Combined Set-Delayed Cement Compositions for Low-Temperature Strength
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Solution Overview
Problem
Set-delayed cement compositions face challenges in developing sufficient compressive strength at lower subterranean temperatures and maintaining acceptable thickening times, limiting their effectiveness in certain subterranean cementing operations.
Innovation Solution
A combination of two set-delayed cement slurries, one comprising Portland cement and a pozzolanic cement, and the other comprising calcium aluminate cement, with specific set retarders and optional additives, which remain pumpable for extended periods and develop compressive strength at low temperatures upon combination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If set-delayed cement compositions are used to remain pumpable for extended periods, then storage and transportation convenience is improved, but compressive strength development at lower temperatures deteriorates
Solution Approach 1:
The patent combines Portland cement and calcium aluminate cement in a composite slurry system. The calcium aluminate cement component specifically addresses low-temperature strength development, while the Portland cement provides the extended pumpable storage time. This composite approach allows both requirements to be met simultaneously.
Solution Approach 2:
The patent modifies the chemical composition parameters of the cement slurry by incorporating specific components (calcium aluminate cement, lithium salt, borate compound) that change the setting and strength development characteristics. These parameter changes enable the slurry to maintain pumpability while developing strength at lower temperatures.
2Ease of operation
If set-delayed cement compositions are formulated for extended pumpability, then on-site preparation flexibility is improved, but thickening time control deteriorates
Solution Approach 1:
The patent introduces lithium salt and borate compound as intermediary substances that mediate between the cement components and water. These intermediaries control the thickening process by regulating the setting reaction, allowing flexible on-site preparation while maintaining acceptable thickening times even in cold conditions.
Solution Approach 2:
The patent adjusts chemical composition parameters including lithium salt and borate compound concentrations to optimize the balance between pumpability duration and thickening time. These parameter modifications enable operators to maintain flexibility while controlling setting characteristics.
3Ease of manufacture
If set-delayed cement compositions are prepared in advance for transportation, then capital expenditures are reduced, but activation and strength development become problematic
Solution Approach 1:
The patent prepares the cement slurry in advance with all necessary components (Portland cement, calcium aluminate cement, lithium salt, borate compound, water) already mixed and ready for transportation. The preliminary action includes incorporating activation-enhancing components that ensure reliable activation upon injection, eliminating the need for additional set activators at the well site.
Solution Approach 2:
The patent creates a universal cement composition that functions both as a long-term stable, pumpable slurry during storage and as a reliable setting material upon activation. The multi-functional design allows the same composition to serve both storage and activation requirements without modification.
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 combined set-delayed cement compositions achieve desirable compressive strength and thickening times, suitable for subterranean formations with low bottom hole static temperatures, without the need for additional set activators, enhancing their suitability for various cementing operations.
Implementation Method 1
When desired for use, the set-delayed cement compositions should be capable of activation and consequently develop reasonable compressive strengths. For example, a set-delayed cement composition that is activated may set into a hardened mass.
Data Source
Figure 1~2A
Figure 2B
AI summary
Methods of using the set-delayed cement slurries and compositions resulting from the combination of the set-delayed cement slurries are also described. A method may comprise providing a first set-delayed cement slurry comprising a pozzolanic cement and/or a Portland cement, water, and a first cement set retarder; providing a second set-delayed cement slurry comprising calcium-aluminate and a second cement set retarder; mixing the first slurry and the second slurry to form a cement composition; and allowing the cement composition to set.