Empirical relations between strength and static and dynamic elastic properties of Asmari and Sarvak limestones, two main oil reservoirs in Iran

Abstract

Asmari and Sarvak limestone are two main oil producer formations in Iran and the Middle East. Perception and optimal utilization of these reservoirs will have a significant impact on the economy of the petroleum industries. Geomechanical modelling of oil reservoirs are widely used in optimum drilling, production and reservoir compaction. Hence, uniaxial compressive strength (UCS) and static Young’ modulus (ES) are the most essential parameters for any reservoir geomechanical modelling. However, information on the value of UCS and ES along the well length is often discontinuous and limited to cross well with the core. Therefore, dynamic Young’s modulus (Ed) determined from open hole log data such as density (ρ) and compressional and shear wave velocities could results in continuous estimation of elastic properties of the well length. Nevertheless, static parameters are more reliable than the dynamic parameters and they are widely accepted by geomechanics community around the world. Therefore, finding a valid correlation between static and dynamic parameters could result in a continuous and more reliable knowledge on elastic parameters. In this study, the uniaxial compressive strength and ultrasonic tests were carried out on 45 Asmariand Sarvak limestone core specimen. Then, local correlations were established between dynamic and static measurements. Suggested equations were compared with previous relations. Moreover, the sensitivity of the suggested relations to crushed and compacted zones were investigated.These expressions are utilized for future wellbor estability analysis, fracture detections and hydraulic fracturing studies across many oil and gas fields in the country.