A sequential indicator simulation program for categorical variables with point and block data: BlockSIS

Stochastic simulation of facies or geologic units is important before the assignment of continuous rock properties. Sequential indicator simulation (SIS) remains a reasonable approach when there are no clear genetic shapes that could be put into object-based modeling. Constraining SIS to soft secondary data coming from geological interpretation or geophysical measurements is important. There are a number of techniques including IK with a local mean, collocated cokriging, Bayesian updating, permanence of ratios, block kriging and block cokriging. BlockSIS implements all of these and more (nine all together). The images may also be cleaned using maximum a-posteriori selection.