Drilling on mature fields presents technical challenges that requires innovate approach to maximize efficiency. At Southern Argentina, one of these challenges, normally associated with near depleted fields are circulation losses, that along with presence of reactive clays; produce hole swelling, leading to additional setup operations for hole conditioning that increases completion’s time, thus having a negative impact on costs and production rate; in addition of poor data acquisition from logging. The project stated in this document shares how hole enlargement tools are applied in these wells to be able to drill at a larger outer diameter, offering an increased annular clearance window. This application reduces the need of additional wiper trips and setup trips, hence offering the opportunity of optimizing completion times and improves the quality of data acquisition from wireline tools, without changing the current well casing architecture for both surface and production sections. After conducting an analysis that evaluates the lithological and drilling environment; an integral hole enlargement polycrystalline diamond cutter (PDC) drill bit, which is a single body that contains a 6.75 inches drill bit pilot, with eccentric blades that enlarges up to 9.5 inches hole diameter, was designed aimed to drill both Comodoro Rivadavia Top and Mina El Carme Top formations, in a single run, at a competitive rate of penetration (ROP). Then a study on the motorized bottom hole assembly allowed to determine further details regarding geometric interference, hydraulic efficiency and operational parameters to ensure effective hole enlargement. This novel approach at Southern Argentina, provided an average hole size of 9.4 inches for the production section, with a drilling time very close to a traditional technique, and allowed to save ten hours in the first experience and near 12 hours in the second experience, by eliminating the conditioning trips while providing the conditions for improved quality of data acquisition. This project expands the horizon of alternatives to maintain cost efficiency and production rate for conventional drilling at Chubut and Santa Cruz province in Southern Argentina.