Categorical fracture orientation modeling: applied to an Iranian oil field

Abstract

Fracture orientation is a prominent factor in determining the reservoir fluid flow direction in a formation because fractures are the major paths through which fluid flow occurs. Hence, a true modeling of orientation leads to a reliable prediction of fluid flow. Traditionally, various distributions are used for orientation modeling in fracture networks. Although they offer a fairly suitable estimation of fracture orientation, they would not consider any spatial structure for simulated fracture orientations, and would not able to properly reproduce the histograms, and the stereogram of dip and azimuth. To respect this geostatistical and statistical parameters, in this paper a new approach has been presented in which the observed fractures on the image log are firstly clustered, and the major facture families are categorically simulated over the area of study. Afterwards, azimuths are simulated using the probability field obtained from categorical simulation, and dips are conditionally simulated to azimuths. The method is illustrated through a case and the results show that the histograms and stereograms are completely reproduced. In addition, the connectivity of modeled fracture network using the presented method is surveyed in comparison with modeled fracture network using Kent distribution.

Keywords

• Fracture orientation
• Geostatistical modeling
• Categorical simulation
• Fracture set
• Fracture connectivity