Historical Strategy Roadmap to Reduce the Operation Time for Drilling 8-1/2 Inch Production Hole Section in an Unconventional Drilling Operation

Abstract

Historically, it was time consuming to drill an unconventional horizontal well with 7,000 ft horizontal length. The most time-consuming part of drilling operation was the production hole section. The drilling team made series of significant efforts to continuously perform various trials to seek the performance improvement. By revising the casing design, optimizing the bottom hole assembly (BHA) and bit, improving the drilling practices and enhancing the drilling parameters, a similar well can be delivered with more than 50 percent time reduction. This paper presents the team strategy roadmap for achieving this improvement. At first, the rotary BHA was used to clean-out 9-5/8" casing and drill the vertical section to kick off point (KOP), then it was pulled out of hole (POOH) and changed to the motor BHA for drilling the buildup section, and finally switched to rotary steerable system (RSS) to drill the horizontal section until total depth (TD). Later on, with the horizontal length of the well extended, the motor was replaced with RSS, and both the buildup and horizontal sections were drilled with RSS in one run. Afterwards, the performance motor replaced the rotary BHA and was used to drill the vertical section, resulting in significant rate of penetration (ROP) improvement. Last step, the entire production hole section was drilled with one single run utilizing a new RSS BHA. The tripping time was minimized, the operation troubles were reduced and the well delivery became tremendously efficient. Among all the trials, it was found that drilling the entire production hole section in one single run without any extra dedicated clean-out run for 9-5/8" casing is the most efficient way to deliver the well. After drilling and delivering more than one hundred wells using this practice, it was found that this strategy can most efficiently help the team deliver the wells in a faster, safer and more cost-effective manner due to the elimination of the trips to switch BHA and performance enhancement during the drilling process. This one single run option was well established because of the utilization of more reliable directional drilling tool, the better cutting technology of the PDC bit, the best practice and other advanced technologies applied to the operation. Drilling the production hole section with one BHA in one single run is a unique example of innovation. This does not only apply to the well with a short to medium (5,000-7,000 ft) horizontal length, but also for those with excessively long horizontal length such as 10,000 ft or even longer. The road map history as stated in this paper will help those who are still seeking the strategy find the better option that fits for their own purpose.