Geomechanical Characterizations and Correlations to Reduce Uncertainties of Carbonate Reservoir Analysis

摘要

Although carbonate reservoirs hold a wealth of hydrocarbon, they are among the most difficult types of reservoirs to be characterized. Carbonate reservoirs by nature have complex depositional environments and diagenetic processes in which brittle, ductile, fractured rocks, and vugular pores may all exist within small interval. This huge variance in the rock mechanical properties can cause challenges in the reservoir's development, especially in applications related to geomechanics.;The main objective of this research is to geomechanically characterize and correlate the carbonate mechanical properties with their petrophysical properties. A comprehensive review for the geomechanical-petrophysical properties of carbonates was conducted from previous studies. Data from offset well have also been used to develop an integrated methodology that examines the uncertainty of carbonate wellbore integrity.;The results present a new engineering classification to evaluate the carbonate drillability and deformability. Additional developments regarding the relationships between the carbonate compressive strength and confining pressure, maximum shear stress and mean stress, and internal friction angle and unconfined compressive strength (UCS) are systematically investigated based on the compiled database. New correlations to predict the UCS and Young's modulus of each carbonate type have been developed from the petrophysical properties. Applying P90 as a threshold on the estimated minimum mud weight proved to be conservative. For fracture mud weight, the field data showed that the P50 threshold did not prevent fluid losses. This study contributes toward better methods to predict shear wave velocities exemplified with field cases in Southeast Iraq.