The Sound of One Fracture Flowing

Abstract

In November 2020, Gustavo Ugueto had an extraordinary in-well experience. The source of his amazement was a stream of fiber-optic data measuring how fractures were altered by slight pressure changes during production. When the principal petrophysicist for unconventional technology at Shell described the Permian well test, he sounded like someone who had used a stethoscope for the first time. “The straining is extended and compressed at all times like breathing,” Ugueto said during a presentation at the 2021 Unconventional Resources Technology Conference (URTeC) about the test done at the Fracturing Test Site 2 in late 2020 (URTeC 5408). He said it was an “aha moment,” as was getting a good signal considering the infinitesimal differences in the fracture dimensions in a well where the daily pressure drop was less than 40 psi. And he was excited to think about what this test could reveal someday about how fractures change during production. If it lives up to that potential, “we will have the ability to measure. We can experiment. What type of treatment? What type of proppant? We can do more of the good one and less of the bad one. The problem [now] is we have been working blind,” he said. While he was clearly excited about the potential, he also repeatedly cautioned that there is so much more work required to learn what is possible. At this point, the few people with access to this data are like new medical students using a stethoscope, wondering how those sounds related to the patient’s health. “We are at the beginning of journey; it may fail,” Ugueto said. The New Strain The data from the Hydraulic Fracture Test Site 2 are only available now to those who backed the project, but three papers cover the work (see For Further Reading), sparking others to try this new way to measure fractures. “Because of the publications by Gustavo and his coauthors, we are seeing a lot of uptake based on what was learned,” said Dana Jurick, Neubrex Energy Services US—the company that supplied the equipment used to measure the strain data. The company has since been hired for similar work by other oil companies curious about what they can learn from this new diagnostic. The coauthors include Ge Jin, an associate professor at the Colorado School of Mines, who was a geophysics consultant at the Hydraulic Fracturing Test Site 2, and Kan Wu, an associate professor at Texas A&M, who is collaborating with Jin. Her group at Texas A&M is working on modeling aimed at turning this qualitative data source into a quantitative measurement. Ugueto said other operators trying it, including Chevron and ConocoPhillips who were among the test site partners, plus other fiber-optic companies, are getting into a field that is so new there is no settled name for it. Two commonly used labels for it reflect varying levels of optimism about its future. One is based on the data gathered: near-wellbore strain analysis. The other is based on a vision where it is possible to measure how fractures react to change: near-wellbore fracture dynamics.