Faced with significant operational problems, this paper describes how a novel application of computational mechanics was used to help to evaluate and gain insight into the stress distribution in the drilled rock volume above the Cusiana Field in the geologically complex foothills of the Eastern Cordillera of the Andes, Colombia, South America. This has contributed to improved understanding of the causal effects of poor hole condition and drilling difficulties, and provided the basis for the development of a mud weight planning tool. Improved drilling performance has lead to savings of millions of dollars.P. 49