Abstract
In this research, a kind of 2-acrylamido-2-methylpropanesulfonic acid sodium salt- (AMPS-Na-) type copolymer additive, the fluid loss additive (FLA), named as FLA A additive, was used for research. The performance of FLA A was tested and found to fail in the effective control of free water and to hinder the hydration process for delaying the breaking of the early hydration shell. The reason for it was the absorbed behavior and chelating effect of the AMPS-Na unit to Ca2+ hydrating cement particles. Thus, a cationic polyvinyl alcohol (PVA) polymer, modified by glyoxal and boric acid, was discovered due to its excellence in associating with the FLA A additive for controlling the free cement-based material water amount and preventing the chelating effect of FLA A chains on the surface of the cement-based material. Glyoxal/boric acid-modified polyvinyl alcohol, abbreviated as PVAGB or PVA-G-B, was with special molecular properties, i.e., positive ZETA (ζ) potential characteristics and cross-linked molecular structure. Due to competitive absorbed behavior of glyoxal-modified hydroxyl groups and free Ca2+ released by the hydration product, the chelating effect of AMPS-Na units to Ca2+ was weakened and the possibility of FLA A chains being absorbed to the surface of the cement-based material was decreased. Then, the formation of a complete fluid loss system was obtained; i.e., the fluid loss volume decreased to less than 50 mL at 30°C and 108 mL at 80°C with 0.2 percentage by weight of cement (%BWOC) of PVAGB and 0.50%BWOC (percentage by weight of cement) of FLA A. Besides, the hydration process of cement-based material was accelerated due to formation of more C-S-H gels in the early hydration period. As a result, the cement-based material not only showed no worse compressive-strength retrogression but also showed a stable 28-day compressive strength of 28 MPa.
Highlights
For more superior comprehensive performance of cementitious materials used in oil well cementing projects, different kinds of additives are being used for optimization of cementitious materials
A new type of cationic cross-linked polyvinyl alcohol, named as PVA-Glyoxal-Boric Acid (PVAGB), had been remarkably regarded, and it had been utilized for better fluid loss control ability and it was beneficial in accelerating the early hydration of cement-based materials [6], in which PVAGB possibly showed no chemically absorbed behaviors to cement particles, so as to keep the microstructure completion of cement itself and reduce its microstructure permeability
The FLA A additive, an AMPStype fluid loss additive, which is a commercial product made in China, was used for research of absorption behaviors and mechanism of AMPS-type fluid loss additive used in cement-based materials
Summary
For more superior comprehensive performance of cementitious materials used in oil well cementing projects, different kinds of additives are being used for optimization of cementitious materials. A new type of cationic cross-linked polyvinyl alcohol, named as PVAGB, had been remarkably regarded, and it had been utilized for better fluid loss control ability and it was beneficial in accelerating the early hydration of cement-based materials [6], in which PVAGB possibly showed no chemically absorbed behaviors to cement particles, so as to keep the microstructure completion of cement itself and reduce its microstructure permeability. A cross-linked cationic polyvinyl alcohol (PVA) polymer, modified by glyoxal (G) and boric acid (B), could be used for better functional synergy of FLA A additives to form an excellent fluid loss control system. This could be a possible solution to form chains in a uniform spatial distribution and could be formed by chemisorption mechanism of the FLA A additive itself
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
