Estimation of permeability and rock mechanical properties of limestone reservoir rocks under stress conditions by strain gauge

Petroleum engineering reservoir parameter calculations are generally performed in the absence of the overburden pressure effect. This leads to serious errors in further development of a hydrocarbon-bearing reservoir. Thus, measurements under stress conditions become important vitally. The objective is to correlate the overburden pressure and the permeability to see the overburden pressure effects on the permeability of Turkish southeastern limestone reservoir rock samples. Stress was applied to four representative limestone samples taken from southeast Turkey. In the laboratory tests, two identical core plugs from every sample were used for each application. This is why a Wheatstone Bridge with a full-bridge strain gauge method was used. A sample is inserted into a load frame and the axial load was increased. Internal friction angles and cohesion factors were determined. An exponential correlation was proposed between permeability and confining pressure. The experimental and correlated results match very accurately. The stress and permeability correlations may be useful with resistivity logs through which permeability may be measured and for stress-strain-related CBL (cement bond logs) which are used for the well bore stability during cementing applications. (c) 2006 Elsevier B.V. All rights reserved.