Real-time monitoring of lab-scale hydraulic fracturing using fiber-optic distributed acoustic sensing (DAS)

In the oil and gas industry, hydraulic fracturing is a widely used technique to enhance the extraction of hydrocarbons from underground oil and gas reservoirs. It is particularly effective for unconventional reservoirs, such as shale formations, which exhibit low permeability and porosity. This process involves injecting a high-pressure fluid mixture of water, sand, and chemical additives to induce man-made fractures in the rock formation surrounding the wellbore, thereby creating contact with the reservoir and enabling oil or gas production. The hydraulic fracturing process generates acoustic noise in the rock volume being stimulated. To monitor and optimize hydraulic fracturing processes, fiber-optic distributed acoustic sensing (DAS) has been increasingly employed for real-time monitoring and insights into fracture behavior. However, further investigations are needed to efficiently explain and understand the fiber-optic DAS data recorded during the hydraulic fracturing process, necessitating a well-controlled environment away from the field. In this work, we report on the use of fiber-optic DAS to monitor hydraulic fracturing in real-time within a controlled lab environment. Although the fracturing mechanisms are similar to those observed in the field, utilizing DAS for laboratory monitoring presents challenges due to changes in rock scale and seismic wavefield frequency. This experiment involves wrapping optical fiber cables around small-scale fractured rocks, localizing DAS spatial channels, and recording spatiotemporal acoustic fracturing data. The results of this work pave the way for a more thorough understanding of DAS data collected during field hydraulic fracturing.