Downhole Flex Joint With Adjustable Stiffness
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Solution Overview
Problem
Conventional flex joints in downhole drilling lack versatility and flexibility, particularly in directional drilling applications, as they are inflexible and prone to high bending loads, which limits their use in varied drilling scenarios and does not effectively manage vibrations and shocks.
Innovation Solution
A compact flex joint with adjustable bending stiffness, incorporating an internal spring assembly and a universal joint, along with a hydraulic actuator system and sensors for active vibration and shock control, and optional electrical insulation and feed-through features, allowing for enhanced flexibility and reduced bending loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional flex joints are used to provide flexibility in bottom hole assembly, then the assembly can deflect the borehole, but the flex joints are long and have high bending loads which limits versatility
Solution Approach 1:
The flex joint is divided into multiple components including a first component, second component, and universal joint assembly. This segmentation allows for a more compact overall structure while maintaining the necessary flexibility and load-bearing capabilities, resolving the contradiction between versatility and length.
Solution Approach 2:
The invention incorporates an adjustable stiffness mechanism that allows the bending stiffness of the flex joint to be modified during operation. This dynamic adjustment capability enables the same flex joint to adapt to different drilling conditions and dogleg severities, improving versatility without requiring multiple different-length components.
2Adaptability or versatility
If conventional flex joints are used to allow borehole deflection, then directional drilling is facilitated, but the fixed bending stiffness limits adaptability to varied drilling scenarios
Solution Approach 1:
The flex joint incorporates an adjustable stiffness mechanism with springs and adjustment features that allow the bending stiffness to be modified. This dynamic capability enables adaptation to different drilling scenarios without requiring completely different joint designs, balancing adaptability with manageable complexity.
Solution Approach 2:
The universal joint assembly serves multiple functions: it provides the necessary flexibility for borehole deflection, acts as a bearing surface for the adjustable stiffness mechanism, and maintains structural integrity under various loading conditions. This multi-functionality reduces the need for additional components, keeping complexity manageable while improving adaptability.
3Reliability
If conventional flex joints are used in directional drilling, then borehole deflection is possible, but high bending loads are generated which reduces reliability
Solution Approach 1:
The invention allows modification of the bending stiffness parameter through the adjustable mechanism. By optimizing the stiffness parameter for specific drilling conditions and dogleg severities, the flex joint can better distribute and manage bending loads, improving reliability by reducing peak stresses compared to conventional fixed-stiffness joints.
Solution Approach 2:
The adjustable stiffness mechanism allows the flex joint to dynamically adapt its mechanical properties to match the actual loading conditions. This reduces excessive bending loads by providing appropriate flexibility when needed while maintaining structural support when loads are lower, thereby improving overall reliability under varying bending conditions.
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 solution enables more efficient directional drilling by providing adjustable stiffness, reducing vibrations and shocks, and facilitating higher dogleg severities, thus improving drilling operations in various rotary and sliding modes.
Implementation Method 1
The flex joint may comprise an in-line integrated stabilizer and may be adjusted to vary the allowed angle of deflection
Implementation Method 2
The flex joint may be used to provide a bottom hole assembly with a sufficient flexibility to better allow deflection of the wellbore being drilled
Data Source
AI summary
A technique facilitates drilling applications by providing a unique flex joint. In one embodiment, the flex joint has an adjustable bending stiffness while being much more compact than conventional flex joints. The flex joint also may be designed to de-couple bending moments from the tool joints and, in some applications, can operate as an active vibration and shock control sub by incorporating suitable sensors and a hydraulic actuator system. The design also enables incorporation of other features, such as electrical insulation features disposed above and/or below the flex joint. In some applications, the flex joint also may have an electrical feed through.