Challenges and best practices in interpreting crosswell strain signals to monitor multicrew zipper-fracturing operations

Crosswell strain measurements using low-frequency distributed acoustic sensing (LF-DAS) are an emerging technique to monitor hydraulic-fracture propagation. Qualitative interpretations of the strain rate data have been used to evaluate fracturing stimulation efficiency, hydraulic-fracture geometry, and crosswell communication. Limited studies have investigated the crosswell strain signals recorded by offset fibers during a zipperfracturing treatment, though zipper fracturing becomes a routine method of stimulating horizontal wells in unconventional reservoirs. This gap will be filled in this research by presenting the methods we developed to investigate complicated LF-DAS signals. These approaches were further demonstrated using the field data sets recorded by two temporary sensing fiber cables during the zipper-fracturing operation of seven offset wells with two fracking crews operating simultaneously. By exploring, comparing, and presenting the LF-DAS data recorded in wireline and disposable fiber cables, this research shares the best practices for visualizing and interpreting crosswell strain signals. The LF-DAS data set shown in this study, is, to the best of our knowledge, one of the most complicated LF-DAS data sets ever presented. The approaches proposed here can be extended and applied to visualize and interpret different kinds of complicated LF-DAS signals recorded using permanent, wireline, and disposable fiber cables.