Application Example: 5-7/8 Inch Openhole Whipstock Sidetrack Set at Longest Horizontal Distance From Casing Shoe in the Middle East

Abstract

An unconventional tight gas well was drilled to a 1,973 feet lateral in hard abrasive sandstone. The drill string became mechanically stuck due to wellbore geometry. A deep, openhole whipstock was set in the 5-7/8 inch lateral section to reduce recovery time from the pipe sticking event and avoid re-drilling the section length. All recent open-hole whipstock pFrom lacements could only achieve a maximum of 300 ft distance from previous 7-inch shoe due to Weight On Bit (WOB) limitations. This necessitates drilling the horizontal footage again, especially costly in cases of a deep stuck point. An openhole hydraulic set whipstock without packer was set at the longest horizontal distance of 639 feet from the 7 inch shoe, and saved redrilling that section length. A risk assessment concluded there was minimal hole washout based on the caliper. The whipstock service company provided a detailed plan with three potential whipstock setting depths ranging from 150 up to 669 feet away from 7 inch shoe. The plan execution involved conducting a successful blind back off, making a dummy run, and evaluation of hole condition based on hole drag and maximum WOB limitation after passing each potential setting depth interval. This detailed and closely monitored approach to setting point selection ensured a record achievement of 639 feet out-of-shoe setting depth in the Middle East. The wellbore was able to be assessed for WOB required to traverse the open hole and setting point locations, absence of a wellbore anomaly present that would preclude passing the whipstock, and integrity of the running and milling assembly. This avoided redrilling 639 feet of lateral section, and saved 14 days of rig time in comparison to using a cased-hole whipstock with casing milling. An openhole whipstock utilizing a hydraulically set Latch Anchor with Extended Reach Slips enabled deep setting of the whipstock at the longest horizontal distance from casing shoe.

Simulation and Application of Windowing for High-Grade Steel Thick-Wall Casing in Ultradeep Wells: A Case Study of ST102 Well

“…Section milling has a large window area and is convenient for later sidetracking operations; however, section milling is opened by hydraulic pressure, and the application of the well depth is limited [19,20], (only suitable for well depths less than 5700 m). Cone milling has the advantages of no electronic and transmission components, strong temperature and pressure resistance, simple operation, and a high success rate; therefore, it is suitable for deep wells [21,22].…”