Drill-Bit Seismic Imaging for Low-Noise Wellbore Mapping
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Solution Overview
Problem
Existing logging while drilling (LWD) tools face challenges in acquiring high-quality formation data due to formation damage, high costs, and noise interference from the drilling process, limiting the ability to determine formation properties like fractures, faults, and bedding interfaces.
Innovation Solution
Utilizing the drill bit as a seismic source to generate acoustic energy, decompose seismic data into monopole and dipole modes, and process these modes to enhance signal-to-noise ratio, allowing for continuous recording and imaging of formation interfaces using monopole and dipole waveforms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional LWD tools are used to acquire formation data, then data acquisition is possible, but the data quality is degraded due to noise interference from the drilling process
Solution Approach 1:
The patent converts the harmful drill bit vibrations into a beneficial seismic source. By treating the drill bit as an active vibrator that generates acoustic energy, the noise is transformed into a useful signal for imaging formation interfaces, eliminating the need for separate seismic sources and improving data quality despite the presence of drilling operations
Solution Approach 2:
The patent extracts and separates monopole and dipole modes from the complex seismic signal using azimuthal receiver elements. By decomposing the wavefield into distinct modes and applying mode-specific processing, the method isolates useful formation information from drilling noise, significantly improving measurement precision
2Productivity
If conventional seismic imaging methods are used, then formation imaging is achieved, but the process is time-consuming and cannot provide near-real-time data
Solution Approach 1:
The patent enables continuous seismic data acquisition during the drilling process by using the drill bit as an ongoing vibrational source. Data are recorded continuously as the drill bit progresses through formations, allowing near-real-time imaging without interrupting drilling operations, thus dramatically improving productivity and reducing time loss
Solution Approach 2:
The system uses the drill bit's own vibrations to generate seismic energy for imaging, eliminating the need for separate data acquisition passes. The drilling operation itself serves dual purposes: creating the wellbore and generating the seismic source, thereby reducing total time required and enabling continuous imaging
3Measurement precision
If detailed formation imaging is performed to detect fractures and interfaces, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the drill bit multi-functional by using it both as a cutting tool and as a seismic source. The same drill bit that removes rock also generates the vibrational energy needed for imaging, eliminating the need for separate seismic sources and reducing overall device complexity while maintaining high measurement precision through advanced signal processing
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 near-real-time imaging of formation properties, simplifies tool design, improves signal-to-noise ratio, and allows for 'look-ahead' capabilities to detect fractures and guide drilling operations.
Implementation Method 1
seismic energy generated by the drill bit
Implementation Method 2
drill bit is utilized as a seismic source; drill bit generates acoustic energy
Implementation Method 3
decomposing the seismic data into monopole and dipole modes
Implementation Method 4
azimuthal receiver elements of a logging-while-drilling tool; recording seismic data at the plurality of azimuthal receiver elements
Data Source
AI summary
A method is described for method of processing seismic data including obtaining seismic data, wherein the seismic data was acquired with a plurality of azimuthal receiver elements of a logging-while-drilling tool while a drill bit is drilling a wellbore; decomposing the seismic data into monopole and dipole modes; cross-correlating each receiver pair of the monopole mode and of the dipole mode to generate monopole and dipole waveforms; identifying a time of direct arrival of acoustic energy from the drill bit and applying bulk time shift for the waveforms; stacking corresponding waveforms from the bulk time shift to improve signal-to-noise ratio; processing the stacked monopole and dipole waveform to isolate reflected arrivals; performing migration to obtain a monopole migrated image and a dipole migrated image; and classifying the interface as either a fracture or an impedance contrast. The method is executed by a computer system.