Evaluation of geomechanical properties via scratch tests: Where are we and where do we go from here?

Abstract

The scratch test is a quasi-non-destructive method made up of pushing a tool across the surface of a weaker rock at a given penetration depth. The unconfined compressive strength (UCS), fracture toughness (KIC), and other geomechanical parameters influence how geological materials fail, and how the succeeding fractures nucleate. Researchers have attempted to evaluate UCS, KIC, and other geomechanical properties in diverse rock formations through the scratch test method, but there remain differing opinions on the fundamental approach and principles to be adopted in estimating these properties. Therefore, the evaluation of geomechanical parameters and their impact on hydrocarbon exploration and exploitation, and underground storage remain an important issue for the energy industry. In this paper, we present a comprehensive review of the methods of approach, applications, and the mechanics of rock scratching. We showed the merits of utilizing scratch tests over other conventional methods of measuring and estimating geomechanical properties. Our review focuses on previous studies in the past few decades that utilized the scratch test method to investigate geomechanical properties and their impact on fractomechanical behavior. Finally, we highlight promising research areas of investigation to improve the application of the scratch test method. We envisage this advancement in our knowledge will improve the optimization of hydrocarbon exploitation, underground storage, and field-scale modeling for energy production operations.