油藏孔隙的剪切-拉伸对弱凝胶调剖特性的影响研究

The Shear-Stretch Effects of Reservoir Pores on Weak Gel Profile-Control Properties

丁名臣 岳湘安 张立娟 赵海龙 王振民

DING Ming-Chen YUE Xiang-An ZHANG Li-Juan ZHAO Hai-Long WANG Zhen-Min

弱凝胶溶液在通过油藏孔隙时，所受的剪切-拉伸作用是影响其成胶及封堵特性的关键因素之一。研究了孔隙的剪切-拉伸作用对一类弱凝胶溶液（HPAM溶液+交联剂）静态成胶特性的影响；将剪切-拉伸前后的弱凝胶溶液注入填砂模型中，以其在多孔介质中形成弱凝胶后的残余阻力系数为指标，评价了孔隙的剪切-拉伸对这类弱凝胶在储层中调剖能力的影响。结果表明：弱凝胶溶液经多孔介质剪切-拉伸前后的黏度值分别为170和43 mPa·s，黏度损失率为74.7%；经孔隙剪切-拉伸的弱凝胶溶液在静态条件下成胶后，与原样相比其黏性模量和弹性模量的最大降幅分别为18%和55%，凝胶强度损失严重。经剪切-拉伸的弱凝胶溶液在填砂模型中成胶后，在注胶部位的最大残余阻力系数为10，与原样（279）相比降低了26.9倍，残余阻力系数随后续注水量的增加降幅明显增大；段塞下游未注胶部位最大残余阻力系数为4.3，与原样（102）相比降低了22.7倍。经油藏孔隙剪切-拉伸后，弱凝胶的调剖能力大幅降低。

The shear-stretch action of reservoir pores on weak gel was one of the key factors which influenced the gelling and plugging properties of weak gel when it flowed through the reservoir. The influences of this shear-stretch action on one kind of weak gel (HPAM solution + crosslinking agent) gelling properties were studied in this paper. The affected and unaffected weak gel solution were injected to sand-packed models and the influences of this shear-stretch action on weak gel profile-control properties were evaluated by the index of residual resistance coefficient. The results showed that the original viscosity of weak gel before and after shear-stretch of reservoir pores was 170 and 43 mPa·s, and the viscosity loss rate of gel was 74.7%. Meanwhile the viscous modulus and elastic modulus of the weak gel whose solution was sheared and stretched by pores and gelled in the static condition was reduced maximumly by 18% and 55% respectively, and the strength of gel decreased sharply. Compared with the unaffected sample, the maximum residual resistance coefficient of the sheared and starched weak gel which gelled in sand pack was reduced by 26.9 times in the gel injection part. And the reduction speed of this residual resistance coefficient was accelerated significantly with increasing water injection. The maximum residual resistance coefficient of sheared and starched weak gel in none gel injection part was reduced by 22.7 times. Thus the profile-control properties of sheared and stretched weak gel were significantly weakened by the pores’ shear-stretch action.