Mechanical Properties of Carbonate Formation and Their Influences on Drilling and Hydraulic Fracture Modeling

Abstract

Abstract Among many challenges encountered during drilling and hydraulic fracturing operations in carbonate reservoirs, wellbore stability related issues while drilling and variability and unpredictability of the outcome of hydraulic fracturing are the most significant ones. Accurate characterizations of the mechanical properties are essential to understand how the carbonate reservoirs respond to these issues. Static mechanical properties can be obtained directly in the laboratories from triaxial tests on core samples, while dynamic properties can be calculated from wireline measurements such as acoustic wave velocities and bulk density of the formation. Core plug samples from Field-A producing carbonate B and C reservoirs were tested for acoustic and mechanical properties using triaxial method. Laboratory studies on the elastic and deformational properties of carbonate B show that this formation exhibits wide range of elastic properties due to heterogeneity, while the trend in carbonate C is much clearer. This study enabled the generation of empirical correlations among different properties, such as density and P-wave velocity, P and S-wave velocities, P-wave velocities to static and dynamic moduli and Unconfined Compressive Strength (UCS). The correlations show a good agreement with available correlations that are commonly used in the industry for carbonate C. The developed equations will improve and enhance hydraulic fracture and wellbore stability models that are related to geomechanics in the carbonate reservoir. The equations compute the mechanical properties for any well within the study area using measured geophysical log data such as density and compressional and shear sonic logs. The derived correlations are implemented in actual cases and are presented in this paper.