Sonic LWD Cement Bond Evaluation with Tool Wave Correction
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Solution Overview
Problem
Traditional cement evaluation techniques using wireline logging tools are costly, time-consuming, and prone to errors due to strong tool waves in logging-while-drilling (LWD) environments, which affect the accuracy of cement bond index (BI) measurements in wellbores.
Innovation Solution
An LWD-CBL wave processing technique that corrects for tool wave interference by isolating and removing tool waves through bandpass and frequency-wavenumber filtering, followed by phase and amplitude adjustments, to enhance the accuracy of cement bond index determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wireline logging tools are used for cement evaluation, then measurement accuracy is maintained, but cost and time consumption increase
Solution Approach 1:
The patent replaces traditional wireline logging mechanical systems with logging-while-drilling (LWD) acoustic systems that measure cement bond index continuously during drilling operations, eliminating the need for separate wireline runs and reducing evaluation time while maintaining measurement capability
Solution Approach 2:
The LWD system enables continuous cement bond evaluation throughout the drilling process rather than requiring discrete wireline logging operations after drilling completion, allowing real-time assessment and immediate decision-making
2Loss of time
If logging-while-drilling tools are used for cement evaluation, then time consumption is reduced, but measurement accuracy deteriorates due to tool wave interference
Solution Approach 1:
The patent extracts and removes tool wave interference from the acoustic signals by identifying characteristic tool wave patterns and subtracting them from the total signal, isolating the cement bond evaluation components from harmful drilling environment noise
Solution Approach 2:
The patent converts the harmful tool wave interference into a beneficial signal processing opportunity by using the known characteristics of tool waves to create reference signals that, when subtracted, enhance the visibility and accuracy of the actual cement bond evaluation signals
3Device complexity
If traditional wave processing is used in LWD environments, then device complexity is maintained, but measurement reliability decreases due to tool wave interference
Solution Approach 1:
The patent segments the acoustic signal into distinct components (tool waves, casing waves, formation waves) and processes each separately using targeted filtering and signal enhancement techniques, improving reliability by addressing each signal type with appropriate processing methods
Solution Approach 2:
The patent introduces intermediate signal processing steps including bandpass filtering, frequency-wavenumber filtering, and phase/amplitude adjustments that act as mediators between the raw LWD acoustic signals and the final cement bond index calculation, enhancing measurement reliability
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 technique provides a more accurate and efficient method for determining cement bond index, reducing resource intensity and improving decision-making in wellbore integrity assessment.
Implementation Method 1
emits an acoustic wave into a wellbore
Implementation Method 2
detecting a reflected portion of the acoustic wave
Data Source
AI summary
Waves from cement bond logging with a sonic logging-while-drilling tool (LWD-CBL) are often contaminated with tool waves and may yield biased CBL amplitudes. The disclosed LWD-CBL wave processing corrects the first echo amplitudes of LWD-CBL before calculating the BI. The LWD-CBL wave processing calculates a tool wave amplitude and a phase angle difference as the difference of the phases between the tool waves and casing waves. The tool waves are then used to correct the LWD-CBL casing wave amplitude and remove errors introduced from tool waves. In conjunction with the sets of operations described, the LWD-CBL wave processing also includes array preprocessing operations. Array preprocessing may employ variation of bandpass filtering and frequency-wavenumber (F-K) filtering operations to suppress tool waves.