Calculating Low Temperature Phase Equilibrium of NaCl-KCl-CaCl2 Completion Fluid Based on Pitzer Model
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摘要: 结晶点是混合盐水完井液的主要性能指标，绝大部分文献和手册只提供了单盐的结晶点数据，混合盐数据只有通过实验才能得到。通过数学模型计算混合盐水的结晶点可省去大量的实验工作，并为完井液组成优化提供依据。采用Pitzer模型和Spencer模型参数进行了完井液常用的NaCl、KCl和CaCl2的单盐及二元混合盐体系的固液相平衡计算。通过文献数据和实验数据验证了计算结果的可靠性。验证结果表明，在25℃以下时，计算值与文献值的相对标准偏差均小于0.1，能够满足完井液研究和施工设计的需要；25℃以上时，KCl的单盐体系计算偏差变大，需调整KCl的Pitzer参数再进行相平衡计算。Abstract: Crystallization point, a main performance index of composite brine completion fluids, can only be obtained through laboratory experiments because most of the articles and handbooks only give the crystallization point of the single salt. If the crystallization point of a composite brine can be calculated with mathematical model, then large amount of tedious experiment can be saved, and the optimization of composite brine completion fluid can be achieved using the calculated data. Using the Pitzer model and the Spencer model parameters, salts commonly used in completion fluids, such as NaCl, KCl and CaCl2, were calculated for their solid-liquid phase equilibrium both as single salt and binary salts. The liability of the calculation was verified using documented data and experiment data. It was shown that at temperatures below 25℃, the relative standard deviation between the calculated values and the documented data was less than 0.1, satisfying the need for completion fluid study and design. At temperatures above 25℃, the relative standard deviation for KCl became larger, and the Pitzer parameters of KCl needed to be adjusted for phase equilibrium recalculation.
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[1] HOOMAN H, ANTONIN C, BAHMAN T. Freezing point depression of electrolyte solutions:experimental measurements and modeling using the CPA equation of state[J]. Industrial & Engineering Chemistry Research, 2008, 47(11):S20-S22. [2] 岳前升, 杨青志, 陈军,等. 无机盐和有机盐对盐膏层溶解性的影响[J]. 钻井液与完井液,2013, 30(3):31-33.YUE Qiansheng, YANG Qingzhi, CHEN Jun, et al. Influence of inorganic and organic salt on solubility of gypsum[J]. Drilling Fluid & Completion Fluid, 2013,30(3):31-33. [3] 牛自得, 程芳琴. 水盐体系相图及其应用[M]. 天津:天津大学出版社, 2005:186-190. NIU Zide, CHENG Fangqin. Phase diagrams and applications of salt-water system[M].Tianjin:Tianjin university press, 2005:186-190. [4] 孙海霞,曹红翠,保英莲,等. 基于Pitzer模型的25℃ KCl-CsCl-H2O体系溶解度预测研究[J]. 西南民族大学学报(自然科学版),2014,40(1):54-57. SUN Haixia, CAO Hongcui,BAO Yinglian,et al. Solubility prediction in the systems of KCl-CsCl-H2O at 25℃ using Pitzer ion-interaction model[J].Journal of Southwest University for Nationalities(Natural Science Edition, 2014,40(1):54-57. [5] CHI GUOXIANG, CHU HAIXIA,RYAN SCOTT, et al. New method for determining fluid compositions in the H2O-NaCl-CaCl2 System with Cryogenic Raman Spectroscopy[J]. Acta Geologica Sinica(English Edition), 2014, 88(4):1169-1182. [6] RONALD J BAKKER,MIRIAM BAUMGARTNER. Unexpected phase assemblages in inclusions with ternary H2O-salt fluids at low temperatures[J].Open Geosciences, 2012,4(2):225-237. [7] SPENCER R J,MOLLER N,WEARE J H.The prediction of mineral solubilities in natural water:A chemical equilibrium model for the Na-K-Ca-Mg-Cl-SO42——H2O system at temperature below 25℃[J]. Geochim Cosmochim Acta, 1989, 54(3):575-590. [8] SANJOY K. BHATTACHARIA, NAZIR HOSSAIN, et al. Thermodynamic modeling of KCl+H2O and KCl+NaCl+H2O systems using electrolyte NRTL model[J].Fluid Phase Equilibaia, 2015, 403(2015):1-9. -
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