REI uses directional drilling and sidetracking to maintain boreholes in the coal seam over distances up to 6,000 feet. Plotting the profile of the borehole from downhole surveys and driller logs provides the mining operation with an indication of coal seam structure. Any discontinuities intercepted during drilling, such as faults, palaeochannels, intrusions, coal burn, etc., are detected by monitoring drilling fluid pressures, changes in thrust, vibration, rate of penetration, and inspection of cuttings. REI will verify the fault location and continue drilling inby the fault to determine the offset and pitch.
