Integrated Fracture Properties by Using Structural and Geological Approaches in the Absence of Borehole Image Logs and Seismic Attributes

Reza Shahali
Tehran, Iran

In recent years considerable effort has been devoted to developing techniques to predict various characteristics of fracture patterns in subsurface hydrocarbon reservoirs. There is a relation between observed fracture intensity at any location and a series of geological and geomechanical derivers at the same location, hence, a good understanding of fracture origin and their controlling factors of distribution is necessary. The spatial distribution of fractures in a reservoir affects future performance. This paper presents a case study drawn from an integrated reservoir study on a faulted and fractured carbonate reservoir in a field in Iran. Our emphasis is to demonstrate how the results of geological judgement and structural understanding impacted the reservoir fracture description. Here owing to lack of borehole image logs and seismic attributes data, we used a new combination of geological techniques to generate fracture distributions and attributes. Based on sedimentary basin and tectonic history, we predict that fractures are controlled by two factors, shale volume and differing stress regimes. Considering these factors, a function consisting of curvature map, magnitude of dip map, and poro–fracture map was used to generate fracture properties. Based on the sedimentary basin model, and extensive shale volume observed in deeper layers, we used a shale distribution map as a key element to predict fracture properties. The method was validated by reservoir history matches that shown accurate prediction of production response.