Model-Based Acoustic Measurements for Perforated Casing Cement Evaluation
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Solution Overview
Problem
Current acoustic cement evaluation techniques, such as ultrasonic cement mapping and sonic cement bond log (CBL), face challenges in interpreting data for perforated casings, as they were developed for standard steel casings and lack a proper database for quantitative cement evaluation in perforated casings, leading to uncertainties in cement quality assessment during plug and abandon (P&A) operations.
Innovation Solution
A method and system for model-based acoustic measurements using numerical modeling, specifically finite difference or finite element methods, to create an interpretation chart for perforated casings, allowing for quantitative cement evaluation by estimating CBL amplitude and attenuation, and applying normalization factors to minimize the impact of perforations on measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional acoustic cement evaluation techniques (ultrasonic cement mapping, sonic CBL) are used for perforated casings, then the measurement process is simple and fast, but the measurement precision and reliability of cement quality assessment deteriorates due to lack of proper database for perforated casings
Solution Approach 1:
The patent performs preliminary numerical modeling to generate synthetic CBL data for perforated casings before actual field measurements. This creates a database of expected acoustic responses for various cement bond conditions in perforated casings, which is then used to interpret actual measurement data and improve assessment accuracy
Solution Approach 2:
The patent creates synthetic copies of CBL measurements through numerical modeling. These synthetic measurements simulate the acoustic response of perforated casings under different cement bond conditions, providing a reference database that copies the expected behavior without requiring physical samples or experiments
2Strength
If perforation guns are used to create holes in casing (perforate, wash and cement method), then the risk of rock failure is reduced compared to milling, but the reliability of cement squeeze success and hydrocarbon isolation deteriorates due to uncertainties in perforated casing status
Solution Approach 1:
The patent uses CBL measurements to provide feedback on cement bond quality in perforated casings. By comparing actual measurements against the synthetic database generated through numerical modeling, the system provides quantitative assessment of cement squeeze success, enabling verification of hydrocarbon isolation reliability
Solution Approach 2:
The patent replaces mechanical assessment methods (such as visual inspection or physical testing) with acoustic measurement techniques. CBL technology uses acoustic wave propagation to non-invasively evaluate cement bond quality, substituting mechanical evaluation systems with acoustic field-based assessment
3Productivity
If heavily weighted viscous mud is used to lift swarf during milling operation, then the swarf removal capability is improved, but the rock strength deteriorates leading to rock failure as the mud density exceeds what rock can withstand
Solution Approach 1:
The patent extracts and removes the problematic milling operation from the P&A process. By eliminating the need for milling through the use of perforation guns, the system removes the source of swarf generation and the associated requirement for heavily weighted mud, thereby preventing rock failure while still achieving the goal of debris removal
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 reliable quantitative cement evaluation in perforated casings, improving the success rate of P&A operations by providing accurate zonal isolation assessment and minimizing the risk of rock failure, thus ensuring well integrity and environmental safety.
Implementation Method 1
acoustic logging tool...measurements of acoustic wave propagation
Data Source
AI summary
A method of model-based acoustic measurements for a wellbore comprises creating an interpretation chart of acoustic measurements by a downhole tool in a wellbore using a numerical modeling and performing an evaluation with respect to the wellbore based on the interpretation chart.