耐温VES压裂液SCF的性能

Performance Properties of Heat Resistant Viscoelastic Surfactant Fracturing Fluid SCF

长链脂肪酸在酸存在下与胺缩合再经季铵化,得到季铵盐型表面活性剂,引入无机和有机阴离子,得到粘弹性表面活性剂,溶于水中制成VES压裂液SCF。测定了体积分数4.0%的SCF压裂液170s-1下40～150℃的粘温曲线,温度升至150℃时粘度为68mPa·s,降温至90℃并维持130min后粘度为88mPa·s;在130℃剪切95min时粘度>80mPa·s,在150℃剪切45min时粘度～70mPa·s。在60℃、100～500s-1区间,上行和下行粘度～剪切速率曲线几乎重叠。少量水和互溶剂、少量原油、大量水可使SCF压裂液完全破胶。残渣率为176mg/L。砂比为10%时,粒径0.5～0.8mm石英砂在SCF压裂液中的悬浮率>90%。SCF压裂液对粘土的防膨率为80.5%。在原油与SCF体积比为1∶4和1∶1时,原油30℃粘度由1832mPa·s分别降至100和48.7mPa·s。图4表2参1。

Viscoelastic surfactant (VES) fracturing fluid SCF is prepared by condensation of long chain fatty acid(s) with amine at the presence of acid, quarternary ammoniation of the condensate, introduction of ballancing inorganic and organic anions into the ammonium salt and dissolution of the VES in water. For 4.0 v.% SCF fluid at shear rate 170 s^(-1), the viscosity at 150℃ is of 68 mPas when temperature raised from 40℃ to 150℃ and of 88 mPas at 90℃ in 130 min after temperature lowered from 150℃ to 90℃; the viscosity is of >80 mPas at 130℃ in 95 min shearing and is of ～70 mPas at 150℃ in 45 min shearing. The viscosity-shear rate curves at 60℃ and 100—500 s^(-1) are nearly superimposed in rate-increasing and -dereasing directions. Complete breakdown of the micelle gel can be caused by mixing with a little amount of water+mutual solvent, a little amount of crude oil or a large amount of water. The residue of the VES fluid accounts 176 mg/L. >90% of quartz of particle size 0.5—0.8 mm is suspended in the fluid when mass ratio of quartz to fluid being of 10%. The decrement of clay swelling in the fluid is of 80.5%. The viscosity of a crude oil at 30℃ is reduced from 1 832 mPas to 100 and 48.7 mPas when the crude mixed with the fluid SCF in volume ratio 4∶1 and 1∶1, respectively.