气体压迫多孔介质中聚合物凝胶行为

Mechanism of gas compressing polymer gel in porous media

关键词:  聚合物凝胶  防气窜  堵气  多孔介质  采收率

Key words:  polymer gel  gas channeling  gas plug  porous medium  enhanced oil recovery

摘要:

结合盐水冲刷多孔介质中凝胶理论,分析聚合物凝胶分别受气体和盐水压迫的作用机制,计算和对比饱和聚合物凝胶的多孔介质中气相和液相饱和度空间分布曲线,完善盐水冲刷多孔介质中凝胶理论模型的使用范围,探讨气体突破后的两种残余凝胶对气体渗流的影响。结果表明:盐水在凝胶中的微观渗流能力较气体强,而气体在凝胶封堵后的多孔介质中微观渗流能力较差,即在其他条件相同前提下,“侵入区”中处于微观渗流状态的气体较少,气体需长时间累积才能逐渐破坏三维网状结构的凝胶,因此凝胶未被突破前,相比于盐水,气体受凝胶高强度封堵有效期会更长;根据盐水冲刷多孔介质中凝胶理论建立的模型具有普遍适用性,凝胶受流体挤压破坏本体结构是多孔介质中聚合物凝胶抵抗外来流体不至破坏的一种共性,与流体类型和聚合物凝胶体系无关,该模型可用来预测各种凝胶体系在不同环境下的封堵性能。

Abstract:

The mechanism of action of polymer gel oppressed by gas and brine respectively was analyzed based on the gel theory of saline washed porous media. The gas and liquid phase saturation space distribution curves in a porous medium which is saturated by polymer gel were calculated and contrasted. The application scope of saline washed porous media theoretical model was improved, and the effects of two residual gel gas produced on gas seepage after gas breakthrough were investigated. The results show that microscopic percolation capacity of salt water is stronger than gas in the gel, while microscopic percolation capacity of gas in porous medium is weak after gel plugging. Under the same condition, the gas under the microscopic percolation state in invaded area is less. Gas needs a long time accumulation to destruct the three-dimensional network structure gel gradually. Therefore, before the gel breaking, the validity period of gas plugged by gel intensely will be longer compared with that of saline. The model based on the gel theory in porous media washed by saline has a general applicability. The gel is extruded by fluid and the body structure is destructed, which is an universality when polymer gel resists foreign fluid in order not to be undermined in porous media. It has nothing to do with the type of fluid and polymer gel system. The model can be used to predict the plugging performance of various gel system in different environments.