Document Type
Conference Paper
Publication Date
2024
Abstract
Carborough Downs Coal Mine experienced isolated areas of reserves with abnormally low seam permeability which had not been successfully drained to below the gas outburst threshold by SIS and UIS methods typically applied by the operation.
As a result, the mine successfully implemented trials of UIS based inseam hydraulic fracturing to increase gas drainage rates. Successful reduction of the in situ gas content from near virgin levels of around 14m3/t to below the required threshold of 7.42m3/t allowed development of gate roads, an installation face and subsequent longwall extraction.
The intensity of UIS drilling and hydraulic fracturing required to rapidly drain the seam in the extremely low permeability zones was at an unprecedented level in the Australian industry. Subsequent development through these zones identified a change in geotechnical conditions. This change resulted in increased levels of strata deformation, rib spall, an increase in TARP triggers and resulted in the need for rapid increases in support levels to maintain strata management. This support includes pre-consolidation of the areas identified as being heavily fractured in the longwall block to manage longwall face and gate road conditions during retreat.
This paper discusses the hydraulic fracturing methods developed and applied at the operation and the results obtained, along with the resultant mining conditions and strata control requirements needed to maintain a stable working environment.
Publication Details
Richard Campbell, Kyle McLennan, Andrew Seccombe, Kerri Smit and Brent Creevey, A case study of coal seam UIS hydraulic fracturing practices and resultant mining conditions, Proceedings of the 2024 Resource Operators Conference, University of Wollongong - Mining Engineering, February 2024, 60-78.