Axial Mandrel Locking in Adjustable Downhole Bend Assemblies
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing downhole mud motors lack the ability to adjust the deflection angle of the drill bit efficiently and effectively during directional drilling, leading to increased bending moments and stress on the BHA and mud motor components, particularly when drilling deviated boreholes.
Innovation Solution
A downhole mud motor with a bend adjustment assembly that allows for adjustable deflection angles between the driveshaft housing and bearing mandrel, enabled by an adjustment mandrel that shifts in response to changes in fluid flowrate, pressure, or relative rotation, and includes locking mechanisms to maintain desired angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed bent housing is used in the BHA to provide deflection angle, then the drill bit can drill deviated boreholes, but the bending moments and stress on the BHA and mud motor components increase
Solution Approach 1:
The patent applies the dynamics principle by making the previously fixed bent housing adjustable. The bend adjustment assembly allows the deflection angle to be dynamically changed during drilling operations by shifting the adjustment mandrel between different axial positions, which changes the relative angular position between the driveshaft housing and bearing mandrel. This enables optimization of the deflection angle to reduce bending moments and stress on components while maintaining the ability to drill deviated boreholes.
2Adaptability or versatility
If the deflection angle is adjusted by changing the bent housing configuration, then the adaptability to different drilling conditions improves, but the device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the bent housing into separable components: a driveshaft housing, a bearing mandrel, and an adjustment mandrel with interlocking protrusions. This allows the deflection angle to be adjusted by shifting the adjustment mandrel to different axial positions, which changes the relative angular positioning between housing segments. This segmented design provides angle variability without requiring complete redesign of the entire BHA structure.
Solution Approach 2:
The adjustment mandrel is disposed within the driveshaft housing and can shift axially within the bearing mandrel, creating a nested configuration. The interlocking protrusions on the adjustment mandrel engage with corresponding features in the housing, allowing compact storage of the adjustment mechanism within the existing BHA structure while providing deflection angle variability.
3Manufacturing precision
If manual adjustment of the bend assembly is required, then the manufacturing precision can be maintained, but the ease of operation during drilling decreases
Solution Approach 1:
The patent applies self-service by enabling automatic adjustment of the deflection angle through changes in drilling parameters. The adjustment mandrel shifts in response to changes in fluid flowrate, pressure, or relative rotation between the driveshaft housing and bearing mandrel. This eliminates the need for manual intervention during drilling operations while maintaining precise angular positioning through the interlocking protrusion mechanism.
Solution Approach 2:
The system incorporates feedback mechanisms where changes in fluid flowrate, pressure, or relative rotation are detected and automatically cause the adjustment mandrel to shift to appropriate axial positions. This creates a closed-loop system where drilling conditions automatically regulate the deflection angle, providing both ease of operation and manufacturing precision through the mechanical interlocking features.
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
Enables in-situ adjustment of the drill bit deflection angle, reducing bending moments and stress on the BHA and mud motor components, thereby enhancing the efficiency and durability of directional drilling operations.
Implementation Method 1
the adjustment mandrel is configured to shift from the first axial position to the second axial position in response to supplying the downhole mud motor with drilling fluid at a threshold pressure or a threshold flowrate
Implementation Method 2
interlocking engagement between the adjustment mandrel and an offset housing prevent the bend adjustment assembly from actuating from the first position to the second position when the adjustment mandrel is in the first axial position
Data Source
Figure 1
Figure 2~3
Figure 4
AI summary
A downhole mud motor includes a driveshaft housing, a driveshaft rotatably disposed in the driveshaft housing, a bearing mandrel coupled to the driveshaft, and a bend adjustment assembly including a first position, wherein the bend adjustment assembly includes a second position, wherein the bend adjustment assembly includes an adjustment mandrel having a first axial position corresponding to the first position of the bend adjustment assembly and a second axial position which corresponds to the second position of the bend adjustment assembly, and wherein the bend adjustment assembly is prevented from actuating from the first position to the second position when the adjustment mandrel is in the first axial position, and wherein the bend adjustment assembly is permitted to actuate between the first position and the second position when the adjustment mandrel is in a second axial position that is axially spaced from the first axial position.