Downhole Shock Isolator with Splined Key and Viscous Damper
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Solution Overview
Problem
MWD and LWD systems face interference from axial vibrations and shocks during the drilling process, which can damage equipment and disrupt signal transmission, and must maintain a fixed rotational orientation despite mechanical vibrations and rotation of the drill string.
Innovation Solution
A shock isolator device is integrated into the drilling system, featuring a main sleeve and plunger with a spline key that restricts axial rotation and a spring/damper system to attenuate longitudinal shocks and resist torsional forces, ensuring the MWD/LWD tool assembly maintains orientation and reduces shock amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the MWD/LWD tool assembly is directly connected to the drill string, then data transmission and drilling operations can proceed continuously, but the tool assembly is subjected to axial vibrations and shocks that can damage equipment and disrupt signal transmission
Solution Approach 1:
A shock isolator device is introduced as an intermediary component between the drill string and the MWD/LWD tool assembly. This device includes a shock damper with a piston and damper fluid, and a splined shaft that transmits rotational motion while isolating axial shocks. The intermediary structure allows continuous drilling operations while protecting the tool assembly from harmful axial vibrations and shocks.
2Stability of the object's composition
If the MWD/LWD tool assembly is rigidly fixed to the drill string, then rotational orientation can be maintained, but torsional forces and axial shocks are transmitted to the tool assembly causing damage
Solution Approach 1:
The shock isolator device serves as a mediator that decouples the rigid connection between the drill string and tool assembly. The splined shaft maintains rotational orientation by transmitting torque, while the shock damper with piston and damper fluid isolates torsional forces and axial shocks, protecting the tool assembly from damage.
Solution Approach 2:
The shock isolator device changes the mechanical parameters of the connection between drill string and tool assembly. By introducing a compliant connection with the shock damper, the system transforms the rigid mechanical connection into a semi-flexible one that can absorb shocks while maintaining rotational control through the splined shaft engagement.
3Reliability
If a shock isolation system is added to protect the MWD/LWD tool assembly, then equipment damage is reduced, but the device complexity increases
Solution Approach 1:
The shock isolator device is segmented into distinct functional components: a shock damper section with piston and damper fluid for absorbing axial shocks, and a splined shaft section for maintaining rotational orientation. This segmentation allows each component to perform its specific function efficiently while keeping the overall design manageable and maintainable.
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 shock isolator device effectively attenuates shocks along the longitudinal axis and resists torsional forces, protecting the MWD/LWD tool assembly and maintaining accurate data measurement and transmission during drilling operations.
Implementation Method 1
a spring/damper system including a piston spring assembly with a piston/orifice/oil-filled cylindrical bore assembly
Implementation Method 2
a spring/damper system including a piston spring assembly with a piston/orifice/oil-filled cylindrical bore assembly
Data Source
AI summary
A shock isolator device for use in a downhole tool attenuates axial shocks to a protected structure and maintains that structure's rotational orientation to the tool while reducing damage to, maintenance costs of, and wear on, the device components. The shock isolator device interposes an internally- and externally-splined key between an internally-splined sleeve on an anti-rotation section and an externally-splined plunger attached to a connector. The key is less wear-resistant than the sleeve or plunger and can be replaced. The meshed sleeve, key, and plunger force the protected structure attached to the connector to maintain its rotational orientation. The sleeve of the anti-rotation system is attached to a shock damper, which damps axial shocks between the plunger and the sleeve, and is connected to a second connector. The shock damper includes a spring assembly and a viscous damper using a piston in an oil-filled cylinder forcing oil through an orifice.