Instrumented Saver Sub for Stick-Slip Mitigation
Solution Overview
Problem
Current methods for mitigating stick-slip in drilling operations are either top-drive specific, costly, or require tripping the entire drill string, limiting their applicability and efficiency across different top drives and drilling conditions.
Innovation Solution
An instrumented saver sub equipped with smart materials and magneto-rheological fluid that adjusts its spring and damping characteristics to match the impedance of the drill string, effectively absorbing stick-slip vibrations and standing waves, and is compatible with various top drives, allowing real-time tuning to the resonant frequency of the drill string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RPM modulation is used to mitigate stick-slip vibrations, then vibration reduction is achieved, but the solution becomes top-drive specific and cannot be easily applied to different top drives
Solution Approach 1:
The saver sub acts as an intermediary device between the top drive and drill string, providing impedance matching and vibration mitigation through its spring-damper mechanism. This mediator approach allows the system to achieve vibration control without being specific to any particular top drive configuration, as the saver sub interfaces with the drill string in a universal manner.
Solution Approach 2:
The saver sub utilizes adjustable spring constants and damping coefficients that can be modified to match the impedance characteristics of different drill string configurations. This parameter adjustability enables the same device to work effectively across various top drives and drilling conditions without requiring reconfiguration of the top drive itself.
2Reliability
If damping materials are placed down hole near the drill bit, then stick-slip vibrations are absorbed, but the cost increases and the entire drill string must be tripped for replacement
Solution Approach 1:
The instrumented saver sub serves as a mediator that provides vibration damping and impedance matching at the surface level, eliminating the need to place damping materials down hole near the drill bit. This approach avoids the time-consuming process of tripping the entire drill string for replacement while still achieving effective vibration absorption through the saver sub's adjustable damping characteristics.
Solution Approach 2:
The patent replaces the mechanical approach of installing physical damping materials down hole with an instrumented saver sub that uses controllable spring-damper mechanisms and smart materials at the surface. This substitution eliminates the need for drill string tripping while maintaining vibration mitigation effectiveness through electronic control and adjustment capabilities.
3Reliability
If impedance matching is implemented at the top drive, then stick-slip vibrations are prevented, but the settings cannot be transferred between different top drives or variable frequency drives
Solution Approach 1:
The instrumented saver sub incorporates adjustable parameters including spring constant and damping coefficient that can be modified to match the impedance characteristics of different drill string configurations. This parameter adjustability allows the same saver sub to work effectively across various top drives and variable frequency drives without requiring transfer of settings, as the device can be reconfigured on-site to match each specific operating condition.
4Reliability
If the drill string elasticity is accounted for in control systems, then resonant motion is reduced, but the system becomes top-drive specific and complex
Solution Approach 1:
The instrumented saver sub acts as a mechanical intermediary that directly addresses drill string elasticity and resonant motion through its spring-damper mechanism, eliminating the need for complex top drive control systems. This mechanical approach is simpler than electronic control systems and does not make the solution top-drive specific, as the saver sub provides passive vibration mitigation that works with any top drive configuration.
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
This solution prolongs the life of down-hole tools, reduces the need for frequent tripping, supports more drilling operations, and provides a cost-effective, portable solution that can be applied across different top drives without extensive reconfiguration.
Implementation Method 1
a spring associated with the body and comprising a shape-memory material, the shape-memory material comprising an adjustable spring constant configured to match an impedance of the top drive to a first drill string impedance of the drill string
Implementation Method 2
a damper associated with the body and comprising a magnetorheological (MR) fluid, the MR fluid comprising an adjustable damping constant configured to absorb the stick-slip vibrations of the drill string
Implementation Method 3
the damper further comprises an electromagnetic (EM) coil configured to maintain a first EM field in the first drill string configuration and change to a second EM field in response to the identified change
Data Source
AI summary
A drilling rig apparatus is disclosed for mitigating stick-slip using a saver sub that is compatible with different top drives. The saver sub includes a smart material adjustable whenever a stand is added to the drill string to have different spring characteristics to generally match the impedance of the top drive to the impedance of the drill string. The saver sub also includes a magneto rheological fluid that is adjusted whenever a stand is added to the drill string to compensate for the changed characteristics of the drill string. The damping constant implemented by the MR fluid enables the saver sub to absorb stick-slip vibrations at the top drive. Each time that a stand is connected to the drill string, the spring and damping constants may be updated to accommodate the changing characteristics of the drill string.