Marine Vibrator Orthogonal Coded Pseudo-Random Sweeps

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Solution Overview

Problem

Marine seismic surveys using impulsive sources face challenges with residual noise contamination from previous vibrator activations, which cannot be effectively mitigated by conventional noise filtering methods, affecting the accuracy of subterranean formation imaging.

Innovation Solution

Operate marine vibrators to generate orthogonal coded pseudo-random sweeps, which produce incoherent residual noise that can be removed using noise filtering techniques, improving the quality of seismic data by reducing coherent residual noise contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional linear sweeps are used in marine seismic surveys, then the seismic data acquisition process is simple and efficient, but coherent residual noise from previous vibrator activations contaminates the seismic data and cannot be effectively removed by conventional noise filtering methods

Engineering Contradiction:

Improveseismic data qualityVSAvoidcoherent residual noise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent changes the temporal pattern parameter of the vibrator activation from linear sweeps to coded pseudo-random sweeps. This parameter change transforms the coherent residual noise into incoherent noise, which can then be effectively removed by conventional noise filtering methods, thereby resolving the contradiction between data acquisition simplicity and seismic data quality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful coherent residual noise into beneficial incoherent noise through the use of coded pseudo-random sweeps. The incoherent noise, while still present, can be effectively filtered out using conventional noise filtering techniques, thus transforming a previously problematic coherent interference into a manageable form that improves overall seismic data quality

Inventive Principle:

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

2Productivity

If marine vibrators are activated consecutively to acquire seismic data efficiently, then productivity increases, but residual noise from previous activations contaminates subsequent recordings

Engineering Contradiction:

Improveseismic data acquisition efficiencyVSAvoidresidual noise contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent maintains high productivity by keeping the consecutive activation pattern but changes the temporal pattern parameter from linear to coded pseudo-random. This allows efficient consecutive activations while transforming the resulting residual noise into an incoherent form that can be filtered, thus resolving the contradiction between productivity and noise contamination

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If conventional noise filtering methods are applied to remove residual noise, then noise reduction is attempted, but coherent residual noise from linear sweeps cannot be effectively mitigated

Engineering Contradiction:

Improveseismic signal clarityVSAvoidcoherent residual noise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies preliminary action by pre-transforming the temporal pattern of vibrator activation to coded pseudo-random sweeps before noise filtering is applied. This preliminary transformation converts coherent residual noise into incoherent noise, making subsequent conventional noise filtering effective and thereby achieving clear seismic signals

Inventive Principle:

Principle #10Preliminary action

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 use of orthogonal coded pseudo-random sweeps significantly reduces coherent residual noise in seismic data, enhancing the resolution and accuracy of subterranean formation imaging by making residual noise incoherent and filterable.

Implementation Method 1

A seismic source may be a marine vibrator that emits acoustic energy over a longer time period. The acoustic energy generated by a seismic source spreads out in all directions. A portion of the acoustic energy travels down through the water and into a subterranean formation to propagate as sound waves within the subterranean formation.

Methodology Applied

Scientific EffectAcoustic energy generation and propagation: Sound

Implementation Method 2

Each streamer contains many seismic receivers or sensors that detect pressure and/or particle motion wavefields of the sound waves.

Methodology Applied

Scientific EffectWavefield detection: Sound

Data Source

PatentUS11914090B2Mitigating residual noise in a marine survey with orthogonal coded pseudo-random sweeps

Publication Date: 2024.02.27 PGS GEOPHYSICAL AS

AI summary

Processes and systems described herein are directed to performing marine surveys with marine vibrators that emit orthogonal coded pseudo-random sweeps. In one aspect, coded pseudo-random signals are generated based on coded pseudo-random sequences. The coded pseudo-random sequences are used to activate the marine vibrators in a body of water above a subterranean formation. The activated marine vibrators generate orthogonal coded pseudo-random sweeps. A wavefield emitted from the subterranean formation in response to the orthogonal coded pseudo-random sweeps is detected at receivers located in a body of water. Seismic signals generated by the receivers may be cross-correlated with a signature of one of the orthogonal coded pseudo-random sweeps to obtain seismic data with incoherent residual noise.