岩心渗透率对复合驱油效率影响的实验研究

An Experimental Study on Oil Displacement Efficiency of ASP Combinational Flooding Solution in Relation to Core Permeability

实验三元复合驱替液由10.0 g/L NaOH、3.0 g/L表面活性剂ORS-41、1.0 g/L聚合物1275A组成,用矿化度4.456 g/L的大庆油田平均地层水配制,45℃下与大庆脱气原油间的动态界面张力平衡值为1.2×10^-3mN/m,瞬时最低值为2.4×10^-3mN/m,黏度为19.0 mPa·s。在气测渗透率在0.017×10^-3-687×10^-3μm^2含油饱和度在42.37%-68.05%的21支人造均质砂岩岩心上,水驱之后注入0.2 PV复合驱替液并恢复水驱,测定水驱后采收率增值,表示复合驱替液的驱油效率。驱油效率-渗透率曲线为典型的S形曲线,渗透率≤1.56×10^-3μm^2≥16.2×10^-3μm^2采收率增值变化很小,渗透率从5.5×10^-3μm^2至16.2×10^-3μm^2,采收率增值由9.76%猛增至21.00%。在本实验条件下,16.2×10^-3μm^2复合驱岩心的临界渗透率值,该复合驱替液适用于渗透率≥16.2×10^-3μm^2油藏。用驱替压力梯度与孔隙半径（毛管半径）之间的关系和聚合物分子线团回旋半径与孔隙半径的配伍性解释了这一实验结果。图2表2参8。

The experimental ASP flooding solution comprises 10.0 g/L alkaline NaOH, 3.0 g/L surfactant petroleum sulfonate ORS- 41, and 1.0 g/L polymer HPAM 1275A, prepared in Daqing standard brine of TSD = 4. 456 g/L and has equilibrium and instant minimum dynamic IFT values 1.2 ×10^-3 and 2.4 ×10^-3 mN/m and viscosity 19.0 mPa＇s （at 45℃ ）. On 21 artificial homogeneoussandstone cores of air permeability, Ka, in range 0. 017 ×10^-3-687 ×10^-3 μm^2 and of oil saturation in range 42.37-68.05%, water flood, 0.2 PV of ASP injection, and water flood again are performed and the enhancement in oil recovery by ASP injection is determined and considered as the oil displacement efficiency （ODE） of ASP flood. A typical S-formed curve ODE vz Ka is obtained; the ODE value changes very slightly when Ka≤1. 56 ×10^-3 μm^2 and ≤16.2 ×10^-3 μm^2 and increases dramatically from 9.76% at Ka = 5.5 ×10^-3 μm^2 to 21.00% at Ka = 16.2 ×10^-3 μm^2. Under the experimental conditions, the critical core permeability for the ASP flooding solution is of 16.2 × 10^-3 μm^2, or the ASP flooding solution is conformable to sandstone oil reservoirs of Ka≥16.2 ×10^-3 μm^2. This experimental phenomenon is explained in terms of the relationship between driving pressure gradient and pore radius （capillary radius） and of the conformity of polymer coil radius of gyration with pore radius.