High Temperature Resistant Portland Cement Slurry for Heavy Oil Recovery
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Solution Overview
Problem
Current cement slurry systems for heavy oil thermal recovery wells suffer from degraded compressive strength at high temperatures, increased permeability, and instability, leading to reduced well integrity and production life, with high costs associated with aluminate and aluminophosphate cements, and compatibility issues with Portland cement.
Innovation Solution
A high temperature resistant Portland cement slurry comprising 100 parts of Portland cement, 60-85 parts of high temperature reinforcing materials, 68-80 parts of fresh water, 1-200 parts of a density adjuster, 0.1-1.5 parts of a suspension stabilizer, 0.8-1.5 parts of a dispersant, 3-4 parts of a fluid loss agent, 0-3 parts of a retarder, and 0.2-0.8 parts of a defoamer, which maintains compressive strength above 40 MPa at 350°C and stabilizes long-term performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If Portland cement plus quartz sand is used as cement slurry system, then cost is reduced, but high temperature compressive strength is severely degraded at 350°C
Solution Approach 1:
The patent uses a composite material system combining Portland cement with specifically selected admixtures (high-temperature resistant water reducer, high-temperature resistant accelerator, and high-temperature resistant retarder) to create a cement slurry that maintains both cost-effectiveness and high-temperature compressive strength. This composite approach allows the use of inexpensive Portland cement while achieving the performance characteristics of more expensive high-temperature cements through synergistic additive effects.
2Strength
If aluminate cement or aluminophosphate cement is used, then high temperature compressive strength is improved, but price increases more than ten times that of Portland cement
Solution Approach 1:
The patent replaces expensive aluminate cement or aluminophosphate cement with inexpensive Portland cement combined with specially formulated admixtures. This substitution uses a cheap base material (Portland cement) enhanced by functional additives to achieve the required high-temperature performance, eliminating the need to use costly alternative cements while maintaining strength requirements.
Solution Approach 2:
The patent modifies the chemical and physical parameters of Portland cement through the addition of specific admixtures (water reducer, accelerator, and retarder) that are designed to resist high-temperature degradation. These parameter changes in the cement slurry composition enable it to achieve high-temperature compressive strength comparable to expensive alternative cements while maintaining cost-effectiveness.
3Strength
If aluminate cement or aluminophosphate cement is used, then high temperature performance is improved, but compatibility with Portland cement deteriorates causing flocculation
Solution Approach 1:
The patent introduces high-temperature resistant admixtures (water reducer, accelerator, and retarder) as intermediary substances that mediate between Portland cement and the high-temperature environment. These admixtures act as compatibility agents that prevent flocculation and maintain slurry stability, eliminating the need to use incompatible aluminate or aluminophosphate cements while achieving the desired high-temperature performance.
Data Source
AI summary
The invention provides a high temperature resistant Portland cement slurry and a production method thereof. The high temperature resistant Portland cement slurry comprises the following components by weight: 100 parts of an oil well Portland cement, 60-85 parts of a high temperature reinforcing material, 68-80 parts of fresh water, 1-200 parts of a density adjuster, 0.1-1.5 parts of a suspension stabilizer, 0.8-1.5 parts of a dispersant, 3-4 parts of a fluid loss agent, 0-3 parts of a retarder and 0.2-0.8 part of a defoamer. The high temperature resistant Portland cement slurry has a good sedimentation stability at normal temperature, and develops strength rapidly at a low temperature. The compressive strength is up to 40 MPa or more at a high temperature of 350° C., and the long-term high-temperature compressive strength develops stably without degradation. Therefore, it can meet the requirements for field application in heavy oil thermal recovery wells, reaching the level of Grade G Portland cement for cementing oil and gas wells.