Sensitivity analysis of the impact of geological uncertainties on production forecasting in clastic hydrocarbon reservoirs

Duration - 01/10/00- 30/09/2004

Funding - European Union Fifth Framework Hydrocarbon Reservoir Programme: Energy Project ENK6 - 2000 - 00073. Funded in part by the European Community (69% of toal project funds). 100% Community funding for Univerisity partners and 50% community funding for non-university partners, with matching funds provided by the individual partners.

Co-ordinator -  Fault Analysis Group, UCD

Research Partners

Objectives and problems to be solved
The principal purposes of the project are: i) to quantify objectively the sensitivity of geological uncertainty on production forecasts, as a function of generic aspects of both the sedimentological architecture and faulted structure of clastic hydrocarbon reservoirs, and ii) to validate these results using real-case reservoir and production data. Because of the case-specific nature of existing production forecasting sensitivity studies, links between geological and production uncertainty cannot be made at present. These links are a prerequisite for early recognition of the most significant geological parameters influencing production forecasting uncertainty and are a necessary basis for establishing optimal methods for including geological uncertainty in reservoir modelling studies.

Description of the work
The project is a systematic assessment of uncertainty in reserves and production estimates within an objectively defined geological parameterisation encompassing the majority of European clastic oil reservoirs. A broad suite of shallow marine sedimentological reservoir types are indexed to continuously varying 3D anisotropy and heterogeneity levels. Structural complexity ranges from unfaulted to compartmentalised, and fault types from transmissive to sealing. Several geostatistical realisations each for the geologically diverse reservoir types covering the pre-defined parameter-space are up-scaled, faulted and simulated with an appropriate production strategy for an approximately 20 year period. The production and reserves uncertainty associated with geological uncertainty and methodological imprecision are quantified as a function of the underlying geology. Production results and recovery factors are combined with the geological and development plan parameters in a relational database, allowing the levels and origins of production uncertainty to be defined within the full parameter-space. Existing and new static and dynamic heterogeneity measures and dimensionless parameters are tested against production results for their ability to discriminate between geological architectures and to predict production characteristics. Sensitivity analyses, performed using reservoir and production data from three North Sea fields, combined with results from the large suite of geological models test our principal technical findings.

Expected results and exploitation plans
The expected project results are i) quantification of the relative and absolute influences of sedimentology, structure and up-scaling on reserves estimation and production forecasting from reservoirs with different sedimentological and structural properties, and ii) definition of geologically relevant dynamic and static heterogeneity measures and dimensionless groups for improved production forecasting in faulted clastic reservoirs. Project results will be tested and implemented through the consulting and software roles of the two service companies and through the practical implementation of the methods developed by the two oil company partners. We expect these results and methods to contribute towards an improvement in the planning and execution of geological reservoir modelling programs, and towards a reduction of the economic risk associated with field development.

Project Publications

Project Proposal

Contact: Tom Manzocchi
Tel: +353 1 716 2605

Project Web Site: for partners only