What Is Really Happening When Parent and Child Wells Interact?

Abstract

When trying to understand the well-to-well events known as frac hits and fracture-driven interactions (FDIs), the first idea to embrace is this: they are not all the same. “And the key physical mechanisms are not the same,” said Mark McClure, who added that, “Until you’ve really dialed in on what those are, you’re really in the dark.” McClure is the cofounder and CEO of ResFrac Corp. In March, the modeling firm began a multiclient study to diagnose the relationships between parent and child wells—or what many consider to be the ultimate subsurface challenge facing the shale sector. Participating operators are Marathon Oil, Hess Corp., Pioneer Resources, Arc Resources, Birchcliff Energy, SM Energy, and Ovintiv Inc. These independent E&Ps represent a cross section of some of the most active plays in North America: the Midland and Delaware basins and the Bakken and Montney shales. But what makes the study unique, McClure said, is that it involves 10 rich data sets from well pads that were subjected to a number of cross-validating diagnostics: tracers, pressure/interference monitoring, geochemistry, and fiber optics. ResFrac has been using that data to calibrate its coupled reservoir-fracture models to see what knobs clients might want to turn in the future to improve well economics. The study is also trying to unearth some firm answers about what is really happening during offset stimulations, why it is happening, and what can be done to mitigate negative outcomes. ResFrac and its clients expect to wrap up this part of the study by the year’s end and to submit an abstract for an SPE technical conference in 2022. As the study nears an end, McClure offered some of his key observations that he noted are supported by previous research found within industry literature. So, What’s the Worst That Can Happen? A growing chorus of subsurface experts consider unwanted chemical reactions in the fracture network as one of the major damage mechanisms resulting from FDIs. McClure is not only among them, he said chemical effects represent the “worst” that can happen when parents and children interact. “This is where you see wells get hit, they lose 80% of their production, and it doesn’t come back,” he explained. Some in the industry have taken to calling the byproduct of these chemical reactions “shmoo” or “gunk.” For answers as to why this is happening, McClure points to two technical papers in particular.