document

Abstract

Between October 2000 and March 2001, Shell Expro, operating in the UK sector of the North Sea on behalf of Shell UK Limited and ExxonMobil UK Limited set three new world records in the application of expandable tubular technology, in 6" horizontal hole. Firstly, deployment and expansion of 4000 ft of 4" Expandable Sand Screens [ESS] in Brigantine B; surpassing the previous record tenfold. Secondly, deployment of 7000 ft of 4" ESS in Brigantine A and fully expanding 4920 ft of this screen. Thirdly, using the modified Compliant Rotary Expansion System [CRES] for full primary expansion of 60 ft of the 2150 ft ESS as Proof of Concept deployed in Brigantine C.

Brigantine is a small offshore gas field located some 100 miles northeast of the Bacton Gas Terminal in the UK Southern North Sea. The field contains three small hydrocarbon-bearing blocks, deemed individually uneconomical since their discovery in 1986. However, Deliver the Limit [DtL] concept, teamwork and application of three new technologies improved the economics of these accumulations and hence another success story for Shell Expro.

The three new technologies are listed below: -

1. The Brigantine Wells were drilled from two minimum facility Trident Platforms, which had won international recognition for their revolutionary design.

2. Geo-steering Technology was chosen to drill the long 6" horizontal sections to maximize reservoir connectivity and overcome the risk of compartmentalisation within the structures.

3. An integrated sand study carried out confirmed the need for downhole sand exclusion. The selected option was the Expandable Sand Screen. This novel approach, developed by Shell Technology with Weatherford Completion Systems (WCS) having a licence, was preferred to conventional methods, such as ‘Gravelpack’, due primarily to the larger bore it provides to maximise deliverability and the high potential to eliminate annular flow when fully expanded against the wellbore. However, ESS Technology was in its infancy and classified internally as ‘new unproven technology’.

The three wells were completed 32 days ahead of plan, achieved initial production of between 23% and 40% above expectation with total ESS added value of £13.5 million.

The following paper documents the decision to choose ESS as the preferred Sand Exclusion Technology, and the ESS delivery process from ‘unproven technology’ to deployment and expansion in the Brigantine Wells.

Brigantine Project Overview

The Brigantine Project produces gas from three small Rotliegend gas reservoirs to the Shell ExproTerminal at Bacton.

The first discovery, Brigantine A, was made in 1986 but was too small to justify development. 3D seismic shot in 1992 lead to the discovery of two more fields, B and C in 1997 and 1998 respectively, making the total development economically viable.