Carbon Nanotube Sponge Cement for Wellbore Integrity

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Solution Overview

Problem

Cement slurries used in the oil and gas industry face challenges in maintaining integrity under cyclic stresses, leading to cracks and reduced wellbore integrity, which can result in decreased production and increased risk of well control events.

Innovation Solution

Incorporating carbon nanotube sponges into the cement slurry, synthesized via chemical vapor deposition, to enhance electrical conductivity and self-healing capabilities, with conductive fibers forming a conductive web within the cured cement to improve piezoresponse and reduce bulk resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional cement slurries are used, then the cement can be easily manufactured and applied, but the cured cement cracks and breaks under cyclic stresses, reducing wellbore integrity

Engineering Contradiction:

Improvewellbore integrityVSAvoidresistance to cyclic stresses

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent incorporates carbon nanotube sponges into conventional cement slurry to create a composite material. The carbon nanotube sponges form a three-dimensional conductive network within the cement matrix, providing both mechanical reinforcement to resist cracking under cyclic stresses and electrical conductivity for monitoring wellbore integrity. This composite approach combines the structural properties of cement with the mechanical strength and electrical conductivity of carbon nanotubes.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent modifies the electrical and mechanical parameters of cement slurry by adding carbon nanotube sponges. The carbon nanotubes change the electrical conductivity parameter from insulating to conductive, and alter the mechanical parameters by providing crack-bridging reinforcement that increases fracture toughness and resistance to cyclic loading. These parameter changes enable both structural reinforcement and functional monitoring capabilities.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If carbon nanotube sponges are added to cement slurry, then electrical conductivity and strength are improved, but the complexity of manufacturing increases

Engineering Contradiction:

Improveelectrical conductivityVSAvoidslurry preparation process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The carbon nanotube sponges are pre-synthesized and prepared as discrete particles before being added to the cement slurry. This preliminary preparation allows the nanotubes to be manufactured and quality-controlled separately, then simply mixed into the slurry at the appropriate concentration. The pre-formed sponge structure ensures uniform distribution and reduces the complexity of on-site nanotube synthesis while maintaining the electrical conductivity improvements.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If carbon nanotube sponges are dispersed throughout cement slurry, then bulk resistance is reduced, but the difficulty of achieving uniform dispersion increases

Engineering Contradiction:

Improvebulk resistanceVSAvoiduniformity of dispersion

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The carbon nanotube sponges are distributed throughout the cement slurry at controlled local concentrations to create regions of enhanced conductivity. Rather than requiring perfectly uniform distribution throughout the entire volume, the invention achieves effective bulk resistance reduction through localized conductive pathways formed by the nanotube sponges. This local quality approach tolerates some variation in distribution while maintaining overall electrical performance.

Inventive Principle:

Principle #3Local quality

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

The modified cement slurries exhibit increased electrical conductivity and reduced bulk resistance, enhancing wellbore integrity and enabling effective monitoring of downhole stresses, thus improving well stability and production efficiency.

Implementation Method 1

Incorporating carbon nanotube sponges into the cement slurry, synthesized via chemical vapor deposition, to enhance electrical conductivity

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Implementation Method 2

conductive fibers forming a conductive web within the cured cement to improve piezoresponse and reduce bulk resistance

Methodology Applied

Scientific EffectPiezoresistive effect: Piezoresistive Effect

Data Source

PatentUS11643587B2Methods of making cement slurries and cured cement and use thereof

Publication Date: 2023.05.09 SAUDI ARABIAN OIL CO

AI summary

Cured cements, cement slurries, and methods of making cured cement and methods of using cement slurries are provided. The method of making a modified cement slurry includes adding particles comprising carbon nanotube sponges disposed on sacrificial templates to a cement slurry to form the modified cement slurry and allowing the sacrificial templates to disintegrate, thereby leaving the carbon nanotube sponges dispersed throughout the modified cement slurry.