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Li L.,No. 88 Zhongshan Dadao Nanerduan
Drilling Fluid and Completion Fluid | Year: 2014

When drilling saltwater zone, gypsum and cement, the contamination of drilling fluid by calcium, sometimes very high concentrations, seemed to be a major concern. Drilling fluid contaminated by calcium results in poor rheology and bad mud cake. ZTL-1, a rheology modifier for high temperature and high calcium use, was developed in laboratory. At concentrations of 0.5%-0.75%, ZTL-1 effectively protect the bentonite slurry to have good rheology, even after aging at 160 °C. ZTL-1 works in two ways; chelation and colloid protection. It functions well at calcium concentration of up to 40,000 mg/L and can reduce the calcium by 85.5% by chelation. With ZTL-1, calcium's ability to compress the electric double layer of bentonite particles is inhibited, increasing the Zeta-potential of bentonite particles from -2.16 mV to -28.21 mV, ensuring the hydration and dispersion of bentonite particles. At concentration of 0.75% of ZTL-1, increasing the calcium concentration from 0-11.1%, three peaks are shown on the particle size distribution curve of bentonite, and the numbers of bentonite particles with sizes ranging from 100-300 nm are relatively stabilized. ZTL-1 is well compatible with other drilling fluid additives regularly used. Source


Li L.,No. 88 Zhongshan Dadao Nanerduan | Xiang C.,No. 88 Zhongshan Dadao Nanerduan | Ou X.,No. 88 Zhongshan Dadao Nanerduan | Liu W.,No. 88 Zhongshan Dadao Nanerduan
Drilling Fluid and Completion Fluid | Year: 2014

When drilling saltwater zone, gypsum and cement, the contamination of drilling fluid by calcium, sometimes very high concentrations, seemed to be a major concern. Drilling fluid contaminated by calcium results in poor rheology and bad mud cake. ZTL-1, a rheology modifier for high temperature and high calcium use, was developed in laboratory. At concentrations of 0.5%-0.75%, ZTL-1 effectively protect the bentonite slurry to have good rheology, even after aging at 160℃. ZTL-1 works in two ways; chelation and colloid protection. It functions well at calcium concentration of up to 40,000 mg/L and can reduce the calcium by 85.5% by chelation. With ZTL-1, calcium's ability to compress the electric double layer of bentonite particles is inhibited, increasing the Zeta-potential of bentonite particles from -2.16 mV to -28.21 mV, ensuring the hydration and dispersion of bentonite particles. At concentration of 0.75% of ZTL-1, increasing the calcium concentration from 0-11.1%, three peaks are shown on the particle size distribution curve of bentonite, and the numbers of bentonite particles with sizes ranging from 100-300 nm are relatively stabilized. ZTL-1 is well compatible with other drilling fluid additives regularly used. Source

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