Schlumberger

Case Study: Deepest Openhole Sidetrack Performed in the Gulf of Mexico at 30,842 ft for McMoRan Exploration

TrackMaster OH whipstock system and FasTrack mill deliver an 8 1/2-in sidetrack in downhole temperatures reaching 428 degF

Challenge: Provide an 8 1/2-in openhole sidetrack under 428-degF conditions in the Gulf of Mexico at 30,842 ft, enabling assemblies to drill ahead smoothly from the exit and subsequently run and cement 7-in casing.

Solution: Run 9 5/8-in TrackMaster OH openhole whipstock and sidetracking system and 8 1/2-in FasTrack one-trip mill.

Result: Delivered a clean 8 1/2-in sidetrack and 124-ft rathole in a single-trip time of 31.4 hours.

Sidetrack exit in ultradeep high-temperature open hole

McMoRan Exploration Co.’s Blackbeard East #1 ultradeep exploration well is located in South Timbalier Block 144 in the shallow waters of the Gulf of Mexico. The company required a full-gauge openhole sidetrack below the 95⁄8-in casing shoe into hard shale at 30,842 ft. At this depth, bottomhole temperatures can reach 428 degF.

High-temperature durability configured for the application

To provide McMoRan Exploration Co with the openhole sidetrack they required, Schlumberger ran a 95⁄8-in TrackMaster OH openhole whipstock and sidetracking system (with an 8-in OD) and set it with a hydraulic anchor at the required depth. Subsequently, an 8 1/2-in FasTrack diamondenhanced mill was run in. Because of the elevated temperatures, special sealing material with a 450 degF rating was used with an upgraded hydraulic fluid. Additional modifications were made to the standard tool configuration to compensate for the increased thermal expansion downhole for this ultradeep application.

Full-gauge exit and rathole at record depth

A clean 8 1/2-in sidetrack was milled in 3.4 hours and a 124-ft rathole was drilled in 28 hours, in one trip. This set a record for the deepest openhole sidetrack. The drilling assembly was conveyed downhole and passed through the kickoff point and into the rathole without delays. This enabled drilling of the interval, after which 7-in casing was successfully run and cemented.


Download: Deepest Openhole Sidetrack Performed in the Gulf of Mexico at 30,842 ft for McMoRan Exploration (0.70 MB PDF)

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