3种新型聚合物驱油效率对比研究

A Comparative Study on Oil Displacement Efficiency of Three Novel Polymers for EOR

在模拟辽河锦16块油藏条件下(温度56℃,地层水矿化度3770mg/L,脱气原油地面粘度68mPa·s,密度0.939g/cm3),实验考察了3种新型驱油用聚合物的应用性能并与常用HPAM作了对比:①梳形聚合物KYPAM 2;②疏水缔合聚合物DH XN;③疏水缔合聚合物与助剂复配物GH YHS;④对比物HPAMMO 4000。在200～2000mg/L浓度范围内,在8s-1下,①的溶液粘度比④约高1.6～1.8倍;②和③的溶液粘度在低浓度下低而在高浓度下高。聚合物浓度为1000mg/L时,在5～120s-1范围内①和④的流变曲线属假塑性流体型,②和③的流变曲线虽为剪切变稀型,但由2个曲线段组成,低剪切速率下粘度下降较平缓。储能模量G′与频率f关系曲线的位置,①最高,即粘弹性最强,②和③居中,④最低,即粘弹性最弱。30～74℃范围的粘温关系,①和④的变化趋势相同,①的增粘能力为④的1.52～1.65倍;②和③的粘度随温度下降幅度大。在人造石英砂胶结岩心上提高水驱残余油采收率的规律,①与④相同,但①的驱油效率较④高一倍;②的注入量由0.2PV增加到0.3PV时采收率急剧增大;③的采收率增幅最小。粘浓曲线表明,疏水缔合聚合物在地层水溶液中显示2个缔合浓度,②和③的第一缔合浓度分别为766和1167mg/L,第二缔合浓度分别为1908和2155mg/L。

Under simulation conditions of reservoir at block Jing16, Liaohe (56℃, formation water with TSD=3 770 mg/L, degased crude of viscosity 68 mPa·s and density 0.939 g/cm3 at surface) the performance properties of 3 novel EOR polymers are studied in comparison with a commonly used HPAM: ① comblike polymer KYPAM2; ② hydrophobically associating polymer DHXN; ③ hydrophobically associating polymer+auxiliary in mixture; ④ HPAM MO4000 as control. The viscosity of 200-2 000 mg/L polymer solutions at 8 s-1 for ① is 1.6～1.8 times higher than that for ④ and is lower at low shear rate (SR) and higher at high SR for ② and ③. The rheological curves of 1 000 mg/L polymer solutions in SR range 5-120 s-1 are of pseudplastic pattern for ① an ④ and are of shear thinning type for ② and ③ with viscositySR curves consisting of 2 sections and the slope of the 1st section being smaller. The highest location of curve(s) of storage modulas G′ vz frequency f is observed for ① owing to strong viscoelasticity, medium - for ② and ③ and the lowerst - for ④ because of weak viscoelasticity. The viscositytemperature relationship in range 30-74℃ are similar for ① and ④ and the viscosifying capacity of ① is 1.52-1.65 times higher than that of ④; for ② and ③ significant reduction in solution viscosity is observed when temperature raises. The enhancement in oil recovery in cemented quartz cores with residual oil after water flood develops similarly by ① and ④ but the oil displacement efficiency of ① is 2 times as high as that of ④; increasing injected volume of ② from 0.2 to 0.3 PV leads to dramatical increase in oil recovery; the enhancement in oil recovery by ③ is the lowest. The viscosityconcentration curves show that there exist 2 associating concentrations (ACs) for the solutions of hydrophobically associating polymers in the formation water: the 1st AC is of 766 mg/L for ② and 1 167 mg/L for ③ and the 2nd AC is of 1 908 mg/L for ② and 2 155 mg/L for ③. The experimental results are explained and discussed in terms of molecular structure and solution properties.