The Planning and Drilling of a Wildcat Well in the Republic of Seychelles by an Operator/Contractor/Integrated Services Alliance
- D.W. Marshall (Enterprise Oil Exploration Ltd.) | D.H. Heenan (CANMAR) | J.T. Reynolds (Halliburton Energy Services Inc.)
- Document ID
- Society of Petroleum Engineers
- SPE Drilling & Completion
- Publication Date
- December 1999
- Document Type
- Journal Paper
- 260 - 265
- 1999. Society of Petroleum Engineers
- 4.3.4 Scale, 7.2.5 Emergency Preparedness and Training, 7.3.3 Project Management, 4.5.10 Remotely Operated Vehicles, 1.6.1 Drilling Operation Management, 1.6.9 Coring, Fishing, 1.12.3 Mud logging / Surface Measurements, 1.6 Drilling Operations
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Constant Bank-1 is a 3,200 m (10,500 ft) wildcat well located in 50 m (164 ft) of water on a carbonate bank in the Republic of Seychelles, a group of tropical islands in the Indian Ocean. In this article we describe the development of a contracting philosophy for planning and executing the project through the formation of an alliance comprised of operator, drilling contractor, and integrated services company. We examine the unique environmental and logistical features of this project and describe how the alliance addressed these critical issues by using the strengths of the respective companies to reduce risks and ensure a cost-effective, successful operation. The logistical management of this rank wildcat well, which was situated in a remote location offering no practical means of resupply and no local resources, was further complicated by the technical difficulties associated with the well.
We conclude by discussing the different objectives of each company in conjunction with the overall project objectives and describing how these respective goals were aligned to the mutual needs of the alliance. The lessons learned by the alliance members are noted and recommendations are made for approaching similar operations.
Enterprise Oil Exploration Ltd., under a license agreement with the Seychelles National Oil Company, committed to drill a subsea exploration well to a total vertical depth of 3,200 m (10,500 ft). The well was located on Constant Bank, 200 km (124 mi) southeast of the main island of Mahe (Fig. 1). Enterprise was the sole licensee with 100% equity in the well.
In this article we describe the various factors that increased the risks and consequently the potential costs of drilling this well. A project management strategy involving integrating all the principal services into two distinct contract groups was devised for managing these risks and reducing costs. The lessons learned from applying this process to a high-risk remote-location single-string venture are noted, and recommendations are made for enhancing this form of management strategy in future drilling operations. In addition, the limitations of this type of approach are defined.
The principal factor governing the drilling project is the well location. Located in 50 m (164 ft) of water on a carbonate bank 200 km (124 mi) from the main island of Mahe and over 5,300 km (3,300 mi) from the Singapore supply base, the well had a number of significant risks associated with it. The Republic of Seychelles is one of the smallest countries in the world with a population of 70,000 people. The nation, which is located in the Western Indian Ocean, consists of several small granite islands totaling 280 km2 (175 mi2). The country is renowned for its unspoiled, pristine environment with the main sources of revenue being tourism and fishing, two businesses that are not usually considered compatible with oil exploration. This situation was complicated by Enterprise's high public exposure in the small country. Consequently, environmental protection was of paramount importance. Moreover, the country was devoid of any infrastructure capable of supporting an offshore exploration program, and the remote location of both the well and the islands themselves meant that any resupply would be very difficult unless performed by air.
Based on these geographical and ecological factors, Enterprise Oil decided to use a drillship. The vessel required for such a job needed to be capable of carrying all the equipment and materials for the well plus considerable contingency equipment. In addition to all the aforementioned challenges, the well was a rank wildcat, and given the difficulties of resupply, it would be necessary for the operator to carry substantial additional materials to allow for any unforeseen well problems. Further, the drillship required state-of-the-art minimum-discharge systems for meeting the onerous environmental restrictions imposed by the Seychelles authorities. Since the few drillships that satisfied these broad criteria were based in the Far East, Singapore was selected as the load-out and mobilization point early in the project planning.
Three wells had been previously drilled in the Seychelles in the mid-1980s, but limited well information was available. In addition, these three wells were located more than 300 km (190 mi) from the location for the current project, placing them in an entirely different geologic setting. Therefore, the comparative value of these wells was limited.
Defining and Implementing a Project Management Strategy
From the outset, we knew that we would have to plan the well for optimal management of various risks. The process would have to address the following interrelated points:
high operating costs.
The fundamental objective of the project was to complete the well as cost effectively and safely as possible.
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