Confidential Energy Client
Agapito Associates, Inc. (AAI) completed a geotechnical evaluation of cavity stability, inter-cavity pillar sizing, and subsidence potential for a proprietary, concept-level borehole hydraulic mining method developed for extracting bitumen-rich oil sands in the Athabasca oil sand deposit in northern Alberta, Canada.
Numerical modeling was conducted using FLAC to simulate cavity response during the mining sequence. The model simulated the complex non-linear and pore-pressure dependent behavior of the oil sands. Under low cavity pressures, cavity stability was shown to be controlled by mechanical degradation of the oil sands caused by gas exsolution.
Surface and subsurface subsidence caused by pillar convergence and overburden movement was modeled over a wide range of mining depths. Alternative mining geometries and the use of backfill were evaluated for optimizing the mining process, minimizing subsidence, and maximizing resource extraction.