Abstract
Hydraulic-fracturing treatments are an essential part of well completions in unconventional reservoirs. Hydraulic fractures provide access to the low-permeability reservoir rock, but they also interact with natural fractures to create unpredictable complex fracture networks. Recently, the concept of hydraulic fracture branching, as opposed to simple planar fractures, has been predicted by numerical models to be a mechanism for the high production rates observed from unconventional oil and gas wells. Here, we investigated this concept by performing laboratory experiments. These used gypsum plaster in a heterogeneous 2D grid for analog-rock samples to quantitatively analyze hydraulic fracture branching. The grid included a low-permeability matrix and high-permeability 'weak layers' that represent closed natural fractures. Oils with different viscosities were used as the injection fluids to induce hydraulic fracture branching with differing intensity. The experimental results indicate that the intensity of fracture branching can be controlled by the injection parameters. This branching phenomenon was observed by simultaneous growth of the hydraulic fractures in orthogonal/oblique directions, eventually creating a dense network of fractures. Ongoing, we seek a criterion to optimize branching for a given rock type using measurable parameters and tailored stimulation fluids.
Original language | English (US) |
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State | Published - 2020 |
Event | 54th U.S. Rock Mechanics/Geomechanics Symposium - Virtual, Online Duration: Jun 28 2020 → Jul 1 2020 |
Conference
Conference | 54th U.S. Rock Mechanics/Geomechanics Symposium |
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City | Virtual, Online |
Period | 6/28/20 → 7/1/20 |
Funding
This work was supported by the U. S. Department of Energy (DOE) Basic Energy Sciences (LANLE3W1). We gratefully acknowledge this support.
ASJC Scopus subject areas
- Geochemistry and Petrology
- Geophysics
- Geotechnical Engineering and Engineering Geology