驱油用聚合物在渤海油田中高渗储层的适应性实验研究

Experiments on adaptability of polymer flooding for medium-high permeability reservoir in Bohai Oilfield

针对渤海油田中高渗储层(渗透率为(200~1000)×10^-3μm^2),在模拟油藏条件下,对3种聚驱用聚合物(线性聚合物、疏水缔合聚合物、聚表剂),开展了流变性、热稳定性、黏弹性和运移性研究。流变性测试结果显示,在低剪切速率下(模拟油藏深部,5.88~14.42 s^-1),疏水缔合聚合物和聚表剂黏度较大;在高剪切速率下(模拟近井地带,149.9~223.4 s^-1),3种聚合物的黏度均较低。振荡频率测试结果表明,疏水缔合聚合物和聚表剂弹性较大,储能模量高于损耗模量。传导性实验结果显示,线性聚合物和聚表剂在多孔介质中的传导性较好,疏水缔合聚合物的传导性较差。透射电镜和激光粒度仪表征结果表明,疏水缔合聚合物的聚集体尺寸较大(1.22μm),线性聚合物(0.28μm)和聚表剂(0.52μm)与油藏孔喉(4μm)的配伍性优于疏水缔合聚合物。研究结果表明:对于目标储层,聚表剂与储层的适应性更好,其次为线性聚合物,疏水缔合聚合物与该储层的适应性较差。海上储层聚驱用聚合物的筛选,需要将聚合物的流变性能与油藏适应性及分子微观结构结合考虑,建立一种多尺度的聚合物筛选评价方法。该研究对海上油田聚驱用聚合物的筛选具有一定的参考意义。

In order to explore the medium-high permeability reservoir with the permeability of(200~1000)×10^-3μm^2,the rheological behavior,thermal stability,viscoelasticity,and propagation performance of three kinds of polymer(linear polymer,hydrophobic association of partially hydrolyzed polyacrylamide(HAHPAM),and active polymer)acting as the chemical flooding agents in Bohai Bay,are studied under the simulated reservoir condition.Results of rheological behavior indicate that HAHPAM and active polymer solutions exhibit shear thickening at low shearing rate(simulation of deep reservoir,5.88~14.42 s^-1),and all three polymers show shear thinning at high shear rates(simulation of immediate vicinity of wellbore,149.9~223.4 s^-1).The oscillation frequency measurements show that HAHPAM and active polymer have larger elasticity,and their storage modulus are greater than their loss modulus.Results of sand-pack flow experiments show that linear polymer and active polymer can propagate better in porous media to achieve in-depth conformance control,whereas HAHPAM shows poor propagation behavior.The results of TEM and LPSA indicate that HAHPAM shows larger aggregation sizes(1.22μm),and the compatibility of linear polymer(0.28μm)and active polymer(0.52μm)with pore throats(4μm)of reservoirs is better than that of HAHPAM.The results show that for the target reservoir,the polymer has better adaptability to the reservoir,followed by the linear polymer,while the hydrophobic association polymer has poor adaptability to the reservoir.The selection of polymer for polymer flooding in offshore reservoirs needs to consider the rheological properties of polymer,reservoir adaptability,and molecular microstructures so as to establish a multiscale evaluation method for polymer screening.This study has a certain significance for screening polymer for polymer flooding in offshore oilfields.