Tieback Cementing Plug System for Subsea Wellbore Remediation
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Solution Overview
Problem
The existing cementing processes for tieback casing strings are often costly and time-consuming due to issues that require removal and reinstallation of the tieback string and cement, necessitating an improved method for efficient cementing.
Innovation Solution
A plug system involving a workstring with specific wiper plugs and release plugs that allow controlled cement slurry flow into the annulus between the tieback casing and outer casing, utilizing shearable fasteners and burst tubes to manage pressure and release, facilitating effective cement placement and remedial operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional cementing processes are used for tieback casing strings, then cement can be placed in the annulus, but the process becomes costly and time-consuming when issues require removal and reinstallation of the tieback string and cement
Solution Approach 1:
The system segments the cementing operation into multiple controllable stages using separate wiper plugs (first, second, and third wiper plugs) that can be independently deployed and released. Each plug manages a specific portion of the cement slurry placement, allowing selective remediation without complete removal of the tieback string
Solution Approach 2:
Release plugs or tags serve as intermediary devices that travel through the workstring to remotely engage and disengage the wiper plugs from the tieback casing string. This intermediary mechanism enables controlled release of individual plugs without requiring physical access or removal of the entire assembly
2Ease of operation
If multiple wiper plugs are used to manage cement slurry flow, then cement placement control is improved, but the device complexity increases
Solution Approach 1:
The wiper plugs are designed with universal functionality to perform multiple operations: they act as flow control barriers, cement placement guides, and removable seals. The same plug design can be deployed at different locations along the tieback string, reducing the need for specialized components for each function
Solution Approach 2:
The system employs a nested structure where release plugs or tags are launched through the workstring to reach and engage the wiper plugs positioned within the tieback casing string. The release plugs nest within the workstring bore while the wiper plugs nest within the tieback casing annulus, creating a compact multi-layered system
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 system enables efficient cement placement and remedial operations, reducing the need for costly and time-consuming reinstallation, thereby improving the efficiency and cost-effectiveness of the cementing process.
Implementation Method 1
The wiper plug includes a burst tube adapted to burst at a pressure between 900 psi and 1100 psi
Implementation Method 2
The first wiper plug is coupled to the second wiper plug by a shearable fastener, the shearable fastener adapted to shear at a pressure between 500 psi and 700 psi
Data Source
AI summary
A method for casing a subsea wellbore includes running a tieback casing string into the subsea wellbore using a workstring including first, second, and third wiper plugs. The method further includes: launching a first release plug or tag into the workstring; pumping cement slurry into the workstring, thereby driving the first release plug or tag along the workstring; after pumping the cement slurry, launching a second release plug or tag into the workstring; and pumping chaser fluid into the workstring, thereby driving the release plugs or tags and cement slurry through the workstring. The release plugs or tags engage and release the respective wiper plugs from the workstring. The first wiper plug or release plug ruptures, thereby allowing the cement slurry to flow therethrough. The method further includes: stabbing the tieback casing string into a liner string; and retrieving the workstring, the workstring still including the third wiper plug.