Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (08): 1803-1808.doi: 10.3866/PKU.WHXB20110823

• THERMODYNAMICS, KINETICS, AND STRUCTURAL CHEMISTRY • Previous Articles     Next Articles

Study on the Precipitation Pathway of Nanyishan Oilfield Brine at Subzero Temperatures

LI Qing-Hai2,3, GU Tong-Xin1, YU Sheng-Song2, YAO Yan2,LI Bing2, LI Wu2   

  1. 1. State Key Laboratory of Frozen Soil Engineering Cold and Arid Regions Environmental & Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000;
    2. Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008;
    3. Graduate University of Chinese Academy of Sciences, Beijing 100049
  • Received:2011-03-28 Revised:2011-05-19 Published:2011-07-19
  • Contact: LI Bing E-mail:libing@isl.ac.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (41073023) and National Science and Technology Pillar Program During the Eleventh Five-Year Plan Period, China (2006BAB09B07).

Abstract:

The crystallization processes of oilfield brine components from the Nanyishan area at temperature between -18.90 and -30.90 °C were studied by a self-designed refrigeration instrument and the precipitation temperatures of the first and second salts were measured accurately. The concentrations of the major ions (Ca2+, Mg2+, K+, Cl-, B2O3, Na+) in the liquid phase of the brine at different temperatures (from -18.90 to -30.90 °C) were determined by chemical analyses. The solids obtained at low temperature were identified and the phase changes of the oilfield brine at temperatures between -10.0 and -30.0 °C were monitored in situ by subzero temperature X-ray powder diffraction. The results show that the first salt (hydrohalite) precipitates at -19.10 °C and the ice and NaCl·2H2O co-precipitate at -23.55 °C.

Key words: Oilfield brine, Freezing, Hydrohalite, Ice, X-ray diffraction at subzero temperature

MSC2000: 

  • O642