United Kingdom Oil and Gas Fields: 50th Anniversary Commemorative Volume
Geological Society Memoir 52 records the extraordinary journey of more than 50 years that has led to the development of some 458 oil and gas fields on the UK Continental Shelf (UKCS). It contains papers on almost 150 onshore and offshore fields in all of the UK's main petroliferous basins. These papers range from look-backs on some of the first-developed gas fields in the Southern North Sea, to papers on fields that have only just been brought into production or may still remain undeveloped, and includes two candidate CO2 sequestration projects.
These papers are intended to provide a consistent summary of the exploration, appraisal, development and production history of each field, leading to the current subsurface understanding which is described in greater detail. As such, the Memoir will be an enduring reference source for those exploring for, developing, producing hydrocarbons and sequestering CO2 on the UKCS in the coming decades. It encapsulates the petroleum industry's deep subsurface knowledge accrued over more than 50 years of exploration and production.
The Ensign Field, Blocks 48/14a, 48/15a and 48/15b, UK North Sea
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Published:October 30, 2020
Abstract
The Ensign Field is located in UK offshore licence Blocks 48/14a, 48/15a and 48/15b. The field is located 100 km east of the Humberside coast within the Sole Pit area of the Southern North Sea. The reservoir consists of sandstones of the Permian Rotliegend Group (Leman Sandstone Formation). Reservoir quality has been impacted by diagenesis during deep burial, whereby illitization has reduced permeability to sub-millidarcy scale. The field has been developed with two horizontal production wells, both completed with five hydraulic fracture stages. First gas from the field was achieved in 2012 via the Ensign normally unmanned installation and exported through the Lincolnshire Offshore Gas Gathering System. The field is compartmentalized by multiple regional-scale De Keyser fault zones. A heterogeneous natural fracture network exists with only a limited contribution to flow. Well performance and ultimate gas recovery have been lower than originally anticipated due to sub-optimal completions and a higher degree of compartmentalization than originally expected. The volume of gas that is connected to the wells is limited by low-offset faults, which have been identified by integrating long-term production data, and core, log and reprocessed seismic data. Production ceased in 2018 when the original export route was decommissioned.
- Atlantic Ocean
- data integration
- England
- Europe
- Great Britain
- history
- Humber Estuary
- Leman Sandstone Formation
- Lower Permian
- natural gas
- North Atlantic
- North Sea
- offshore
- oil and gas fields
- Paleozoic
- Permian
- petroleum
- production
- reserves
- stratigraphic traps
- traps
- United Kingdom
- Western Europe
- Rotliegend Group
- Silverpit Formation
- Ensign Field