多元泡沫分流作用及其驱油效果影响因素研究

Investigation on Divded Flow of Multivariate Foam and Factors Influencing on Its Oil-Displacement Efficiency

所研究的多元泡沫由天然气和三元复合驱油液生成 ,驱油液由 1.2× 10 4 mg/LNaOH、3× 10 3 mg/L表面活性剂ORS41、1.2× 10 3 mg/LHPAM 12 75A组成 ,用矿化度 370 0mg/L的盐水配制。将气液质量比 1∶1的天然气和ASP液同时注入渗透率变异系数VK=0 .72、地层水饱和的并联三岩心组 ,测量通过高、中、低渗均质岩心的分流率 (以质量计 ) ,与注水作对比 ,发现注水时高渗岩心的分流率高达 93% ,注多元泡沫时中渗岩心的分流率由7%大幅增加至 30 % ,高渗岩心的分流率大幅降低 ,低渗岩心的分流率仅略有上升 ;VK 由 0 .72增大到 0 .80时 ,多元泡沫的分流作用明显减弱。在两维纵向非均质正韵律物理模型上进行了多元泡沫驱油实验 (4 5℃ ) ,气液同时注入 ,ASP液注入量为 0 .3PV ,以 6 0 0mg/L 12 75A溶液作后续保护段塞 ,实验原油密度 0 .83g/cm3 ,酸值 0 .0 2mgKOH/ g油 ,饱和模型地层水矿化度 6 788mg/L ,驱替水矿化度 370 0mg/L。实验结果表明 :模型VK 在 0 .6～ 0 .8范围内变化时 ,在各个气液比下VK=0 .72的模型多元泡沫驱油效果均最好 ;当VK=0 .72 ,气液比在 1∶1～ 5∶1范围内变化时 ,气液比为 3∶1时多元泡沫驱油效果最好 ,流出液Cl-浓度变化曲线表明 ,这时多元泡沫扩大波及体积的作用最强 ;当VK=0 .6 5 ,气?

The multivariate foam is generated by natural gas and an ASP flooding solution, which is composed of 1.2×10 4 mg/L NaOH, 3×10 3 mg/L surfactant ORS41, and 1.2×10 3 mg/L HPAM 1275A in water of TSD=3 700 mg/L. With water injection as control, natural gas and the ASP solution in mass ratio 1∶1 are injected into three parallel core sets of permeability variation coefficiency V K=0.72 and satuated by the formation water and the percentage of mass flow rate (MFR%) is measured for the high, medium and low permeable (HP,MP,and LP) homogeneous cores. It is found that for the HP core the MFR% of the water is very high (93%) and of the foam - dramatically decreased while the MFR% through the MP core acounts 30% for the foam and 7% for the water; the MFR% through the LP core changes slightly. Increasing V K from 0.72 to 0.80 results in weakened dividid flow of the foam. Multivariate foam flooding experiments are conducted on two-dimentional, longitudinally heterogeneous and positive-rhythm physical models at 45℃ with the gas and the foaming ASP solution (0.37 PV) being injected simultaneously followed by a 600 mg/L HPAM solution as protective slug. The oil and waters used have characteristics: density of the crude 0.83 g/cm 3, its acid value 0.02 mg KOH/g crude; TSD of the formation water 6 788 mg/L for model saturation and 3 700 mg/L for injection. The experimental results show that the highest oil-displacing efficiency (the most enhancement in oil recovery) is observed on models of V K=0.72 with various gas-to-solution ratios R g/l and V K values varying in range 0.6-0.8; or with R g/l=3∶1 when V K=0.72 and R g/l values varying in range 1∶1-5∶1 (in this case curve of Cl - concentration in effluent indicates highest volumetric sweep efficiency of the foam); when V K=0.65 and R g/l=2∶1, the higher the residual oil saturation (in range 52-47%) the higher the oil-displacing efficiency, or the earlier foam flood begins the higher the ultimate oil recovery; when V K=0.65 and R g/l=2∶1, the higher the HPAM concentration in foaming ASP solution (in range 100-2 000 mg/L) the higher the foam flooding effect.