Well Control Tool for Shallow Leak Upward Crossflow
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Solution Overview
Problem
Existing wellbore control tools face challenges in safely managing upward crossflow due to shallow leaks, where the flow control sub cannot be safely installed, posing risks to personnel and ineffective in isolating the leak area.
Innovation Solution
A well control tool with a lower tool string and upper tool string, featuring a unidirectional valve and radially expandable packer, is incrementally assembled and lowered into the wellbore, forming a metal-to-metal seal and using kill fluid to divert and stop upward flow, allowing for safe isolation and repair of the leak.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a flow control sub is installed to prevent upward wellbore flow, then wellbore flow can be controlled, but the installation becomes unsafe when the leak is at shallow depth
Solution Approach 1:
The well control tool is divided into a lower tool string and an upper tool string that can be assembled incrementally. The lower tool string contains the unidirectional valve and is lowered first to establish the seal, while the upper tool string is assembled separately and connected later, allowing safe installation even when the leak is at shallow depth
Solution Approach 2:
The unidirectional valve is preinstalled inside the lower tool string before lowering it into the wellbore. This preliminary placement ensures the valve is already positioned to prevent upward flow as soon as the lower tool string is in place, eliminating the need to install the valve separately in the hazardous shallow leak environment
2Reliability
If the flow control sub is installed downhole of the leak, then upward flow can be diverted, but the tool cannot be safely assembled when the leak is very shallow
Solution Approach 1:
The tool is segmented into lower and upper tool strings that can be assembled in stages. The lower tool string with the preinstalled unidirectional valve is lowered first and connected to the end receptacle, establishing flow diversion. The upper tool string is then assembled and connected, completing the tool without requiring complex assembly in the hazardous shallow zone
Solution Approach 2:
The unidirectional valve is nested inside the lower tool string during assembly at the surface, then the entire lower tool string is lowered as a complete unit. This nested arrangement simplifies the assembly process by eliminating the need to handle and install the valve separately in the difficult-to-reach shallow leak area
3Reliability
If the unidirectional valve is preinstalled in the lower tool string, then upward flow is inhibited during lowering, but the valve must be retrieved afterward for additional operations
Solution Approach 1:
The unidirectional valve is temporarily used during the critical phase of lowering and securing the well, then it is retrieved from the lower tool string to allow additional operations. The valve is recovered and discarded from the wellbore after its temporary function is complete, enabling subsequent operations through the lower tool string without the valve in place
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
Effectively manages upward crossflow by diverting fluid flow and providing a safe environment for leak isolation and repair, reducing risks to personnel and ensuring wellbore stability.
Implementation Method 1
movement of the crossflow from the lower tool string into the upper tool string is inhibited by a unidirectional valve preinstalled inside the lower tool string
Implementation Method 2
The weight of the kill fluid is selected to provide a hydrostatic head in the wellbore with an overbalance
Implementation Method 3
A metal-to-metal seal is formed between the tool and casing section so that the upward wellbore flow is diverted into the downhole end of the tool rather than around the tool
Implementation Method 4
The packer provides an additional seal between the leaking casing section and the tool
Data Source
AI summary
A method of securing a wellbore experiencing upward crossflow includes determining a depth of a leak in a first wellbore casing tubular and identifying a second wellbore casing tubular downhole of the leak depth. From a surface, a well control tool is incrementally lowered into the wellbore until a lower tool string of the well control tool is positioned in mating contact with an end receptacle of the second wellbore casing tubular. The lower tool string is exposed to the upward crossflow during lowering of the well control tool. A unidirectional valve preinstalled inside the lower tool string inhibits movement of the upward crossflow into an upper tool string of the well control tool while permitting kill fluid pumped into the upper tool string from the surface to flow into the wellbore. The unidirectional valve is retrieved to allow additional operations in the wellbore through the lower tool string.