Optical Electromagnetic Wellbore Sensor for Cement Integrity
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Solution Overview
Problem
Current well monitoring technologies are inadequate for sensing cement or other substances outside the casing in a well annulus, particularly in monitoring cement cure and integrity, as they do not effectively characterize fluids or detect contamination that can affect curing and structural integrity.
Innovation Solution
An optical electromagnetic sensing system with distributed sensors and transmitters that use time-lapse measurements to characterize fluids in the annulus by measuring resistivity changes over time, employing electric or magnetic field sensing and inversion algorithms to monitor cement curing and fluid displacement without obstructing the casing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional monitoring technologies are used, then the wellbore structure is simple and easy to install, but the ability to sense cement and detect contamination in the annulus is insufficient
Solution Approach 1:
The patent replaces conventional electrical or mechanical sensing systems with an optical sensing system. Optical fibers are used to detect electromagnetic fields (electric and magnetic) in the annulus, substituting traditional mechanical or electrical sensors that would be more complex and invasive. This optical approach enables cement and contamination detection without compromising wellbore integrity or requiring complex installation.
2Reliability
If sensors are placed inside the casing to monitor the annulus, then the sensing capability is improved, but the casing interior is obstructed and fluid flow is affected
Solution Approach 1:
The patent uses the casing wall itself as an intermediary medium. Optical fibers are positioned against the outer surface of the casing, and the casing wall acts as a mediator that transmits electromagnetic field information from the annulus to the sensors without requiring penetration into the casing interior. This maintains unobstructed fluid flow while enabling accurate fluid characterization through the casing wall.
3Loss of time
If traditional monitoring methods are used, then the system is simple to operate, but real-time cement curing evaluation and long-term integrity monitoring are not achieved
Solution Approach 1:
The patent implements continuous monitoring by deploying optical fibers along the wellbore that remain in place throughout the cementing process and beyond. The system continuously measures electromagnetic field changes in real-time, enabling ongoing evaluation of cement curing progress and long-term integrity monitoring without requiring repeated interventions or complex temporal scheduling of measurements.
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
Enables real-time evaluation of cement curing and long-term integrity monitoring, providing valuable insights into fluid types and dielectric properties, thereby ensuring the structural integrity and sealing ability of the cement.
Implementation Method 1
optical electromagnetic sensors can be remotely interrogated to thereby detect strain, if any, induced in the optical fiber by the electrically or magnetically sensitive material
Implementation Method 2
electromagnetic transmitters can be disposed in the well and an electromagnetic field can be induced in the substance
Implementation Method 3
discrete optical electromagnetic sensors include electrically or magnetically sensitive material bonded to an optical fiber
Implementation Method 4
optical electromagnetic sensing based on fiber optic strain measurements
Data Source
AI summary
A method of monitoring a substance in a well can include disposing at least one optical electromagnetic sensor and at least one electromagnetic transmitter in the well, and inducing strain in the sensor, the strain being indicative of an electromagnetic parameter of the substance in an annulus between a casing and a wellbore of the well. A system for monitoring a substance in a well can include at least one electromagnetic transmitter, and at least one optical electromagnetic sensor with an optical waveguide extending along a wellbore to a remote location, the sensor being positioned external to a casing in the wellbore.