Reaming with Casing Technology Reduces Rig Time by 50% in Challenging Limestone and Shale Formation in Pakistan

Abstract

This paper covers successful Reaming with Casing job in Maino-17 located in Sindh, Pakistan. Throughout previous jobs during drilling in Miano block, Operator observed hole packoff and continuous caving, which raised concerns about running casing to TD. Specifically, drilling 12 ¼" hole section in Sui Main Limestone and Ghazij Shale, pressure and mechanical caving were observed throughout till TD. During wiper trip prior to run in hole 9–5/8" casing the hole condition was not good as it was packing off. Based on the challenges faced in Miano, Reaming with Casing technology was selected. The objective was to run and ream 9 5/8" casing to a total depth (TD) of 5,581 ft (1,701 m) in unstable hole conditions using Reaming with Casing. The difference in pressures between the limestone and the shale increased the possibility of hole caving during casing running. Operator’s team deployed the technology with internal catch tool to run and ream the casing through the pressurized formation. The Reaming with Casing technology provided remotely operated casing running, which eliminated the need for a stabber in the derrick, reduced the number of floor hands, integrated self-interlock system and reduced the risk of casing drop. While running in, the mud weight was 9.7ppg (1,162 kg/m3), which was kept to the minimum to avoid hydrostatic burden on loss prone formations, encountered an obstruction at 5,213 ft (1,589 m) and could not pass through. Using the Reaming with Casing, operator reamed the last ten joints of casing to casing shoe depth at 5,590 ft (1,701 m). The job was completed in approximately 12 hours without incurring any nonproductive time. Based on results, Reaming with Casing Technology was found very efficient, reducing approximately 50% of non-productive time, risk of POOH of whole casing string and associated cost as compare to conventional 9–5/8" casing job bedsides drill string/casing stuck in unstable hole. Using the Reaming with Casing technology enabled OMV to run the casing string to TD and improve operational efficiency in a challenging shale formation and enhanced safety by eliminating or removing personnel from the rig floor.