黄原胶溶液在多孔介质中的渗流规律及其对提高采收率的作用

Flow rules of Xanthan solution in porous media and their effects on enhancing oil recovery

通过实验测定了黄原胶溶液在流变仪中的流变性、通过多孔介质的流变性和残余阻力系数 ,用不同的浓度、注入速率和岩心渗透率进行驱油实验。结果表明 :随浓度增加 ,黄原胶溶液的体相黏度增加 ,浓度高于缠结浓度时 ,残余阻力系数随浓度的增加而增加 ,但衰竭层厚度、表观黏度和提高采收率的幅度变化不大 ,同低于缠结浓度的情况相比 ,采收率保持较高的数值 ,最佳的黄原胶驱浓度应稍高于缠结浓度。注入速率增加时 ,黄原胶溶液的残余阻力系数下降 ,衰竭层厚度降低 ,采收率变化不大。渗透率增加能使采收率增加。对采收率提高起作用的是黄原胶分子的缠结作用引起的表观黏度的增加或衰竭层厚度的降低 ,这种作用能使平行于油水界面拉动残余油的力增加。图 4表 1参 11(张宏方摘 )

The rheological behaviors of Xanthan solution in a rheometer and in porous media as well as residual resistance factors are measured through experiments. Oil displacement experiments are proceeded with various concentration, injection speed and core permeabilities. The results show that with the concentration increase of Xanthan solution, the bulk viscosities increase, but residual resistance factors increase only when the concentrations are above overlap concentration, and in this case the depleted layer thickness, the apparent viscosities and the extent to enhance oil recovery do not vary much. Compared with the situation that concentration is lower than overlap concentration, recovery remains a higher amount, so that the optimal concentration for Xanthan displacement should be a little higher than overlap concentration. The residual resistance factors and the depleted layer thickness of Xanthan solution decrease with injection speed increase, but recovery does not vary much. The increase of permeability can increase recovery. What can increase recovery is the increase of the force parallel to oil-water interface generated by the increase of apparent viscosity or the decrease of depleted layer thickness, which is the results of the overlap of Xanthan molecules.