Sonic LWD Cement Bond Evaluation With Tool-Wave Filtering
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Solution Overview
Problem
Traditional cement evaluation techniques using wireline logging tools are costly and time-consuming, and the use of logging-while-drilling tools introduces biased cement bond index (BI) measurements due to strong tool waves, which affect the accuracy of cement bonding assessment in wellbores.
Innovation Solution
An LWD-CBL wave processing technique that corrects for tool waves by isolating and removing them from acoustic echo responses using bandpass and frequency-wavenumber filtering, along with forward modeling to enhance casing wave amplitudes and phases, thereby improving 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 combines cement bonding evaluation with the drilling operation by integrating a sonic logging tool into the drilling assembly, allowing simultaneous drilling and cement evaluation without requiring separate wireline logging operations, thus reducing time loss while maintaining measurement accuracy
Solution Approach 2:
The drilling assembly performs self-evaluation of cement bonding by incorporating sonic logging capabilities directly into the drilling toolstring, eliminating the need for separate evaluation operations and enabling the system to assess cement quality during its own operation
2Productivity
If logging-while-drilling tools are used for cement evaluation, then time efficiency is improved, but measurement accuracy deteriorates due to tool wave interference
Solution Approach 1:
The patent extracts and removes tool wave interference from the sonic logging signals through specialized processing techniques, isolating the desired cement bonding evaluation data from the harmful tool wave components generated during drilling operations
Solution Approach 2:
The patent converts the harmful tool wave interference into a beneficial signal processing opportunity by using the tool waves as reference signals to calibrate and correct the cement bonding measurements, thereby improving accuracy while maintaining time efficiency
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 resource-efficient method for assessing cement bonding along wellbores, reducing errors and enhancing the reliability of cement bond index measurements.
Implementation Method 1
an acoustic transmitter (116) configured to generate an acoustic wave in response to a trigger signal
Implementation Method 2
an acoustic receiver (124) configured to receive an acoustic echo response from the at least one transmitted acoustic wave
Implementation Method 3
An LWD-CBL wave processing technique that corrects for tool waves by isolating and removing them from acoustic echo responses using bandpass and frequency-wavenumber filtering
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 include array preprocessing operations. Array preprocessing may employ variation of bandpass filtering and frequency-wavenumber (F-K) filtering operations to suppress tool wave.