低渗透砂岩油藏注入阴阳离子聚合物深部调剖技术研究

针对具有窜流大孔道的低渗透砂岩油藏条件,对交替注入阴、阳离子聚合物的深部调剖技术进行了研究。通过室内试验评价了各种因素对聚合物吸附量的影响。结果表明,随着温度的升高,聚合物吸附量减小,且地层对阳离子聚合物比对阴离子聚合物更容易吸附。随着矿化度、吸附时间、聚合物浓度的增加,聚合物吸附量也增加。阳离子聚合物的吸附平衡浓度为1 500mg/L,吸附平衡时间为8h;阴离子聚合物的吸附平衡浓度为1 000mg/L,吸附平衡时间为6h。物理模拟试验表明,采用阴阳离子聚合物交替注入方式比注入单一聚合物有更好的封堵效果,并且先注入阳离子聚合物效果好于先注入阴离子聚合物的效果。随着注入轮次的增加,封堵性能提高。但是,综合考虑经济成本,不要超过3个轮次。交替注入阴阳离子聚合物可以大大提高采收率,水驱采收率增值为41%。

Alternative injection of anionic and cationic polymers for deep profile control in low-permeability sandbody reservoir

The alternative injection of anionic and cationic polymers technology was studied for deep profile control of the low-permeability sandstone reservoir with big channels. The various affecting factors on the polymer adsorption capacity were evaluated in laboratory. When temperature increased, the polymer adsorption capacity decreased, and the cationic polymer adsorption was easier than the anionic one. With the increases of salinity, adsorption time and polymer concentration, the adsorption capacity of polymers increased. The adsorption equilibrium concentration of the cationic polymer is 1500mg/L, and the time is 8h. The adsorption equilibrium concentration of the anionic polymer is 1000mg/L, and the corresponding time is 6h. The physical simulation experiment shows that the alternative injection method of anionic and cationic polymers is better than the single polymer injection method, and the preferential injection method of cationic polymer is better than that of anionic polymer. With the increase of injection times, the sealing capacity of polymers gets better. In the view of cost, the alternative injection cycle should be not more than 3 times. The profile control technique can obviously enhance oil recovery, and the water-displacement recovery increases by 41%.