Improved Hydrocarbon Recovery in the United Kingdom Continental Shelf: Past, Present and Future

Abstract

Gas production from the UKCS commenced in 1967 and oil production in 1975. The North Sea area is now very much a mature province with the large fields in the Southern, Central and Northern North Sea producing at significantly below their early plateau production rates. Here the drive is to maximise the overall economic hydrocarbon recovery from the province, by making the best use of the infrastructure that has been built up to bring in new discoveries and improve recovery from the mature fields. New areas (deeper, harsher climate) are being opened up for exploration on the Atlantic Margin. This paper reviews the evolution of the mature areas of the UKCS, with case studies to illustrate the technical challenges that have been overcome. Over the years government and industry have expended considerable resources in developing innovative techniques for improved hydrocarbon recovery. These range from developments in the application of EOR processes to advances in drilling and reservoir management technology, including novel seismic techniques to identify new or bypassed oil. Technological advances have also unlocked reserves in heavy oils and in high-pressure high-temperature (HPHT) condensate fields, which were left undeveloped until the 1990s. Finally the potential for further exploitation and life extension of the UKCS as a significant hydrocarbon province will be reviewed. This will cover perceived technology gaps in opening up the new areas in deeper water, opportunities for redeveloping mature fields using new technology, combining IOR with carbon dioxide sequestration, and the need to drive down costs to be competitive in the international arena, while honouring environmental commitments. Introduction Oil exploration and production in the UK began onshore in the early part of the 20th century in the East Yorkshire, Lincolnshire and East Midlands areas. Later the interest extended to include the Dorset basin in the south of England. These were typically mechanical pump assisted fields producing a few 100 bbls/day/well. The first offshore gas field, West Sole in the Southern North Sea (SNS), was discovered in 1965 and brought onstream in 1967. Oil was first discovered in the Central North Sea (CNS) in 1969 and the first oilfield to come onstream was Argyll in 1975, followed soon after by the Forties field. The UK became self-sufficient in oil around 1980. Oil production on the UKCS has followed a typical exploitation path for a hydrocarbon producing area with large conventional fields being developed first and thereafter smaller fields utilising the infrastructure. It has now entered a third phase with the development of technically more difficult fields such as heavy oil fields and High Pressure High Temperature (HPHT) fields. A recent paper1 reviewed the UKCS heavy oil fields, so the primary focus of this paper is light oil fields. In the early days the industry used the term Enhanced Oil Recovery (EOR) to describe the deliberate injection of an alternative fluid to displace further oil from reservoir rock, over and above the standard pressure maintenance strategy (waterflooding for most UKCS oil fields). In the 1990s the industry began to use the term Improved Oil Recovery (IOR) to cover any operation (including the EOR techniques) that increased oil recovery above the figure that had been initially accepted as economically and technically exploitable. ‘Improved Hydrocarbon Recovery’ is a more general term that will cover all hydrocarbon types, including gas, but it is not commonly used as an acronym.

Recovery rates, enhanced oil recovery and technological limits

“…It originally contained approximately 2.4 × 10 8 m 3 (or 1.5 × 10 9 barrels) of oil (measured at surface conditions). Like most oilfields, one company operates the field (in this case BP with 85% equity) although it is co-owned by a number of other companies (in this case JX Nippon Exploration & Production (7.5%), Eni (UK) Ltd (5%) and Marubeni North Sea Ltd (2.5%)) [85][86][87][88].…”

Technical Challenges for Offshore Heavy Oil Field Developments

“…Discussions of current or planned IOR projects and technology requirements in the North Sea have already been presented. 5,12 In addition to the issue of what can be done offshore, the other issue that must be considered is implementation timing. Many studies have shown that various improved recovery processes are very sensitive to implementation timing, with recoveries being much better when the processes are implemented before a critical event such as before pressure falls below the bubble point or before water breakthrough occurs.…”

Can Producing Oil Store Carbon? Greenhouse Gas Footprint of CO2EOR, Offshore North Sea

“…In the United States where large volumes of CO 2 are readily available from natural sources, CO 2 has been injected as the primary recovery agent in these EOR operations. In Europe however the lack of availability of low cost CO 2 has meant that EOR operations have conventionally used water injection or methane gas injection, with currently no CO 2 EOR projects in an offshore environment. − With the prospect of Carbon Capture technology developing across the EU however, the required volumes of CO 2 may become available through anthropogenic sources . CO 2 EOR is regarded as an option for storing large volumes of this captured CO 2 with the added benefit of improving the recovery rate from depleted oil fields.…”