Seismic Inversion for Formation Properties and Attenuation

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Solution Overview

Problem

Seismic inversion methods face challenges due to unknown seismic wavelets, band-limited data, and noise, which limit the accuracy of subsurface formation property estimation and fail to effectively account for attenuation effects, particularly in the absence of low-frequency seismic sources.

Innovation Solution

A method that estimates the source signature and inverts seismic data simultaneously for subsurface formation properties and attenuation effects, using causality relationships to constrain unknown variables and integrate over ray-paths, allowing for more accurate estimation of reflection properties and impedance without relying on small time windows or well information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If traditional convolutional model inversion is used, then the process is simple, but the seismic wavelet is unknown and both data and wavelet are band limited, leading to inaccurate formation property estimation

Engineering Contradiction:

Improvesimplicity of inversion processVSAvoidaccuracy of formation property estimation

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent applies preliminary action by first measuring or estimating the source signature (seismic wavelet before attenuation) before performing the inversion. This pre-characterization of the wavelet allows the subsequent inversion to accurately separate attenuation effects from reflection properties, resolving the uncertainty problem without complicating the overall process

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the parameter set by simultaneously solving for reflection properties and attenuation quality factor rather than treating them separately. This parameter transformation allows the inversion to account for both wavelet characteristics and formation properties, improving accuracy while maintaining computational feasibility

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If small time windows are used in inversion, then the seismic wavelet appears stationary, but this limits the inversion to small windows and reduces the use of available data

Engineering Contradiction:

Improvestationarity of seismic waveletVSAvoidamount of data used in inversion

Core Design Contradiction:

Stability of the object's compositionVSQuantity of substance

Solution Approach 1:

By pre-measuring the source signature and characterizing attenuation effects before inversion, the patent removes the need to assume wavelet stationarity within small time windows. This allows the full seismic trace to be used in inversion while maintaining accuracy, as the wavelet variations are explicitly modeled rather than assumed constant

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies dynamics by allowing the wavelet to vary with time and frequency through explicit attenuation modeling. Rather than forcing the wavelet to be stationary, the method dynamically accounts for wavelet changes caused by propagation through the earth, enabling use of the entire data trace

Inventive Principle:

Principle #15Dynamics

3Device complexity

If attenuation effects are ignored in the inversion model, then the inversion is simpler, but considerable loss of high frequencies occurs and the wavelet changes with propagation distance

Engineering Contradiction:

Improvecomplexity of inversion modelVSAvoidaccuracy of inversion results

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent transforms the inversion by adding attenuation quality factor as an explicit parameter to be solved simultaneously with reflection properties. This parameter expansion incorporates attenuation effects into the model without excessive complexity, as the attenuation is modeled systematically rather than requiring complex iterative corrections

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces the attenuation quality factor as an intermediary parameter that mediates between the source wavelet and the observed seismic data. This intermediary allows the inversion to account for frequency-dependent attenuation effects while maintaining a manageable model structure

Inventive Principle:

Principle #24Intermediary (Mediator)

4Ease of operation

If the seismic wavelet is not pre-measured, then the source signature is unknown, but this leads to wavelet uncertainty and time varying or changing seismic wavelets

Engineering Contradiction:

Improveease of data processingVSAvoidwavelet uncertainty

Core Design Contradiction:

Ease of operationVSLoss of information

Solution Approach 1:

The patent applies preliminary action by measuring or estimating the source signature before performing the main inversion. This pre-characterization of the wavelet eliminates uncertainty about the source characteristics and allows accurate separation of wavelet effects from formation properties in the subsequent inversion step

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9442204B2Seismic inversion for formation properties and attenuation effects

Publication Date: 2016.09.13 EXXONMOBIL UPSTREAM RESEARCH COMPANY(US)

AI summary

Method for inverting seismic data to obtain reflection properties by estimating or measuring (301) the source signature for the seismic data, then inverting (302) simultaneously for subsurface formation properties or reflection properties and for the amplitude attenuation and velocity dispersion effects integrated over the raypath from the source to the reflectors and to the receiver.