Spherical RF MEMS Tags for Wellbore Cement Monitoring
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Solution Overview
Problem
There is an ongoing need for methods to monitor the conditions and integrity of wellbore sealants throughout their service lifetime, as they can be adversely affected by factors such as cracks, moisture, and temperature changes, which can lead to reduced strength and service life.
Innovation Solution
Geometrically shaped Radio-Frequency (RF) Micro-Electro-Mechanical System (MEMS) tags are integrated into cement mixtures, featuring RF circuitry that resonates at a specific frequency, allowing for real-time monitoring through interrogation tools that emit and detect response signals, enabling the evaluation of sealant integrity and location within the wellbore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional monitoring methods are used, then sealant integrity can be assessed, but continuous real-time monitoring is not achievable and service life cannot be maximized
Solution Approach 1:
The MEMS tag is a passive device that does not require an external power source. It harvests energy from the interrogating RF signal to power its circuitry and enable monitoring of sealant conditions throughout the service life of the wellbore completion
Solution Approach 2:
The patent replaces conventional active monitoring systems with passive MEMS tags that use electromagnetic resonance instead of mechanical or electronic power systems, enabling long-term monitoring without power sources
2Reliability
If standard MEMS tags are used in cement mixtures, then sealant monitoring is enabled, but flow efficiency is reduced due to irregular shapes
Solution Approach 1:
The MEMS tag is formed with a substantially spherical outer shape, which minimizes turbulence and maximizes flow efficiency when the tag is suspended in the cement mixture during pumping operations
3Reliability
If protective structures are added to protect RF circuitry, then reliability in downhole environment is improved, but flow efficiency is reduced due to increased size and irregular shape
Solution Approach 1:
The protective structure is designed with a substantially spherical outer shape that encloses the RF circuitry, providing protection while maintaining optimal flow characteristics in the cement mixture
Solution Approach 2:
The RF circuitry is nested within the protective spherical structure, allowing the circuitry to be protected without significantly increasing the overall hydrodynamic diameter of the tag
4Productivity
If geometric shaping is applied to improve flow, then flow efficiency is enhanced, but manufacturing complexity increases
Solution Approach 1:
The spherical geometry is achieved through standard fabrication processes including photolithography, etching, and spheroidization techniques that are well-established in MEMS manufacturing, balancing flow efficiency with manufacturability
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 MEMS tags provide efficient flow and protection in the downhole environment while enabling continuous monitoring of sealant conditions without the need for continuous power, allowing for timely maintenance and maximizing service life by detecting issues such as cracks and hydration processes.
Implementation Method 1
circuitry positioned on the first side of the first planar structure, the circuitry being configured to resonate at a resonant frequency
Data Source
AI summary
Radio frequency Micro-Electro-Mechanical System (“MEMS”) tags are geometrically shaped using protective structures. The MEMS tags may be added to wellbore cement, and pumped downhole. In addition to protecting the MEMS tags from the harsh downhole environment, the protective structures produce a more rounded shape which, in turns, increases the flow efficiency of the MEMS tags. An interrogation tool may be deployed downhole to interrogate the MEMS tags, to thereby perform a variety of wellbore operations such as assessing the integrity of the cement seal.