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Mining Technology Consultants and Associates, 113 Roskear Road, Camborne, Cornwall TR14 8BY, UK
The use of isopach or contour plans for geological surfaces as the basis for fault interpretation of coal data, even when a dense drilling pattern has been applied, is often unsatisfactory. These plans tend to ‘smooth’ or underemphasize the effects of faulting, making assessment of the likely fault pattern difficult.
Within the SURPAC2 Software system a series of modelling tools is available to assist with this interpretation process. An appropriately oriented grid is overlain on a digital terrain model (DTM) of the geological surface in question to regularize the data. The dip between data points is calculated, and a model of dip change created using the DTM method. A new contour model, which highlights trends in dip change, is produced, clearly showing likely fault traces and throw. This model may be sectioned to illustrate more graphically the disturbed and undisturbed areas. The fault model is then used as the basis for interpretation, to be compared with other models of the geology, and known local and regional faulting trends. Use of the macro facilities within SURPAC2 allows a series of surfaces to be rapidly analysed to build up a picture of likely fault continuity and pattern within the succession.
Once the fault pattern is established, it can then be used elsewhere in SURPAC2 for further modelling and evaluation. Application can be simple, such as the formation of boundaries of faulted areas for estimation of mineable coal resource. More complex modelling can be achieved by interaction between geological surfaces and the fault surfaces defined by the interpretation process. A complete model of the faults and their impingement on the coal and associated layers is formed, for further use within the SURPAC2 design tools.
