Bureau of Economic Geology

FRAC Embarks On Next Quarter Century

January 20, 2022
Students in the field
Geothermal outcrop analogs, upstate New York. FRAC students and staff along with Cornell
students and professors describe a premier fracture exposure. FRAC research established
principles for selecting appropriate subsurface analogs. Photos: Ann Laubach.

The Fracture Research and Application Consortium (FRAC) recently held its 25th Annual Research Meeting, marking 25 years of progress in learning how to characterize and predict fractures and their effects on engineering operations. The meeting was held online and included 17 live presentations, 7 prerecorded talks, a virtual fieldtrip to the Canadian Foothills with field trip leader Esti Ukar, and a software demonstration workshop.

FRAC Principal Investigators Steve Laubach and Jon Olson gave an overview of FRAC’s cutting edge work on fracture modeling. The challenge of building predictive models to understand and optimize energy extraction is widely recognized. The goal is to break down the complexity of fracture system behavior and rebuild it into a modeling approach that reliably and verifiably predicts attributes that govern fluid flow and rock strength. FRAC research is investigating fully 3D interactions between individual fractures governed by friction laws and communicating via chemistry and fluid flow, using simulations, laboratory experiments, and natural examples to unravel these interactions. To make reliable predictions, it is necessary to include interactions between fractures at all scales and to couple mechanical and diagenetic processes. BT Lee, a Ph.D. student in the program, presented new work on a computationally efficient physics-based modeling approach that couples mechanics and diagenesis and showed that for the first time a numerical code reproduced the types of fracture size distributions observed in nature. Collaborator John N. Hooker illustrated a numerical approach that is being incorporated into the predictive model that accounts for the effects of variable cement accumulation on fracture spatial arrangement. Geoscience Ph.D. students are using novel approaches to reconstruct natural fracture pattern evolution to compare with model results. This basic research direction promises to revolutionize fracture pattern prediction over the next few years.

Practical engineering solutions and technology transfer are also central to the FRAC mission. The annual meeting workshop, led by Jiacheng Wang and Jon Olson, was an interactive demonstration of in-house hydraulic fracture modeling software that uses innovative methods to take geology into account. Prior to the Zoom session, FRAC members had the opportunity to install the software and were able to run models in real time. These types of workshops are a hallmark of FRAC interaction with sponsors. During 2021, there were two other workshops on “Paleo-Fluid Flow and Charge History Reconstruction” featuring fluid inclusion analysis methods, led by Peter Eichhubl and Andras Fall, and on “Fracture Spatial Organization” featuring new 1D- and 2D-spatial arrangement analysis software, led by Ph.D. students, Rodrigo Correa, Mahmood Shakiba, and Qiqi Wang.

Fracture research remains highly relevant to the development of naturally fractured geothermal and petroleum reservoirs and to improved efficiency in unconventional reservoirs that require stimulation. Work on fundamental natural fracture processes and on hydraulic fracture generation will continue. For major initiatives, we leverage industry support with other resources. For example, Julia Gale and Sara Elliott are describing fractures in core as part of a new DOE-funded hydraulic fracture test site project, where the interest is on refracturing. In a cross-disciplinary initiative, Esti Ukar is leading a project aiming to capture fracture information from drilling data. A big challenge is sorting useful information on fractures from other signals in the data. Colleagues with drilling expertise in the UT Department of Petroleum Engineering are working on this aspect. New fracture characterization protocols and spatial arrangement software are under development as inputs for discrete fracture models. Collaboration with FRAC sponsors on case study projects has also been strong, allowing us to take in-depth looks at issues from which general principles can be inferred.

Looking to the future, and the next quarter century, fracture research is going to be key for successful endeavors in energy transition projects; there will be opportunities in both geothermal and carbon sequestration initiatives. FRAC scientists are developing collaborations in several such projects. For example, Steve Laubach will lead core fracture description work on a Cornell University geothermal research well. Preliminary fieldwork in New York in collaboration with Cornell scientists (see photos) on a geothermal outcrop analog saw the deployment of FRAC’s new drone, and Ph.D. student Stephanie Forstner’s work in Wyoming is also an exceptional outcrop analog for geothermal sources. The possibility of sequestering carbon dioxide (CO2) in unconventional reservoirs will also require fracture knowledge, especially regarding risk associated with CO2 containment. Julia Gale is building a team to work on this topic, taking advantage of the Bureau’s collective knowledge of unconventional reservoir geology and fracture systems.

The FRAC group looks forward to the next phase of innovation in research and is actively seeking new datasets, collaborative projects, and sponsors to add to the portfolio.

University of Texas at Austin

University of Texas

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