UCG, CBM AND SHALE GAS FRACKING HYDROGEOLOGICAL ASSESSMENT
Underground Coal Gasification (UCG) is a process where coal is gasified in place, where a matrix of boreholes are drilled into the coal seam, sealed wells are created, the coal is ignited and air is pumped into the injection wells. Fire is essentially used to ‘mine’ the coal and produce synthetic gas (syngas) which can be used directly as a fuel for power generation.
Groundwater plays two important roles in the UCG process, it supplies water needed for the gasification reactions. The pressure exerted by groundwater, provides containment of the UCG process. By operating the process below the containment pressure, there is a net migration of groundwater towards the operating UCG cavity. UCG can also have a negative impact on the groundwater environment by creating drawdown around the cavity and being a potential source of contamination.
Coal-bed methane (CBM) also known as coal seam gas (CSG) involves the drilling of boreholes into the coal seam and the consequent abstraction of groundwater to decrease the water pressure within the coal bed. When the pressure is decreased, the methane gas naturally desorbs from the coal and migrates through the coal bed. Potential groundwater impacts include dewatering of aquifers, water disposal, and groundwater recovery potential.
GCS has also a working relationship with consulting engineers in the USA in terms of shale gas hydraulic fracturing, commonly known as “fracking” and has undertaken various study tours. Not only does the fracking process require a water source, but poor management of wells could pose a contaminant risk.
GCS thus provides the following solutions tailored to UCG and CBM:
Baseline hydrogeological studies
Field testing including pump testing, packer testing and SRT/FOT testing
Site selection
Feasibility evaluations
Groundwater quality and geochemical characterisation of water, rock and coal
Flow and contaminant transport modelling
Groundwater management and monitoring