压裂用超临界CO₂增稠剂制备及增稠性能评价

Synthesis and performance evaluation of supercritical CO2 thickener for fracturing

 李强 王彦玲 李庆超 王福玲 李永飞 汤龙浩

中国石油大学（华东）石油工程学院，山东 青岛 266580 中国石油大学（华东）石油理学院，山东 青岛 266580

School of Petroleum Engineering, China University of Petroleum, Qingdao 266580, China College of Science, China University of Petroleum, Qingdao 266580, China

 CO2在压裂过程中黏度较小，导致携砂能力较弱，压裂效果不明显。为改善CO2的黏度，增强压裂效果，基于相似相溶理论和分子作用力理论，制备了具有一定分子质量可显著增稠的硅氧烷聚合物，并以甲苯作为助溶剂，使用毛细管压差计，对不同压力和温度下不同质量浓度的增稠剂进行增稠性能测试，分析测试效果。结果表明：分子中加入恒定比例的疏CO2基团，其溶解性能不变，但增稠效果显著增大；相同质量浓度的增稠剂，相同压力下随温度的升高，其增稠效果显著降低，相同温度下随压力的升高，其增稠效果升高不明显；文中测试最大黏度为1.2 mPa·s（增稠30倍）。另外，较小的分子质量有利于聚合物在CO2中的溶解和增稠，硅氧烷类增稠剂在压裂过程中可以避免地下水和地表水的污染。合成的聚合物能够明显提高液态CO2的黏度，测试结果表明，硅氧烷作为CO2增稠剂时的合成规则及其使用条件，可以为压裂用超临界CO2增稠剂的设计提供参考。

 The small viscosity of supercritical CO2 leads to a weak sand-carrying performance and an invisible fracturing effect in CO2 fracturing. In order to deeply transform the situation of the poor fracturing effect, a silicone polymer molecule with a certain molecular weight which can significantly thicken supercritical CO2 was synthesized based on the similar phase solution theory and molecular force theory. With the assistance of toluene, thickening performance test was conducted by self-designed capillary viscometer at different pressures and temperatures, and test results were analyzed in details. The experimental result shows not only the excellent solubility but also a superior thickening performance due to a constant ratio CO2-phobic group in polymer molecular; under the premise of constant pressure and polymer concentration, thickening performance decreases with the temperature increasing, by contrast, an almost constant viscosity is exhibited with increasing the pressure when the temperature is unchanged; the maximum test viscosity is 1.2 mPa·s. A smaller molecular weight is beneficial to the dissolution and thickening performance of polymer in liquid CO2, and then it can also protect the water resources from contamination. The synthesized polymer can improve the viscosity of liquid CO2 significantly, and the experimental results show a synthesis rule of the silicone polymer and a screening of applicable conditions, which provides a reference for the design of supercritical CO2 thickener for CO2 fracturing.

10.6056/dkyqt201804029