Electrochemical Impedance Spectroscopy for Drilling Fluid Sag Monitoring

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Solution Overview

Problem

The existing methods for determining sag in drilling fluids, such as static sag testing, are time-consuming and prone to errors, which can lead to inadequate hydrostatic pressure and wellbore failure due to density variations caused by sedimentation of weighting agents.

Innovation Solution

The use of electrochemical impedance spectroscopy (EIS) to monitor the sag behavior of drilling fluids by measuring impedance over time and correlating it with equivalent circuit models to characterize sedimentation, allowing for real-time monitoring and prevention of density variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If static sag testing is used to determine sag in drilling fluids, then measurement can be performed, but the process is time-consuming and prone to errors

Engineering Contradiction:

Improvesag measurement accuracyVSAvoidtesting duration

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces mechanical/static sag testing methods with electrochemical impedance spectroscopy (EIS), an electrical measurement technique. The EIS system applies alternating current signals to the drilling fluid and measures impedance changes, substituting the mechanical measurement approach with an electrical field-based method that provides faster, more accurate results without human intervention

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from mechanical displacement or visual assessment to electrical impedance. By monitoring impedance magnitude and phase angle changes over time, the system detects sag behavior through electrical property variations rather than mechanical or visual parameters, enabling real-time continuous monitoring

Inventive Principle:

Principle #35Parameter changes

2Stress or pressure

If weighting agents are added to increase drilling fluid density, then hydrostatic pressure is improved, but sedimentation and sag occur causing density variations

Engineering Contradiction:

Improvehydrostatic pressureVSAvoiddrilling fluid homogeneity

Core Design Contradiction:

Stress or pressureVSStability of the object's composition

Solution Approach 1:

The patent implements a feedback monitoring system using EIS that continuously measures impedance changes in the drilling fluid. The system detects early signs of sag through impedance variations and provides real-time feedback on density uniformity, allowing operators to take corrective actions before significant density variations and wellbore pressure problems occur

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses electrical impedance as an intermediary parameter to indirectly monitor density distribution and sag behavior. Instead of directly measuring density or particle position, the EIS system measures electrical impedance changes caused by particle settling, providing a non-invasive indicator of compositional stability and hydrostatic pressure uniformity

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If circulation of drilling fluid is stopped, then drilling operations can be paused, but sag occurs due to sedimentation of particulates

Engineering Contradiction:

Improveoperational flexibilityVSAvoidfluid homogeneity

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

The patent enables continuous monitoring of drilling fluid stability even during paused circulation operations. The EIS system maintains continuous electrical measurements during stop periods, detecting sag development in real-time without requiring fluid circulation, thus maintaining surveillance of compositional stability during operational pauses

Inventive Principle:

Principle #20Continuity of useful action

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

EIS provides a non-invasive, accurate method for characterizing sag behavior, enabling timely adjustments to maintain consistent hydrostatic pressure and preventing wellbore failures by detecting sedimentation and stratification of particulate additives.

Implementation Method 1

measuring an impedance of a portion of the drilling fluid over time

Methodology Applied

Scientific EffectElectrochemical impedance spectroscopy: Electrical Impedance Tomography

Implementation Method 2

as one or more particulate additives in the drilling fluid settle

Methodology Applied

Scientific EffectSedimentation: Sedimentation

Implementation Method 3

These particles may be prone to sedimentation within the drilling fluid under the influence of gravity

Methodology Applied

Scientific EffectGravitation: Gravitation

Data Source

PatentUS11143024B2Application of electrochemical impedance spectroscopy for analyzing sag of drilling fluids

Publication Date: 2021.10.12 HALLIBURTON ENERGY SERVICES INC

AI summary

Systems and methods for determining the composition of a drilling fluid using electro-rheology may be provided. A method for drilling a wellbore may include: circulating a drilling fluid in a wellbore; extending the wellbore into one or more subterranean formations; measuring impedance of at least a portion of the drilling fluid over time as one or more particulate additives in the drilling fluid settle; determining one or more model elements of an equivalent circuit model for modeling frequency responses of the drilling fluid from the impedance; and determining sag behavior of the drilling fluid based, at least partially, on the one or more model elements.