Authors: Mejia, C; Azad, E; Roehl, D; Vallejos, JA; Rojas, E

Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2205_84

Cite As:
Mejia, C, Azad, E, Roehl, D, Vallejos, JA & Rojas, E 2022, 'Stress shadowing effects during hydraulic fracturing in block caving operations', in Y Potvin (ed.), Caving 2022: Fifth International Conference on Block and Sublevel Caving, Australian Centre for Geomechanics, Perth, pp. 1211-1226, https://doi.org/10.36487/ACG_repo/2205_84

Download citation as:   ris   bibtex   endnote   text   Zotero


Abstract:
The hydraulic fracturing (HF) technique is mainly used to precondition the orebody before mining in the block caving extraction method. Weakening the rock mass to enhance its caveability, reduce seismic risks and reduce fragment sizes are the primary objectives of HF in mining. HF is used mainly in large-scale deep underground mines with low-grade metal orebodies. In this paper, hydraulic fracturing simulation is conducted based on the finite element method to study the effect of simultaneous and sequential multiple hydraulic fracturing schemes. The input and in situ data used for this simulation come from the El Teniente porphyry Cu-Mo mine. The fracture propagation is modelled with the cohesive elements using a traction-separation law. Comparing 3D and axisymmetric analysis, the similarity between fracture propagation shape and crack length prompted us to adopt axisymmetric analyses with reduced computational cost. Scenarios of simultaneous and sequential operations were analysed to consider the stress shadow effect, an understandable consequence of deformation during hydraulic fracturing. This comparison determined the fracture aperture, pore pressure, stress, and crack length. Due to the stress shadowing effect, different fracture lengths are observed. In addition, sequential injections have a subtler effect than simultaneous injections.

Keywords: hydraulic fracturing, stress shadowing effect, cohesive element, hydro-mechanical coupling, block caving

