Downhole Resistivity Correction for Filtrate Contamination

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Solution Overview

Problem

The challenge in accurately determining water-based mud contamination in formation fluids downhole is exacerbated by the miscibility of water-based mud with formation water, leading to inaccurate resistivity and conductivity measurements due to temperature variations, which complicates the assessment of hydrocarbon reserves and contaminant quantification.

Innovation Solution

A downhole acquisition tool system that corrects measured resistivity and conductivity for temperature variations using temperature-dependent models and algorithms, enabling accurate estimation of water-based mud filtrate contamination by employing sensors and data processing systems to analyze fluid properties and composition in real-time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If water-based mud is used for drilling operations, then drilling efficiency is improved, but formation fluid contamination occurs leading to measurement inaccuracies

Engineering Contradiction:

Improvedrilling efficiencyVSAvoidresistivity measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent extracts the temperature variable from the measurement system and applies it as a correction factor. By measuring temperature separately and using it to correct resistivity readings, the system removes the harmful effect of temperature-induced measurement errors while maintaining the use of water-based drilling mud.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter being measured from raw resistivity to temperature-corrected resistivity. By applying temperature correction algorithms, the system transforms inaccurate measurements into accurate ones, allowing continued use of water-based mud without compromising measurement precision.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If temperature correction is applied to resistivity measurements, then measurement accuracy is improved, but device complexity increases

Engineering Contradiction:

Improveconductivity measurement accuracyVSAvoiddata processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs self-correction by automatically measuring temperature and applying the appropriate correction algorithm to resistivity readings. This self-service approach handles the complexity internally without requiring external intervention or complex manual processing, making the temperature correction feature practical to implement.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If real-time fluid analysis is performed downhole, then contaminant quantification accuracy is improved, but operational costs increase

Engineering Contradiction:

Improvecontaminant quantification accuracyVSAvoidoperational costs

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent replaces complex mechanical laboratory analysis systems with electronic sensors and digital correction algorithms. By using electrical resistivity measurements combined with temperature correction, the system achieves accurate contaminant quantification without the high costs associated with bringing samples to surface laboratories.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enhances the accuracy of water-based mud filtrate contamination quantification, improving the assessment of hydrocarbon reserves and reducing operational costs by providing reliable, real-time data on fluid composition and contaminant levels.

Implementation Method 1

obtaining a measured resistivity, a measured conductivity, or both of the portion of the fluid using the downhole acquisition tool

Methodology Applied

Scientific EffectElectrical resistivity: Electrical Resistance

Implementation Method 2

correcting the measured resistivity, the measured conductivity, or both for temperature variations downhole to obtain a temperature-corrected resistivity, a temperature-corrected conductivity, or both

Methodology Applied

Scientific EffectTemperature correction: Thermal Expansion

Data Source

PatentUS10941655B2Downhole filtrate contamination monitoring with corrected resistivity or conductivity

Publication Date: 2021.03.09 SCHLUMBERGER TECH CORP

AI summary

A method includes operating a downhole acquisition tool in a wellbore in a geological formation. The wellbore or the geological formation, or both, contains a fluid that includes a native reservoir fluid of the geological formation and a contaminant. The method also includes receiving a portion of the fluid into the downhole acquisition tool, obtaining a measured resistivity, a measured conductivity, or both of the portion of the fluid using the downhole acquisition tool, and using a processor of the downhole acquisition tool to obtain a temperature-corrected resistivity, a temperature-corrected conductivity, or both based on a downhole temperature of the portion of the fluid and the measured resistivity, the measured conductivity, or both.