Resistivity Monitoring of Acid-Carbonate Reaction Kinetics

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Solution Overview

Problem

Current methods for monitoring and optimizing chemical treatments in downhole stimulation operations, such as acidizing in carbonate reservoirs, lack effective real-time monitoring of reaction kinetics and ion concentration changes, leading to poor zonal coverage and reduced production rates due to limited monitoring capabilities.

Innovation Solution

A method involving a measurement cell with electrodes to measure resistivity changes in reactive fluids, allowing real-time assessment of ion concentration and reaction kinetics, which can be used to optimize stimulation treatment design and predict wormhole and stimulation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional monitoring parameters (injection pressure, injection rate, temperature) are used during acidizing operations, then the treatment process can be monitored, but the monitoring is insufficient to effectively assess reaction kinetics and ion concentration changes, resulting in poor zonal coverage and reduced production rates

Engineering Contradiction:

Improvemonitoring capabilityVSAvoidproduction rate

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent replaces traditional mechanical/physical monitoring methods (pressure gauges, temperature sensors) with electrical measurement methods. By measuring the electrical conductivity or resistivity of the reactive fluid, the system can directly assess ion concentration changes and reaction kinetics, providing more precise monitoring data that correlates directly with the chemical reaction progress and stimulation effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces electrical conductivity/resistivity measurements as an intermediary parameter that bridges the gap between injection parameters and actual reaction effectiveness. This intermediary measurement provides real-time information about ion concentration changes in the reactive fluid, allowing operators to assess reaction kinetics and optimize treatment parameters to improve both monitoring precision and production outcomes.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of information

If temperature monitoring is used to assess treatment efficiency, then some information about treatment extent can be obtained, but temperature monitoring is not effective in every instance and may result in poor zonal coverage

Engineering Contradiction:

Improvetreatment efficiency informationVSAvoidmonitoring effectiveness

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The patent changes the monitored parameter from temperature to electrical conductivity or resistivity. This parameter change provides more direct and reliable information about the chemical reaction progress, as conductivity/resistivity directly reflects ion concentration changes in the reactive fluid, which is a more immediate and accurate indicator of reaction kinetics compared to temperature changes that may be influenced by multiple factors including heat loss and formation thermal properties.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If conventional monitoring methods are used during stimulation operations, then the treatment process can proceed, but real-time assessment of reaction kinetics and ion concentration changes is not possible, leading to suboptimal chemical injection efficiency

Engineering Contradiction:

Improvechemical injection efficiencyVSAvoidtreatment optimization time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent implements a feedback mechanism by continuously measuring the electrical conductivity or resistivity of the reactive fluid during injection and using this information to assess reaction kinetics in real-time. This feedback allows operators to monitor chemical injection efficiency, detect changes in formation properties, and adjust treatment parameters dynamically, eliminating the time loss associated with post-treatment assessment and enabling optimal chemical usage throughout the operation.

Inventive Principle:

Principle #23Feedback

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

Enables real-time measurement of reaction kinetics and ion concentration changes, optimizing stimulation treatment design, reducing operator errors, and improving production rates by providing accurate data for field design models under high pressure and high temperature conditions.

Implementation Method 1

measuring the resistivity of the reactive fluid using the two or more electrodes, wherein the resistivity is proportional to the ion concentration in the reactive fluid

Methodology Applied

Scientific EffectElectrical resistivity measurement: Electrical Resistance

Data Source

PatentUS11237144B2Using resistivity measurements to monitor the reaction kinetics between acids and carbonate rocks

Publication Date: 2022.02.01 SCHLUMBERGER TECH CORP

AI summary

In an embodiment a method is described which includes emplacing a sample within a measurement cell, wherein two or more electrodes are configured in the measurement cell; introducing a reactive fluid into the measurement cell; reacting the sample with the reactive fluid, wherein reacting the sample with the reactive fluid results in a change in an ion concentration in the reactive fluid; and measuring the resistivity of the reactive fluid using the two or more electrodes, wherein the resistivity is proportional to the ion concentration in the reactive fluid.