Recent enhancements to measurement-while-drilling (MWO) tools have increased drilling efficiency in directional wells on the North Slope of Alaska. With information provided by downhole weight on bit (WOB) and torque sensors, more timely and accurate decisions have been made, resulting in lower costs per foot. Specific applications of this technology include bit optimization, directional feedback, and drillstring-friction analysis. This paper discusses actual cases where the use of data from these downhole sensors has improved drilling performance. This information will benefit those interested in optimizing polycrystalline-diamond-compact (POC) and rollercone bit runs, improving directional-drilling assembly predictability and performance, minimizing surface torques, and planning high-departure wells.Theory PDC Bit Optimization. Koskie et al. 's1 procedure for optimizing the POC bit requires measuring the forces on the bit and knowing the formation. The MWO's of downhole WOB and torque measure actual forces on the POC bit. The formation type being drilled is predicted with the dimensionless torque value, T D , the torque per unit weight:

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Worldwide exploration and exploitation of hydrocarbons has been driven into remote and environmentally sensitive areas as other traditional areas are being depleted. Such is the case in the South American nation of Ecuador. Petroleum exploration began in Ecuador in the 1920s when drilling commenced off the coast of Guayaquil. In the 1930s, the activity migrated inland and today, most of it is centered around the Amazon region or "Oriente". The Oriente is a vast area of tropical rain forest which is home to many of the indigenous tribes of Ecuador as well as exotic flora and fauna unique to the world. Because of the sensitive landscape, directional drilling is a technique commonly used by oil companies in the Oriente to enhance their production while leaving the smallest footprint on the environment. The paper discusses in detail the directional drilling techniques used by YPF Ecuador to achieve their development objectives in Block 16. The paper also introduces the technique of horizontal drilling, a step change in directional drilling technique with superior results. Finally, the paper demonstrates why directional drilling is the key to exploration and development while minimizing the impact on the environment.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA rapid acceptance of the rotary steerable drilling system by the drilling teams of the Niger Delta operators has been occasioned by the increasing difficulties associated with directional drilling in this region. Excluding new discoveries in the deep offshore region, operators have focussed largely on finding economic and competitive ways of exploiting the mature fields already developed beyond the reach of available technologies, and the rotary steerable system presents the opportunity for further development of these fields.A major operator deployed the rotary steerable system for the first time in Nigeria early 2000. The result was a noticeable improvement in well delivery time, and significant drilling cost reduction for the project. Today, few years after inception, the system has gained wide acceptance and its application has resulted in numerous runs on several projects for these operators, with each reporting marked improvement in drilling performance and significant associated cost reduction. This paper details application of the tool in solving complex field directional drilling problems, ranging from penetration rates to drillability beyond the scope of the conventional mud motor in the Niger Delta. Improvement modules to the tools facilitated by field experiences and the future of the technology are also discussed.

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