Hydrostatic Equalization Device for Downhole Actuator Resetting
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Solution Overview
Problem
In low-level wells, the hydrostatic imbalance between the column of fluid in the pipe string and the well annulus prevents the piston from moving, making it difficult to reset the hydraulic actuator, which is essential for repeated operation of downhole tools like the DHPT for casing recovery.
Innovation Solution
A downhole assembly with a hydrostatic equalization device that allows fluid to flow between the pipe string and the annulus, enabling pressure equalization and piston movement for actuator resetting, independent of the actuator's position, using a mechanism that opens and closes radial ports mechanically rather than hydraulically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hydraulic actuator is operated in a low level well using conventional hydraulic resetting, then the actuator can perform its task, but the hydrostatic imbalance prevents the piston from moving back to reset the actuator
Solution Approach 1:
A hydrostatic equalization device is introduced as an intermediary mechanism between the pipe string and the well annulus. This device includes a valve and equalization ports that allow controlled fluid exchange to balance hydrostatic pressures, enabling the piston to reset without requiring additional trips or fluid drainage operations
Solution Approach 2:
The invention changes the hydrostatic pressure parameter by opening equalization ports that allow fluid to flow between the pipe string and the annulus. This equalizes the pressure differential across the piston, transforming the impossible reset operation into a feasible one by modifying the pressure conditions
2Reliability
If multiple trips are made to cut casing into shorter lengths for recovery, then casing can be recovered, but time and operational efficiency are reduced
Solution Approach 1:
The hydrostatic equalization device is installed and configured in advance on the pipe string before entering the well. This preliminary setup ensures that the resetting mechanism is ready to operate immediately, allowing continuous multi-cycle actuator operation without needing to retrieve and re-install equipment between trips
3Ease of operation
If the radial port is opened to allow fluid flow for resetting, then the piston can move back, but fluid may leak into the annulus when it should remain contained
Solution Approach 1:
The valve mechanism provides feedback control by automatically closing the equalization ports after pressure equalization is achieved. The system monitors the pressure balance condition and closes the fluid passage once the piston can reset, preventing unnecessary or uncontrolled fluid leakage into the annulus
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 repeated operation of the hydraulic actuator and hydraulic jack in low-level wells, facilitating efficient casing recovery by overcoming hydrostatic imbalances and allowing for effective resetting of the actuator without the need for additional trips or fluid drainage.
Implementation Method 1
a hydrostatic equalisation device, the hydrostatic equalisation device having a first tubular member with a first end configured to connect to a pipe string, a second tubular member arranged to move relative to the first tubular member and at least one radial port being selectively openable and closeable to give fluid access between a throughbore of the pipe string and an annulus around the downhole assembly
Implementation Method 2
a hydraulic actuator to perform a task by the assembly downhole, the hydraulic actuator having a tool body including a central bore and a first end configured to connect to the hydrostatic equalisation device, a piston moveable in a chamber, the chamber having an access port from the central bore on a first side of the piston and an exhaust port to the annulus on a second side of the piston
Data Source
AI summary
A downhole actuator (16) includes a piston (15) within a chamber (17) on which fluid can act on either side to hydraulically activate the actuator. A hydrostatic equilibrium device (18) and a valve (14) are mounted around the hydraulic actuator. With a radial port (28) of the hydrostatic equilibrium device closed and the valve closed to seal the string, pumping fluid through the string operates the actuator. Pressure overbalance prevents movement of the piston (15). The radial port (28) is opened to drain fluid from the string until equilibrium is reached with the annular volume and the piston (15) can be moved.