Wellbore Annular Seal Integrity Assessment via Geological Formation Logging
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Solution Overview
Problem
Existing well sealing methods in the oil and gas industry are inefficient and costly, as they often require remedial operations like cutting or perforating casing to create new annular seals, which can damage the casing and have low success rates, especially in wells lacking necessary certification and annular barriers.
Innovation Solution
A method to determine the integrity of annular seals by using wellbore tools to obtain and compare response data with characteristic geological formation responses, allowing for the qualification of geological formations as effective annular barriers without the need for extensive pressure testing, utilizing tools like cement bond logging and ultrasonic scanning to assess seal strength and bonding quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If remedial operations like cutting or perforating casing are performed to create new annular seals, then annular sealing capability is improved, but casing integrity deteriorates and operation complexity increases
Solution Approach 1:
A bridge element is introduced as an intermediary component between the existing casing and the new annular seal. This bridge element facilitates the creation of a new seal without requiring direct damage to the casing structure, thereby maintaining casing integrity while achieving the desired sealing capability
Solution Approach 2:
The method involves preliminary assessment and preparation steps including evaluating existing cement bonds, identifying suitable bridge elements, and planning the seal creation process before actual intervention. This preliminary action prevents unnecessary casing damage by selecting appropriate sealing strategies based on existing well conditions
2Reliability
If remedial operations are performed to create new annular seals, then sealing effectiveness is improved, but operation time and cost increase
Solution Approach 1:
Instead of performing comprehensive remedial operations throughout the entire wellbore, the method applies partial action by targeting only specific intervals where sealing is needed. Bridge elements are deployed selectively at problematic zones, reducing overall operation time and complexity while achieving adequate sealing effectiveness
Solution Approach 2:
The method uses logging data and pressure test results from existing wells to create models and predict sealing behavior, allowing for optimized intervention strategies that reduce trial-and-error operations and minimize time spent on ineffective remedial attempts
3Measurement precision
If extensive pressure testing is performed to verify seal integrity, then measurement accuracy is improved, but operation complexity and time increase
Solution Approach 1:
The pressure testing procedure is segmented into multiple stages with progressively increasing complexity. Initial simple pressure holds are performed first, followed by more complex leak-off tests only if needed. This segmentation allows for efficient verification of seal integrity while minimizing overall testing complexity and time
Solution Approach 2:
The method incorporates real-time feedback from pressure test results to adjust subsequent testing and intervention strategies. Pressure responses are continuously monitored and analyzed, allowing for adaptive decision-making that reduces unnecessary testing while maintaining measurement precision for critical assessments
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 method reduces costs and enhances the efficiency of well sealing operations by qualifying geological formations as effective annular barriers, ensuring compliance with industry standards without damaging the casing, and allows for more reliable abandonment and sidetracking procedures.
Implementation Method 1
cement is pumped into the inside of the casing string and down to the casing shoe. The cement is then pumped back upward toward the surface via the casing shoe into the annular space (or casing annulus) defined between the wellbore wall and an outer surface of the casing section. The cement is then left to harden, thereby fixing the casing in place.
Implementation Method 2
The cement is then left to harden, thereby fixing the casing in place.
Implementation Method 3
providing a characteristic response that is associated with a geological formation providing an effective annular seal around a lining tubing section located in a wellbore
Data Source
AI summary
A method for determining integrity of annular seals in wellbores. In an embodiment, two wellbores are selected that extend through a common geological formation which is capable of sealing against casing sections located in the wellbores. A pressure test is typically carried out in a first of the wellbores to check that the formation provides an effective seal, and a logging tool is typically run to obtain well log data from which can be derived a characteristic response that is associated with the formation providing an effective annular seal around the casing section in the first wellbore. A logging tool may then be run in the second of the wellbores to obtain a second set of well log data, which are comparable with the characteristic response to determine whether the formation provides an effective annular seal in the second wellbore.