Downhole Annular Barrier Sequencing for Complete Zonal Isolation
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Solution Overview
Problem
Existing downhole completion systems face challenges in ensuring that all annular barriers fully expand to abut the inner face of the borehole or well tubular metal structure for proper zonal isolation, particularly when multiple barriers are expanded simultaneously, leading to incomplete expansion of middle barriers due to liquid entrapment.
Innovation Solution
A downhole completion system with a configuration of annular barriers where the second annular barrier expands at a lower pressure than the first and third barriers, utilizing differences in thickness, material ductility and flexibility, and pressure intensifiers to ensure sequential expansion, allowing all barriers to fully abut the inner face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple annular barriers are expanded simultaneously at the same pressure, then the expansion process is simple and fast, but the middle barriers cannot fully expand due to liquid entrapment between them
Solution Approach 1:
The patent applies parameter changes by setting different expansion pressure thresholds for different annular barriers. The first annular barrier is designed to expand at a first expansion pressure, while the second annular barrier expands at a second expansion pressure that is lower than the first. This pressure differential ensures that the middle barrier expands fully before the outer barriers, preventing liquid entrapment and ensuring reliable zonal isolation for all barriers.
2Stress or pressure
If the second annular barrier is designed with thinner wall thickness and more ductile material, then it expands at lower pressure, but the manufacturing precision and strength are reduced
Solution Approach 1:
The patent applies local quality by designing the second annular barrier with different material properties and wall thickness compared to the first and third barriers. Specifically, the second barrier uses a thinner wall thickness and more ductile material to enable expansion at lower pressure. This localized modification allows the middle barrier to expand first without compromising the overall structural integrity, as the outer barriers maintain their original strength characteristics.
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
Ensures complete expansion of all annular barriers, maintaining effective zonal isolation and load-bearing capacity by prioritizing the expansion of the middle barrier first, thereby preventing liquid entrapment and ensuring proper zonal isolation and structural integrity.
Implementation Method 1
an expansion opening in the tubular metal part and a fluid channel fluidly connecting the expansion opening and the annular barrier space through which pressurised fluid passes for expanding the expandable metal sleeve and bringing the annular barrier from an unexpanded position to an expanded position
Data Source
Figure 1A~2
Figure 3
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AI summary
The present invention relates to a downhole completion system for isolating several zones in a well having a top, comprising a well tubular metal structure arranged in a borehole having an inner face in the well, and a first annular barrier, a second annular barrier and a third annular barrier, each annular barrier comprising a tubular metal part, the tubular metal part being mounted as part of the well tubular metal structure, an expandable metal sleeve surrounding the tubular metal part, each end section of the expandable metal sleeve being connected with the tubular metal part, an annular barrier space between the tubular metal part and the expandable metal sleeve, and an expansion opening in the tubular metal part and a fluid channel fluidly connecting the expansion opening and the annular barrier space through which pressurised fluid passes for expanding the expandable metal sleeve and bringing the annular barrier from an unexpanded position to an expanded position, wherein the second annular barrier is arranged in between the first annular barrier and the third annular barrier, and the second annular barrier is configured to expand at a lower pressure than the first and third annular barriers. The invention also relates to a downhole completion method for completing a downhole completion system.