Passivated Cement Accelerator for Gelation Control
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Solution Overview
Problem
Traditional cement accelerators used in subterranean cementing operations often face issues such as gelation and flash setting, which can lead to operational delays and formation damage, and are not effective at low temperatures or in the presence of certain additives, such as CaCl2, which can corrode equipment and increase costs.
Innovation Solution
The use of passivated cement accelerators, which are prepared by hydrating cementitious materials in an abundance of water to prevent agglomeration and setting, creating a semi- or completely impermeable barrier that allows for increased early strength development without gelation or flash setting, and can be used in a wide range of temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional cement accelerators (e.g., CaCl2) are used to accelerate strength development, then early strength is improved, but gelation and flash setting occur causing operational delays and formation damage
Solution Approach 1:
The patent introduces a passivated accelerator as an intermediary substance that mediates between the cementitious materials and the acceleration process. This passivated accelerator contains a passivating layer formed by hydration products that control the release of acceleration ions, preventing direct contact that would cause gelation or flash setting while still enabling controlled early strength development.
Solution Approach 2:
The passivated accelerator is prepared in advance by hydrating cementitious materials to form a passivating layer before use. This preliminary hydration action creates a controlled barrier that regulates the acceleration process during actual cementing operations, preventing premature setting while maintaining strength acceleration benefits.
2Loss of time
If traditional cement accelerators are used to reduce hydration time, then operational time is reduced, but they are not effective at low temperatures and can corrode equipment
Solution Approach 1:
The patent changes the physical and chemical parameters of the accelerator by creating a passivated form with a hydrated surface layer. This modification allows the accelerator to function effectively across a wider temperature range including low temperatures, while the controlled ion release mechanism prevents equipment corrosion associated with traditional CaCl2-based accelerators.
3Reliability
If dispersants are added to prevent gelation, then gelation is reduced, but gelation issues persist and operational problems continue
Solution Approach 1:
The passivated accelerator is designed to be self-regulating through its passivating layer structure. The hydration products in the passivating layer automatically control the release of acceleration ions without requiring additional dispersants or chemical additives, eliminating the need for complex formulation adjustments and resolving gelation issues inherently.
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 passivated cement accelerators provide a low-cost, logistical means to accelerate early strength development and increase compressive strength in cement compositions, preventing gelation and flash setting, and are effective across various temperature ranges, including low temperatures, thus improving the efficiency and safety of cementing operations.
Implementation Method 1
prepared by hydrating cementitious materials in an abundance of water to prevent agglomeration and setting, creating a semi- or completely impermeable barrier
Implementation Method 2
provide a low-cost, logistical means to accelerate early strength development and increase compressive strength in cement compositions
Implementation Method 3
preventing gelation and flash setting
Data Source
AI summary
Embodiments relate to cementing operations and, in certain embodiments, to passivated cement accelerators and methods of using passivated cement accelerators in subterranean formations. An embodiment may comprise a method of cementing comprising: providing a cement composition comprising cement, water, and a passivated cement accelerator; and allowing the cement composition to set.