Faulting & Fracturing
SOB Hill relay ramp, Canyonlands, Utah
Active research projects:
Faults play a key role in the initiation and development of a basin, and in the formation and exploitation of their hydrocarbon and mineral resources. Faults are being examined using a wide array of data, including field mapping, seismics and boreholes. The geometry, kinematics (including displacement distribution) and mechanics of isolated and segmented faults are being studied, with particular reference to structures formed by fault linkage. This work is being extended to studies of fault networks and fault zone evolution. Research on various aspects of fracturing induced by stress concentration and wall-rock strain (damage) includes:
- fracture initiation in response to basin development and stress history,
- processes controlling the distribution of damage,
- the mechanics of fracture opening and slip, and
- the role of fluid pressure in the formation of natural fractures.
The role of fractures in controlling fluid flow is being studied, based on field investigation of vein systems and hydrothermal mineralisation, and by numerical modelling using fully coupled models to investigate the role of stress on fluid flow. For instance the influence of fracture intersections on flow channelling is poorly understood and is beginning to be investigated numerically.
In addition to these studies of the fundamental processes in fractured rock, much research is concerned with developing a methodology for prediction of sub-seismic fractures and permeability distribution. Flow through fractured rocks is also important in several key areas, such as production from fractured hydrocarbon reservoirs, nuclear waste disposal, coal-bed methane production and the sequestration of CO2 in subsurface.
Future Developments
Future research trends will involve the following activities:
- development of models of the rheology of the upper crust based on the micromechanics of fracture and the known distribution of crustal stress and fluid pressure,
- development of improved models of rock-mass properties (seismic, permeability, porosity, etc.) in terms of fracture mechanics, which will involve collaboration between the SBSF, Geophysics and Petroleum Engineering groups,
- experiments involving the imaging of fluid distribution and movement in response to imposed stress, which are designed to elucidate the fundamental processes involved in flow through fracture networks,
- experimental and numerical study of phase transfer between fractures and a less permeable matrix, which would aid understanding of oil recovery from fractured reservoirs,
- assessment of continuity, connectivity and permeability of a fractured rock mass by the superposition of fracture sets, and
- evolution of fractures and folds within an active tectonic regime (e.g. the Zagros) and their controls on hydrocarbon migration and entrapment.
