CO_(2)-C_(2)H_(6)吞吐提高致密油藏采收率实验研究  

Experimental study on enhancing oil recovery of tight reservoirs through CO_(2)-C_(2)H_(6) huff and puff

作　　者：王程伟 苏玉亮[1,2] 王文东 李蕾[1,2] 郝永卯 WANG Chengwei;SU Yuliang;WANG Wendong;LI Lei;HAO Yongmao(School of Petroleum Engineering,China University of Petroleum(East China),Qingdao City,Shandong Province,266580,China;MOE Key Laboratory of Unconventional Oil&Gas Development,China University of Petroleum(East China),Qingdao City,Shandong Province,266580,China)

机构地区：[1]中国石油大学(华东)石油工程学院,山东青岛266580 [2]非常规油气开发教育部重点实验室中国石油大学(华东),山东青岛266580

出　　处：《油气地质与采收率》2024年第1期111-118,共8页Petroleum Geology and Recovery Efficiency

基　　金：“十四五”前瞻性基础性重大科技项目“致密油可动用性评价及提高采收率机理研究”(2021DJ2202);国家自然科学基金项目“页岩油CO_(2)吞吐多尺度流动模拟研究”(51974348)。

摘　　要：注CO_(2)已经成为致密油藏提高采收率的重要手段之一,相较于纯CO_(2),部分烃类气体对原油的降黏及混相能力更强。为此,通过高温高压PVT实验研究了CO_(2)及复合气体(CO_(2)-C_(2)H_(6))-原油的饱和压力及黏度的变化特征,并利用高温高压岩心吞吐实验揭示了不同气体介质、吞吐压力及吞吐轮次下原油动用程度。研究结果表明:复合气体中C_(2)H_(6)增强了气液两相混相能力,提高了CO_(2)降黏及溶解能力,原油流动性显著增加。复合气体中随着C_(2)H_(6)摩尔分数的增加,原油饱和压力由14.24 MPa增至18.02 MPa,提高了26.54%;原油黏度由23.68 mPa·s降至8.76 mPa·s。不同吞吐压力下复合气体(CO_(2)-C_(2)H_(6))的采收率提高效果均强于纯CO_(2)的,且吞吐压力在最小混相压力附近采收率提高程度高于其他吞吐压力。复合气体(CO_(2)-C_(2)H_(6))对孔隙半径为0.0001~0.001和0.01~1μm孔隙中的原油动用程度强于纯CO_(2)的。CO_(2) injection has become one of the most important methods of enhanced oil recovery in tight reservoirs,but some hy-drocarbon gases have more viscosity-reducing and miscibility on oil compared to pure CO_(2).Therefore,this article studied the satura-tion pressure and viscosity changes of oil with CO_(2) and composite gas(CO_(2) and C_(2)H_(6))by PVT experiments at high-temperature and high-pressure and revealed the percentage of producing oil with different gases,huff and puff pressures,and rounds by core huff and puff experiments at high-temperature and high-pressure.The results show that the C_(2)H_(6) in the composite gas enhances the gas and liquid miscibility,improves the CO_(2) viscosity reduction and dissolution ability,and significantly increases the fluidity of oil.With the increase of C_(2)H_(6) mole fraction in the composite gas,the saturation pressure of oil increases by 26.54%from 14.24 MPa to 18.02 MPa,and the viscosity of crude oil decreases from 23.68 mPa·s to 8.76 mPa·s.Under different huff and puff pressures,the oil recoveries of composite gas(CO_(2) and C_(2)H_(6))are better than that of pure CO_(2),and the increase of recovery near the minimum miscibility pressure is higher than under other huff and puff pressures.The percentage of producing oil by composite gases is higher than that of pure CO_(2)in the pores of 0.0001-0.001μm and 0.01-1μm.

关 键 词：致密油藏 饱和压力 黏度 岩心实验 核磁共振技术 

分 类 号：TE357[石油与天然气工程—油气田开发工程]