Drill String Check Valve Retainer for Self-Filling Pressure Barrier
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Solution Overview
Problem
Existing drill string check valves in drilling operations pose challenges such as self-filling issues and incomplete pressure barriers, particularly in high pressure high temperature (HPHT) wells, risking fluid expansion and flow up the drill string, and requiring top filling during tripping operations.
Innovation Solution
A drill string check valve apparatus with a flapper valve and an axially extending valve retainer that maintains the flapper in an open position during running, transitioning to a closed position for drilling, using a catcher to retain the retainer and prevent upward fluid flow, facilitated by an activating device like a ball or dart.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is incorporated in the BHA to prevent fluid flow up the drill string, then safety against kicks and gas influx is improved, but the drill string cannot self-fill during tripping operations requiring additional top filling operations
Solution Approach 1:
The check valve incorporates a movable flapper that dynamically changes position between open and closed states. During tripping operations, the flapper remains open allowing self-filling; during drilling, the flapper closes to prevent kick and gas influx, providing adaptive functionality that resolves the contradiction between safety and ease of operation
Solution Approach 2:
A valve retainer acts as an intermediary component that physically holds the flapper in the open position during tripping operations. This intermediary mechanism enables self-filling capability when needed, while allowing the flapper to close and provide safety protection during drilling operations
2Reliability
If the drill string is made up and tripped into the bore with a closed check valve, then safety is maintained, but the drill string cannot self-fill and requires top filling at intervals
Solution Approach 1:
The valve retainer is pre-installed in the valve body, positioned to hold the flapper open during tripping operations. This preliminary configuration allows the drill string to self-fill as it is tripped into the bore, eliminating the need for time-consuming top filling operations while maintaining safety through the ability to close the flapper during drilling
3Ease of operation
If flapper type check valves with an orifice are used to minimize top filling, then self-filling is improved, but the valve does not provide a complete pressure barrier
Solution Approach 1:
The flapper valve design allows the valve to dynamically adapt its flow characteristics. When open, the full bore allows rapid self-filling; when closed, the flapper provides a complete pressure barrier. This dynamic behavior resolves the contradiction between self-filling capability and pressure barrier completeness
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 self-filling of the drill string during assembly, maintains a complete pressure barrier, and allows fluid pumping during drilling without top filling, enhancing safety and efficiency in HPHT wells.
Implementation Method 1
allowing fluid to be pumped down through the drill string from surface to a drill bit, but preventing flow in the opposite direction
Implementation Method 2
an axially extending valve retainer mounted in the body and being translatable from a running position to a drilling position
Data Source
Figure 1
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AI summary
Drill string check valve apparatus comprises a tubular body and a flapper valve mounted in the body with a flapper movable between an open position and a closed position. An axially extending valve retainer is also mounted in the body and is translatable from a running position to a drilling position. In the running position the valve retainer extends through the valve to maintain the flapper in the open position. In the drilling position the valve retainer permits the flapper to move to the closed position to prevent flow up through the body.