渗透率和渗透率变异系数对复合体系非均质模型驱油效果的影响

Oil Displacement Efficiency of Some Combinational Chemical Flooding Solutions on Heterogeneous Sandstone Reservoir Models of Different Permeability and Permeability Variation Coefficient

在二维纵向非均质砂岩储层模型上,考察了气测渗透率(0.3,0.7,1.5,2.0μm2)和渗透率变异系数(0.60,0.72,0.80)对三种复合体系驱油效果的影响,实验体系含碱10.0 g/L、表面活性剂3.0 g/L、聚合物1.5 g/L,聚合物相对分子质量2.5×107(模型渗透率为0.3μm2时除外,为1.8×107),实验温度45℃。将模型水驱至含水>98%之后注入0.35 PV复合体系及0.20 PV保护段塞(0.8 g/L聚合物溶液),再水驱至含水>98%。对于所有实验体系,当渗透率不变而变异系数增大时,复合驱采收率增大,总采收率则减小,而当变异系数不变而渗透率增大时(不考虑0.3μm2的情况),复合驱采收率也增大;在同一渗透率、同一变异系数条件下的驱油效果,以甜菜碱表面活性剂BS/聚合物二元体系为最好,碳酸钠/石油磺酸盐Ss/聚合物三元体系次之,氢氧化钠/重烷基苯磺酸盐Sy/聚合物三元体系最差。

The oil displacement efficiency on 2D vertically heterogeneous sandstone reservoir models of gas permeability,K,0.3,0.7,1.5,and 2.0 μm2 and permeability variation coefficient,Vk,0.60,0.72,and 0.80 at 45℃ was investigated for three combinational chemical flooding solutions（CCFSs）,containing 10.0 g alkaline,3.0 g surfactant,and 1.5 g polymer per liter solution where the polymer was HPAM of molar mass 2.5×107 besides that of 1.8×107 for models of K=0.3 μm2.The models were flooded by water to 〉98% watercut,injected with 0.35 PV of CCFS and 0.20 PV of 0.8 g/L polymer solution as postpad and flooded again by water to 〉98% watercut.It was shown that for all the three CCFSs the enhancement in oil recovery（EiOR） by chemical flood was increased and the total,extremal,enhanced oil recovery was decreased with raising value Vk at any given value K and the EiOR was increased with raising K from 0.7 to 2.0 μm2 at equal value Vk.At every combination of K and Vk the highest EiOR,or the oil displacement efficiency,was observed for the betain surfactant BS/polymer flooding solution followed by the alkalescent sodium carbonate/petroleum sulfonate Ss/polymer flooding solution and the lowest——for the strong alkaline soduim hydroxide/heavy alkylbenzene sulfonate Sy/polymer flooding solution.