Multiple-point geostatistical simulation using the bunch-pasting direct sampling method

Multiple-point geostatistics has opened a new field of methodologies by which complex geological phenomena have been modeled efficiently. In this study, a modified form of direct sampling (DS) method is introduced which not only keeps the strength of DS simulation technique but also speeds it up by one or two orders of magnitude. While previous methods are based on pasting only one point at a time, here the simulation is done by pasting a bunch of nodes at a time, effectively combining the flexibility of DS with the computational advantages of patch-based methods. This bears the potential of significantly speeding up the DS method. The proposed simulation method can be used with unilateral or random simulation paths. No overlap occurs in the simulation procedure because the bunch takes the shape of the empty space around the simulated nodes. Systematic tests are carried on different training images including both categorical and continuous variables, showing that the realizations preserve the patterns existent in the training image. To illustrate the method, a Matlab implementation of the method is attached to the paper.

► Bunch-DS is an intermediate state between pixel- and bunch-based simulations.
► The CPU time scales down in a quasi-linear fashion when the bunch size is increased.
► There is a general trend of decreased quality with increased bunch size.
► A bunch size between 9 and 25 is recommended.
► A Matlab implementation of the method presented.