Floating Sub Tool Axial Load Compensation
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Solution Overview
Problem
Top-drive-equipped drill rigs face challenges in managing axial loads during make-up and break-out operations of drill and casing strings, leading to thread wear and damage, especially with less robust threads used in casing and production tubing, where existing floating cushion subs are not optimally effective due to limitations in hoisting capacity and precision adjustments.
Innovation Solution
A floating sub tool that provides axial load compensation through an axial stroke range using positive pressure or vacuum, comprising a housing, upper and lower members with splines, and a stinger, with fluid communication and pressure regulation mechanisms to manage loads without requiring frequent adjustments of the top drive's vertical position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the vertical position of the top drive is not adjusted during make-up, then connection operations can be performed, but axial tensile loading is induced in the drill string leading to thread wear and damage
Solution Approach 1:
A floating sub tool is introduced as an intermediary component between the top drive and the drill string. This sub tool includes a floating cushion element that acts as a mediator to absorb axial loads and accommodate vertical movements during connection operations, preventing direct transmission of tensile forces to the thread interface
Solution Approach 2:
The system changes the axial load parameters by introducing a floating mechanism that can dynamically adjust the axial position. The floating cushion element allows for axial movement within a limited range, changing the load state from fixed tensile loading to a more flexible load distribution that reduces thread stress
2Ease of operation
If existing floating cushion subs are used, then some axial load compensation is provided, but they are not optimally effective due to limitations in hoisting capacity and precision adjustments
Solution Approach 1:
The patent replaces the traditional mechanical hoisting mechanism with a fluid-based pressure regulation system. A hydraulic or pneumatic actuator is used to control the axial position of the floating cushion element, providing more precise and capable load compensation compared to mechanical means
Solution Approach 2:
The floating sub tool incorporates a fluid pressure regulation mechanism that uses hydraulic or pneumatic pressure to control the axial movement of the floating cushion element. This allows for smooth, precise, and powerful axial load compensation that overcomes the limitations of purely mechanical systems
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The floating sub tool effectively reduces axial loads on threads, minimizing wear and damage, and allows for efficient make-up and break-out operations by compensating for axial movements, thus extending the life of drill and casing string components and improving operational efficiency.
Implementation Method 1
provides axial load compensation through an axial stroke range by means of positive pressure or vacuum
Implementation Method 2
provides axial load compensation through an axial stroke range by means of positive pressure or vacuum
Implementation Method 3
Together with frictional drag, this cushion tends to damp the transmission of drilling vibrations
Implementation Method 4
this cushion tends to damp the transmission of drilling vibrations initiated at the drill bit
Data Source
AI summary
An axially-floating sub tool for axial load compensation in conjunction with a top drive comprises cylindrical upper and lower members, with the upper member being coaxially disposed within a cylindrical housing. The upper member has an upper section slidably disposed within an opening in the upper end of the housing, plus a middle section that slidably and sealingly engages the housing bore. The lower-member bore has a splined upper interval, and a coaxial stinger extending upward from an annular shoulder medially located in the lower-member bore. The lower member is connected to the lower end of the housing with the stinger slidingly and sealingly disposed within the upper-member bore, and with the lower-member splines slidingly engaging the upper-member splines, thus defining upper, middle, and lower annular chambers, with the middle and lower chambers in fluid communication, and with a regulator/check valve regulating pressure in the middle and lower chambers.