fax 01-972-952-9435. AbstractTorque and drag can be critical issues in drilling directional wells especially in extended reach drilling (ERD). During well planning, torque and drag must be projected to ensure the rig's rotating and hoisting equipment are adequately sized and to evaluate the limits for slide-oriented drilling motors. Depending upon formations, typical open hole friction factors (FF) used in simulation range from 0.22 in oil base mud to 0.35 in water based mud. These friction factors are scaled to a higher value than those measured in the field in order to account for tortuosity created by drilling assemblies.A new drilling technology has been developed with the objective to reduce torque and drag by drilling a smooth and straight wellbore. The technology involves extended-gauge bit design with a matched steerable motor system or a point-thebit rotary steerable system. Friction factor was studied for North Sea's wells drilled by the conventional motor systems and by new drilling systems. Significant reductions in the actual friction factors and the tortuosity index have been seen from the wells drilled by the new drilling systems.

Brazil's Campos Basin, home of several fields in water depth ranging from 100 m to more than 2000 m, is one of the most important deepwater developments in the world. Campos Basin also accounts for nearly 80 percent of Brazil's overall crude output. Drilling in Campos Basin, however, has been quite challenging due to difficult pore pressure prediction and close margin between pore pressure and fracture gradient. In addition, poor hole cleaning and high drilling vibrations have also resulted in substantial non-productive time (NPT) and related costs. To improve drilling performance, Petrobras has employed a new drilling optimization operation focused on optimization specialists with state-of-the-art technologies such as real-time modeling and LWD/MWD tools. Over the past three years, over sixty drilling optimization operations were completed in the Campos Basin area. Those fit-for-purpose optimization operations have substantially reduced the drilling cost, reduced NPT, and increased drilling efficiency. This paper will discuss the drilling problems and the technologies used to solve these problems.