Lithology Map Determination via Uniform Geophysical Values

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Solution Overview

Problem

Current methods for determining lithology maps in petroleum and gas reservoirs face challenges in accurately transferring seismic soft probabilities to a grid scale for geo-modeling, leading to less contrasted results and debates over combining geological and geophysical probabilities.

Innovation Solution

A method that computes uniform geophysical attribute values within zones and integrates these with geological probability values using exact interpolation techniques like Kriging to determine facies, creating a lithology map that associates points with estimated facies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If soft probabilities are derived from rock physics and statistical analysis of geophysical properties, then geological information can be obtained at log scale, but up-scaling to grid cell level leads to less contrasted soft probabilities and deceiving geostatistical processes

Engineering Contradiction:

Improvelog scale analysis precisionVSAvoidgrid cell prediction accuracy

Core Design Contradiction:

Measurement precisionVSManufacturing precision

Solution Approach 1:

The patent transforms the geophysical attribute values through a cumulative distribution function (CDF) to create uniform values. This parameter transformation changes the probability distribution from the original geophysical attribute distribution to a uniform distribution, thereby preserving contrast information during up-scaling and avoiding the loss of geological variability that occurs with traditional up-scaling methods.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If seismic soft probabilities are directly used in geostatistical processes, then the entire reservoir can be represented, but the results are often deceiving due to up-scaling issues and lack of contrast

Engineering Contradiction:

Improvereservoir-wide representationVSAvoidlithology estimation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent replaces the traditional direct use of soft probabilities in geostatistical processes with a transformed uniform value approach. By substituting the original geophysical attribute values with uniform values derived from CDF transformation, the method maintains reservoir-wide adaptability while significantly improving lithology estimation accuracy and avoiding the deceiving results of conventional methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If transformations are applied to use seismic soft probabilities, then the data can be utilized for lithology mapping, but the transformations are usually subjective and case dependant

Engineering Contradiction:

Improvelithology map creationVSAvoidtransformation objectivity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies a universal CDF transformation method that can be used across different cases and reservoir types. This universal approach replaces subjective, case-dependent transformations with an objective mathematical transformation that consistently maps geophysical attribute values to uniform values, thereby improving reliability while maintaining ease of lithology map creation.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Quantity of substance

If soft probabilities are combined with well data and geological analysis, then more comprehensive information can be integrated, but debates arise over which combination and which probability is most representative

Engineering Contradiction:

Improveinformation integrationVSAvoidcombination methodology complexity

Core Design Contradiction:

Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent introduces uniform values as an intermediary between geophysical soft probabilities and well data. This intermediary transformation creates a common framework that facilitates objective integration of multiple data sources without the complexity of debating combination methods or determining which probability is most representative, as the uniform values provide a standardized basis for comparison and integration.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10585199B2Method for determining a lithology map

Publication Date: 2020.03.10 TOTALENERGIES ONETECH

AI summary

The present invention relates to a method for determining a lithology map. The method comprises receiving a geophysical attribute image comprising a plurality of points associated with geophysical attribute value, and receiving first information data representing a plurality of zones in the image, each point of the image being contained in a zone. For at least one point of the image, computing a uniform value associated with said point based on the geophysical attribute value and distributions values of the geophysical attribute values. The method further comprises receiving second information data representing geological probability value for a plurality of facies associated with the points of the image, and for at least one point of the image, determining a facies in the plurality facies based on the computed uniform value and the geological probabilities associated with said point.