Rugosity Correction for Resistivity Measurements

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Solution Overview

Problem

Resistivity measurements in geological formations are often inaccurate due to factors like borehole rugosity and invasion zones, which can distort shallow resistivity measurements, especially when the contrast between formation and mud resistivity is high, leading to inconsistent results between shallow and deeper modes.

Innovation Solution

A method for correcting rugosity effects in resistivity measurements by using a novel approach for radial inversions of measured resistivity data, which involves detecting rugosity zones, estimating effective borehole diameters, and applying rugosity correction to improve the accuracy of shallow mode measurements, thereby aligning them with deeper mode results.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If shallow mode resistivity measurements are performed in a borehole with rugosity, then the measurements can be obtained quickly, but the measurement accuracy deteriorates due to distortion from borehole irregularities

Engineering Contradiction:

Improvemeasurement speedVSAvoidshallow resistivity measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent replaces mechanical correction methods with computational/electrical solutions. Instead of physically correcting the borehole rugosity, the system uses electrical modeling and signal processing to simulate and remove the rugosity effect from the measurements, thereby maintaining measurement speed while improving accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the parameters used in resistivity measurement by introducing effective borehole diameter as a corrected parameter. The system varies the apparent borehole diameter in simulations to find the value that best matches deep mode measurements, thereby compensating for rugosity effects and improving shallow mode measurement accuracy

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If borehole rugosity is present, then the natural borehole structure is maintained, but resistivity measurement consistency deteriorates between shallow and deeper modes

Engineering Contradiction:

Improveborehole structureVSAvoidmeasurement consistency

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The patent replaces mechanical intervention in the borehole with computational methods. The system uses electrical and computational modeling to simulate the effect of borehole rugosity and remove it from the measurements, maintaining the natural borehole structure while achieving consistent measurements across different modes

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary computational model that acts as a mediator between the raw measurements and the final corrected values. This model simulates the borehole-rugosity-effect and uses it to transform the inconsistent measurements into consistent results that reflect true formation properties

Inventive Principle:

Principle #24Intermediary (Mediator)

3Loss of information

If high contrast between formation and mud resistivity exists, then the formation properties are more distinct, but measurement accuracy deteriorates due to increased rugosity effect

Engineering Contradiction:

Improveformation property distinctionVSAvoidresistivity measurement accuracy

Core Design Contradiction:

Loss of informationVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameters by introducing effective borehole diameter correction that adapts to the resistivity contrast conditions. The system adjusts the correction based on the apparent borehole diameter derived from matching deep and shallow mode measurements, thereby compensating for the enhanced rugosity effect that occurs with high resistivity contrast

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS9971058B2Correction of galvanic tool data to account for rugosity and cave effect

Publication Date: 2018.05.15 HALLIBURTON ENERGY SERVICES INC

AI summary

Apparatus, systems, and methods may operate to detect rugosity in a borehole. Additional activity may include generating a rugosity correction, responsive to detecting rugosity in the borehole, by finding an effective borehole diameter, consistent with the presence of rugosity, for which a simulation of a model of the borehole using the effective borehole diameter generates simulation resistivity measurements that match, within a tolerance, resistivity measurements before execution of a borehole correction algorithm. Additional activity may include applying rugosity correction by generating resistivity logs, using the effective borehole diameter, that are corrected for rugosity and borehole effect. Additional apparatus, systems, and methods are disclosed.