Technology Focus: Drilling Technology (February 2009)

Abstract

Technology Focus To reach reserves in increasingly complex wells, drilling challenges are numerous and very impressive, requiring highly skilled engineers who must deal with many disciplines, such as tubular and rock mechanics, hydraulics, data acquisition and processing, and modeling, among others. Nowadays, drilling is faced with several limits that intensify uncertainty and risks. Hydraulics and mechanics issues illustrate these drilling limits. From a hydraulic point of view, because of narrow drilling margin (e.g., very small difference between fracture and pore pressure) coupled with inaccurate knowledge of what is happening downhole, automated control and measurements while drilling are required to maintain equivalent circulating densities within a tight margin. Indeed, the uncertainty of temperature and pressure downhole may be greater than the margin itself. As a result, this managed- or controlled-pressure drilling technology enables reducing lost circulation, formation fracturing, and differential sticking, and it enables close monitoring of static, dynamic, and transient hydraulic behavior. From a mechanical point of view, because wells are deeper and temperatures and pressures are higher, drilling equipment is pushed to its mechanical and endurance limits. Even though it is recognized that new resistant and higher-strength material needs to be developed for the future, downhole measurements with a high-speed-telemetry drillstring will aid in determining accurate mechanical limits of existing technology. This information should lead to a better understanding of drillstring mechanics to prevent vibration, friction heating, wear, fatigue, and finally failure. To reduce uncertainty on downhole mechanical and hydraulic conditions, one must measure accurately, transmit quickly, and react accordingly to make the best drilling decisions. Therefore, data processing and modeling are important aspects of measurements or control while drilling. To manage, and add value to, this massive amount of information collected downhole, real-time and accurate mechanics and hydraulics models are required. Future generations of drillers will have to push these technical limits even further. Drilling Technology additional reading available at the SPE eLibrary: www.spe.org SPE 112669 • "Challenges of Directional Drilling Through Salt in Deepwater Gulf of Mexico" by R.R. Israel, Schlumberger, et al. SPE 114050 • "Modeling of an Underbalanced-Drilling Operation Utilizing Supercritical Carbon Dioxide" by Faisal Al-Adwani, Kuwait University, et al. SPE 112683 • "A New Mud-Pulse-Telemetry System for Enhanced MWD/LWD Applications" by C. Klotz, SPE, Baker Hughes, et al. Additional reading available at OnePetro: www.onepetro.org OTC 19550 • "Overcoming Weight-Transfer Challenges in Complex, Shallow, Extended-Reach Wells on Alaska's North Slope" by Randy Thomas, SPE, ConocoPhillips Alaska, et al. See JPT November 2008, page 70.