Drake F-76, In-Situ Abandonment of a High Arctic Offshore Completion and Facilities

Abstract

Abstract The Drake F-76 well was drilled in 1978 from an ice platform, in 55 m of water, offshore Melville Island, NWT, Canada. The well was completed as a prototype gas producer using a subsea production tree and subsea pipeline bundle to shore. Well testing and project feasibility testing were completed by 1979 and the project suspended. In 1993 a decision was made to abandon the well. An extensive program of research, planning, equipment refit and design was undertaken and completed over two years. Technical and environmental approvals were solicited and received from regulatory bodies. In the winter of 1995 - 1996 the wellhead was relocated and an ice platform constructed. A selection of purpose built and contracted equipment was mobilized to site and assembled. A subsea reconnection was completed, the wellhead was successfully function and pressure tested and the well subsequently re-entered and permanently plugged. The subsea tree and all associated flowline equipment were decommissioned and abandoned in-situ. This paper describes the subsea completion, the technical evaluation of the abandonment operation, and the methods used to successfully abandon the installation. FIGURE 1: Location of Drake F-76 project (Available in full paper) Introduction The Drake gas field is located on the east coast of the Sabine Peninsula, Melville Island, NWT as shown in Figure 1. The field, with approximately 5.7 tcf of proved and probable reserves is about 30 km in length and straddles the coastline with the reserves distributed almost equally between land based and offshore portions of the reservoir. The land-based portion of the field was explored and developed in conventional fashion in the early 1970s. While exploratory wells drilled from sea ice platforms had proven up the offshore reserves, there was a desire to develop and test production methods for this offshore gas. It was intended to show this gas could be delivered to production facilities for subsequent sale into the gas marketing projects then proposed for the early 1980s. In 1978, Panarctic Oils Ltd. successfully drilled, completed, and flow tested the Panarctic Hmstd et al. Drake F-76 well from a strengthened ice platform located approximately 1 km offshore Melville Island. The well was drilled to a depth of 1,128 m (KB) in water 54.9 m deep. The well was completed with a subsea production tree, two bundled 152 mm subsea flowlines to shore and gas processing and testing facilities onshore as shown in Figure 2. FIGURE 2: Drake Point facilities (Available in full paper) Remote wellhead control was provided from a shore-based control unit, through subsea control lines in the flowline bundles to a control module located on the wellhead. The Drake F-76 project was designed to demonstrate that offshore gas could be delivered into a land-based gathering system, through remotely operated subsea wells, despite the problems of sea ice, permafrost and generally challenging conditions. Although the project in itself was a success, no market for Arctic gas has been developed and the facilities have been dormant since 1978.