This paper is hosted with the kind permission of the Universidad de Chile, Eighth International Conference & Exhibition on Mass Mining, 2020.
Rimmelin, R, Chitombo, G & Rojas, E 2020, 'Hydraulic fracturing in cave mining: Opportunities for improvement', in R Castro, F Báez & K Suzuki (eds), MassMin 2020: Proceedings of the Eighth International Conference & Exhibition on Mass Mining
, University of Chile, Santiago, pp. 275-288, https://doi.org/10.36487/ACG_repo/2063_15
Hydraulic Fracturing (HF) in cave mining is commonly used in competent rock under high stresses and seismic conditions, to manage risks associated with induced seismicity and cave propagation. The HF process is done using up holes drilled from the undercut level (e.g. El Teniente - Codelco) or down holes from an upper level (e.g. Newcrest mining). Discrete fractures assumed to be in the order of 20 to 40 m in diameter are then created every 1.5 m or 2.5 m along the drill holes, using water at higher pressures. In comparison, other industry experience such as Petroleum, HF is based on similar principles in terms of the drill hole alignment with the principal stresses and the use of water at high pressures, but more efficient during the process of the creation of the network of fractures. The network of fractures thus created covers a volume rather than discrete fractures and could be as long as 100 m. Currently, petroleum HF process is carried out from the surface down to 3,000 m in depth. Also, the use of additional materials such as “sand” to improve the propagation of fractures is another example of Petroleum practices that can be used in Cave Mining. Another point of discussion relies on the current practices in Cave mining, in which, stress anisotropy is not considered to address important topics such as efficiency of the HF process and spatial distribution of the HF holes, for a better coverage of the rock mass. Hydraulic Fracturing is increasingly becoming an essential enabling tool in deep hard rock cave mining, and some of the current HF practices used in the Petroleum industry offer an opportunity to improve the cave mining HF processes. This paper proposes the use of known rock mechanics principles for the cave mining industry to adopt practices used in the Petroleum to achieve the intended outcomes from HF as currently used in cave mining.
Bayer, S, Wunderle, M, Araujo, E, Alcalde, R, Yao, C, Suhy, F, Jo, T, Bases, F, Sani, A, Ma, Y, Bansal, A, Peterson, E, Goudge, R, Awasthi, A & Bhatia, M 2016, ‘Geological and geomechanical modelling of the Haynesville Shale: A full loop for unconventional fractured reservoirs’, Unconventional Resource Technology Conference, Texas.
Behrmann, L & Elbel, J 1991, ‘Effect of perforations on fracture initiation’, Journal of Petroleum Technology, vol. 43, no. 5.
Belyadi, H, Fathi, E & Belyadi, F 2019, Hydraulic Fracturing in Unconventional Reservoirs. Theories, Operations, and Economic Analysis – First Edition, Elsevier.
Brumley, J & Abbas,H 1996, ‘Hydraulic fracturing of deviated wells: interpretation of breakdown and initial fracture opening pressure’, Society of Petroleum Engineers, Columbus.
Brzovic, A & Gonzalez, R 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’, 53rd US Rock Mechanics/Geomechanics Symposium, New York.
Bunger, A, Jeffrey, R, Kear, J, Zhang, X & Morgan,M 2011, ‘Experimental investigation of the interaction among closely spaced hydraulic fractures’, 45th US Rock Mechanics/Geomechanics Symposium, San Francisco.
Catalan, A, Onederra, I & Chitombo, G 2017, ‘Evaluation of intensive preconditioning in block and panel caving – Part I, quantifying the effect on intact rock’, Mining Technology, vol. 126, no. 4, pp. 209-220.
Catalan, A & Suarez, C 2010, ‘Geotechnical characterisation – Cadia East panel caving project, New South Wales, Australia’, Proceedings of the Second International Symposium on Block and Sublevel Caving, Perth, pp. 371-387.
Deeg, W 1998, ‘Hydraulic Fracture-Initiation in Deviated or Horizontal Openhole Wellbores’, Society of Petroleum Engineers Inc./ISRM, Eurock ’98, Trondheim.
