Downhole Sonic Velocity Scan for Reflection Identification
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Solution Overview
Problem
Conventional sonic logging methods face challenges in accurately determining if full waveform sonic data contains sufficient reflection events to perform reliable velocity analysis of formation boundaries and fractures, leading to potential inaccuracies in imaging processing.
Innovation Solution
The system and method filter out direct waves and focus on analyzing reflected waves, using apparent velocities derived from these waves to create a velocity analysis that accounts for the geometry of the borehole, allowing for the identification of quality reflections and improved imaging of formation structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full waveform sonic data is used to create velocity analysis, then comprehensive formation imaging is achieved, but it cannot be determined if the data contains sufficient reflection events, leading to potential inaccuracies
Solution Approach 1:
The patent applies preliminary action by performing a velocity scan analysis before the main imaging processing. The method pre-processes the full waveform sonic data to generate a velocity scan that identifies whether sufficient reflection events are present, allowing the system to determine data quality before committing to full imaging operations.
Solution Approach 2:
The velocity scan serves as an intermediary between the raw full waveform sonic data and the final velocity analysis. This intermediate step provides objective criteria for assessing whether the reflected waves contain adequate reflection events, bridging the gap between raw data and reliable imaging results.
2Productivity
If direct waves are included in the analysis, then complete wavefield information is captured, but the analysis becomes computationally intensive and less objective in identifying quality reflections
Solution Approach 1:
The patent extracts and isolates the reflected waves from the complete wavefield, separating them from direct waves and other components. This extraction allows the analysis to focus specifically on the reflection events of interest, improving both computational efficiency and the reliability of reflection identification.
Solution Approach 2:
The wavefield is segmented into distinct components (direct waves, reflected waves, etc.), with the analysis specifically targeting the reflected wave portion. This segmentation enables more efficient processing by concentrating computational resources on the relevant data portion while maintaining objective reflection quality assessment.
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 enables objective and less computationally intensive identification of quality reflections, providing accurate apparent velocities that can be used for forming migrated images of the reservoir, improving the reliability of sonic logging data analysis.
Implementation Method 1
a transmitter emits acoustic signals into the fluid-filled borehole
Implementation Method 2
some of the signals may traverse through the formation and are reflected back to the borehole by a reflector in the formation
Implementation Method 3
The reflected signals may travel back to the borehole and are captured by the receivers in the borehole
Data Source
AI summary
Systems and methods for obtaining downhole images through velocity analysis may be provided. For example, systems and methods may disposing a borehole sonic logging tool into a borehole disposed in a formation, wherein the borehole sonic logging tool comprises: a transmitter configured to transmit sonic energy comprising at least one or more waveforms into a formation; and one or more receivers configured to record a sonic wave field comprising at least one or more reflected waveforms and one or more direct and/or guided waveforms. In addition, systems and methods may select a group of traces from a receiver; select a set of trial velocities from at least a sonic profile; compute a coherence value between at least two or more traces from the shifted group of traces; record the coherence value for the shifted group of traces at its initial trial velocity and depth; and determine reflections.