GOODWYN ‘A’ DRILLING FACILITIES

Abstract

The Drilling Facilities Package designed and developed by Atwood Oceanics Australia Pty. Ltd. for operation on Woodside Offshore Petroleum Pty. Ltd.'s Goodwyn 'A' Platform will break new ground in the development and application of offshore modular drilling rig technology when commencement of offshore drilling is achieved. These facilities are among the largest, specifically designed, offshore demountable drilling rigs in the world today.

Initially, Woodside performed sufficient engineering to determine a design specification for the Drilling Facilities which detailed the types of equipment necessary and the final performance characteristics required by the finished facility to drill the Goodwyn 'A' production wells.

Following award of the Drilling Facilities Contract to Atwood Oceanics in 1989, Woodside's role was essentially related to technical interface and contract administration management. The responsibility for the design, fabrication, commissioning and operation of the Drilling Facilities lay with Atwood Oceanics.

The Drilling Facilities consist of fifty-two (52) small modules, each weighing up to 105 tonne. These modules are assembled into three (3) major structural packages, these being the Drilling Support Facilities, weighing some 1300 tonne, the Sub-Base weighing 1100 tonne and the Derrick weighing 260 tonne. Total operating weight of the facilities will exceed 4500 tonne.

The modular design of these facilities was developed by Atwood Oceanics from previous modular rig design of relatively simple facilities and technical scope, up to the high capacity, technical complexity and flexibility in design demanded for operation on the Goodwyn 'A' Platform. Following the issue of the Cullen Report on the Piper Alpha Disaster, extensive control and monitoring safety systems were included in the design. These systems have had an adverse impact on the modular concept due to the large increase in electrical interfaces, however the modular concept remains sound and viable.

Modular rig design has allowed a Drilling Facility to be developed which has accrued savings in design, fabrication, fit-out, transport and installation and has resulted in reduced overall installed weight. These savings are real and demonstrable when compared with conventional large-module drilling rig packages of similar scope and complexity. Unlike its North Rankin 'A' development, Woodside elected to have the Drilling Facilities for Goodwyn 'A' designed, procured, fabricated and commissioned by an experienced drilling contractor, who will then operate and maintain the rig during the drilling phase (P.Scott et al., 1991). Woodside will realise substantial cost savings at the point when the facilities are installed and ready to drill. Further savings will accrue during drilling operations by allowing the drilling contractor more autonomy and responsibility (eg. maintenance of the complete drilling facilities will be by contractor personnel).

The relative ease of removal of the facilities and potential for re-use on other installations will generate additional significant cost benefits in the future.

The Drilling Facilities are state-of-the-art in their applied technology and are capable of year-round, self-contained operation for the drilling of highly deviated, long reach wells of up to 72° deviation from the vertical and up to 7000 m along hole depth.

This paper provides an overview of the design, fabrication, fit-out, onshore commissioning, transport and installation of the modules which comprise the Goodwyn 'A' Drilling Facilities, for which Atwood Oceanics were awarded a Commendation for a High Standard of Engineering Achievement at the Institution of Engineers, Australia 1992 Engineering Excellence Awards.