Detournay, E & Cheng, A 1993, ‘Fundamentals of Poroelasticity’, Comprehensive Rock Engineering: Principles, Practice & Projects, Volume 2: Analysis and Design Methods, pp. 113-171.
Dusseault, M & McLennan,J 2011, ‘Massive Multi-Stage Hydraulic Fracturing: Where are we?’, 45th Rock Mechanics/Geomechanics Symposium, San Francisco, California.
He, Q, Suorineni, F T & Oh, J 2016a, ‘Review of Hydraulic Fracturing for Preconditioning in Cave Mining’, Journal of Rock Mechanics & Rock Engineering, vol. 49, pp. 4893-4910.
He, Q, Suorineni, F T & Oh, J 2016b, ‘Strategies for Creating Prescribed Hydraulic Fractures in Cave Mining’, Journal of Rock Mechanics & Rock Engineering, vol. 50, pp. 967-993.
Hormazabal, E, Villegas, F, Rovira, F & Carranza-Torres, C 2010, ‘Geomechanical evaluation of macro-block caving options using 3D numerical modelling at Chuquicamata underground project in Chile’, Proceedings of the Second International Symposium on Block and Sublevel Caving, Perth, pp. 469-482.
Ishida, T, Chen, Q, Mizuta, Y & Roegiers, J-C 2004, ‘Influence of fluid viscousity on the hydraulic fracturing mechanism’, Journal of Energy Resources Technology, vol. 126 / 199.
Jaeger, J, Cook, N & Zimmerman,R 1976, Fundamentals of Rock Mechanics, Blackwell Publishing.
Jarufe, J & Vasquez, P 2008, ‘Mine-Scale 3D Stress Model for the New Mine Level Project, El Teniente, Codelco, Chile’, Proceedings of the First Southern Hemisphere International Rock Mechanics Symposium, Perth.
Jeffrey, R, Van As, A, Zhang, X, Bunger, A & Chen, Z 2010, ‘Measurement of hydraulic fracture growth in a naturally fractured orebody for application to preconditioning’, Proceedings of the Second International Symposium on Block and Sublevel Caving, Perth, pp. 647-662.
Jonsson, K & Martinsson, J 2018, ‘Evaluating the effect on seismicity of a hydraulic fracturing trial using Bayesian data analysis’, Caving 2018, Vancouver.
Pardo, C & Rojas, R 2016, ‘Selection of exploitation method based on the experience of hydraulic fracture techniques at the El Teniente mine’, 7th International Conference & Exhibition on Mas Mining, Sydney.
Rojas, E 2018, ‘Undercut rates and cave rules presentation’, Internal Caving Workshop, Phoenix.
Rojas, E & Balboa, S 2017, ‘Management of seismic risk in high stress conditions, El Teniente mine’, 9th Symposium on Rockbursts and Seismicity in Mines, Santiago.
Sainsbury, B, Sainsbury, D & Carroll, D 2018, ‘Backanalysis of PC1 cave propagation and subsidence behaviour at the Cadia East mine’, Caving 2018, Vancouver.
Sneddon, E 1946, ‘The distribution of stress in the neighbourhood of a crack in an elastic solid’, Proc R Soc Lon, pp. 229-260.
Talu, S, Van As, A, Seloka, W & Henry, R 2010, ‘Lift 2 North extension cave performance’, Proceedings of the Second International Symposium on Block and Sublevel Caving, Perth, pp. 407-421.
Windsor, C, Cavieres, P, Villaescusa, E & Pereira, J 2006, ‘Rock stress tensor measurements at El Teniente Mine, Chile’, In-Situ Rock Stress International Symposium on In-Situ Rock Stress, Trondheim.
Yew, C & Weng,X 2015, Mechanics of hydraulic fracturing - Second Edition, Elsevier.
Zham, C & Enderlin, M 2010, ‘Characterisation of rock strength in Cretaceous strata along the Stuart City Trend’, Guld Coast Association of Geological Societies Transactions v 60, Texas, pp. 693-702.
Zhang, J & Yin, S 2017, ‘Fracture gradient prediction: an overview and an improved method’, Petroleum Science, pp. 720-730.