Fracture interpretation and flow modelling in fractured reservoirs. JOULE III - Contract JOF3-CT95-0015. Report from European Commission. EUR 18946.

This book outlines the results of an EU project which investigated a variety of technical issues related to fractured reservoirs. Progress is outlined on defining methods for how to conceptually describe faults and fractures, how to collect relevant geological information about fractures from various sources, and how to assign meaningful hydraulic parameters to the various geometric elements that comprise faults and fractures. A case study from central Italy is presented which shows that quantitative field observations from outcrop can be gathered and used to supply the parameters necessary for flow modelling in a complex-gridded simulator. Algorithms have been successfully used to translate these measurements into a form suitable for input into a conventional reservoir simulator.
We have also examined the geometries of faults and other fracture systems (e.g. microfractures, joints and veins) from outcrop data and identified fundamental differences in the geometrical scaling properties, and therefore flow properties, of different types of system. Using outcrop analogue data, preferably linked to subsurface well and flow data, it is possible to capture the range of behaviour for wells within heterogeneous fractured reservoirs. Bimodal effective permeability distributions of faulted and fractured reservoirs, as evidenced from our outcrop analogue studies, may be a characteristic of many hydrocarbon reservoirs. This characteristic necessitates improvement of present procedures, in order to be better captured in existing fracture modelling packages used by the petroleum industry. Using our improved knowledge of fault and fracture geometric and porosity-permeability properties, existing systems can be further refined, beyond the relatively simple geometrical constraints they currently use.