胜坨油田高温高盐油藏自发乳化驱提高采收率

Spontaneous Emulsification Flooding for Enhancing High Temperature and High Salinity Reservoirs Oil Recovery of Shengtuo Oilfield

史胜龙 王业飞 汪庐山 靳彦欣 王涛 王静

SHI Shenglong WANG Yefei WANG Lushan JIN Yanxin WANG Tao WANG Jing

通过乳化能力、油水界面张力测定优选出适合胜坨高温高盐油藏的碱/表面活性剂自发乳化体系，并通过驱油实验考察了自发乳化体系的驱油效果。结果表明，在2 g/L NaOH+2 g/L Na2CO3复合碱溶液中加入0.5 g/L表面活性剂B4，可使油/水界面张力达到超低，有助于油滴在界面扰动作用下发生自发乳化，形成乳状液。乳化体系在多孔介质的剪切作用下将油滴乳化，依靠乳滴在孔喉处聚并产生的贾敏效应，有效地降低了水油流度比，提高了波及系数和采收率。乳状液液滴的夹带作用可使油滴被驱替液携带着通过地层，提高洗油效率。但乳化夹带作用提高采收率和驱替压力的幅度不如乳化捕集作用显著。最佳的自乳化体系配方为：2 g/L B4+2 g/L NaOH+2 g/LNa2CO3，自发乳化驱采收率在水驱基础上可提高21.5%，采收率并未随着填砂管长度的延长而降低。图9表1参15

Emulsification tests and oil/water interfacial tension measurements were conducted to develop alkali/surfactant spontaneous emulsification system which was suitable to shengtuo high temperature and high salinity reservoir，and oil displacement efficiency of the spontaneous emulsification system were investigated by flooding test. The results showed that the interfacial tension of oil/water could be lowered to an ultralow level when adding 0.5 g/L of surfactant B4 to the 2 g/L NaOH+2 g/L Na2CO3 compound alkaline solution，leading to easy spontaneous emulsification of oil and forming emulsion under interfacial disturbance. Oil was emulsified by spontaneous emulsification system under the shearing action of porous media，the droplets might coalesce in the pore throat and generate strong jamin effect，and the mobility ratio of water to oil could be effectively reduced so as to increase the sweep efficiency and oil recovery. Droplets were ether entrained along with flowing aqueous phase to improve oil displacement efficiency. While emulsification and entrainment still leaded to the oil recovery enhance and pressure drop，it did not seem to be as effective as emulsification and entrapment. The optimal spontaneous emulsification formula was as follows: 2 g/L B4+2 g/L NaOH+2 g/L Na2CO3，and the oil recovery increased by 21.5% by spontaneous emulsification flooding and the oil recovery did not decrease with the increase of the sandpack length.