Delayed Fluid Loss Valve for Gravel Packing
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Solution Overview
Problem
Existing fluid loss control valves in gravel pack systems require significant tensile force to close, leading to string recoil and induced flow that can draw sand into the wellbore, complicating gravel packing operations.
Innovation Solution
A redesigned fluid loss valve that separates surface signal from actual movement, allowing tension relief before valve closure, preventing sand influx by using a mechanism that retracts collets without string recoil and enabling selective closure under tension or release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If significant tensile force is applied to close the fluid loss valve, then the valve can be reliably actuated, but the string recoils and induces flow that draws sand into the wellbore
Solution Approach 1:
The valve actuation process is segmented into two distinct phases: first, applying tensile force to shear the pin and release the flapper; second, allowing the string to recoil and close the valve. This segmentation separates the reliable actuation mechanism from the harmful sand influx, allowing each phase to occur independently and controlably.
Solution Approach 2:
The pin is sheared and the flapper is released in advance before the string recoils to close the valve. This preliminary action ensures the valve is ready to close without inducing sand influx, as the closure occurs during the recoil phase rather than during the tensile force application phase.
2Ease of operation
If the string is pulled up to close the valve, then the valve can be actuated, but the stretched string recoils and creates pressure reduction that draws sand into the annulus
Solution Approach 1:
The operation is segmented into releasing the flapper (first phase) and closing the valve (second phase). The flapper is released before the string recoils, so the closure occurs during the recoil phase rather than during the pulling phase, eliminating the harmful pressure reduction effect.
Solution Approach 2:
The flapper acts as an intermediary mechanism between the tensile force application and the valve closure. It is released by the tensile force but does not close the valve immediately; instead, it allows the string to recoil and close the valve during the recoil phase, mediating between the pulling action and the closure action to eliminate sand influx.
3Reliability
If the shear pin is sheared to release the flapper, then the valve can close, but the string stretches before the pin shears and recoils after shearing
Solution Approach 1:
The valve release process is segmented into two phases: first, applying tensile force to shear the pin and release the flapper; second, allowing the string to recoil and close the valve. This segmentation allows the string to stretch during the first phase (accepting the temporary instability) while ensuring the valve closes during the second phase when the string is in a stable, relaxed state, preventing sand influx.
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
Minimizes sand influx into the annulus during gravel packing, ensuring effective gravel deposition and preventing fluid loss, allowing for successful gravel pack operations without the complications of sand interference.
Implementation Method 1
The relative movement also freed the flapper to be biased by a pivot spring to go to the closed position
Data Source
AI summary
A fluid loss valve is disposed in a wash pipe in a gravel packing assembly. It is preferably held open initially and when in the process it is time for the valve to be able to go closed a pulling force is applied that creates relative movement to either close the valve or allow it to close without release of the assembly when under tension. This allows a surface signal that the valve is to be released for closure. The tension is relieved before string movement with the valve can occur. This can happen by slacking off before picking up again or through other time delay features that allow the tension to be removed and a lock to collapse before a lift force is applied for subsequent gravel packing operations. The valve in its closed position acts to eliminate fluid loss when excess gravel is reversed out.