SPE Journal
Volume 16, Number 3, September 2011, pp. 575-581

SPE-124884-PA

Numerical Modeling of Multistranded-Hydraulic-Fracture Propagation: Accounting for the Interaction Between Induced and Natural Fractures

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DOI  More information 10.2118/124884-PA http://dx.doi.org/10.2118/124884-PA

Citation

  • Dahi-Taleghani, A. and Olson, J.E. 2011. Numerical Modeling of Multistranded-Hydraulic-Fracture Propagation: Accounting for the Interaction Between Induced and Natural Fractures. SPE J.  16 (3): 575-581. SPE-124884-PA. http://dx.doi.org/10.2118/124884-PA.

Discipline Categories

  • 5.3.3 Hydraulic Fracturing and Gravel Packing
  • 6.1.5 Geologic Modeling

Keywords

  • Production and Operations

Summary

Recent examples of hydraulic-fracture diagnostic data suggest that complex, multistranded hydraulic-fracture geometry is a common occurrence. This reality is in stark contrast to the industry-standard design models based on the assumption of symmetric, planar, biwing geometry. The interaction between pre-existing natural fractures and the advancing hydraulic fracture is a key condition leading to complex fracture patterns. Performing hydraulic-fracture-design calculations under these less-than-ideal conditions requires modeling fracture intersections and tracking fluid fronts in the network of reactivated fissures. Whether a hydraulic fracture crosses or is arrested by a pre-existing natural fracture is controlled by shear strength and potential slippage at the fracture intersections, as well as potential debonding of sealed cracks in the near-tip region of a propagating hydraulic fracture. We present a complex hydraulic-fracture pattern propagation model based on the extended finite-element method (XFEM) as a design tool that can be used to optimize treatment parameters under complex propagation conditions. Results demonstrate that fracture-pattern complexity is strongly controlled by the magnitude of anisotropy of in-situ stresses, rock toughness, and natural-fracture cement strength, as well as the orientation of the natural fractures relative to the hydraulic fracture. Analysis shows that the growing hydraulic fracture may exert enough tensile and shear stresses on cemented natural fractures that the latter may be debonded, opened, and/or sheared in advance of hydraulic-fracture-tip arrival, while under other conditions, natural fractures will be unaffected by the hydraulic fracture. Detailed aperture distributions at the intersection between fracture segments show the potential for difficulty in proppant transport under complex fracture-propagation conditions.

© 2011. Society of Petroleum Engineers

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History

  • Original manuscript received: 20 August 2010
  • Meeting paper published: 5 October 2009
  • Revised manuscript received: 3 February 2011
  • Manuscript approved: 17 February 2011
  • Published online: 9 June 2011
  • Version of record: 15 September 2011