Vibratory Casing Recovery Assembly with Dynamic Amplification
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Solution Overview
Problem
Existing methods for well abandonment and casing recovery are inefficient due to stuck casings caused by drilling fluid sediments and cement, requiring multiple trips and excessive time and cost, with prior vibratory solutions experiencing low dynamic amplification factors due to damping in shock subs and complex resonance systems.
Innovation Solution
A vibratory casing recovery assembly with a dynamic amplification tool tuned to resonate at the frequency of a flow modifier, maximizing the dynamic amplification factor by eliminating damping and optimizing the natural frequency of the bottom hole assembly, allowing for enhanced vibration and efficient casing recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a shock sub is used to generate vibrations for casing recovery, then vibrations are produced to assist in freeing stuck casing, but the dynamic amplification factor is low due to damping in the shock sub system
Solution Approach 1:
The patent extracts the damping element (spring) from the vibration generation system. Instead of using a shock sub with a spring that provides damping, the invention uses a flow modifier that generates vibrations without inherent damping, thereby achieving high dynamic amplification factors and maximizing vibration amplitude for effective casing recovery
Solution Approach 2:
The patent employs mechanical vibration generated by a flow modifier that creates cyclic pressure variations in the fluid stream. This vibration is transmitted through the drill string to the casing, enabling the casing to vibrate at its natural frequency and break its bond with surrounding materials, thus achieving effective recovery with high dynamic amplification
2Force
If resonance is used to free stuck drill pipes and objects in wellbores, then vibration amplitude increases to assist in freeing stuck objects, but the system becomes complex requiring electrical connections and trained technicians
Solution Approach 1:
The flow modifier system is self-regulating and does not require external electrical controls or trained technicians to operate. The cyclic pressure variations are generated automatically by the fluid flow through the flow modifier geometry, and the resonance occurs naturally when the vibration frequency matches the casing's natural frequency, eliminating the need for complex control systems
Solution Approach 2:
The patent replaces complex electrical control systems with a purely hydraulic/mechanical solution. Instead of using electronically controlled resonators that require power and feedback control, the invention uses a flow modifier that generates vibrations through fluid dynamics alone, simplifying the system while maintaining effective vibration amplitude for casing recovery
3Force
If multiple trips are made into the well to cut casing into shorter lengths for recovery, then the pulling capacity is sufficient to recover the casing, but the time and cost increase significantly
Solution Approach 1:
The patent uses mechanical vibration to break the bond between the casing and surrounding materials (drilling fluid sediments, cement, sand). By inducing resonance in the casing at its natural frequency, the vibration amplitude increases sufficiently to free the stuck casing in a single trip, eliminating the need for multiple trips to cut and recover casing sections
Solution Approach 2:
The vibration generation is applied preliminarily to the stuck casing before the pulling operation. By pre-vibrating the casing at its natural frequency to break its bond with surrounding materials, the casing is freed in advance, allowing the pulling operation to succeed in a single trip without requiring multiple attempts or intermediate cutting operations
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 effective casing recovery by maximizing vibration amplitude at the gripping point, reducing the number of trips and time required, and increasing the efficiency of casing removal while minimizing stress on the assembly.
Implementation Method 1
a flow modifier for producing cyclic variations at a first frequency in the pressure of fluid through the string
Implementation Method 2
the bottom hole assembly being configured to have a resonant frequency when vibrated wherein: 0.61 < ω/n < 1.21
Implementation Method 3
the dynamic amplification tool being arranged between the anchor mechanism and the flow modifier; and the dynamic amplification tool being configured to provide a natural resonant frequency in the bottom hole assembly
Data Source
AI summary
A vibratory casing recovery bottom hole assembly and a method of recovering casing in a wellbore. The vibratory casing recovery bottom hole assembly includes a casing spear, a flow modifier and a dynamic amplification tool. The flow modifier produces cyclic variations in fluid pressure through the assembly at a first frequency and the bottom hole assembly is configured to have a natural or resonant frequency when vibrated to be near or at the first frequency. The dynamic amplification tool induces vibration in the bottom hole assembly while ensuring the dynamic amplification factor of the system is greater than one so as to transmit maximum vibration to the casing at the casing spear. Embodiments of dynamic amplification tools are described.