Technology Focus: Horizontal and Extended-Reach Wells
Authors: Menand Stéphane 
Published: November 2019

Technology Focus
Since the first horizontal well was drilled in 1929, or since the development of steerable mud motors and measurement-while-drilling (MWD) systems in the early 1980s, the technology used to drill horizontal wells has changed and improved significantly. If steerable mud motors are still mainly used despite the growth of the rotary-steerable-systems market, new technologies with names not even thinkable at that time are now necessary to drill these greater-than-15,000-ft lateral sections with perfect well-trajectory control and placement to maximize production and get the most of the oil in place. Indeed, one now hears about nano-drilling fluids, oscillation tools, automatic steering, cloud computing, artificial intelligence, hybrid and adaptable drill bits, embedded and miniature sensors, and fiber optics.
High-technology products have played a key role in lowering breakeven prices on shale horizontal wells. Even though the idea was suspected some time ago, recent studies have established some correlations between wellbore quality (quantified by various tortuosity indexes) and rate of penetration (ROP), occurrence of vibrations, and production. One understands now better why wellbore quality, especially along the horizontal section, is gaining momentum in the industry. Mindsets are about to change regarding weight on bit, high values not always being the preferred or best recommendation. It is now common to sacrifice some ROP for directional purposes to avoid creating an abrupt dogleg that might compromise the completions to bottom.
Drilling a horizontal well now involves a combination of various and complex technologies and variables that need to be controlled or operated almost at the same time. To overcome friction along these long wells, downhole and surface-oscillation tools are combined to transfer the most weight to the bit. To control the wellbore trajectory and counteract potential rock formation dip effect, automatic steering might be used along with geosteering to minimize tortuosity while staying in the pay zone. Survey management along with anticollision calculations are now recommended to optimize the position and spacing of wells. To select the optimum operating parameters that maximize ROP and minimize vibrations and mechanical specific energy, a drilling-data-analytics system at the surface with dashboards must•be•used.
Drilling has become a complex operation that requires a multitude of tasks to be managed at the same time, making the decision process even more difficult. Not surprisingly, then, drilling automation will gain momentum in the near future to deliver consistent execution and performance safely and with good wellbore quality.
Some of the papers selected for this month’s feature illustrate well the latest improvements to drill these complex wells.
Recommended additional reading at OnePetro: www.onepetro.org.
SPE 191495 A Practical Approach to Casing-Wear Prediction, Modeling, and Mitigation in Challenging Extended-Reach-Drilling Wells by Weifeng Dai, ConocoPhillips, et al.
SPE 191740 A Method for Calculating More-Accurate Stratigraphic Positioning of Horizontal Wells Using Continuous Inclination and Azimuthal Gamma Ray Images Even While Sliding by Susana Gutiérrez, Halliburton, et al.
SPE 192673 A Breakthrough in Extended-Reach Drilling by Introduction of a Redesigned Drillpipe Connection by Edvin Kvalvaag, ADNOC, et al.