DAS VSP Angular Response Compensation
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Solution Overview
Problem
Vertical Seismic Profiling (VSP) surveys using fiber optic-based Distributed Acoustic Sensing (DAS) face challenges in recovering seismic amplitudes due to angular response distortions, which are not effectively compensated by existing methods without additional hardware or operational efforts, limiting the accuracy of formation evaluation and monitoring.
Innovation Solution
The integration of real-time and offline data stream processing to recover seismic amplitudes affected by angular response, utilizing a system that includes a DAS data collection system with optical fibers and an information processing system capable of performing tau-p transforms and amplitude corrections, allowing for improved survey control and amplitude recovery at various granularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional DAS VSP processing methods are used, then the processing workflow is simple, but the seismic amplitude recovery is inaccurate due to angular response distortions
Solution Approach 1:
The patent introduces an intermediary processing system that sits between the traditional DAS VSP processing and the final amplitude recovery. This intermediary performs tau-p transforms and angular response compensation calculations, acting as a mediator that converts the distorted seismic data into corrected amplitudes without requiring hardware changes to the original DAS system.
Solution Approach 2:
The patent replaces the need for additional physical hardware (such as multiple fiber orientations or specialized sensors) with a computational approach. By substituting mechanical/hardware solutions with software-based tau-p transforms and angular response compensation algorithms, the system achieves accurate amplitude recovery through information processing rather than physical system modifications.
2Measurement precision
If additional hardware is added to compensate for angular response, then the amplitude recovery accuracy improves, but the system complexity and cost increase
Solution Approach 1:
The patent explicitly substitutes hardware-based angular response compensation with a software-based processing solution. Instead of adding physical sensors, multiple fiber orientations, or specialized equipment, the invention uses tau-p transforms and computational angular response compensation algorithms to achieve the same amplitude recovery accuracy, thereby eliminating the need for additional hardware complexity.
Solution Approach 2:
The processing system performs self-service by using the existing DAS VSP data and wellbore geometry information to automatically calculate and compensate for angular response distortions. The system serves itself by generating the necessary correction factors from the available data without requiring external hardware additions or additional measurement equipment.
3Productivity
If real-time processing is implemented for angular response compensation, then the survey control capability improves, but the processing time and computational load increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating the angular response compensation factors based on wellbore geometry and seismic ray tracing before the actual amplitude recovery process. By performing these computationally intensive tau-p transforms and angular response calculations in advance, the system enables real-time processing during the actual VSP survey without excessive computational delays.
Solution Approach 2:
The processing system segments the VSP data into manageable components for parallel processing. By dividing the seismic data stream and processing different depth intervals or time windows separately, the system reduces the computational burden on any single processing unit, enabling real-time compensation while maintaining survey control capability.
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 accurate recovery of seismic amplitudes, enhancing the precision of VSP surveys by compensating for angular response distortions, thereby improving the quality of formation evaluation and monitoring data without requiring additional hardware or operational efforts.
Implementation Method 1
Acoustic sensing based on DAS may use the Rayleigh backscatter property of a fiber's optical core and may spatially detect disturbances that are distributed along a length of fiber positioned within a wellbore
Data Source
AI summary
A system for processing DAS VSP surveys is provided. The system includes a DAS data collection system coupled to at least one optical fiber at least partially positioned within a wellbore and configured to either activate or passively listen to a seismic source of energy for one or more times. The system further includes an information processing system connected to the DAS data collection system. A seismic dataset is received from the DAS data collection system recorded in a spatiotemporal domain. The seismic dataset is converted into intercept-time ray-parameter domain dataset. Local apparent slope is determined for each seismic signal in the received seismic dataset. Amplitude correction is performed for the received seismic signals by using the slowness profile and the determined local apparent slope in the intercept-time ray-parameter domain dataset. The corrected intercept-time ray-parameter domain dataset is converted back into the spatiotemporal domain.