Set-Delayed Cement Activators for Low-Temperature Strength
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Solution Overview
Problem
Set-delayed cement compositions, particularly those with Portland cement, face gelation issues and limited compressive strength at lower temperatures, restricting their effectiveness in subterranean cementing operations.
Innovation Solution
The development of set-delayed cement compositions comprising water, pumice, hydrated lime, and a set retarder, optionally with a dispersant, which remain pumpable for extended periods and develop reasonable compressive strengths at low temperatures, using a cement set activator like a combination of a monovalent salt and polyphosphate to accelerate setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If set-delayed cement compositions are prepared with Portland cement, then they can be stored for extended periods, but they experience undesired gelation issues
Solution Approach 1:
The patent changes the chemical composition parameters by replacing Portland cement with a blend of hydrated lime and settable material, and by optimizing the water-to-cementitious materials ratio to below 0.40, thereby extending storage time while preventing gelation
Solution Approach 2:
The patent uses a composite cementitious system combining hydrated lime with settable materials (such as Class H or Class G cement at reduced percentages, or alternative settable materials like magnesia or calcium aluminate cement), creating a composite formulation that achieves both extended storage stability and reliable gelation control
2Duration of action of stationary object
If set-delayed cement compositions use hydrated lime and quartz, then they can be stored for extended periods, but they do not develop sufficient compressive strength at lower temperatures
Solution Approach 1:
The patent modifies the compositional parameters by incorporating set accelerators (such as calcium chloride, calcium nitrate, or triethanolamine) and optimizing the cementitious materials blend to enhance early-age strength development at low temperatures while preserving extended storage capability
Solution Approach 2:
The patent creates a composite formulation combining hydrated lime with specific settable materials and additives that work synergistically to provide both extended storage stability and adequate compressive strength development in cold environments
3Strength
If set accelerators are added to activate set-delayed cement compositions, then compressive strengths are developed, but the setting time is reduced
Solution Approach 1:
The patent uses controlled amounts of set accelerators added only at the time of activation, applying partial action to achieve sufficient strength development without completely eliminating the delay benefit, allowing optimization between strength gain rate and available working time
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
These compositions effectively maintain a pumpable state for extended periods and achieve desirable compressive strengths at various temperatures, enhancing their suitability for subterranean formations with low bottom hole static temperatures.
Implementation Method 1
a cement set activator, such as a combination of a monovalent salt and polyphosphate, to accelerate setting
Implementation Method 2
optionally with a dispersant
Data Source
AI summary
Disclosed herein are cement compositions and methods of using set-delayed cement compositions in subterranean formations. In one embodiment, a method of cementing in a subterranean formation is described. The method may comprise providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder; activating the set-delayed cement composition with a liquid additive to produce an activated cement composition, wherein the liquid additive comprises a monovalent salt, a polyphosphate, a dispersant, and water; and allowing the activated cement composition to set.