Whilst faults in carbonate reservoirs often act as conduits for fluid flow, those within clastic reservoirs often act as flow barriers or baffles. Clastic reservoirs are composed of porous sedimentary host rocks, and cross-cutting faults are detrimental to flow because they offset the reservoir sequence and because they are characterised by low permeability fault rocks. Faulting can therefore restrict or prevent fluid flow resulting in reservoir compartmentalisation, but the precise extent of compartmentalisation is a function of the detailed distribution of fault offset within the fault zone. Since seismic surveys do not generally detect the detailed structure of fault zones, early identification of the presence of fault-related reservoir compartmentalisation and prediction of the associated impact of faults on fluid flow is a major challenge for the oil and gas industry.

The funding for this project is allowing research at the best outcrops of faults in the world. Researchers are examining faulted sedimentary sequences, quantifying aspects of fault zone structure, such as displacement partitioning (e.g. fault lenses and relays), normal drag and fault rock distributions. Consideration is being given to the potential impact of fault zone structure and related complexities on fluid flow. This study could therefore be of key importance in providing an improved understanding of subsurface reservoirs.

The QUAFF project will help define enhanced algorithms for fault property modelling and will investigate the frequency, nature and origin of critical geometric complexities, in different geological circumstances (e.g. sequences and deformation conditions). Quantitative parameterisation of fault zones from outcrop studies and from selected high quality seismic datasets will be complemented by numerical mechanical modelling using the innovative Discrete Element Method and by modelling flow in high resolution faulted volumes built using techniques developed by the Fault Analysis Group. Altogether, the project will provide insights into fault zone processes and structure, as well as defining criteria for including their effects in flow models.

The results from this study will be synthesised into a form that can be included in modelling workflows as well as in a more detailed on-line atlas/handbook documenting the structure of fault zones within siliciclastic sequences and outlining procedures for decision making on fault zone modelling issues. The production of this online handbook is of key importance in the implementation of the results from this study.

The most important outcome from this study will be the establishment of quantitative parameters for fault zone characteristics. When combined with flow and mechanical modelling, they will provide an improved basis for defining and modelling faults in reservoir models, which will help companies to optimise their field development and production processes. Earlier recognition of faults within a reservoir will reduce the risk of reservoir compartmentalisation problems in the future and will ultimately improve reservoir management decisions.