Analyzing fracture connectivity from flowmeter tests using coupled modeling of borehole and fracture flows with Brinkman equations

Abstract

Boreholes, where flow tests such as tracer and flowmeter tests are conducted, present analytical challenges due to the pipe flow behavior that differs significantly from Darcian flow in porous media. This study addresses these challenges by employing the Brinkman equations, which combine the Navier-Stokes equations and Darcy’s law to create a unified model that integrates borehole and fracture flow. Fracture networks integrated with boreholes are constructed using fracture attributes obtained from borehole acoustic televiewer logs, and their permeabilities are calibrated by comparing simulated flows with measured data, enabling accurate reproduction of observed profiles and the development of a high-resolution 3D fracture network. The results indicate that groundwater flow is primarily controlled by a limited number of highly permeable fractures, but fracture connectivity, regardless of permeability, plays a crucial role in flow between boreholes. This enhanced method provides a robust framework for analyzing borehole-altered flow dynamics in fractured rocks and improves our understanding of complex fracture systems.