Drill String Check Valve Reconfiguration for Self-Filling Tripping
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Solution Overview
Problem
Drilling operations face challenges with check valves in drill strings, particularly in HPHT wells, as they can become dislodged, jam, or obstruct the bore, and require top filling to prevent fluid collapse, which is time-consuming and risky, especially during tripping operations.
Innovation Solution
A drill string check valve system that allows self-filling by maintaining a float or one-way valve in an open configuration during string deployment, with the option to reconfigure to a drilling configuration that prevents fluid flow up the string, utilizing a ported flapper or poppet valve mechanism activated by a pressure differential, and optionally incorporating a bypass valve for fluid circulation and safety.
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 is improved by preventing kicks and gas influx, but the drill string cannot self-fill during tripping operations requiring time-consuming top filling
Solution Approach 1:
The check valve is designed with a movable flapper that can dynamically change its position between open and closed states. During tripping operations, the flapper remains open to allow self-filling. During drilling, the flapper closes to prevent fluid flow up the string, providing dynamic adaptation to different operational requirements
Solution Approach 2:
The drill string is pre-filled with drilling fluid before tripping operations begin. This preliminary action ensures the string is ready for immediate self-filling when the flapper opens during tripping, eliminating the need for time-consuming top filling operations
2Reliability
If a flapper type check valve is used with large flappers pivoting on a small diameter pin, then the valve provides good sealing, but the flappers may become dislodged or misaligned in extreme situations
Solution Approach 1:
A spring mechanism is introduced to provide a counterbalancing force that opposes the weight and potential dislodging forces on the flapper. The spring maintains the flapper in its proper position and ensures reliable sealing while preventing dislodgement during extreme drilling conditions
Solution Approach 2:
The sealing function and the anti-dislodgement function are merged into a single integrated spring-flapper mechanism. The spring both maintains sealing contact and prevents dislodgement, eliminating the need for separate retention mechanisms
3Reliability
If a plunger type check valve is used to provide robust valve operation, then reliability is improved, but the sliding parts increase the likelihood of jamming or sticking
Solution Approach 1:
The sliding plunger mechanism is replaced with a hinged flapper mechanism that pivots on a pin. This substitution eliminates the sliding contact that causes jamming while maintaining the robustness of a positive sealing mechanism. The flapper rotates to open and close the valve without sliding friction
4Reliability
If a plunger type check valve is used to provide robust valve operation, then safety is improved, but the valve obstructs the bore limiting access to tools and devices
Solution Approach 1:
The valve components (flapper, spring, pin) are segmented and arranged within the BHA to minimize their projection into the bore. The flapper seals against the wall of the BHA rather than blocking the central bore, allowing tool access while maintaining sealing functionality
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 deployment, reducing operational time and risk of fluid spillage, while ensuring safety by preventing fluid flow up the string during drilling, and allowing for flexible reconfiguration to manage various drilling conditions.
Implementation Method 1
A drill string check valve for location towards the distal end of a drill string, the valve comprising a body defining a flow passage and a hinged flapper, in a dormant configuration the flapper being retained in an open position by a retainer, the body configured to cooperate with an activating device which has been translated through the string to reconfigure the retainer to permit the flapper to close and the valve to assume an active configuration in which the valve permits fluid to be pumped down through the valve but prevents flow up through the valve
Implementation Method 2
the body and the activating device being configured to move the flapper from the dormant configuration to the active configuration in response to fluid pressure
Data Source
Figure 1
Figure 1a
Figure 2
AI summary
A drilling method comprising running a drill string part way into a bore; then pumping fluid through the drill string; then running the drill string further into the bore; and then reconfiguring a check valve located towards the distal end of the drill string from a running configuration, in which the valve permits flow both up and down the string, to a drilling configuration in which the valve permits flow down through the string but prevents flow up through the string.