Monitoring Chemo-Mechanical Fracture Behavior through Engineering Geophysics Experiments

Summary The extremely low permeability of many tight formations has required hydraulic and acid fracturing which introduce both geochemical and mechanical alterations to reservoir rock. There is an increasing need to effectively monitor those changes in situ for both economic and environmental considerations. We have been conducting engineering geophysics experiments to enhance the interpretation of hydraulic fracturing by characterizing acoustic velocity of propped and acidified fractures as well as acoustic emissions occurring upon chemo-mechanical rock deformation. Our experiments show that P- and S-waves are affected differently, with S-wave velocity being particularly prone to geochemically altered and propped fracture zones. Acoustic emission accounts only for a small portion of the total energy released from rock fracturing process.