Borehole Plug Retrieval via Split Lock Ring and Adaptive Wipers
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Solution Overview
Problem
Borehole plugs face high shear loading issues due to differential pressure, leading to ratchet teeth breakage during milling, and existing solutions fail to efficiently retrieve plugs to the surface, especially when the tubular size increases, causing loss of contact with borehole walls and incomplete travel.
Innovation Solution
A split lock ring with a wedge-shaped section and downhole-oriented surface treatment is used to maintain pressure differential, allowing for axial movement and reducing shear stress, while an apparatus aids in flowing plugs back to the surface by bridging the growing gap, enabling retrieval without milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a body lock ring assembly with ratcheting teeth is used to maintain differential pressure, then the plug can hold pressure from above, but the ratchet teeth break under high shear loading during milling operations
Solution Approach 1:
The invention removes the upper slip assembly and its associated ratcheting lock ring from the plug design. By eliminating the upper locking mechanism, the plug relies solely on the lower slip assembly for pressure containment, thereby eliminating the shear loading problems that caused ratchet tooth breakage during milling operations.
Solution Approach 2:
The invention divides the pressure containment function between the lower slip assembly (which provides both sealing and locking) and the upper slip assembly (which is eliminated). This segmentation allows the lower assembly to be optimized for pressure holding without the compromising upper ratcheting mechanism.
2Shape
If the tubular string size increases toward the surface, then the wellbore geometry changes, but the plug loses contact with borehole walls and fails to complete travel to capture equipment
Solution Approach 1:
The invention employs a dynamic wiper assembly that can expand and contract radially to maintain contact with the borehole walls as the tubular diameter changes. The wiper's ability to adapt its size allows the plug to navigate through varying wellbore geometries and complete its travel to the capture equipment.
Solution Approach 2:
The wiper assembly acts as an intermediary between the plug and the borehole walls. It provides the necessary contact and guidance to ensure the plug completes its journey to the surface capture equipment, even when the tubular string size increases toward the surface.
3Ease of repair
If milling is used to remove plugs after use, then plugs can be extracted, but milling time is prolonged and operational efficiency is reduced
Solution Approach 1:
The invention enables the plug to be retrieved automatically through flow-back mechanisms without requiring external milling operations. The plug's lower slip assembly allows it to be pulled free and retrieved through the wellbore using normal production flow, eliminating the time-consuming milling process entirely.
Solution Approach 2:
Instead of using mechanical milling to remove the plug from the wellbore, the invention inverts the approach by using fluid flow to naturally transport the retrieved plug to the surface. This reverses the traditional removal methodology and significantly reduces operational time.
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 reduces milling time, avoids plug failure during retrieval, and ensures efficient removal of borehole plugs by managing differential pressure and facilitating upward movement through the use of wipers that adapt to increasing tubular sizes.
Implementation Method 1
The ring is tapered in cross section to allow it to act as a wedge against reaction force tending to relax the components from the set position
Implementation Method 2
The side of the ring facing the mandrel has a surface treatment that provides minimal resistance in the setting direction and digs into the mandrel to resist reaction forces from the compressed sealing element
Implementation Method 3
a surface treatment that provides minimal resistance in the setting direction and digs into the mandrel to resist reaction forces
Implementation Method 4
an apparatus that bridges a gap to the surrounding tubular wall as the tubular increases in dimension toward a surface location
Data Source
AI summary
A borehole plug or packer for treating is designed to be flowed back to a surface location after use. When the treatment is concluded pressure from above is relieved or lowered, and well fluid is flowed back, so that the plug or plugs disengages at slips designed to resist differential pressure from above. The application of differential pressure from below causes the lower slips to release one or more of such plugs in the hole into specialized sub surface or surface capture equipment so that well pressure is relieved before removal of the plugs from specialized subsurface or surface capture equipment. At least one apparatus is used to bridge transitions in wellbore dimension on the way to the surface and close the gaps to allow produced formation fluid to continue taking a packer or plug past the well diameter transition.