Significance Statement
Hydraulic fracturing is a process by which pressurized fluid creates fractures in rock. It permits an increased flow of hydrocarbons from the reservoir formation towards the well. This technique is widely and successfully used in horizontal wells in unconventional reservoirs. However, it is still shows 20-40% inefficiency in production.
One contributing factor for this reduced production is suppression of hydraulic fractures caused by compressive stresses exerted on them by nearby hydraulic fractures. Several simulation models tried to study this “stress shadowing effect” to improve the hydraulic fractures. However, the models proposed are time exhaustive and can take weeks to resolve.
Professor Andrew P. Bunger and Cheng Cheng a PhD student at Department of Chemical and Petroleum Engineering at University of Pittsburgh were able to come up with approximate model called ‘C2Frac’ that requires only seconds to run, thereby providing a factor of roughly a million times reduction in computational time.
The authors demonstrated its accuracy and utility and compared it successfully with full simulations carried out using the ILSA II model. This new modelling approach presented in this study expected to advance simulation of multiple hydraulic fracture growth in a fraction of the computational time which will lead to well completion optimization.
Figure Legend: Illustration of multiple hydraulic fracture growth simulation with C2Frac for 5 fractures with different non-uniform spacing distributed over a 20m long interval of a horizontal well.
These illustrate: a) Suppression of the inner fractures due to elevated stresses induced by fracture growth for the case of uniform fracture spacing, b) Suppression of outer fractures upon placement of the second and fourth fractures very near the outer fractures, c) Uniform growth of all fractures when the spacing is adjusted to balance the influence of the fracture-induced stresses to be equally distributed to all 5 fractures.
Journal Reference
Cheng Cheng 1,Andrew P. Bunger 1,2. Rapid simulation of multiple radially growing hydraulic fractures using an energy-based approach. International Journal for Numerical and Analytical methods in Geomechanics, 2016, Volume 40, pp 1007-1022.
[expand title=”Show Affiliations”]- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA, U.S.A.
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, U.S.A.
Go To International Journal for Numerical and Analytical Methods in Geomechanics