References:
Adams, J & Rowe, C 2013, ‘Differentiating applications of hydraulic fracturing’, paper presented at the ISRM International Conference for Effective and Sustainable Hydraulic Fracturing.
Azad, E, Peik, B & Abbasi, B 2018, ‘A numerical simulation of thermo-mechanical behaviour of a single fracture in porous rock’, paper presented at the 52nd US Rock Mechanics/Geomechanics Symposium.
Basson, G, Bassom, A P & Salmon, B 2021, ‘Simulating hydraulic fracturing preconditioning in mines with the material point method’, Journal of Applied Geophysics, vol. 195, 104471.
Brown, E 2007, ‘Rock mechanics-the basic mining science: challenges in underground mass mining’, Paper presented at the 11th ISRM Congress.
Brzovic, A, Celhay, F, Gonzalez, R & Hurtado, J 2019, ‘Evidence of a consistent process of rock fracturing during material flow within ore columns – 25 Years of fragmentation experience at the El Teniente Mine’, paper presented at the 53rd US Rock Mechanics/Geomechanics Symposium.
Bunger, A, Jeffrey, R, Kear, J, Zhang, X & Morgan, M 2011, ‘Experimental investigation of the interaction among closely spaced hydraulic fractures’, paper presented at the 45th US Rock Mechanics/Geomechanics Symposium.
Carrier, B & Granet, S 2012, ‘Numerical modelling of hydraulic fracture problem in permeable medium using cohesive zone model’, Engineering Fracture Mechanics, vol. 79, pp. 312–328.
Catalan, A, Dunstan, G, Morgan, M, Green, S, Jorquera, M, Thornhill, T, … Chitombo, G 2012, ‘How can an intensive preconditioning concept be implemented at mass mining method? Application to Cadia East panel caving project’, paper presented at the 46th US Rock Mechanics/Geomechanics Symposium.
Chen, B, Barboza, B R, Sun, Y, Bai, J, Thomas, H R, Dutko, M, … Li, C 2021, ‘A review of hydraulic fracturing simulation’, Archives of Computational Methods in Engineering,
Cordero, J A R, Sanchez, E C M & Roehl, D 2019, ‘Hydromechanical modelling of unrestricted crack propagation in fractured formations using intrinsic cohesive zone model’, Engineering Fracture Mechanics, 221, 106655.
Darling, P 2011, SME Mining Engineering Handbook, vol. 1, Society for Mining, Metallurgy & Exploration, Englewood.
Dou, L-M, Lu, C-P, Mu, Z-L & Gao, M-S 2009, ‘Prevention and forecasting of rock burst hazards in coal mines’, Mining Science and Technology (China), vol. 19, no. 5, pp. 585–591.
Eberhardt, E & Amini, A 2018. Hydraulic Fracturing. In P Bobrowsky & B Marker (Eds.), Encyclopedia of Engineering Geology, pp. 1–6. Springer International Publishing, Cham.
Escobar, R G, Sanchez, E C M, Roehl, D & Romanel, C 2019, ‘Xfem modelling of stress shadowing in multiple hydraulic fractures in multi-layered formations’, Journal of Natural Gas Science and Engineering, vol. 70, 102950.
Flores, G & Catalan, A 2019, ‘A transition from a large open pit into a novel ‘macroblock variant’ block caving geometry at Chuquicamata mine, Codelco Chile’, Journal of Rock Mechanics and Geotechnical Engineering, 11(3), 549–561.
Gao, Q & Ghassemi, A 2020a, ‘Finite element simulations of 3D planar hydraulic fracture propagation using a coupled hydromechanical interface element’, International Journal for Numerical and Analytical Methods in Geomechanics, vol. 44, no. 15, pp. 1999–2024.
Gao, Q & Ghassemi, A 2020b, ‘Three dimensional finite element simulations of hydraulic fracture height growth in layered formations using a coupled hydro-mechanical model’, International Journal of Rock Mechanics and Mining Sciences, vol. 125, 104137.
Geomechanics LLC 2015, Stress Shadows Explained: What It Is, What It Isn’t, And Why You Should Care,
Gonzalez, F, Vallejos, J, Rojas, E & Landeros, P 2022, ‘Evaluation of the seismic rock mass response to mining and the impact of preconditioning using an epidemic-type aftershock model’, International Journal of Rock Mechanics and Mining Sciences, vol. 150, 104975.
Haimson, B & Cornet, F 2003, ‘ISRM suggested methods for rock stress estimation—part 3: hydraulic fracturing (HF) and/or hydraulic testing of pre-existing fractures (HTPF)’, International Journal of Rock Mechanics and Mining Sciences, 40(7–8), 1011–1020.
Haimson, B C 1972, ‘Earthquake related stresses at Rangely, Colorado’, Paper presented at The 14th US Symposium on Rock Mechanics (USRMS).
Han, W, Cui, Z & Zhu, Z 2021, ‘The Effect of Perforation Spacing on the Variation of Stress Shadow’, Energies, vol. 14, no. 13, 4040.
Hao, C, Cheng, Y, Wang, L, Liu, H & Shang, Z 2019, ‘A novel technology for enhancing coalbed methane extraction: hydraulic cavitating assisted fracturing’, Journal of Natural Gas Science and Engineering, vol. 72, 103040.
