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Fracture sealing and its impact on the percolation of subsurface fracture networks
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  • Weiwei Zhu,
  • Xupeng He,
  • Siarhei Khirevich,
  • Tad W Patzek
Weiwei Zhu
Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC), King Abdullah University of Science and Technology

Corresponding Author:[email protected]

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Xupeng He
Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC)
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Siarhei Khirevich
Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC)
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Tad W Patzek
Ali I. Al-Naimi Petroleum Engineering Research Center (ANPERC)
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Abstract

Fractures play an essential role in formations with low permeability; however, fracture sealing significantly reduces the permeability of fractures. The mechanism of how fracture sealing impacts the macro-scale fluid flow is rarely investigated. Here, we simulate sealing in two- and three-dimensional orthogonal fracture networks and investigate the impact of sealing on the percolation of these fracture networks. We find that a small amount of sealing can prevent the formation of spanning clusters, which suggests that global connectivity is rarely realized. Without significant stress perturbations, most fractures are partially sealed and non-critically stressed, and they usually do not contribute much to the fluid flow. However, under a significant stress perturbation, such as hydraulic fracturing, the well-connected and critically oriented fractures become critically stressed and slide because of the increased pore pressure. Partially sealed and non-critically stressed fractures can also contribute to the fluid flow by enlarging the stimulated reservoir volume (SRV). We estimate the stimulated reservoir volume in two dimensions by dividing the target distance (LSRV) into two parts. One is the distance limiting generation of hydraulic fractures (ΔLh), and the other is the limiting distance of making natural fractures slide (ΔLs). A rough estimation yields an elongated shape of the SRV, which is consistent with observations from microseismicity maps.