Subsurface Safety Valve for Rotating Downhole Pumps
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Solution Overview
Problem
Conventional subsurface safety valves are ineffective in sealing the wellbore quickly in emergency situations when a pump motor is positioned on top of the wellhead and a rotating shaft is used, as they fail to close due to the design constraints.
Innovation Solution
A subsurface safety valve design featuring a valve housing with a piston and a flexible sealing member, where the valve is held open by hydraulic pressure and seals the annulus upon pressure loss, utilizing a biasing element and a flexible sealing member, such as a bladder or umbrella, to ensure rapid sealing in emergency conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pump motor is positioned on top of the wellhead with a rotating shaft extending down the wellbore, then the motor size can be larger and maintenance is easier, but conventional subsurface safety valves cannot close in an emergency
Solution Approach 1:
The safety valve is divided into separate functional components: a valve body, a piston with circumferential lands, a flexible sealing member, and a biasing element. This segmentation allows each component to perform its specific function independently, enabling the valve to close reliably even when the motor is positioned above the wellhead.
Solution Approach 2:
The piston acts as an intermediary mechanism between the hydraulic pressure and the flexible sealing member. When hydraulic pressure is lost, the biasing element pushes the piston, which in turn forces the flexible sealing member to close against the annulus, ensuring reliable sealing without direct motor involvement.
2Device complexity
If conventional subsurface safety valves are used with a rotating shaft configuration, then the valve structure remains simple, but the valve fails to close quickly in emergency situations
Solution Approach 1:
The biasing element is pre-positioned to exert constant force on the piston, keeping the flexible sealing member in a ready-to-close state. When hydraulic pressure is lost, the sealing member closes immediately without delay, as the biasing element has already positioned the piston and sealing assembly for rapid actuation.
Solution Approach 2:
The flexible sealing member, designed as a flexible element, rapidly deforms and closes against the annulus when actuated by the piston. This flexible design enables quick sealing response time while maintaining a relatively simple overall valve structure.
3Productivity
If the valve is held open by hydraulic pressure, then normal production operations are maintained, but emergency sealing response may be delayed
Solution Approach 1:
The valve system is self-regulating: hydraulic pressure during normal operation automatically holds the piston and sealing member in the open position, maintaining production. When pressure is lost due to emergency conditions, the same hydraulic system failure automatically triggers the biasing element to close the valve, eliminating the need for external control systems.
Solution Approach 2:
The valve incorporates inherent feedback through the balance between hydraulic pressure and biasing element force. When hydraulic pressure is sufficient, the piston remains pushed open. When pressure drops below a threshold, the biasing element automatically compensates and closes the valve, providing automatic emergency response without additional sensing or control mechanisms.
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
The solution effectively seals the annulus around the rotating pump shaft, enhancing safety and reliability by ensuring quick closure in emergency situations, even with a pump motor positioned above the wellhead.
Implementation Method 1
a flexible sealing member for selectively sealing the annular space when a hydraulic force is exerted thereupon
Implementation Method 2
a biasing element to assist in placing the valve in a sealed condition, the biasing element positioned between the first circumferential ledge of the hollow cylinder and the first radially extending circumferential land
Implementation Method 3
the safety valve is held in an open position by filling the first reservoir of the piston and the first portion of the hollow cylinder of the valve housing with the first fluid and pressurizing the first fluid to a level sufficient to overcome the force exerted by the biasing element
Data Source
AI summary
A subsurface safety valve and method for sealing an annulus within a tubular, including a valve housing having a first section having a hollow cylinder for receiving a piston, the hollow cylinder having a first portion, a second portion and a first circumferential ledge; a piston positioned within the hollow cylinder, the piston having a first end, a second end, a first radially extending circumferential land positioned therebetween, and a first reservoir for receiving a first fluid; a biasing element to assist in placing the valve in a sealed condition, the biasing element positioned between the first circumferential ledge of the hollow cylinder and the first radially extending circumferential land; and a flexible sealing member for selectively sealing the annular space when a hydraulic force is exerted thereupon.