Well Drilling and Completion in the Seychelles
Authors: MacFarlane Timothy 
Published: December 2007

As a well-known holiday resort, the Seychelles economy depends on tourism and fishing. The activities associated with drilling a wildcat well in that environment are not considered compatible with the image of unspoiled nature. However, an operating company was contracted by the Seychelles National Oil Company to drill a subsea exploration well to a total vertical depth of 3,200 m at a location on Constant Bank, 200 km southeast of the main island of Mahe.

The planning and drilling of this well has been described in an earlier paper (SPE 35092). In SPE 35092, the authors explain how a service company was chosen to provide the integrated drilling services along with a contractor to provide the drillship and associated services. The successful outcome of the project management methods used and the efficiencies obtained from their approach are identified in SPE 35092. In this team, the service company's role and responsibilities required the project management and delivery of six services:Drilling-fluid material and engineeringCementing materials and engineeringDirectional surveyingWireline loggingMud loggingDrill bits

Introduction

From the beginning, the service company was aware that environmental protection was a prime issue in planning the project, the execution of the services, and the demobilization after completion of the job. The environment and other health and safety issues would be reviewed on completion of the job. These issues had to be addressed so that the other subcontracting businesses would be familiar with and would adhere to the health, safety, and environmental (HSE) management system used by the service company. The benefits of planning and open communication in the team assembled by the operating company are stressed in the SPE 33092 paper. The focus of this paper is the effective delivery of all services, where a structured approach to the management of risk was needed with a high level of awareness in the drilling services team. Failure in this respect could have been damaging to all the key players in the project.

After contributing to the team producing the Exploration and Production (E&P) forum's guidelines for the development of HSE management system, the service company adopted the management system. Using a common system in the field of HSE management is important in the oil and gas industry. With the growth of alliances and integrated services, it is vital at the operational level of the service and down the line that the systems and procedures are known and practiced by all staff, even if they do not work for the same organizations. Getting the jobs done requires a degree of interdependence and reliance on common factors. An HSE management system that provides a common framework is essential for defining the relationship and interface between the services and the drillship operation.

The operating company's strategy from the conceptual stages of planning had prepared an environmental-impact assessment with oil-spill prevention and waste-management plans. The findings from the initial assessment and findings were shared so that it was possible for the service company to consider how it could contribute in mitigating environmental risk. Two main areas applied in this planning phase:Choice of chemical substancesReview of options and proposals for supply and logistics support

During the early part of the project planning, it was possible to identify and specify drilling muds, cementing, and associated chemicals that were already proven in application and design. These chemicals had been determined to have a limited-to-negligible impact when released to the environment.