Flexible Liner Isolating Lost Circulation Zones
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Solution Overview
Problem
Conventional methods for addressing lost circulation zones in wellbores are hindered by the migration of lost circulation materials into natural fractures, dilution by mud, and instability due to static head, leading to ineffective plugging and continued fluid loss.
Innovation Solution
A flexible liner made of interstitial free steel with a tensile strength of 30,000 pounds per square inch is deployed and expanded radially using pressure to conform to the wellbore sidewalls and fractures, forming a barrier to prevent fluid loss without obstructing the wellbore diameter, utilizing a system with a piston assembly and expander to ensure contact and structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lost circulation material is pumped downhole to plug cracks, then fluid loss is mitigated, but the material migrates into natural fractures before being set, reducing effectiveness
Solution Approach 1:
The liner is deployed and expanded into contact with the wellbore sidewalls before pumping lost circulation material, creating a physical barrier that prevents material migration into fractures. This preliminary barrier ensures the LCM remains in the intended zone and sets effectively.
Solution Approach 2:
The flexible liner acts as an intermediary barrier between the wellbore and the lost circulation material. It prevents direct contact between the LCM and natural fractures, allowing the material to set properly without migrating, while still enabling fluid loss mitigation.
2Reliability
If large amounts of lost circulation material are pumped to address significant circulation losses, then fluid loss is addressed, but the material is diluted by mud in the wellbore, reducing plugging effectiveness
Solution Approach 1:
The liner is installed and expanded before pumping lost circulation material, creating a confined space that prevents dilution by wellbore mud. This ensures the LCM maintains its intended concentration and bridging properties for effective plugging.
Solution Approach 2:
The flexible liner forms a confined chamber that isolates the lost circulation material from surrounding mud. This thin film barrier prevents dilution while allowing the LCM to accumulate at the necessary concentration for effective crack plugging.
3Reliability
If lost circulation material is pumped to plug cracks, then fluid loss is mitigated, but the large static head downhole destabilizes the lost circulation zone, preventing effective plugging
Solution Approach 1:
The liner is expanded and anchored to the wellbore sidewalls before introducing lost circulation material. This preliminary stabilization creates a supported structure that resists the destabilizing effects of static head, allowing the LCM to set effectively without being disrupted by pressure fluctuations.
Solution Approach 2:
The liner expansion changes the mechanical parameters of the wellbore structure, creating a stabilized configuration that can withstand the static head. This parameter change from unexpanded to expanded state provides the structural support needed to maintain lost circulation zone stability under high pressure conditions.
4Reliability
If cement slurry is set in the wellbore to plug lost circulation zones, then fluid loss is controlled, but the cement must be drilled out later, causing loss of time
Solution Approach 1:
The flexible liner is designed as a temporary, disposable solution that provides fluid control during drilling operations. Unlike cement that requires drilling out, the liner can be left in place or easily removed, eliminating the time-consuming cement removal process while maintaining effective fluid control.
Solution Approach 2:
The liner material properties are selected to provide effective sealing and fluid control without requiring removal. The material parameters (flexibility, tensile strength, conformability) enable the liner to perform its function permanently or be easily retrieved, avoiding the time loss associated with cement drilling out operations.
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 isolates the lost circulation zone, maintaining wellbore integrity and allowing continued drilling operations without the need for special lost circulation materials or cement, reducing formation damage and ensuring effective fluid control.
Implementation Method 1
pressurizing an inside of the liner
Implementation Method 2
conforming the liner with a contour of the wellbore by pressing the liner against the sidewalls
Implementation Method 3
Cutting elements on the drill bit scrape the bottom of the wellbore as the bit is rotated and excavate material
Implementation Method 4
drilling fluid is typically pumped down the drill string and directed from the drill bit into the wellbore; the drilling fluid then flows back up the wellbore in an annulus
Implementation Method 5
While drilling the wellbore mudcake typically forms along the walls of the wellbore that results from residue from the drilling fluid and/or drilling fluid mixing with the cuttings or other solids in the formation
Data Source
AI summary
A method and system for remediating a lost circulation zone in a wellbore. A flexible liner is deployed adjacent the lost circulation zone that blocks fluid communication between the wellbore and surrounding formation. The liner material has a designated yield and tensile strength, so that in response to pressure applied in the wellbore the liner flexes and conforms to contours in the wellbore. The liner remains intact during deformation to maintain the flow barrier between the wellbore and formation. The liner is set in the wellbore with a bottom hole assembly that includes an outer housing for protecting the liner during the trip downhole. Drill pipe can be used for deploying the bottom hole assembly, and for conveying pressurized fluid for setting the liner. An expander is included with the bottom hole assembly for mechanically conforming the liner to the wellbore sidewalls.