Set-Delayed Cement Composition Using Pumice and Hydrated Lime
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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, hindering their effectiveness in subterranean cementing operations.
Innovation Solution
A set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder, which remains pumpable for extended periods and develops reasonable compressive strengths at low temperatures, using pumice with a specific particle size and hydrated lime ratio, along with optional dispersants and additives for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If set-delayed cement compositions are prepared with Portland cement to enable extended pumpable state, then the cement composition can be stored and transported in advance, but gelation issues occur and compressive strength is insufficient at lower temperatures
Solution Approach 1:
The patent changes the chemical composition parameters by replacing Portland cement with a blend of Class N and Class S lime (specifically hydrated lime) and using pumice with controlled particle size distribution (d10, d50, d90 values). This parameter change enables the cement composition to remain pumpable for extended periods (at least 24 hours) while developing adequate compressive strength at low temperatures (as low as 50°F or 10°C), resolving the contradiction between extended pumpability and reliable strength development.
2Device complexity
If set-delayed cement compositions remain in pumpable fluid state for extended period, then capital expenditures are reduced by reducing on-site bulk storage and mixing equipment, but the composition may not develop sufficient compressive strength when used in subterranean formations having lower bottom hole static temperatures
Solution Approach 1:
The patent uses a composite material system consisting of Class N and Class S lime (hydrated lime) combined with pumice having specific particle size characteristics. This composite approach allows the cement slurry to maintain pumpability for extended periods while developing sufficient compressive strength at low temperatures, eliminating the need for complex on-site equipment and bulk storage while ensuring reliable strength development in cold subterranean formations.
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 composition effectively sets into a hardened mass at low temperatures, providing a stable and effective cement sheath for subterranean formations, reducing capital expenditures and on-site mixing needs, and is suitable for offshore operations.
Implementation Method 1
set-delayed cement compositions are characterized by remaining in a pumpable fluid state for an extended period of time
Implementation Method 2
When desired for use, the set-delayed cement compositions should be capable of being activated whereby reasonable compressive strengths are developed
Data Source
AI summary
A variety of methods and compositions are disclosed, including, in one embodiment, a method of cementing in a subterranean formation, comprising: providing a set-delayed cement composition comprising water, pumice, hydrated lime, and a set retarder; activating the set-delayed cement composition; introducing the set-delayed cement composition into a subterranean formation; and allowing the set-delayed cement composition to set in the subterranean formation.