Cement Retarder Well Tool for Selective Zone Fluid Communication
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Solution Overview
Problem
Existing methods for providing fluid communication through cement in wellbore operations face challenges in maintaining fluidity and preventing cement hardening, which hinders the efficient fracturing and stimulation of specific zones in a subterranean well.
Innovation Solution
The use of well tools that release a cement retarder chemical into the annulus between the casing string and the wellbore, preventing or retarding the hardening of cement at specific locations, allowing for controlled fluid communication and fracturing operations by maintaining unset cement sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cement is placed in the annulus to secure the casing string and provide pressure isolation, then the casing string is secured and pressure isolation is achieved, but fluid communication through the cement is prevented
Solution Approach 1:
The patent divides the cemented annulus into multiple segments by creating discrete channels or pathways through the cement at specific locations. This allows the cement to maintain its pressure isolation function in most areas while permitting targeted fluid communication at selected zones for fracturing operations.
Solution Approach 2:
The patent applies local quality by modifying the cement properties or structure at specific locations to create fluid communication pathways, while maintaining the original cement characteristics in other areas to preserve pressure isolation. This localized modification enables both functions to coexist.
2Strength
If cement hardens to provide structural support and sealing, then the wellbore integrity is maintained, but fluid flow and fracturing operations are hindered
Solution Approach 1:
The patent incorporates fracturing channels or pathways into the cement structure before the fracturing operation begins. These pre-established pathways eliminate the need to fracture the cement itself during production, allowing direct fluid communication once the cement has hardened and provided its structural support.
Solution Approach 2:
The patent introduces an intermediary structure (such as a conduit, channel, or weakened plane) within the cement that facilitates fluid flow. This intermediary element allows fluid communication without compromising the overall structural integrity and sealing function of the hardened cement.
3Reliability
If the annulus is fully cemented to secure the casing, then pressure isolation is achieved, but selective zone fracturing becomes difficult
Solution Approach 1:
The patent segments the cemented annulus by creating discrete, isolated channels at specific depths or zones. Each channel provides independent access to a particular formation zone, enabling selective fracturing while the surrounding cement maintains pressure isolation between zones.
Solution Approach 2:
The patent modifies the cement structure locally at target zones to create fluid communication pathways, while leaving the cement intact in non-target areas. This localized modification enables selective access to specific zones without compromising the overall pressure isolation provided by the cemented annulus.
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 approach enables effective fluid communication and fracturing of multiple zones by preventing cement hardening, allowing for the application of sufficient fracturing pressure and enhancing the efficiency of well operations.
Implementation Method 1
releasing a cement retarder chemical into the annulus between the casing string and the wellbore, preventing or retarding the hardening of cement at specific locations
Data Source
AI summary
A well system can include a well tool with a retarder chemical. The retarder chemical is released from the well tool into an annulus and retards setting of cement therein. A method of retarding setting of cement at a location in an annulus can include releasing a retarder chemical from a well tool connected in a casing string, after the cement is placed in the annulus. A well tool can include a valve that controls fluid communication via a port between an exterior of the tool and a flow passage extending through the tool, an annular recess, and a dispersible annular exterior component received in the recess. Another well tool can include a valve that controls fluid communication between an exterior of the tool and a flow passage extending through the well tool, an internal chamber, and a retarder chemical in the chamber.