超稠油注气次生泡沫油生成机理及渗流特征

为探索泡沫油在超稠油油藏中的形成机理、渗流特征及驱油效果，采用准噶尔盆地西北缘乌夏断裂带侏罗系齐古组原油及油藏参数，进行注气形成泡沫油介质筛选及原油泡点压力测定实验，并开展注气微观可视化和填砂管驱油实验，深入解析注气形成泡沫油过程中的渗流特征，评价了注气泡沫油驱油效果。研究结果表明：①准噶尔盆地西北缘乌夏断裂带侏罗系齐古组原油泡点压力为9.7 MPa，拟泡点压力随着注气量的增加而增加，随温度的上升而上升，50℃的拟泡点压力随着CO₂注入量的增加而增大，压力上升速度较缓，储层具有较好的注气特性。②研究区的泡沫油渗流可分为5个阶段：无气泡阶段、气泡析出阶段、气泡扩张阶段、气泡聚并阶段和气泡消亡阶段。③研究区蒸汽+CO₂方式驱油开采过程较纯蒸汽填砂管驱的采收率可提升13.3%，开采过程中随着压力的释放，气泡数目逐渐增多，产油量逐步缓慢上升；当压力降至泡点压力后，气泡数目趋于平稳，形成较稳定的泡沫油，产油量大幅提升，为主力产油期；当压力释放至拟泡点压力后，气泡数目迅速下降，泡沫油逐渐消亡，产油量缓慢下降。

Formation mechanism and percolation characteristics of secondary foamy oil by gas injection in super heavy oil

In order to explore the formation mechanism， percolation characteristics and displacement effect of foamy oil in super heavy oil reservoir， the oil and reservoir parameters of Jurassic Qigu Formation in Wuxia fault zone in the northwestern margin of Junggar Basin were used to select gas injection medium for foamy oil formation and carry out the testing experiment of bubble point pressure of crude oil. The gas injection microscopic visualization and sand-filling pipe displacement experiments were carried out to analyze the percolation characteristics of foamy oil formed by gas injection， and the oil displacement effect of gas injection foamy oil was evaluated. The results show that： （1）The bubble point pressure of the crude oil of Jurassic Qigu Formation in Wuxia fault zone in the northwestern margin of Junggar Basin is 9.7 MPa. The pseudo-bubble point pressure increases with the increase of gas injection volume and temperature， the pseudo-bubble point pressure at 50 °C increases with the increase of CO₂ injection，and the pressure rises slowly. The reservoir has good gas injection characteristics. （2）The flow of foamy oil in the study area can be divided into five stages：no bubble stage， bubble precipitation stage， bubble expansion stage，bubble coalescence stage and bubble extinction stage.（3）The recovery of steam+ CO₂ flooding is 13.3% higher than that of pure steam sand-filled pipe flooding. With the release of pressure，the number of bubbles increases gradually， and the oil production increases gradually. When the pressure drops to the bubble point pressure，the number of bubbles tends to be stable and form relatively stable foamy oil，and the oil production increases greatly，which is the main oil production period. When the pressure is released to the pseudobubble point pressure，the number of bubbles will decrease rapidly，the foam oil will disappear gradually，and the oil production will decrease slowly.