部分枝化黏弹性颗粒溶液的增黏性及抗剪切性

Tackifying and Shear-resistant Properties of Partially Branched Viscoelastic Particle Solution

为了研究剪切条件下B-PPG溶液的黏度及黏弹性变化的机理,通过机械剪切(模拟聚合物从设备到井筒注入过程中所受剪切)和射孔孔眼(炮眼)剪切(模拟聚合物溶液通过射孔孔眼及近井地层所受剪切)方法,研究了B-PPG在不同剪切强度作用下溶液的黏度保留率,并利用原子力显微镜观察B-PPG溶液的微观结构。结果表明,B-PPG的增黏性较好。70℃下当溶液质量浓度大于3.5 g/L时,颗粒的支化链相互缠绕形成的网络结构导致溶液黏度迅速增大。B-PPG的抗剪切性较好。B-PPG溶液的表观黏度随剪切速率增加而降低;B-PPG溶液浓度越高,溶液黏度降幅越大。机械剪切后B-PPG溶液的黏度保留率大于50%,模拟射孔孔眼剪切后的黏度保留率大于20%。剪切前后的B-PPG溶液均以储能模量为主。两种剪切条件下B-PPG原有的交联网络结构均有不同程度地破坏,分子间连接较弱,不同剪切类型及强度对网络结构的破坏程度不同,射孔孔眼剪切对网络结构的破坏最大。

In order to study the viscosity and mechanism of viscoelastic change of partially branched viscoelastic particle(B-PPG) solution under shear condition,the viscous retention of B-PPG solution under different shear strength was studied by mechanical shear simulating the shear of polymer from equipment to wellbore injection and perforation hole(blasthole)shear simulating the shear of polymer solution through perforation hole and near wellbore formation. Furthermore,the microstructure of B-PPG solution was observed by atomic force microscopy. The results showed that B-PPG had a good viscosifying property. When the concentration of solution was more than 3.5 g/L at 70℃,the network structure formed by branched chains of particles led to the rapid increase of solution viscosity. B-PPG had good shear resistance. The apparent viscosity of B-PPG solution decreased with the increase of shear rate. The higher concentration of B-PPG solution,the greater decrease of solution viscosity was. The viscosity retention of B-PPG solution after mechanical shear was more than 50%,and that of simulated perforation was more than 20%. The elastic modulus of B-PPG solution before and after shearing was dominant. Under two shear conditions,the original cross-linking network structure of B-PPG was destroyed to varying degrees,and the intermolecular connection was weak. Different shear types and strengths had different degrees of damage to the network structure,and perforation shear had the greatest damage to the network structure.