Rapid simulation of multiple radially growing hydraulic fractures using an energy-based approach

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.

Rapid simulation of multiple radially growing hydraulic fractures using an energy-based approach. Advances in Engineering

Rapid simulation of multiple radially growing hydraulic fractures using an energy-based approach. Advances in Engineering

About the author

Cheng Cheng is a PhD student in the Department of Chemical and Petroleum Engineering at the University of Pittsburgh where he is focusing his studies on efficient modeling of hydraulic fracture growth. Prior to undertaking his PhD studies, Mr. Cheng received an MS in Petroleum Engineering from the University of Pittsburgh, a BS in Geological and Earth Sciences from the Missouri University of Science and Technology, and a Bachelor of Engineering in Petroleum Geology from China University of Petroleum, Beijing.

He recently received the Fall 2015 Best Paper Award from the University of Pittsburgh Department of Chemical and Petroleum Engineering for the paper “Rapid Simulation of Multiple Radially-Growing Hydraulic Fractures Using an Energy-Based Approach” (International Journal of Numerical and Analytical Methods in Geomechanics, 71: 281–282). 

About the author

Andrew Bunger is an Assistant Professor of Civil and Environmental Engineering at the University of Pittsburgh. He is jointly appointed in the Department of Chemical and Petroleum Engineering. Dr. Bunger has over 15 years of experience in experimental, analytical, and computational investigation of hydraulic fracturing and rock mechanics. Prior to joining the University of Pittsburgh in 2013, he was a Project Leader and Group Leader with Australia’s Commonwealth Scientific and Industrial Research Organisation (CSIRO). There he was responsible for CSIRO’s hydraulic fracturing laboratory and for a 17 member Geomechanics Group which includes research teams in hydraulic fracturing, wellbore stability/sand production, and drilling mechanics.

His current research interests include the mechanics of hydraulic fractures, coupled fluid-shale interaction, and the emplacement dynamics of magma-driven dykes and sills. In addition to his research activities, Dr. Bunger teaches Principles of Soil Mechanics, he is instructor and course developer for Hydraulic Fracturing Mechanics and Applications, and he serves on the editorial board of ASTM-Geotechnical Testing Journal.  He holds a PhD in Geological Engineering from the University of Minnesota. 

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”]
  1. Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA, U.S.A.
  2. Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, PA, U.S.A.
[/expand]

 

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