Sliding Stage Cementing Tool Port Control
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Solution Overview
Problem
Deep well cementing processes face challenges due to impracticality of single stage cement injection, especially in low formation pressure areas or porous formations where high cement slurry pressure can cause formation breakdown, leading to incomplete cementation.
Innovation Solution
A downhole cementing tool with an annular casing box section and mandrel, featuring a bladder for pressure sealing and a sliding sleeve to control flow, allowing selective registration and unregistration of apertures and ports to manage cement flow effectively, and an inflatable packer for maintaining pressure seals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If single stage cement injection is used, then the cementing process is simple, but it becomes impracticable for deep wells and cannot provide complete cementation
Solution Approach 1:
The cementing process is divided into multiple stages using a casing string with multiple staging tools at different depths. Each staging tool has a port that can be selectively opened to allow cement to flow into specific annular sections. This segmentation allows complete cementation of deep wells by treating different sections separately, overcoming the limitation of single-stage injection while maintaining process manageability.
2Productivity
If high cement slurry pressure is applied to force cement into porous formations, then cement can be pushed through, but formation breakdown occurs leading to cement losses
Solution Approach 1:
The staging tool provides localized cement injection at specific depths through selectively opened ports. By controlling which ports are open, cement can be directed to specific annular sections with appropriate pressure levels. This local quality approach allows lower pressure injection in porous formations to avoid breakdown, while maintaining productivity by ensuring cement reaches all required zones through multiple staged injections.
3Reliability
If staging tools with packers are used to seal annular areas, then sectioned cementing can be achieved, but tool failures occur including packer inflation failure and port opening/closing failures
Solution Approach 1:
The staging tool uses a mandrel with ports as an intermediary mechanism between the cement slurry and the annular space. The mandrel can be selectively positioned to open or close ports, controlling cement flow to specific sections. This intermediary approach provides reliable sectioned cementing capability while simplifying the overall tool design by using a straightforward mechanical port control system rather than complex packer inflation mechanisms.
4Ease of operation
If the casing string is lowered to register apertures and ports for cement flow, then cement can be directed to specific sections, but precise alignment is required
Solution Approach 1:
The mandrel is designed to slide axially within the tool body, dynamically changing the registration between apertures and ports as the casing string is lowered. This dynamic positioning allows precise alignment to be achieved through controlled movement rather than requiring extreme manufacturing precision. The ease of operation is improved by simply lowering the casing string to the desired depth, while the manufacturing precision requirement is reduced by using this dynamic alignment mechanism.
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 reliable and complete cementing of wellbores by ensuring proper sealing and flow control, preventing formation breakdown and ensuring cement is distributed effectively across the wellbore, even in challenging deep well conditions.
Implementation Method 1
The bladder can be inflated by directing pressurized fluid from the bore through the flow line and to an inner surface of the bladder. When inflated, the bladder forms a pressure seal between the tool and outer casing string.
Implementation Method 2
An end of the mandrel slides into the body. The aperture and port are registered by lowering the casing string and cement is flowed through the registered port and aperture.
Data Source
AI summary
A downhole tool provided within a casing string for use in cement staging operations. The tool includes an inflatable packer that is integral to the body of the tool and ports in sides of the tool. The ports are selectively opened and closed for circulating cement from within the tool so that cement can flow between the casing string and a wellbore. The ports are actuated by sliding the casing string upward or downward within the wellbore. The packer can be pressure tested after being set to ensure its efficacy.