Seismic Source Encoding for Resolution and Noise Reduction

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Solution Overview

Problem

Current seismic data acquisition methods face challenges in achieving sufficient resolution with increased distance between grid points or using tighter grids, and in accurately positioning sources and receivers for time-lapse seismic surveys, while also dealing with residual shot noise that limits image accuracy and resolution.

Innovation Solution

The use of orthogonal sequences for activating seismic sources, allowing for simultaneous or sequential encoding and decoding of monopole and multi-pole data to separate wavefields from multiple sources, and the application of source-side derivatives to enhance image accuracy and reduce residual shot noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the distance between grid points is increased to reduce acquisition costs, then the cost decreases, but the resolution of seismic data deteriorates

Engineering Contradiction:

Improveacquisition costVSAvoidseismic data resolution

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The wavefield from multiple sources is segmented into individual source contributions using orthogonal encoding sequences. Each source is assigned a unique orthogonal code, allowing the receiver to separate and identify waves from different sources through correlation processing, enabling resolution enhancement without requiring denser spatial sampling

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the temporal parameter of source activation by using coded sequences instead of simple impulsive sources. By modulating the source activation patterns with orthogonal codes and processing the received signals through correlation with these codes, the system achieves enhanced resolution and noise rejection without increasing spatial density

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If sources and receivers are positioned with high precision for time-lapse surveys, then the accuracy of comparison improves, but the difficulty of positioning and operational complexity increases

Engineering Contradiction:

Improvepositioning accuracyVSAvoidpositioning difficulty

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The orthogonal encoding scheme provides an inherent feedback mechanism for position verification. The correlation processing of received signals with known orthogonal codes produces distinct peaks that confirm proper source-receiver pairing and positioning, allowing operators to verify positioning accuracy through the quality and position of correlation peaks rather than relying solely on GPS or other positioning systems

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs self-verification of positioning through the orthogonal code structure. The mathematical properties of orthogonal sequences automatically provide identification and verification of source locations without requiring external positioning aids, as the correlation process inherently confirms which receiver recorded which source's signal

Inventive Principle:

Principle #25Self-service

3Ease of operation

If traditional seismic acquisition methods are used, then the system is simple to operate, but residual shot noise limits image accuracy and resolution

Engineering Contradiction:

Improveoperational simplicityVSAvoidimage accuracy

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent converts the harmful effect of residual shot noise into a beneficial signal by using orthogonal encoding. The coded sequences allow the system to distinguish between desired seismic signals and random noise, as the correlation process enhances signals that match the orthogonal codes while suppressing uncorrelated noise, effectively converting noise interference into a signal-to-noise ratio improvement

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The orthogonal codes act as an intermediary between the seismic sources and receivers. By modulating sources with orthogonal codes and correlating received signals with these codes, the system creates a mathematical intermediary layer that separates useful seismic information from residual shot noise, improving image accuracy without complicating the physical acquisition system

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS9594178B2Seismic data acquisition and source-side derivatives generation and application

Publication Date: 2017.03.14 REFLECTION MARINE NORGE AS

AI summary

The technologies described herein include systems and methods for performing a first seismic survey and performing a second seismic survey after a predetermined amount of time has lapsed between the first seismic survey and the second seismic survey. The shot times and the shot positions of the second seismic survey may be substantially the same as the shot times and the shot positions of the first seismic survey. After performing the seismic surveys, seismic data generated by the first seismic survey may be processed to generate a first image, and seismic data generated by the second seismic survey may be processed to generate a second image. After generating the first and second images, a difference between the first image and the second image may be computed to generate a time lapse difference image.