be put into production in the Greater Enfield Area. These fields lie in deep water off the North West Cape area of Western Australia. Operated by Woodside on behalf of the Enfield Joint Venture, this was the first oil field development for Woodside requiring horizontal open hole completions with sand control. The challenge for this project was to deliver early oil production from a low well count with wells producing from an unconsolidated and faulted formation containing shale. The remote location posed an additional challenge for the development.
The initial development consisted of 5 producers, 6 water injectors and 2 gas disposal wells, with subsequent campaigns adding 3 production well sidetracks, a new producer and a water injector to the total reservoir penetrations. Both low angle deviated and horizontal wells have been completed. A number of different sand face completion types have been used over the initial phases of the Enfield development. Both water and oil based reservoir drilling fluids were used for this field development. This paper will review the evolution of the design used for the production wells.
Initial horizontal gravel packs were done with a circulating gravel placement technique using brine as the carrier fluid. Subsequently a single barrier sand control technique using expandable screens alone to control sand production was installed. Due to difficulties encountered with these approaches, completion designs reverted to gravel packing. However at this second attempt at gravel packing, a gel slurry packing technique using screen fitted with alternative paths for gravel placement was successfully used.
Whilst deep water open hole gravel packing was a new challenge for Woodside; due to the high productions rates achievable, only a limited number of wells were required for the field development. This implied both a very short learning curve, and a need to react rapidly to any difficulties encountered. This paper reviews the performance of these completions and the drivers for the evolution of the completion technology during the field development. This has provided a pathway for future completions in the development of similar reservoirs in the portfolio.
