Application of fractal method for quantifying fault geometry

Abstract

Abstract The knowledge of fault system geometry plays an important role in oil prospecting and is also a primary requisite to a better understanding of the mechanics of faulting in terms of the concentrations of stress and other departures from stress homogeneity which arise from complicated fault geometries. It is very important to be able to quantify the fault geometry and in this paper we discuss the application of the fractal method for quantifying fault geometries. Because of their rough appearance over many length scales, faults can be regarded as fractal in which the fault's geometrical complexity or irregularity can be quantified by the fractal dimension number. The fractal dimension then can be related to other faulting mechanics processes such as the stress condition, degree of faulting or fracturing, fracturing energy density and physical properties of materials. For example we have calculated the fractal dimension of Semangko Fault System in South Sumatra and found the value of 1.35–1.56 which means that compared to the geometry of the San Andreas Fault System which has fractal dimension of 1.12–1.43, the fault pattern of Semangka Fault System is much more random and chaotic. Therefore the fractal dimension number is a quantitative measure of the fault geometry complexity. The application of the method is not only limited to fault geometry, but can also be applied to quantifying the extent of fracturing and any structural lineaments. The data used in this type of analysis can be taken from any scale from petrographic observation, from field observation or even air photography and satellite imagery.