ABSTRACT:

Fracture initiation and propagation are important research topics in reservoir geomechanics. A high proportion of the oil and gas reservoirs around the world are carbonate reservoirs, dominated by brittle and fractured carbonate rocks such as calcium carbonate (CaCO3) and dolomite (CaMg(CO3)2). Investigation of fracture behavior has been extensively carried out by different approaches but usually involving macro-scale continuum-based methods. Such methods have limitations for analyzing discontinuous porous media like carbonate rocks. Dis-continuum based methods are needed for understanding fracture complexity challenges in naturally fractured strata. Micro-scale dis-continuum methods such as Molecular Dynamic (MD) modelling have been widely used in physics and mechanics, but much less so in rock mechanics. This article contains a literature review of MD modeling and dis-continuum methods for fracture simulation, addressing their advantages and disadvantages. Subsequently, the context of MD as a micro-scale dis-continuum method is described. Then, a MD model of pure calcium carbonate (Calcite) is developed and a numerical simulation of a uniaxial test is carried out. Results are compared to simple uniaxial experiments, and results showed fair agreement. This preliminary application of MD at a small scale may aid in understanding and implementing fracture initiation and small-scale fracture propagation during early stages of the fracture stimulation process.

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