Downhole Pressure-Gradient Monitoring for Annulus Leaks
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Solution Overview
Problem
Existing methods for monitoring the integrity of a tubing casing annulus in wells are inefficient, leading to unnecessary fluid refill operations and increased operational costs due to the inability to continuously detect leaks, especially in non-active wells where pressure drops to zero.
Innovation Solution
A dual sensor permanent downhole monitoring system that uses multiple pressure and temperature sensors to continuously monitor the tubing casing annulus, determining pressure and temperature gradients to detect leaks and determine when refilling is necessary, reducing unnecessary refilling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fluid refill operations are performed periodically, then the tubing casing annulus is maintained with sufficient fluid, but unnecessary refilling operations increase operational costs and time consumption
Solution Approach 1:
The system continuously monitors pressure gradients from multiple sensors in the tubing casing annulus and provides real-time feedback on fluid integrity. This feedback mechanism enables detection of actual leaks versus normal pressure variations, allowing refilling operations to be performed only when necessary, thereby eliminating unnecessary operational time and costs while maintaining reliable annulus integrity
Solution Approach 2:
The patent replaces periodic mechanical refilling operations with a continuous electronic monitoring system that uses pressure sensors and gradient calculations. This substitution transforms the approach from reactive mechanical intervention to proactive electronic detection, reducing both time loss and operational costs by eliminating unnecessary refilling while maintaining annulus integrity through continuous surveillance
2Measurement precision
If multiple pressure sensors are deployed to continuously monitor the annulus, then leak detection precision is improved, but system complexity increases
Solution Approach 1:
The system divides the tubing casing annulus into multiple monitoring zones by deploying pressure sensors at different depths. Each sensor monitors a specific segment, and the system calculates pressure gradients between segments to detect leaks. This segmentation approach improves measurement precision by localizing leak detection while managing system complexity through modular zone-based monitoring rather than requiring comprehensive continuous monitoring of the entire annulus
Solution Approach 2:
The patent uses a limited number of discrete pressure sensors at strategic locations rather than continuous monitoring throughout the entire annulus. This partial action approach provides sufficient leak detection precision by monitoring critical zones where leaks are most likely to occur or have greatest impact, while avoiding the excessive complexity of deploying sensors at every possible location
3Quantity of substance
If the tubing casing annulus is refilled when pressure drops to zero, then fluid level is maintained, but unnecessary refilling occurs during flowing conditions due to thermal expansion
Solution Approach 1:
The system dynamically adjusts refilling decisions based on real-time pressure gradient measurements and well operating conditions. By continuously monitoring pressure gradients rather than using fixed pressure thresholds, the system can distinguish between pressure drops caused by thermal expansion during flowing conditions versus actual leaks. This dynamic approach maintains the required fluid quantity in the annulus while preventing unnecessary refilling operations that would reduce operational efficiency
Solution Approach 2:
The patent changes the monitoring parameter from absolute pressure to pressure gradient. This parameter change enables the system to account for thermal expansion effects during flowing conditions, as the gradient measurement reflects relative pressure changes between sensor locations rather than absolute pressure. This allows the system to maintain appropriate fluid levels while avoiding false refilling triggers, thereby improving operational efficiency
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 system effectively reduces operational costs by continuously monitoring the annulus integrity, detecting leaks promptly, and optimizing fluid refill operations, thereby minimizing unnecessary refilling and protecting shallow fresh water aquifers from reservoir fluid.
Implementation Method 1
determining pressure differences between the at least three baseline pressure gradients and the at least three current pressure gradients
Implementation Method 2
when the well is a flowing condition, the fluid within the tubing casing annulus can expand (for example, due to temperature rises), which increase the tubing casing annulus pressure
Data Source
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AI summary
Some methods of determining a tubing and casing annulus fluid leak of a well include receiving pressure information and depth information from three or more pressure sensors in fluid communication with a fluid of the tubing casing annulus; receiving at least three baseline pressure gradients; determining at least three current pressure gradients based on the pressure information and depth information of the three or more pressure sensors; determining pressure differences between the at least three baseline pressure gradients and the at least three current pressure gradients; and determining whether any of the pressure differences are above a pressure threshold, and responsive to determining that at least one of the pressure differences is above the pressure threshold, determining a fluid level of the fluid within the tubing casing annulus based on the pressure differences.