Successful Deployment of a Purpose-Built Rig on Multi-Well Platform in a Swamp Location for Concurrent Drilling and Production
Authors: Adekuajo Charles Olusegun , Madu Theophilus Chuckwuemeka , Faga Abraham Tativ 
Published: December 2007

The ‘lean and green’ operating philosophy adopted for a field development plan in a Nigeria major E &P company in 1996 focuses on spending less and leaving the environment with minimal impact. Previously, the company cuts an average of 0.7 hectares of vegetation per well in the swamp to create drilling locations. Entry to a pre-installed multi well platform in a dredged drilling location by a specially built rig in October 1999 marked the inception, industry-wide, of platform drilling in the swamp.

The successful deployment of this custom made rig to a six-well platform, each well spaced 2.5 meters (8 feet) apart, and the hooking up of the first well in the cluster Monday, 27 November 2000, ushered in the first oil from a multi-well platform operating in a concurrent drilling and production mode from an inland water location. This is indeed company and industry-wide achievement. Since then, five more wells have been drilled and completed from the same location, thereby saving over $2.0m from location preparation and avoiding multiple rig moves. The use of one single location to drill six wells significantly reduced the footprints on the environment in line with the company's mission in that respect.

This paper presents the planning and execution of drilling, completion and production in a cluster location concurrently using the purpose-built rig during a recent campaign.

Background:

During the preparation of the field development plan (FDP) that ushered in the project there was recognition of the financial losses suffered by the company due to high rate of host community disturbances, particularly during rig moves in the inland waterways. There was also the need to conserve the environment in the swamp by reducing the land take for drilling activities. At that time the technology for drilling in multi-well platforms in inland water locations, which is however normal in offshore environment, was non-existent. For well engineering department and the company, this was a big challenge. This led to initiating the project, which has resulted in the custom design and construction of the new rig. The rig, commissioned on 1st July 1999 in New Iberia, USA moved to location in Nigeria in October 1999. However, due to community problems, the first well in the cluster was only spudded in July 2000. The last of the six wells was completed for production on March 21, 2001. The cumulative production from the five wells hooked-up while the 6th well was being prepared for handover was some 900,000 bbls. This translates to accelerated revenue of $27m at the then prevailing oil price. Apart from this, there was a saving of about $1.5m from location dredging and another $0.5m saving on rig moves. Before commencement of concurrent drilling and production operations on the jacket, a Hazards and Effects Management Process (HEMP) was carried out to reduce the risks of the operation to as low as reasonably practicable (ALARP). The wells were planned and drilled to reduce chances of collision. The hookup of the wells on the cluster posed some problems as the cluster was congested. However, the whole project was very successful and has proved to be the way forward for future inland water drilling campaign efforts.