降黏剂作用下油水两相渗流特征

Flow characteristics of oil-water two-phase seepage under action of viscosity reducer

通过室内试验对比研究水溶性降黏剂和油溶性降黏剂的在常规旋转黏度计测试条件下的降黏效果、岩心渗流条件下的流动特征以及微观渗流特征,分析油水比对其渗流特征的影响及其提高采收率机制。结果表明水溶性降黏剂作用下油水两相渗流阻力大幅度升高,油溶性降黏剂能够降低油水混合物的视黏度和渗流阻力,但降低幅度较低;含水率越高,水溶性降黏剂溶液与原油形成的水包油乳状液造成的渗流阻力越大,油溶性降黏剂作用下油水混合物渗流特征与未添加降黏剂条件下渗流特征类似,其更适合应用于高含油饱和度条件下的地层降黏;乳状液渗流是水溶性降黏剂与原油在地层中混合后主要的流动形式,水溶性降黏剂与原油形成的水包油乳状液通过变形、叠加和堆积等形式堵塞喉道,增大渗流阻力,扩大波及范围和采收率。

The effects of viscosity reduction of water-soluble and oil-soluble viscosity reducer,the flow characteristics under core flow condition,as well as the micro flow characteristics were comparatively studied via conventional rotary viscometer test.The influence of oil-water ratio on flow characteristics and the mechanism of enhanced recovery were analyzed.It is shown that the resistance of oil-water two-phase flow increases greatly under the action of water-soluble viscosity reducer.Oil-soluble viscosity reducer can decrease the apparent viscosity and flow resistance of oil-water mixture,whereas the decreasing range is lower.It is also found that the higher the water content,the greater the percolation resistance caused by water-in-oil emulsion formed by water-soluble viscosity reducer and crude oil.The flow characteristics of oil-water mixture under the action of oil-soluble viscosity reducer is similar to those without it,which is more suitable for the formation viscosity reduction under the condition of high oil saturation.Emulsion flow is the main flow form of water-soluble viscosity reducers mixed with crude oil in formation.Water-in-oil emulsion formed by water-soluble viscosity reducer and crude oil blocks the throat,increases the flow resistance,and enlarges the swept area and recovery by the means of deformation,superposition and accumulation.