|APPRAISAL OF THE FRAM DISCOVERY, UK CENTRAL NORTH SEA - REDUCING SUBSURFACE UNCERTAINTY IN A COMPLEX TURBIDITE RESERVOIR|
|Field Developments and Case Studies|
1Shell UK Limited
The drilling of exploration well 29/3-1 in 1969 resulted in one of the first gas discoveries in the UK Central North Sea for the Shell/Esso Joint Venture. The Fram discovery, located in Blocks 29/3c and 29/8a, comprised gas-condensate within Palaeocene age deep marine turbidite sandstones trapped within a 4-way dip closure around a pierced salt diapir.
At the time, Fram was considered to be uneconomic due to the complex structural and stratigraphic nature of the discovery, concerns over reservoir quality and compartmentalisation, the relatively small in-place volumes by comparison with other contemporary discoveries and the comparatively higher market value of oil and lack of nearby gas processing and export infrastructure.
The Fram discovery was later appraised in 1999 by well 29/3a-6. Although it failed to definitively establish the field fluid contacts, it was successfully DST production tested at a rate of 18.6 MMscf/d of gas and 1473 bpd condensate. Despite the encouraging results from the 29/3a-6 appraisal well, significant uncertainty remained with the reservoir thickness and N/G distribution, hydrocarbon saturations and fluid contact depth, resulting in a wide range of both in-place and recoverable volume estimates.
In 2007 and 2008 the Joint Venture undertook a re-evaluation of the Fram discovery, including reservoir characterisation studies, 3D seismic interpretation, AVO amplitude analysis and inversion, petrophysical analysis and integrated 3D static and dynamic reservoir modelling. This detailed subsurface evaluation, in conjunction with subsea and facilities engineering studies the decision was taken to further appraise the discovery through the drilling of the 29/3c-8,8z appraisal wells in Q1 2009 by the Sedco 711 semi-sub rig.
Justified on a value-of-information (VOI) basis the objectives of the appraisal well were to reduce the key subsurface uncertainties with the overall aim of gathering critical data to allow the optimal field development concept to be selected for the field.
This presentation provides an overview of the Fram discovery, reservoir characterisation studies undertaken pre-drill and an overview of the results of the 29/3c-8,8z appraisal wells including the drilling, coring, wireline logging, DST well testing and the impact of the well results and post-well evaluation on the key subsurface uncertainties.
Field development planning for Fram is currently ongoing based on the results of the appraisal well and includes further subsurface evaluation, well and facilities engineering studies and an evaluation of surface host options. The development feasibility studies will culminate in the submission of a field development plan (FDP) for Fram subject to internal project approvals by Shell and Esso and project sanction by DECC.
Ahmed Helmi, Graeme Will, John Banks, Richard Moon, Alan McQueen and Samantha Large all at Shell U.K. Limited are all acknowledged for their contributions either directly to the presentation or for their work which forms the basis for much of the presentation material.
Brian Taylor, Ron Thomas and Russell Dedmon at ExxonMobil are acknowledged for their technical support during the planning, drilling, post-well evaluation and field development planning phases of the project.
Both Shell U.K. Limited and ExxonMobil are acknowledged and thanked for their permission to present.