Detection and Characterization of Fractures in Naturally Fractured Reservoirs

Abstract

Abstract Imaging log, sonic log, optical microscopy, NMR, MRI, and tomography have greatly enhanced the possibility of measuring fracture geometric characteristics. However, the fracture hydraulic width and permeability can only be evaluated from dynamic data revealing production or adsorption along the wellbore. Different analytical approaches accounting for mud rheology and their application to several field cases where mud losses were recorded with electromagnetic flowmeters are presented to evaluate the fracture hydraulic width from mud loss measurements. Observation of mud loss evolution in time also revealed whether a single fracture or an intensely fractured zone had been intercepted by the drilling bit. Results are discussed with respect to imaging log data, core analyses, and well test interpretation results. In general, a very good correspondence was found between mud loss occurrence, fracture detection from imaging log, core data, and productivity tests.