变粘酸用转向稠化剂VCA的研制

Preparation of Cationic Surfactant VCA as Thickener for Hydrochloric Acidizing Fluid with Self-Changeable Viscosity

由长链脂肪酸衍生物合成了分子量～480、易溶于水和酸的阳离子表面活性剂VCA,实验考察了VCA作为自变粘盐酸液稠化剂的性能.VCA为50%水溶液,呈棕红色,粘度～10 mPa·s,在22%盐酸中当温度＜40℃时可稳定存在7天以上.在25℃模拟酸岩反应中,含VCA的22%盐酸液逐步被Ca(OH)2中和,当酸浓度降至17%以下时,在Ca2+作用下VCA球形胶束变为蠕虫状胶束并形成网状结构,酸液变为粘弹性凝胶,20和40 g/L VCA酸液粘度最高达～450和接近900mPa·s(乏酸浓度3%时),酸岩反应完成、pH值升至4以上时凝胶完全破解.VCA酸液耐温性良好,浓度由22%被中和至16%的含40 g/L VCA的盐酸液,在90℃、170 s-1粘温性测定中,初始粘度～82 mPa·s(～25℃),最高粘度～95 mPa·s(90℃),1J时后粘度≥19 mPa·s(90℃).含20 g/L VCA的22%盐酸液与大理石在90℃、常压、静态反应100min,大理石剩余质量＞50%,表明该酸液缓速性良好.含40 g/L VCA的22%盐酸液在相同条件下与大理石完全反应后,乏酸液粘度＜5.0 mPa·s,无沉淀,与水完全混溶.图3参5.

A cationic surfactant, VCA, of M≈480 and readily soluble inwater and acids is prepared from a derivative of long chain fatty acid and evaluated eperirnentally as thickener for HCI acidizing fluids with self-changeable viscosity. VCA is a 50% aqueous solution of brown-red color, has viscosity - 10 mPa＇s and is stable in 22% HCl solution at ≤40℃ over 〉 7 days. In a simulation acid-rock reaction at 25℃, VCA containing 22% HCl solution is neutralized stepwise by Ga（OH）2 and, when the acid concentration is lowered down to 〈 17 %, a gradual transition of globular micellae of VCA to wormlike ones and of micellar solution to gel ocurrs at the presence of increasing concentration of Ca^2 ＋ and a gradual increase in acid viscosity is observed with peak value- 450 mPa＇s for 20 g/L VCA solution in acid and nearly 900 mPa＇s for 40 g/L VCA solution in acid at spent acid concentration 3 % and when the acid-rock reaction finished and the pH value of the acid raised up to 〉4, the acid gel completly breaks down. VCA containing acids are thermally resistant and the viscosity-temperature relationship at 90℃ and 170 s^-1 for 40 g/L VCA solution in 22% HCl acid having been neutralized to 16% HCl acid is characterized by following figures： initial viscosity --82 mPa·s; the highest viscosity at 90℃ mPa＇s; the viscosity maintained at 90℃ in 60 min ≥19 mPa·s. 〉50% （m/m） of marble is remainded unreacted after 100 minutes reaction of 20 g/L VCA solution in 22% HCl acid and marble at 90 --95℃, atmospheric pressure, and static condition, which demostrates good retardation capacity of VCA acids. When 40 g/L VCA solution in 22% HCl acid is completly reacted with marble under the same conditions, a spent acid of viscosity of 〈5.0 mPa·s and readily compatible with water is formed without any precipiatation.