Ultrasonic Transit Time Analysis for Cement Slurry Shrinkage
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Solution Overview
Problem
Current methods fail to accurately determine the non-plastic state shrinkage (NPSS) of cement slurries, which is crucial for predicting stresses in cement sheaths as they cure, leading to potential integrity issues and premature well failure.
Innovation Solution
A system and method using an ultrasonic cement analyzer to record transit time and maintain constant pressure, allowing for the identification of NPSS by plotting transit time and shrinkage data, enabling the calculation of stresses that develop in the cement slurry during curing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional methods focusing on short-term liquid cement slurry properties and 24-hour compressive strength are used, then ease of operation during mixing and placement is improved, but measurement precision of non-plastic state shrinkage and long-term stress prediction deteriorates
Solution Approach 1:
The invention performs preliminary measurement of total shrinkage and plastic state shrinkage before the cement slurry reaches non-plastic state, allowing calculation of non-plastic state shrinkage by subtraction. This preliminary action enables accurate long-term stress prediction while maintaining ease of operation during mixing and placement.
Solution Approach 2:
The invention replaces direct mechanical measurement of non-plastic state shrinkage with an indirect calculation method using ultrasonic transit time measurements. By substituting complex mechanical measurement with acoustic wave propagation measurements, the system achieves precise NPSS determination without complicating the mixing and placement operations.
2Ease of manufacture
If non-plastic state shrinkage is not accurately determined, then cement slurry composition design becomes simpler, but reliability of cement sheath integrity prediction deteriorates
Solution Approach 1:
The invention introduces feedback through ultrasonic transit time measurements during curing, which provide real-time data on cement slurry stiffening. This feedback mechanism allows accurate determination of when plastic state shrinkage ends and non-plastic state shrinkage begins, enabling reliable integrity prediction while maintaining straightforward composition design procedures.
Solution Approach 2:
The invention monitors changes in ultrasonic transit time as a parameter that indicates the transition from plastic to non-plastic state. By tracking this parameter change during curing, the system accurately identifies the onset of NPSS without complicating the cement slurry composition design, thereby maintaining both ease of manufacture and prediction reliability.
3Device complexity
If stress development in cement slurry is not predicted, then cement slurry composition design becomes less complex, but loss of information regarding long-term cement integrity increases
Solution Approach 1:
The invention uses ultrasonic wave transit time as an intermediary parameter to predict stress development. By measuring how long ultrasonic waves take to traverse the curing cement slurry, the system indirectly captures information about stiffening and stress development without requiring complex direct stress measurement equipment, thus reducing device complexity while preserving critical integrity information.
Solution Approach 2:
The ultrasonic measurement system serves multiple functions: it tracks curing progression, determines the transition from plastic to non-plastic state, measures total shrinkage, and predicts stress development. This multi-functionality reduces overall device complexity compared to having separate systems for each measurement, while preventing loss of long-term integrity information.
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 approach provides accurate determination of NPSS, allowing for optimized cement slurry composition design to minimize stress development, thereby enhancing long-term cement sheath integrity and preventing well failure.
Implementation Method 1
transmitting an ultrasonic signal through the cement slurry from the transmitter to the receiver
Implementation Method 2
recording a transit time of the ultrasonic signal through the cement slurry as the cement slurry cures
Data Source
AI summary
A system and method to determine a non-plastic state shrinkage (NPSS) characteristic of a cement slurry. The system and method can include operations of transmitting an ultrasonic signal through the slurry, recording a transit time of the ultrasonic signal as the slurry cures, plotting the transit time, measuring and plotting a shrinkage of the slurry, determining a transition of the transit time from an increased rate of change to a decreased rate of change, determining a first curing time at the transition, determining the detected volume at the first curing time based on the second plot; and determining a change in the detected volume from the first curing time to a second curing time, wherein the second curing time is after the first curing time.