Over the years, Underbalanced Drilling has been viewed in different ways. Drilling, may see it as a cost benefit for increased Rate of Penetration (ROP) or as a method of fluid loss control, or both. Sometimes, they view it as a cost obstacle, for the reasons of additional equipment and personnel needed. Reservoir Management (Geology, Reservoir, and Production) see it as a method to increase reserves, production, and/or access additional reserves with less emphasis to cost. In reality they all want the same thing, and this presentation will highlight the application of Underbalanced Drilling as it relates to the Ellenberger formation in Pecos County, and the Devonian formation. And the tools used to achieve, reserves, access, and cost.