阴离子瓜尔胶溶液及其弱酸性冻胶的流变性研究

Rheologic Properties of an Anionic Guar Gum Solution and Its Weakly Acidic Gel

合成了水溶性好、水不溶物含量低(≤1.6%)、阴离子度为3.0%3.5%的羧甲基羟丙基瓜尔胶。该阴离子瓜尔胶的0.1%1.0%水溶液均显示假塑性,随溶液浓度增大,K值增大而n值减小。0.5%水溶液的表观黏流活化能为12.58kJ/mol,较一般的瓜尔胶、羟丙基瓜尔胶小。水溶液在酸性条件可与有机锆交联剂WZG形成压裂液冻胶,聚交比10∶1(WZG含Zr4+10%)、pH=4时形成的弱酸性冻胶表观黏度最高。研究了弱酸性冻胶的动态力学性能G′、G″和tgδ,结果表明:在25℃下经过150min后该弱酸性冻胶的性能才达到稳定;在25℃下形成的0.7%和0.5%阴离子瓜尔胶冻胶的性能,好于1.0%和0.35%阴离子瓜尔胶冻胶;0.7%阴离子瓜尔胶冻胶在2560℃温度范围均可形成,最佳温度为55℃,高于或低于55℃形成的冻胶形能变差,表明冻胶三维网络结构完善程度变差。G′、G″和tgδ曲线在较高频率区复杂化,即G′降低,G″和tgδ出峰,这与网络结构缺陷有关,如一端自由的网链。

A readily soluble anionic guar gum（AGG） of low insoluble substances content, ≤ 1.6% , chemically being carboxymethyl hydroxypropyl guar gum of anionization degree 3. 0--3. 5%, was prepared. 0. 1--1.0% aqueous AGG solution was theologically pseudplastic fluid with K value increased and n value decreased with increasing AGG solution concentration; an apparent viscous flow activation energy of 12. 58 kJ/mol was determined for 0. 5% AGG solution,being lower than that for guar gum and hydroxypropyl guar gum solutions. AGG solution with organic zirconium crosslinker WZG（ containing 10% Zr4＋） forms gelled fracturing fluid in acidic media and the highest apparent viscosity was created for the weakly acidic gel（WAG） at AGG to WZG ratio 10：1 and pH =4. The dynamic mechanical properties（DMPs） G′ ,G＂,and tg δof the WAG were investigated. The G′ and G＂ of WAG became stable at 25℃ in 150 rain;the DMPs of WAG of 0. 7% and 0. 5% AGG formed at 25℃ were better than that of WAG of 1.0% and 0. 35% AGG formed at the same temperature ;0. 7% AGG solution and WZG could form WAG at temperatures 25--60℃ with the optimal gelling temperature being of 55 ℃ and the WAG formed at higher or lower temperatures revealed some what worse DMPs, that showed some degree of deterioration in network of the WAG, Complications, that is, G′ drop down and G′ and tg δpeaks appeared on higher frequency sections of G′, G＂, and tg δ curves and displayed the imperfectness of the WAG network, possibly pendent chain segments.