Merging Buoyancy Technology and Low Friction Centralizers in Deploying a Long 9-5/8" Casing String: Case History of an Ultra Extended Reach Well

Abstract

Drilling into the fields with the presence of communities, will limit closer surface well placement and eliminate the option of conventional well design. With the continuous advancement of Extended Reach Drilling (ERD) technologies, it is possible to drill in such areas; although this approach does present numerous challenges in particular while casing deployment. The project began by preparing a surface location which required a long stretch of the planned well to penetrate the reservoir target(s), thereby, placing it in the ultra-extended reach well category. Due to the shallow TVD and long well departure, the frictional forces developed in the horizontal sections were of significant magnitude. As a result of this, torque and drag were major challenges to overcome during casing running operations. This paper will examine the planning, design, simulation and practices implemented during the (1) drilling of a 12.25 in. horizontal hole section with a stepout of over 16,000 ft., and (2) the deployment of a long 9.5/8 in. casing string with partial flotation and low friction centralizers technologies. Effectively deploying such a long 9.5/8 in. casing string to the bottom of this uniquely challenging wellbore, requires significant engineering and close operational scrutiny. This involves managing frictional and drag losses through effective hole cleaning practices and fluids performance. This study documents using both partial flotation technology and low friction polymer centralization where drag and torque limits, along with potential casing lock up were considered to allow for successful casing running operations. The casing flotation is allowed by employing a buoyant chamber length over 8,800 ft., thus effectively reducing drag in the lateral section as well as the required force to deploy the casing into the extended horizontal section. This results in complete buckling elimination and significant torque reductions. Tailoring the buoyant chamber length/capacity proves to be a critical factor to allow for extended formation exposure and/or reach for casing deployment. A detailed pre-job planning methodology and modeling technique are provided to demonstrate the technical limits and improvement achieved with such technologies to effectively run the 9.5/8 in casing. Expected vs. actual friction factors will be defined and evaluated in order to enhance the assessments and predictions of the computational tools. A tailored methodology to tackle ERD challenges is also presented herein based on the combination of real time data vs. designed simulations.