The AEC’s Intermediate Scale Field Test Lab is located near the city of Devine in Medina County, Texas. The site has a set of wells (approximately 100m deep) for demonstration of proof-of-concept of fracture network mapping with electromagnetic (EM) methods. The center steel-cased injection well was permitted for stimulation by EM proppants, and the four fiber glass-cased observation wells are instrumented with permanent electrical resistivity tomography (ERT), and distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) fiber-optic cables. Two rounds of hydraulic fracturing with EM proppants have already been carried out, and various EM and geophysical logs have been collected to image the location of fractures. This design allowed the AEC to verify its results with drilling and logging of eight vertical wells. In addition, two wells were cored, and these samples further corroborated the presence of EM active proppant (EAP) at the predicted depth. Together, these results conclusively corroborated the accuracy of the EM inversion models to within 5 ft. of the physical edge of the EM-filled fracture anomaly.
The EM methods developed and demonstrated at the Intermediate Scale Field Test Lab by the AEC will lead to a better understanding of the extent of proppant-filled networks, formation stress state, and characteristics of engineered fracture systems which are critical to efficient production of hydraulically fractured reservoirs. The well-characterized contrast-agent-filled fracture target at the Test Lab is an extremely unique field-laboratory resource for technology development and validation. AEC is open to collaborate with other researchers who are interested in this topic to validate their tools and models.