非均质油层粘弹性凝胶颗粒提高采收率机理研究

通过非均质双填砂管调驱实验、平板夹砂模型驱油实验和微观驱油实验对黏弹性凝胶颗粒(PPG)提高非均质油层采收率机理进行了研究。非均质平行管岩心调驱实验表明:PPG可在孔隙介质中不断重复封堵与运移,具有良好的调驱性能;PPG优先进入并封堵高渗透层,调整非均质地层吸水剖面,将高渗和低渗岩心的分液量比由原来的高于90∶10调整至30∶70,具备显著的液流转向及油层分流能力;同时,PPG可将低渗透油层的采收率在水驱基础上再提高32.1%;而高渗透油层及整体采收率则分别提高13%和22.9%。微观驱油实验结果表明,PPG能够对不同孔径的孔道进行动态交替封堵,具有显著的封堵高渗孔道、调整非均质、增大波及系数的能力。非均质平板夹砂模型驱油实验中,PPG对不同渗透率条带中的原油都有驱动作用,最终采收率达89%。微观驱油实验结果表明,PPG在非均质油层中实现动态液流转向、扩大波及系数是其提高采收率的主要机理。

The mechanism of using PPG to enhance oil recovery in heterogeneous reservoir

In this paper the mechanism responsible for the enhancement of oil recovery using visco-elastic pre-formed particle gel(PPG)in heterogeneous reservoir was studied systematically through heterogeneous parallel dual core flooding test, micro flooding and visual sand-packed glass model flooding test. The heterogeneous parallel dual core flooding test results show that: PPG moves in the porous media in the form of continuous plugging and pass due to its elasticity. PPG can adjust the water adsorption profile by selectively blocking high permeability layer, making the shut rates of high and low permeability core from higher than 90:10 to 30:70, which illustrates that PPG has obvious flow diverting and reservoir diversion adjustment ability. The increment of oil recovery after water flooding in the low permeability core is 32.1%, and a 13% and 22.9% increment was also achieved in the high permeability core and the whole cores. The micro experiments show that: With the ability of plugging different pore throats with different diameters dynamically and alternatively, PPG can adjust heterogeneity and increase sweeping efficiency significantly. The ultimate recovery of PPG flooding in the heterogeneous sand packed glass model reached 89%. Making a dynamical flow diverting and increasing sweeping efficiency is the main mechanism of using PPG to enhance oil recovery in heterogeneous reservoir.