Mid-string wiper plug with shearing elements for long casing
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Solution Overview
Problem
Wiper plugs used to clean residual cement from tubular strings in the oil and gas industry lose effectiveness beyond 5,000 feet due to wear from abrasion, reducing their ability to effectively clean long pipe sections.
Innovation Solution
The design includes elongated wiper plugs with flexible wiping flanges and shearing elements that extend beyond the pipe diameter, allowing the plugs to maintain position between pipe sections while allowing fluid flow, and a carrier system that deploys new wiper plugs at intervals to ensure effective cleaning over distances exceeding 10,000 feet by overcoming shearing elements with increased pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If wiper plugs are used to clean pipe strings beyond 5,000 feet, then the cleaning distance is extended, but the cleaning effectiveness deteriorates due to wear from abrasion
Solution Approach 1:
The pipe cleaning system is divided into multiple segments with wiper plugs positioned at different locations along the pipe string. Each wiper plug cleans a specific section, preventing any single plug from traveling the entire distance and wearing out. The shearing elements segment the deployment process, allowing controlled release of wiper plugs at predetermined intervals.
Solution Approach 2:
Wiper plugs are pre-positioned at predetermined locations along the pipe string using carriers with shearing elements. This preliminary placement ensures that fresh wiper plugs are already in position before cleaning is needed, eliminating the wear problem associated with long-distance travel. The shearing elements are pre-installed to break at specific pressures, enabling timed deployment.
2Length of stationary object
If multiple wiper plugs are deployed to clean long pipe sections, then cleaning coverage is improved, but the complexity of the deployment system increases
Solution Approach 1:
Wiper plugs are nested within carrier assemblies that include shearing elements. The carriers are positioned within the pipe string, and the wiper plugs are contained within the carriers until deployment. This nested structure simplifies the overall system by integrating multiple functions (holding, positioning, and deploying wiper plugs) into compact units.
Solution Approach 2:
The deployment system is self-actuating through pressure-activated shearing elements. When pumping pressure exceeds the shear strength of the elements, the wiper plugs are automatically released and deployed without requiring external intervention. This self-service mechanism reduces operational complexity while maintaining precise control over deployment timing.
3Length of stationary object
If wiper plugs travel long distances through the pipe, then complete cleaning coverage is achieved, but the wiping flanges become torn and worn
Solution Approach 1:
The cleaning operation is segmented into multiple shorter trips, with fresh wiper plugs deployed at predetermined intervals. Each wiper plug travels only a short distance to clean its local section, preventing the cumulative wear that would occur with long-distance travel. The shearing elements enable this segmentation by controlling deployment at specific locations.
Solution Approach 2:
The system uses disposable wiper plugs that are deployed, used for their intended short-distance cleaning function, and then discarded. Rather than recovering and reusing worn plugs, fresh plugs are continuously deployed from carriers positioned along the pipe string. This approach prioritizes cleaning effectiveness over plug recovery, accepting the cost of replacement plugs as necessary for maintaining flange integrity.
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
This solution enhances the effectiveness of cement cleaning in long pipe strings by ensuring new, undamaged wiper plugs are deployed at intervals, maintaining cleaning efficiency over distances up to 25,000 feet or more, preventing cement buildup and ensuring operational integrity.
Implementation Method 1
shearing elements that extend from the rearward end of the elongated body member by a distance that is greater than the inner diameter of the pipe to be cleaned
Implementation Method 2
spaced radially outwardly projecting wiping flanges made of flexible material and configured to extend beyond the inner diameter of the pipe to be cleaned but that deform to apply contact wiping pressure to the inner diameter of the pipe
Implementation Method 3
the rearward end of the plug has an opening that is larger in diameter than that of the central bore of the body member, and the forward end of the plug has an outer diameter that is smaller than the diameter of the opening in the rearward end of the plug
Data Source
AI summary
A wiper plug that includes an elongated body member having a forward end, a rearward end, and an open central bore; spaced radially outwardly projecting wiping flanges made of flexible material and configured to extend beyond the inner diameter of the pipe to be cleaned but that deform to apply contact wiping pressure to the inner diameter of the pipe as the wiper plug travels through the pipe; and shearing elements that extend from the rearward end of the elongated body member by a distance that is greater than the inner diameter of the pipe to be cleaned. The shearing elements hold the wiper plug in position in between two connected pipe sections while the open central bore allows cement to flow therethrough. Also, a carrier pipe for the wiper plug and method of use thereof for cleaning cement from the wellbore annulus of long casing strings.