Bulletin of Canadian Petroleum Geology

A common task in coal exploration is evaluating reserves by estimating some form of isopach map. Available machine-contouring packages, because of their gridding/contouring sequence, are generally unsatisfactory for this purpose. A different approach considers an isopach map as the difference between two complete digital models of the upper and lower surfaces involved. In addition, whereas a topographic surface can be modelled directly from a topographic map, an outcropping geological surface can be modelled best by using a structural cross section and the fold axis. These methods lead to realistic maps and are illustrated by means of data from the Mountain Park coalfield in the Rocky Mountain Foothills of west-central Alberta.