Calcium Aluminophosphate Cement for High-Temperature Corrosion Resistance
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Solution Overview
Problem
Extended-life cement compositions face challenges in high-temperature and corrosive subterranean environments, such as those with temperatures greater than 230°F and the presence of carbon dioxide or hydrogen sulfide, leading to cement degradation and loss of support for casings and undesirable fluid communication.
Innovation Solution
The development of extended-life calcium aluminophosphate (CAP) cement compositions, which include calcium aluminate, polyphosphate, water, and a cement set retarder, capable of remaining in a pumpable state for extended periods and developing compressive strength at high temperatures, while resisting corrosive attacks from carbonic acid and hydrogen sulfide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If extended-life Portland cement compositions are used, then the cement can be stored for extended periods in a pumpable state, but the cement fails at temperatures greater than 230°F
Solution Approach 1:
The patent changes the chemical composition parameters of the cement from traditional Portland cement to a calcium aluminate-based system with specific ratios of calcium aluminate cement, alumina, and alumino-silicate. This parameter change enables the cement to maintain both extended storage life and high-temperature stability, resolving the contradiction between storage duration and temperature resistance.
Solution Approach 2:
The patent creates a composite cement composition by combining multiple materials: calcium aluminate cement, alumina, alumino-silicate, and various additives. This composite approach allows the cement to achieve properties that individual components cannot provide alone, specifically maintaining structural integrity at temperatures above 230°F while remaining pumpable during extended storage.
2Duration of action of moving object
If extended-life calcium aluminate cement compositions are used, then the cement can be stored for extended periods, but the hydroxides in the composition are subject to corrosive attacks by carbonic acid
Solution Approach 1:
The patent addresses the corrosion issue by using calcium aluminate-based chemistry that forms protective hydration products. Instead of merely resisting corrosion, the cement composition is designed to create a protective barrier that actually protects the casing from corrosive environments, converting the potential harm into a beneficial protective effect.
Solution Approach 2:
The patent modifies the chemical composition to use calcium aluminate cement with specific ratios and additives that alter the hydration products formed. This parameter change results in a cement that sets into a hardened mass resistant to carbonic acid and other corrosive substances, while maintaining extended storage capability.
3Speed
If conventional cement compositions are used, then the cement sets quickly upon preparation, but on-site bulk storage and mixing equipment are required
Solution Approach 1:
The patent applies preliminary action by pre-mixing the cement composition components and storing them in a pumpable state for extended periods. This allows the cement to be prepared in advance at a convenient location, eliminating the need for on-site bulk storage and mixing equipment, while still achieving proper setting when pumped into the wellbore.
Solution Approach 2:
The patent creates a dynamic system where the cement maintains a fluid, pumpable state during storage but transitions to a hardened state upon placement. This dynamic property allows the cement to be stored for extended periods without setting, then activate and set quickly when needed, resolving the contradiction between setting speed and equipment requirements.
Data Source
AI summary
Methods, compositions, and systems for cementing are included. The method comprises providing an extended-life calcium aluminophosphate cement composition comprising calcium aluminate cement, a polyphosphate, water, and a cement set retarder. The method further comprises mixing the extended-life calcium aluminophosphate cement composition with a cement set activator to activate the extended-life calcium aluminophosphate cement composition, introducing the activated extended-life calcium aluminophosphate cement composition into a subterranean formation, and allowing the activated extended-life calcium aluminophosphate cement composition to set in the subterranean formation.