低黏度清洁压裂液黏弹性与悬砂能力的关系

RelationshipbetweenSuspendedProppantAbilityandViscoelasticityofCleanFracturingFluidwithLow Viscosity

陶红胜 王满学 杏毅 何静 张守江 段玉秀 乔红军

TAO Hongshen WANG Manxue XING Yi HE Jing ZHANG Shoujiang DUAN Yuxiu QIAO Hongjun

为揭示清洁压裂液悬砂机理，研究了低黏度清洁压裂液的黏性和弹性对其悬砂性的影响。以十八烷基二羟乙基甲基溴化铵、异丙醇、邻羟基苯甲酸钠和水作为压裂液主剂，按4% 主剂+ 2% KCl 配制压裂液。分析了表面活性剂、盐和pH调节剂（Na2CO3）对压裂液黏度和沉砂速度的影响，研究了不同Na2CO3加量下压裂液沉砂速度与弹性模量G' 和黏性模量G' ' 的关系。研究结果表明：在室温下，当支撑剂一定时，在不同加量主剂、椰子油脂肪酸二乙醇酰胺（CDEA）、KCl、NH4Cl 、CaCl2 和Na2CO3 条件下的压裂液黏度和沉砂速度关系与Stoke’s 静态沉砂规律相吻合。当十二烷基磺酸钠（SDS ）加量≥6.25% 或EDTA 加量≤0.2% 时，压裂液的黏度和悬砂性关系与Stoke’s 沉砂规律相反；当压裂液pH值为10时，随着十二烷基苯磺酸钠（ABS ）浓度增大，压裂液的黏度和沉砂速度关系完全与Stoke’s 规律相背离。随Na2CO3 加量增大，压裂液的黏度先增后降，沉砂速度先降后增、G' /G' ' 先增后降。表面活性剂型压裂液的悬砂性能不仅与黏性有关，还与弹性相关，其中弹性对液体悬砂性贡献最大。图14 表1 参11

The effects of viscosity and elasticity on the proppant settling velocity of clean fracturing fluid with low viscosity were studied. The fracturing fluid was composed of 2% KCl and 4% main agent including octadecyl 2-hydroxyethyl methyl ammonium bromide，isopropyl alcohol，adjacent hydroxyl sodium benzoate and water. The effect of surfactant，salt and Na2CO3 on the viscosity and proppant settling velocity of fracturing fluid and that on the correlation of Stoke ’s static settling formula was analyzed. At the same time，the relationship between settling velocity of fracturing fluid and elastic modulus ( G') and viscous modulus (G") was studied with different dosage of Na2CO3. Experiment results showed that at the condition of room temperature and some proppant ，the effect of the concentration of main agent ，CDEA ，KCl，NH4Cl ，CaCl2 and Na2CO3 on the relationship between viscosity of fracturing fluid and proppant settling velocity coincided with the law of Stoke ’s static settling. When the concentration of sodium dodecyl sulfate was greater than or equal to 6.25% or that of EDTA was less than or equal to 0.2% ，the relationship between viscosity of fracturing fluid and suspended sand was opposite to Stoke’s sand sinking law. When the pH value of fracturing fluid was 10，with increasing ABS concentration，the relationship between viscosity of fracturing fluid and suspended sand was contrary to Stoke’s sand sinking law completely. When the concentration of Na2CO3 increased ，the viscosity of fracturing fluid increased first and then decreased ，the proppant settling rate decreased first and then increased ，and G'/ G" increased first and then decreased. The suspended sand performance of surfactant fracturing fluid was not only related to the liquid viscosity，but also related to its elasticity. The elastic contribution to the liquid suspended sand was the largest.