Abandonment of Subsea Wells in the Jabiru and Challis Fields

Fig. 2—Flowline-support-base/PGB/TGB/wellhead recovery on the post-rig ROV program.

This paper describes the preplanning and execution of Australia’s largest subsea well-abandonment campaign to date. The Jabiru and Challis fields are located in the Timor Sea, 640 km from Darwin, Australia. The fields consist of 13 subsea producers and six suspended or partially abandoned wells. The paper describes actual experience in a relatively uncommon operation in the industry and includes learnings that can be applied to future development planning.

Introduction

The Jabiru field was discovered in July 1983, with a total of 17 wells drilled to appraise and develop the structure. The field was developed with five subsea production wells tied back to a floating production, storage, and offtake (FPSO) facility. Water depth is approximately 120 m. In addition to the five subsea producers, there were three suspended or partially abandoned wells in the field.

The Challis and Cassini fields were discovered in October 1984 and June 1988, respectively. Cassini is a single-well satellite field, but for the purposes of this paper has been classified as part of the Challis field. In total, 18 wells were drilled to appraise and develop the structure. Production commenced in December 1989 and ceased in September 2010. The field was developed with eight subsea production wells tied back to an FPSO facility. Water depth is approximately 110 m. In addition to the eight subsea producers, there were three suspended or partially abandoned wells in the field.

It was originally intended to carry out the entire abandonment in one continuous program. However, time pressures required two phases. The four simplest wells were moved forward into a Phase 1 program and carried out at the beginning of the rig campaign. The remaining wells were abandoned in Phase 2 following the drilling of three exploration wells. A semisubmersible rig was deemed best for the project.

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 170523, “Abandonment of 19 Subsea Wells in the Jabiru and Challis Fields,” by Iain Clyne and Neil Jackson, PTTEP, prepared for the 2014 IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, Bangkok, Thailand, 25–27 August. The paper has not been peer reviewed.
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Abandonment of Subsea Wells in the Jabiru and Challis Fields

01 January 2015

Volume: 67 | Issue: 1

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