Mechanism and performance of a lithium chloride accelerator

• Published in: Petroleum science 2011-09, Vol.8 (3), p.328-334
• Main Authors: Wang, Chengwen, Wang, Ruihe, Cheng, Rongchao, Chen, Erding
• Format: Article
• Language: English
• Subjects: Accelerators; Ca（OH）2; Cementing; Cements; Crystals; Dicalcium silicate; Earth and Environmental Science; Earth Sciences; Economics and Management; Energy Policy; Hydration; Industrial and Production Engineering; Industrial Chemistry/Chemical Engineering; Lithium chlorides; Mineral Resources; Thickening; 加速器; 固井作业; 机制; 氯化锂; 水化产物; 碱金属氯化物; 绩效
• ISSN: 1672-5107; 1995-8226
• DOI: 10.1007/s12182-011-0149-6

To address present concerns about thickening time and high early-strength in deepwater cementing at low temperatures when using conventional accelerators, a new type of set-accelerating admixture comprising of lithium chloride, aluminium hydroxide and alkaline metal chlorides, named as LS-A, was studied in this paper. Mechanism analysis and performance tests show that the accelerator LS-A accelerated the hydration of tri- and dicalcium silicates （C3S and C2S） at low-temperatures by speeding up the breakdown of the protective hydration film and shortening the hydration induction period. Therefore, LS-A could shorten the low-temperature thickening time and the transition time of critical gel strength from 48 to 240 Pa of the Class-G cement slurry, and improve the early compressive strength of set cement at low-temperatures. It exhibited better performance than calcium chloride and had no effect on the type of hydration products, which remain the same as those of neat Class-G cement, i.e. the calcium silicate gel, Ca（OH）2 crystals and a small amount of ettringite AFt crystals. LS-A provides an effective way to guarantee the safety of cementing operations, and to solve the problems of low temperature and shallow water/gas flowing faced in deepwater cementing.