Drill Stem Disconnect Assembly With Serrated Blocking Sleeve
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Solution Overview
Problem
Current tubing disconnects for rotary drilling lack the ruggedness and reliability to operate in extreme conditions, failing to meet industry standards for rotary drilling due to issues like shoulder separation, fretting wear, and the need for well fluid circulation or pressure activation, which can lead to accidental disconnection and obstruction of the well bore.
Innovation Solution
A drill stem disconnect assembly with a rotary shouldered threaded connection that can be selectively activated within the well bore, allowing for disconnection at multiple locations without requiring fluid circulation or pressure application, and featuring a blocking sleeve with incremental serrations for precise torque retention and release, enabling the drill stem to withstand dynamic loads and facilitate easy reconnection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current tubing disconnects are used for rotary drilling, then disconnection can be achieved, but they lack reliability and may cause shoulder separation and fretting wear
Solution Approach 1:
The disconnect assembly incorporates a blocking sleeve with incremental serrations that can dynamically transition between locked and unlocked positions. The serrations engage with corresponding features on the tubular members to prevent rotation during drilling, then can be selectively disengaged to allow controlled disconnection. This dynamic mechanism eliminates shoulder separation and fretting wear by maintaining proper alignment and preventing unintended movement.
Solution Approach 2:
The blocking sleeve acts as an intermediary component between the upper and lower tubular members. It mediates the rotational connection by providing a positive locking mechanism through its serrations, which engage with the tubular members to prevent relative rotation. This intermediary structure eliminates the harmful effects of shoulder separation and fretting wear that occur in conventional disconnect assemblies.
2Ease of operation
If pressure activation is used for disconnect, then disconnection can be achieved, but it may lead to accidental disconnection and obstruction of the well bore
Solution Approach 1:
The disconnect assembly is designed to remain in a default locked state where the blocking sleeve's serrations automatically engage with the tubular members, preventing rotation without requiring any activation mechanism. Disconnection requires a deliberate, controlled action to rotate the blocking sleeve and disengage the serrations. This self-service design eliminates the need for pressure activation, thereby preventing accidental disconnection and well bore obstruction while maintaining ease of operation through simple rotational control.
3Strength
If rotary shouldered threaded connection is used, then the drill stem can withstand dynamic loads, but it requires precise torque retention and release
Solution Approach 1:
The blocking sleeve is segmented with multiple incremental serrations around its circumference, allowing for precise angular positioning and torque control. Each serration represents a discrete angular increment, enabling precise torque retention at specific intervals. The segmented design allows the blocking sleeve to be rotated in controlled increments to achieve exact torque values, then released to the next increment for controlled disconnection. This segmentation provides the manufacturing precision needed for torque retention and release while maintaining the strength of the rotary shouldered threaded connection.
Data Source
AI summary
Disclosed is an assembly for disconnecting portions of a downhole tubular string, such as a drill stem or drill string, and removing an upper portion of the tubular string from the lower stuck portion in a well. The disconnect assembly includes a connection between joints of two portions of the tubular string. The assembly includes two tubular members and an inner sleeve having two splines each with different angular pitches or teeth counts. The assembly may include a rotary shouldered threaded connection, wherein the two tubular portions are disconnectable at the rotary shouldered threaded connection in the assembly. The assembly may include a sleeve lock, a selective no-go for landing in a profile, and a selectively deployable unlocking and unblocking tool for activating the assembly. The assembly may include connectable cylindrical members other than downhole tubulars.