Duration - 01/06/99- 31/05/2001
Funding - Multi-company project supported by
Co-ordinator - ITF (formerly CMPT).
Research Partners
This project aims to solve one aspect of a recurring problem in reservoir flow modelling - how to incorporate the effects of sub-seismic structures? We intend to provide a method for determining the flow effects of sub-seismic relay zones, or fault discontinuities. As seismic resolution has improved over the years, fault surfaces/traces which previously appeared continuous have been seen to be discontinuous (Fig.1), with breaks at relays, or overlaps, which previously were sub-resolution. Evidently, no matter how good theseismic resolution, there are always likely to be discontinuities in fault surfaces which are sub-seismic resolution.
A new opportunity to solve this problem has come about throughthe recent development of commercial software (PFC3D - Particle Flow Code in Three Dimensions) which provides sufficiently realistic fracture simulation to enable 3D modelling of fault growth. Crucially, as fault relays occur on all scales the modelling results can be validated by the seismically imaged structures, allowing some confidence to be placed in the predicted sub-resolution structures. The project will be carried out by a new partnership between the Fault Analysis Group, with experience of analysing fault relays and of flow simulation problems, and George Tuckwell, a new staff member in liverpool Earth Sciences with expertise in applying numerical modelling techniques to the rock mechanics of geological problems.
This JIP will provide a method for assessing the likely impact of sub-resolution fault discontinuities on the risking of fault seal prediction and on estimates of effective permeabilities of faults, for either exploration or development purposes.
Basis of the project
This project will develop numerical models of relay zones which, when combined with existing empirical data from outcrop and 3-D seismic, providea basis for predicting the geometries of sub-resolution relay zones. Depending on the strains which can be sustained prior to relay breaching, sub-resolution relays can have geometries ranging from those of an intact relay ramp to those of a single fault; for a segmented array of a given displacement, earlier relay breaching will be characterised by less displacement partitioning. Although existing data provide useful constraints on the main geometrical characteristics of relays and on the strains they can accommodate prior to breaching (Figs 1-4); e.g. Peacock & Sanderson 1991, 1994; Childs et al. 1994, 1995, 1996, 1997; Foxford et al. in press; Huggins et al. 1996; Walsh & Watterson 1987, 1990, 1991), only numerical modelling will allow examination of the growth and breaching of relay zones and their sensitivity to the mechanical properties of the faulted sequence: a factor which cannot be rigorously assessed from available empirical data. These models will allow prediction of the geometries and strains associated with relays, at various stages of growth, from relay initiation to relay breaching and beyond (Figs 2-4). Emphasis will be placed on prediction of the geometries of relay zones which may occur at resolutions below the scale of seismic data for either reservoir bounding or intra-reservoir target faults. The numerical modelling will be complemented by geometric modelling and flow modelling of the effects of sub-resolution intact and breached relays on both the sealing properties and the transmissibilities of faults for a variety of reservoir sequences.
Contact: John Walsh
Tel: +353 1 716 2169
Email
Project Web Site: for sponsors only