Single-Step Inversion for Petrophysical Parameter Estimation

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Solution Overview

Problem

Classical methods of electromagnetic borehole logging face challenges in accurately interpreting dielectric logs due to noise contamination, leading to ill-posed inverse problems and inaccurate petrophysical parameter estimation.

Innovation Solution

A single-step inversion method is introduced, which combines the estimation of petrophysical parameters and electromagnetic properties using a regularization model, incorporating a priori data and petrophysically based mixing models to improve the robustness and accuracy of results.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If classical electromagnetic borehole logging methods are used, then the logging process can be performed, but noise contamination leads to ill-posed inverse problems and inaccurate petrophysical parameter estimation

Engineering Contradiction:

Improvepetrophysical parameter estimation accuracyVSAvoidinverse problem well-posedness

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by incorporating a priori data and petrophysically based mixing models into the inversion process before solving the inverse problem. This pre-constraint approach stabilizes the inversion by embedding geological and petrophysical knowledge about probable parameter ranges and relationships, transforming the ill-posed problem into a well-posed one while maintaining measurement precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes parameters by introducing regularization terms into the inversion objective function that constrain petrophysical parameters based on physical laws and geological knowledge. This parameter transformation approach converts the unstable inverse problem into a stable one by modifying the optimization landscape to reflect realistic parameter relationships and ranges

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If traditional multi-step inversion methods are used, then the inversion process can be performed, but the process is complex and prone to error propagation

Engineering Contradiction:

Improveinversion result accuracyVSAvoidinversion process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges multiple inversion steps into a single integrated inversion process that simultaneously estimates electromagnetic properties and petrophysical parameters. This consolidation eliminates the need for sequential processing, reduces computational complexity, and prevents error propagation between steps while maintaining or improving inversion accuracy through joint optimization

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If conventional inversion methods are used, then the processing can be completed, but the results are sensitive to spatial resolution and depth of investigation variations

Engineering Contradiction:

Improveparameter estimation robustnessVSAvoidparameter estimation stability

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent converts the harmful effect of noise and measurement uncertainties into a benefit by using regularization that explicitly accounts for spatial resolution and depth of investigation variations. The regularization terms are designed to be tolerant of these variations, transforming potential sources of error into constraints that guide the inversion toward physically realistic solutions that are robust to measurement conditions

Inventive Principle:

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

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 reduces the impact of noise and instrumentation errors, providing more reliable and resilient petrophysical parameter estimation, tolerant to spatial resolution and depth of investigation variations.

Implementation Method 1

using at least one transmitter to generate a plurality of electromagnetic (EM) waves propagating through the formation

Methodology Applied

Scientific EffectElectromagnetic wave generation: Electromagnetic Induction

Data Source

PatentUS11119239B2Measuring petrophysical properties of an earth formation by regularized direct inversion of electromagnetic signals

Publication Date: 2021.09.14 BAKER HUGHES CO

AI summary

Methods and apparatus for evaluating an earth formation intersected by a borehole. Methods include using at least one transmitter to generate electromagnetic (EM) waves propagating through the formation; generating measurement signals at at least one receiver responsive to the propagating EM waves; taking a plurality of propagation measurements from the measurement signals representative of the propagating EM waves, where each propagation measurement of the plurality comprises at least one of: i) a relative phase shift between a first wave of the plurality of propagating EM waves and a second wave of the plurality of propagating EM waves; and ii) a relative attenuation between a first wave of the plurality of propagating EM waves and a second wave of the plurality of propagating EM waves; and performing a single inversion which uses the plurality of propagation measurements as input and generates at least one petrophysical parameter as output.