He, Q 2017, Creating Prescribed Hydraulic Fractures in Cave Mining, doctoral dissertation, University of New South Wales, Australia.
He, Q, Suorineni, F & Oh, J 2016a, ‘Review of hydraulic fracturing for preconditioning in cave mining’, Rock Mechanics and Rock Engineering, 49(12), 4893–4910.
He, Q, Suorineni, F, Oh, J & Ma, T 2016b, ‘Modeling directional hydraulic fractures in heterogeneous rock masses’, MassMin, Sydney.
He, Q, Suorineni, F T, Ma, T & Oh, J 2017, ‘Effect of discontinuity stress shadows on hydraulic fracture re-orientation’, International Journal of Rock Mechanics and Mining Sciences, vol. 91, pp. 179–194.
Jamaloei, B Y 2021, ‘A critical review of common models in hydraulic-fracturing simulation: A practical guide for practitioners’, Theoretical and Applied Fracture Mechanics, 113, 102937.
Jeffrey, R & Mills, K 2000, ‘Hydraulic fracturing applied to inducing longwall coal mine goaf falls’, Paper presented at the 4th North American rock mechanics symposium.
Jeffrey, R, Zhang, X, Settari, A, Mills, K & Detournay, E 2001, ‘Hydraulic fracturing to induce caving: fracture model development and comparison to field data’, Paper presented at the DC Rocks 2001, The 38th US Symposium on Rock Mechanics (USRMS).
Kaiser, P K, Valley, B, Dusseault, M B & Duff, D 2013, ‘Hydraulic fracturing mine back trials—design rationale and project status’, paper presented at the ISRM International Conference for Effective and Sustainable Hydraulic Fracturing.
Kumar, D & Ghassemi, A 2018, ‘Three-dimensional poroelastic modelling of multiple hydraulic fracture propagation from horizontal wells’, International Journal of Rock Mechanics and Mining Sciences, 105, 192–209.
Ma, Y Z & Holditch, S 2015, Unconventional Oil and Gas Resources Handbook: Evaluation and development, Gulf Professional Publishing.
McTaggart, P, Slifirski, M, Shillaker, M, Kronborg, M, Webb, S, Gurry, J, … Shah, N 2012, Block Caving with Rio and NCM, viewed 12/7/2022,
Potts, D M, Zdravković, L, Addenbrooke, T I, Higgins, K G & Kovačević, N 2001, Finite Element Analysis in Geotechnical Engineering: Application, vol. 2, Thomas Telford, London.
Preisig, G, Eberhardt, E, Gischig, V, Roche, V, van der Baan, M, Valley, B, … Lowther, R 2015, ‘Development of connected permeability in massive crystalline rocks through hydraulic fracture propagation and shearing accompanying fluid injection’, Geofluids, vol. 15, no. 1–2, pp. 321–337.
Puller, J W, Mills, K W, Jeffrey, R G & Walker, R J 2016, ‘In-situ stress measurements and stress change monitoring to monitor overburden caving behaviour and hydraulic fracture pre-conditioning’, International Journal of Mining Science and Technology, vol. 26, no. 1, pp. 103–110.
Puri, R, King, G & Palmer, I 1991, ‘Damage to coal permeability during hydraulic fracturing’, paper presented at the Low Permeability Reservoirs Symposium.
Rimmelin, R, Chitombo, G & Rojas, E 2020, ‘Hydraulic fracturing in cave mining: Opportunities for improvement’, Paper presented at the MassMin 2020: Proceedings of the Eighth International Conference & Exhibition on Mass Mining.
Roussel, N P & Sharma, M M 2011, ‘Optimizing fracture spacing and sequencing in horizontal-well fracturing’, SPE Production & Operations, vol. 26, no. 02, pp. 173–184.
Rueda, J, Mejia, C, Quevedo, R & Roehl, D 2020, ‘Impacts of natural fractures on hydraulic fracturing treatment in all asymptotic propagation regimes’, Computer Methods in Applied Mechanics and Engineering, 371, 113296.
Sanchez, E C M, Cordero, J A R & Roehl, D 2020, ‘Numerical simulation of three-dimensional fracture interaction’, Computers and Geotechnics, 122, 103528.
Shojaei, A & Shao, J 2017, Porous Rock Fracture Mechanics: With Application to Hydraulic Fracturing, Drilling and Structural Engineering, Woodhead Publishing.
Sun, Y, Fu, Y & Wang, T 2021, ‘Field application of directional hydraulic fracturing technology for controlling thick hard roof: a case study’, Arabian Journal of Geosciences, vol. 14, no. 6, pp. 1–15.
Turon, A, Camanho, P P, Costa, J & Dávila, C 2006, ‘A damage model for the simulation of delamination in advanced composites under variable-mode loading’, Mechanics of materials, 38(11), 1072–1089.
Van As, A & Jeffrey, R 2000, ‘Caving induced by hydraulic fracturing at Northparkes mines’, Paper presented at the 4th North American Rock Mechanics Symposium.




© Copyright 2022, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
Please direct any queries or error reports to repository-acg@uwa.edu.au