Published: November 2000 | SEN 2000 “ Tieback Technology for the New Millennium” | November 28 – 29, 2000 | London, England
Abstract
Unstable oil prices over the past number of years have resulted in a slowdown of oil & gas field developments. Many of the marginal field developments are no longer viable at typical development budgets and consequently there is a need to continue to develop technology to meet the challenges whilst in parallel substantially reduce associated costs.
Since the mid 1990’s Granherne has been proactive in the drive to reduce costs of Normally Unmanned Installation (NUI) developments around the world in order to release marginal field developments and achieve facility cost reduction of 25-30%. A major element in the future oil and gas business is to find ways of releasing marginal field developments in the 10-25mmbls range characterised by small numbers of wells, Capex budgets of less than $100m and a limited field life of about 2-5 years. Here the potential reuse of facilities and pipelines becomes increasingly financially viable provided they are designed for ease of adaptation and reuse during their lifetime.
Wellstream, has always been proactive in providing cost effective solutions of flexible flowline and riser systems for field developments. Typically a flexible pipe is designed specifically to the operators requirements for a given field with a design life up to 25 or 30 years. However the field may cease production in as little as 5 years but more commonly in 10 to 15 years. In some areas of the world operators have taken advantage of this and consequently flexible pipe is relocated up to 7 times in its life in similar applications. Wellstream has assisted in evaluating the condition of the pipe structures after life of field has been reached.
Much focus has been on reducing subsea and NUI platform costs but the one remaining significant challenge is to find ways of reducing the costs of infield pipelines to host facilities. This area offers at least as much scope as that of the minimum facilities for cost reduction. One way forward is to look at the use of reelable flexible products which offer the greatest potential for reuse. Halliburton companies, Granherne and Wellstream are looking at the development of more cost effective solutions for the marginal field developments. One of the critical issues is the lack of operational data available to assess the remaining life in flexible pipes that have fulfilled the life of field requirement at their current location. Use of condition monitoring allows a service record to be maintained and ease of certification for reuse. Wellstream has been involved in the area of developing online monitoring systems since the early 1990’s and are also proactive participants in Joint Industry Programs in this area. The goal is to achieve a flexible pipeline solution which can be laid and recovered with a modular construction to allow a range of tieback distances to be accommodated. Using this approach it is possible to achieve a serial development of marginal fields around an existing host where both the surface NUI or subsea facilities and associated flowline/umbilical system can be relocated over sequential developments.
This paper discusses the significant potential for cost reduction and savings in this approach to marginal field developments. It addresses the requirement for a change in philosophy and thinking. It also requires collaborative support and co-operation from operators.
Authors:
Tuohy, J., Robinson, Dr. R.
Justin Tuohy | @pen 