**Acknowledgements**

**Stage I** Establishing base line

888 Effective and Sustainable Hydraulic Fracturing

**Table 1.** Proposed experimental stages.

**Stage IV** Solids injection **Stage V** Mine-through

**Stage II** Stimulation injection in virgin rock mass

difficult not to exceed the optimal pressure for stimulation.

costs predicted for the upcoming decades in North America.

its properties, and to enhance shear slip.

hydraulic injection treatments.

**5. Conclusion**

**Stage III** Connect fracture network using hydraulic fracturing to enhance stimulation potential

Stage II will comprise a stimulation of the lower section of the experimental holes. The length of the stimulated section will be determined based on televiewer data and formation testing in order to ensure connectivity with the natural fracture network. It is expected, since the natural fracture network is probably poorly connected (below the percolation threshold), that the borehole injectivity (the capacity of the formation to accept flow for a given pressure increase or reciprocally the pressure increase at a given flow rate) will be so low that it will be

At Stage III, the low borehole injectivity will be remediated through increasing fracture network connectivity by creating an array of hydraulic fractures before performing a second stimulation of the borehole. A final injection stage (Stage IV) will focus on the placement of solids in the fractured rock mass in order to better understand proppant penetration, to modify

The final stage of the experiment (Stage V) will be a diagnostic exercise where the injected volume will be mined-through in small increments to evaluate the impact of the injection treatments on the fracturing, the rock mass behaviour and the stress state in stimulated volume. Characterisation will be repeated between stages in order to evaluate changes to the base line data collected in Stage I, including change of rock mass permeability induced by the applied

Hydraulic fracturing (HF) currently has found current applications in mining environments in the promotion of rock caving and fragmentation control and has potential for stress and stiffness modification and rock mass pre-conditioning. In the O&G industry, HF in tight oil or gas shales, rocks of similar properties (low k, high E, naturally fractured…), is a vital technol‐ ogy used to develop unconventional oil and gas resources with long horizontal wells and numerous fracture stages at sites distributed along the axis of the horizontal well. We note that the properties of the rocks involved are quite similar in both industries, and the economical need for better HF predictive tools in the O&G industry is large, given the huge development

Experiments in deep mines, one planned for 2013 in Australia, and two to follow later in Canada, will be based on extensive pre-characterization, intensive monitoring, staged Tatyana Katsaga, David O. Degagné and Branko Damjanac from Toronto and Minneapolis Itasca offices, respectively, are warmly thanked for their contribution to this project in the form of a thorough literature compilation: Fig. 3 and 4 of this paper are directly built from their literature review database. Geoff Capes and Glenn Sharrock from Newcrest Mining Ltd in Australia are thanked for their incredible support and data sharing for this project.
