HR: 1330h
AN: H42F-1133    [PDF]
TI: Discriminating Between Different Fracture Network Geometries Using Well Test Analysis
AU: * Leckenby, R J
EM: Robert.Leckenby@Imperial.ac.uk
AF: Imperial College London, Department of Earth Science and Engineering South Kensington Campus, London, SW7 2AZ United Kingdom
AU: Lonergan, L
EM: L.Lonergan@Imperial.ac.uk
AF: Imperial College London, Department of Earth Science and Engineering South Kensington Campus, London, SW7 2AZ United Kingdom
AU: Rogers, S F
EM: SRogers@golder.com
AF: Golder Associates (UK) Ltd, Attenborough House Browns Lane Business Park, Stanton-on-the-Wolds, NG12 5BL United Kingdom
AU: Sanderson, D J
EM: David.Sanderson@Imperial.ac.uk
AF: Imperial College London, Department of Earth Science and Engineering South Kensington Campus, London, SW7 2AZ United Kingdom
AB: Realistic 3D geometrical models of different styles of fracture networks have been investigated based on well-exposed examples of fault and joint networks from exposures in southwest England. From these, generic models of various types of strike-slip and normal faults have been built. These form the basis of a series of well test simulations designed to analyse and quantify the influence of different fracture elements on hydraulic behaviour. In this methodology, each fault and fracture segment is discretised individually as a plane using a triangular mesh; realistic transmissivity and storativity values are then assigned to the different parts of the mesh. A commercial finite element code is used to solve the pressure diffusion equation for a transient case in these meshes. The simulations have been tested against other numerical codes. Experiments were conducted with constant and varying fault transmissivities and varying well positions relative to the fault network. Monitoring pressure drawdown in observation wells around the fault network simulated interference tests. The results demonstrate that a single geometrical structure may display significantly different pressure responses at a single well; as a function of distance to the well and of the transmissivity distribution within the fracture network and matrix. Where the fracture network is well connected, it is the ratio of the fracture to matrix transmissivity that dominates the behaviour of the pressure diffusion. Preliminary conclusions are that fracture properties have a higher order effect on pressure diffusion than fracture density.
DE: 1829 Groundwater hydrology
DE: 1894 Instruments and techniques
DE: 5104 Fracture and flow
DE: 5114 Permeability and porosity
SC: Hydrology [H]
MN: 2003 Fall Meeting