适合高温高矿化度油藏的弱凝胶体系研究

LABORATORY STUDY ON WEAK GEL PROFILE CONTROL SYSTEM FOR

为满足96℃,地层水矿化度12 000～20 000mg/L,Ca2+和Mg2+含量520 mg/L的油藏提高采收率的需要,研制了适合高温高矿化度油藏用的弱凝胶调驱体系。针对高温高矿化度条件下弱凝胶体系稳定性差,利用疏水缔合聚合物溶液的物理网络结构和通过加入乌洛托品350 mg/L,苯酚250 mg/L,硫脲200 mg/L在溶液中形成化学交联结构,使弱凝胶体系在96℃和矿化度为15400 mg/L条件下具有良好的稳定性和抗剪切性。研究表明,疏水缔合聚合物溶液浓度为2 000 mg/L时,弱凝胶体系经过射孔孔眼模型剪切作用后,具有良好的抗剪切性能,在180 d后凝胶强度可达到10 000 mPa.s,未出现脱水、破胶的现象,表现出良好的长期稳定性;在1 852×10-3μm2和774×10-3μm2填砂管组成的并联模型上,弱凝胶体系优先进入水驱后的高渗岩心而使后续注入液转向进入低渗岩心,改善了高温高盐非均质油藏开发效果。

A flowing organic weak gel is developed to meet the requirements for EOR in higher temperature and higher salinity reservoirs with the temperature of 96℃,TSD of about 12000-20000mg/L,Ca2+ and Mg2+ concentration of about 520mg/L.In order to improve the stability of conventional weak gel systems,urotropine,350mg/L;phenol,250mg/L;and,200mg/L was added into the solution of hydrophobic associating polymer,the chemical crosslinking structure was formed in hydrophobic associating polymer solution,which has better stability and shearing resistance in the environment with the temperature of 96℃,TSD of 15400mg/L.The study has shown that,when the concentration of hydrophobic associating polymer is about 2000mg/L,the weak gel system has better shearing resistance after being sheared by the model of perforation and can keep high viscosity about 10000mPa.s in 180 days,meanwhile no syneresis is observed.On sets of 1852×10-3μm2 and 774×10-3μm2 cores in parallel,the oil recovery and water-cut curves for every single core showed that the weak gel system enter preferentially into the higher permeability core and divert the fluid injected later into the lower permeability one,the weak gel can improve the development effect of reservoir.