驱油剂在孔喉中的微观流动和宏观渗流特性

Macroscopic percolation characteristics and microscopic flow of oil displacement agent through pore throat

驱油剂控制流度比以及其改善吸水剖面的能力主要取决于其在油藏中的实际渗流特性。通过数值计算和实验方法研究了牛顿型、幂律型和粘弹型3类驱油剂在单个孔喉中的流动规律,并在此基础上探讨了驱油剂在非均匀并联孔喉模型中的渗流特性。分别给出了牛顿型、幂律型和粘弹型驱油剂在孔喉中的流动方程。孔喉模型中的压力分布表明,粘弹型驱油剂在孔隙变截面处的拉伸流动中存在储能过程,具有较高的局部阻力和渗流阻力;牛顿型和幂律型驱油剂在拉伸流动中无储能过程,局部阻力和渗流阻力相对较低。在宏观上,驱油剂在非均匀并联孔喉模型中的分流率显示,当油藏层间非均质性较弱时,粘弹型驱油剂比幂律型驱油剂更易于流入中、低渗透层;当油藏层间非均质性较强时,增加驱油剂的粘弹性对液流转向中、低渗透层的影响不明显。

The capability of mobility ratio control and injection profile im-provement mainly depends on actual percolation property of oil displacement agent in the oil reservoir. The flow behavior of three kinds of oil displacement agent through individual pore throat was researched by numerical and experimental method,and the percolation characteristics of the oil displacement agents in het-erogeneous parallel pore throat models were discussed. Flow e-quations were developed for Newtonian fluid,power law fluid and viscoelastic fluid in the pore throat. Pressure distribution in the pore throat model suggests that the viscoelastic agent stores ener-gy during stretch flow at the varied cross section,thus local re-sistance and percolation resistance are high. Whereas,those of Newtonian agent and power law agent are low,which have no a-bility to store energy. On the macroscopic,diverting rate of the oil displacement agent in the heterogeneous parallel pore throat models shows that the viscoelastic agent is inclined to flow into low and middle permeability formation than the power-law agent for the reservoir whose interlayer heterogeneity is not so serious. An increase in viseoelasticity of the oil displacement agent has no obvious effects on flow diversion in middle and low permeabil-ity formation for the reservoirs whose interlayer heterogeneity are very serious.