Rotor Catch Assembly with Burst Disk for Downhole Retention
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Solution Overview
Problem
Downhole motors in drilling operations often experience failures of retention components, leading to issues with retaining the rotor and rotating components within the drill string, which can result in incomplete removal of equipment from the wellbore, necessitating a reliable mechanism to ensure safe retrieval and maintenance.
Innovation Solution
A rotor catch assembly with a tubular housing, a rotor catch stem, and a burst disk assembly that includes a landing ring and nozzles to provide a flowpath and restrict fluid flow until the rotor catch stem is in a landed position, allowing identification of component failure through pressure changes when the burst disk ruptures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional retention components are used to retain the rotor and rotating components, then the device structure is simple, but the reliability of retention during drill string removal is compromised when components fail
Solution Approach 1:
The rotor catch assembly is pre-installed in the drill string before drilling operations begin. The burst disk is pre-positioned in the restricted bore, and the piston is pre-loaded in the compressed state. When retention components fail and the rotor catch stem lands on the landing ring, the system automatically activates without requiring additional intervention, ensuring reliable retention during removal.
Solution Approach 2:
The burst disk acts as a pre-prepared protective barrier that contains the piston in a compressed, ready-to-activate state. This preliminary cushioning arrangement ensures that when retention failure occurs, the piston can immediately extend to engage and secure the rotor and rotating components, preventing loss during drill string removal.
2Loss of information
If fluid flow is unrestricted through the rotor catch stem bore, then fluid circulation is maintained, but pressure changes cannot be used to identify component failure
Solution Approach 1:
The burst disk is extracted from the continuous fluid flow path by positioning it to restrict flow through the rotor catch stem bore. This creates a controlled bottleneck that amplifies pressure changes when the disk ruptures, enabling detection of rotor catch stem landing on the landing ring. The restriction is strategically placed to provide detection capability while maintaining overall system fluid circulation through alternative paths.
3Reliability
If the rotor catch stem is positioned within the rotor catch housing with landing flange on landing ring, then retention of rotor and rotating components is ensured, but fluid flow restriction prevents identification of failure through pressure monitoring
Solution Approach 1:
The burst disk serves as an intermediary element between the rotor catch stem positioning system and the pressure monitoring system. When the rotor catch stem lands on the landing ring, the burst disk ruptures due to pressure differential, creating a detectable pressure change signal. This intermediary mechanism translates the mechanical positioning event into a measurable pressure signal for failure identification.
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 reliable retention and retrieval of downhole components by identifying retention component failures through pressure changes, ensuring safe operation and maintenance by maintaining fluid circulation during removal.
Implementation Method 1
allowing identification of component failure through pressure changes when the burst disk ruptures
Implementation Method 2
maintaining fluid circulation during removal
Data Source
AI summary
A rotor catch assembly includes a rotor catch housing and a rotor catch stem. The rotor catch housing is tubular and includes a landing ring formed on an inner surface thereof. The rotor catch stem is tubular and includes an annular landing flange about the rotor catch stem. The landing flange is positioned within the bore of the rotor catch housing above the landing ring. The interior of the rotor catch stem defines a rotor catch stem bore, which is coupled to the bore of the rotor catch housing below the landing ring by a rotor catch nozzle. The rotor catch stem includes a piston assembly, burst disk assembly, or nozzle assembly positioned to reduce or stop flow through the rotor catch stem bore through the rotor catch nozzle until the landing flange of the rotor catch stem lands on the landing ring of the rotor catch housing.