PRESSURE LOSS THROUGH ROCK FRACTURE INTERSECTIONS

Abstract

Over time, the extraction and reinjection of geothermal fluid to generate electricity results in a decrease in the overall pressure of a geothermal reservoir. This results in the precipitation of minerals that cause blockages in the power station equipment and the rock fractures in the reservoir; as well as a lower flow rate available for electricity generation. A better understanding of fluid flow in a fracture network is required to better predict the performance of the reservoir over time. This paper aims to determine a relationship for the pressure loss of flow through the intersection of two rock fractures connected end-to-end. The model uses an electrical circuit analogy, where the pressure loss of the intersection is equivalent to an additional electrical resistance in a fractured network. Computational Fluid Dynamics (CFD) simulations were carried out for various aspect ratios, Reynolds numbers and the angle of orientation of the two fractures. Using data fitting methods, a general expression was found linking the pressure loss, Reynolds number, and angle of orientation, given a specific aspect ratio. The model was able to predict three fracture in series within 14% accuracy.