耐高温酸性清洁压裂液性能研究及适用性探讨

Research and Discussion on Applicability of High Temperature Resistant Acidic Clean Fracturing Fluid

张 艳 张士诚 张 劲 王 雷

ZHANG Yan ZHANG Shi-Cheng ZHANG Jin WANG Lei

耐高温酸性清洁压裂液配方为：0.1%~5%乙酸、0.1%水杨酸、0.5%~1%阴离子型聚丙烯酰胺稠化剂、0.1%~0.2%季胺盐型阳离子双子表面活性剂和0.5%~3%黏土稳定剂(氯化钾、氯化铵)，其余为自来水。研究了不同稠化剂加量下，酸性压裂液的流变性、稠化时间、携砂性以及破胶性等。酸性压裂液呈弱酸性，pH值为4～5。其耐温抗剪切性较好，120℃时的黏度为30~50 mPa·s，140℃时黏度稳定在20 mPa·s左右。压裂液稠化时间在60 s以内。稠化剂加量为1.0%时，压裂液成胶黏度可达140 mPa·s。其携砂能力强，稠化剂加量为0.8%的酸性压裂液单颗砂沉降速率仅0.023 mm/s，而0.8%胍胶压裂液的为0.169 mm/s。压裂液遇到一定量的油、气及地层水时会自动破胶，60~80℃的破胶时间在1 min内，加入过硫酸铵可加快破胶。该酸性压裂液适用于120℃以下的高含钙低渗透储层。

The formula of high temperature resistant acidic clean fracturing fluid was obtained as follows: 0.1%—5% acetic acid, 0.1% salicylic acid, 0.5%—1% anionic polyacrylamide, 0.1%—0.2% quaternary ammonium salt cationic gemini surfactant, 0.5%—3% clay stabilizers (potassium chloride, ammonium chloride) and water. The rheological properties, thickening time, sand-carrying properties and gel-breaking performance as a function of thickener concentration of acidic fracturing fluid were studied. The pH value of acidic clean fracturing fluid was 4—5. The viscosity of fracturing fluid was 30—50 mPa·s at 120℃ and 20 mPa·s at 140℃, which indicated a good shear and temperature resistance. The thickening time of fracturing fluid was within 60 s. The gel viscosity reached 140 mPa·s when the dosage of thickening agent was 1.0%. The acidic clean fracturing fluid possessed excellent proppant-carrying performance. The settling velocity of single sand in acidic fracturing fluid was only 0.023 mm/s with 0.8% thickener, while that in guar-based fracturing fluid with same thickener concentration was 0.169 mm/s. The acidic fracturing fluid would break automatically when it encountered a certain amount of oil, gas and formation water. And there was a accelerating in gel-breaking when ammonium persulfate was added. The gel-breaking time of acidic clean fracturing fluid was less than 1 min at 60—80℃. The acidic clean fracturing fluid was suitable for low permeability reservoir with high-calcium under 120℃.