Epoxy-Modified Cement Slurry Prevents Fluid Migration
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Solution Overview
Problem
Conventional wellbore cements are prone to micro-crack formation due to thermal and pressure cycling, leading to fluid migration and increased casing-casing annulus pressure, and struggle to penetrate deep into high-pressure formations and narrow fracture gradient zones.
Innovation Solution
A cement composition incorporating a cement slurry with silica sand, silica flour, manganese tetraoxide, and an epoxy resin system, which includes an epoxy resin and a curing agent, providing enhanced compressive strength, reduced density, and elasticity to resist micro-crack formation and improve zonal isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional wellbore cement is used, then the cement can be injected into the wellbore, but micro-cracks form due to thermal and pressure cycling leading to fluid migration
Solution Approach 1:
The patent combines conventional wellbore cement with an epoxy resin system to create a composite cement composition. The epoxy resin system includes epoxy resin, curing agent, and reactive diluent, which when cured forms a flexible, crack-resistant network within the cement matrix. This composite structure prevents micro-crack formation while maintaining zonal isolation functionality, thereby eliminating fluid migration pathways.
2Length of moving object
If conventional wellbore cement is used, then the cement provides basic sealing, but it cannot penetrate deep into high-pressure formations and narrow fracture gradient zones
Solution Approach 1:
The patent modifies the rheological parameters of the cement composition by incorporating an epoxy resin system with reactive diluents. This reduces the viscosity and improves the flow characteristics of the cement slurry, enabling it to penetrate deeper into high-pressure formations and narrow fracture gradient zones before setting. The modified parameters allow the cement to reach target depths while withstanding formation pressures.
3Strength
If conventional wellbore cement is used, then the cement provides basic structural support, but it lacks sufficient compressive strength and elasticity to withstand thermal and pressure cycling
Solution Approach 1:
The patent creates a composite material system where epoxy resin penetrates and bonds with the cement matrix. The cured epoxy resin network provides enhanced compressive strength and elasticity to the cement composition, enabling it to withstand repeated thermal and pressure cycling without degradation. This composite structure maintains structural integrity and prevents micro-crack formation under cyclic loading conditions.
4Reliability
If conventional wellbore cement is used, then the cement can seal the annulus, but it is susceptible to corrosive fluids and has limited chemical resistance
Solution Approach 1:
The patent combines cement with epoxy resin to create a composite sealing material that leverages the chemical resistance properties of epoxy. The cured epoxy resin forms a chemically resistant barrier within the cement matrix, protecting the annulus seal from corrosive fluids such as sour gas, formation water, and other aggressive chemicals. This composite structure significantly improves the chemical durability of the wellbore seal.
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 cement composition effectively prevents fluid migration, withstands higher pressures, and can be injected deeper into high-pressure formations, including narrow fracture gradient zones, offering improved wellbore isolation and resistance to corrosive fluids.
Implementation Method 1
an epoxy resin system that includes an epoxy resin and a curing agent
Implementation Method 2
enhanced compressive strength, reduced density, and elasticity to resist micro-crack formation
Implementation Method 3
a cement slurry with silica sand, silica flour, manganese tetraoxide
Implementation Method 4
reduced density, and elasticity to resist micro-crack formation
Implementation Method 5
enhanced compressive strength, reduced density, and elasticity to resist micro-crack formation
Implementation Method 6
micro-crack formation due to thermal and pressure cycling
Implementation Method 7
prevents fluid migration, withstands higher pressures
Implementation Method 8
resistance to corrosive fluids
Data Source
AI summary
A cement composition is disclosed that includes a cement slurry and an epoxy resin system that includes at least one epoxy resin and a curing agent. The cement slurry has a density in a range of from 65 pcf to 180 pcf and includes a cement precursor material, silica sand, silica flour, a weighting agent, and manganese tetraoxide. The epoxy resin system includes at least one of 2,3-epoxypropyl o-tolyl ether, alkyl glycidyl ethers having from 12 to 14 carbon atoms, bisphenol-A-epichlorohydrin epoxy resin, or a compound having formula (I): (OC2H3)—CH2—O—R1—O—CH2—(C2H3O) where R1 is a linear or branched hydrocarbyl having from 4 to 24 carbon atoms; and a curing agent.