Reynolds, Mark A.1, Gary D. Couples1, Helen Lewis1, Jingsheng
Ma1, Gillian E. Pickup1
(1) Heriot-Watt University, Edinburgh, United Kingdom
ABSTRACT: Effective Fluid-flow Properties of Load-sensitive Fractured Bedding Plane Pavements in Large-scale Structures Influenced by Flexural-slip: Coupled Matrix-Fracture Flow Systems
Fractures present within a hydrocarbon reservoir can have a major effect on the movement of fluids. The permeability of open fractures, while often significantly higher than the matrix blocks they surround, is likely to be effected by variations in geomechanical and hydraulic loading resulting from the injection and production of fluids from the reservoir.
A series of fracture models have been generated, based on fieldwork at a number of locations with the Western US and UK. The models are based on typical pavement exposures that were observed on the flanks of the structures. Fracturing within the outcrops was often on two different scales. Fracture zones, 0.5-2 m wide, linked together to define a series of panels within which lay small-scale fracture network.
The main aim of this work has been to produce a range of effective permeability values for the small-scale fracture networks, using code called HYDRO-DDA. The effective permabilities can then be used within large-scale simulations where it would not be possible to model such a detailed fracture system due to the different scale of fractures present. The large-scale fracture zones, which define the edge of the panels, have been modelled explicitly and the load sensitive effective permeability placed within the panels allowing the inclusion of the small-scale fracture network without having to model each fracture explicitly. The added value of this technique is that by using a coupled hydrogeomechanical simulator from which the effective permeability data has been obtained it has been possible to include the effects of geomechanics within a static fluid-flow simulation.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.