凝析气藏开发中后期注气提高采收率
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摘要
柯克亚凝析气田目前地层压力已经大幅下降,基本接近甚至低于最大反凝析压力,使得井筒周围析出的凝析油增多,渗流阻力增大致使多井无法正常生产。通过调研类比以及室内凝析油注干气抽提相态实验和长岩心驱替实验,结合现场试注结果,评价分析凝析气藏开发中后期注气提压、提高采收率的可行性。研究表明,随注气量增加,注入气对凝析油的抽提作用明显加强,同时凝析油注气膨胀后流动性能明显改善;在地层压力高于最大反凝析压力时注气,可提高凝析油采收率10%～25%,但地层压力若低于最大反凝析压力时注气,采收率增幅十分有限。柯克亚凝析气田部分砂体封闭性好,规模有限,地层压力接近最大反凝析压力,结合矿场情况优化注采参数,采用控制注采比,注气逐步增压,可以有效避免气窜,提高气藏开发效果。
Currently the formation pressure in Kekeya condensate gas field has dramatically declined, which is close to or lower than the maximum retrograde condensation pressure, resulting in many wells idle or unable to produce due to the increases of precipitated condensate oil around wellbores and flowing resistance. For this kind of condensate gas reservoir, it is urgent to study whether the gas injection can effectively improve the recovery rate and the development effect. Based on the investigation, indoor dry gas injection into condensate oil extraction experiment, long core displacement experiment and combined with the field injection test results, the paper evaluates and analyzes the feasibility of gas injection EOR at the mid-late development stage in the condensate gas reservoirs. The results show that with the increase of the injected gas volume, the condensate oil extraction effect is significantly enhanced and the fluidity of the condensate oil is obviously improved; gas injection is carried out when the formation pressure is higher than the maximum retrograde condensation pressure and the recovery rate of condensate oil can be improved by 10%～25%; but when the formation pressure is lower than the maximum retrograde condensation pressure, the improvement of the recovery rate of gas injection is very limited. Partial sand bodies with small scales in Kekeya condensate gas field have good sealing capabilities, in which the formation pressure is close to the maximum retrograde condensation pressure. Injection-production parameter optimization, injection-production ratio control and gradual pressurization according to the actual field situation can effectively avoid gas channeling and improve the development effect of the gas reservoirs.
Currently the formation pressure in Kekeya condensate gas field has dramatically declined, which is close to or lower than the maximum retrograde condensation pressure, resulting in many wells idle or unable to produce due to the increases of precipitated condensate oil around wellbores and flowing resistance. For this kind of condensate gas reservoir, it is urgent to study whether the gas injection can effectively improve the recovery rate and the development effect. Based on the investigation, indoor dry gas injection into condensate oil extraction experiment, long core displacement experiment and combined with the field injection test results, the paper evaluates and analyzes the feasibility of gas injection EOR at the mid-late development stage in the condensate gas reservoirs. The results show that with the increase of the injected gas volume, the condensate oil extraction effect is significantly enhanced and the fluidity of the condensate oil is obviously improved; gas injection is carried out when the formation pressure is higher than the maximum retrograde condensation pressure and the recovery rate of condensate oil can be improved by 10%～25%; but when the formation pressure is lower than the maximum retrograde condensation pressure, the improvement of the recovery rate of gas injection is very limited. Partial sand bodies with small scales in Kekeya condensate gas field have good sealing capabilities, in which the formation pressure is close to the maximum retrograde condensation pressure. Injection-production parameter optimization, injection-production ratio control and gradual pressurization according to the actual field situation can effectively avoid gas channeling and improve the development effect of the gas reservoirs.
引文
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[2]周兴熙.塔里木盆地凝析气的相态成因[J].天然气工业,1996,16(2):5-8.ZHOU Xingxi. Phase genesis of condensate gas in Talimu basin[J].Natural Gas Industry,1996,16(2):5-8.
[3]郑小敏,钟立军,严文德,等.凝析气藏开发方式浅析[J].特种油气藏,2008,15(6):59-63.ZHENG Xiaomin,ZHONG Lijun,YAN Wende,et al. Approach tocondensate gas reservoir development schemes[J]. Special Oil&Gas Reservoirs,2008,15(6):59-63.
[4]崔立宏,付超,刘韬,等.大张坨凝析气藏循环注气开发方案研究[J].石油勘探与开发,1999,26(5):43-45.CUI Lihong,FU Chao,LIU Tao,et al. Cyclic gas injection develop-ment plan for Dazhangtuo condensate gas reservoir[J]. PetroleumExploration and Development,1999,26(5):43-45.
[5]孙雷,黄全华,李士伦,等.凝析气藏近井地层油气产状及渗流特征[J].新疆石油地质,2004,25(4):403-406.SUN Lei,HUANG Quanhua,LI Shilun,et al. Oil-gas occurrenceand flowing features of near wellbore formation in condensate gasreservoir[J]. Xinjiang Petroleum Geology,2004,25(4):403-406.
[6]宋化明,陈叔阳,张云,等.塔里木盆地大涝坝凝析气田循环注气开发设计[J].石油钻采工艺,2010,32(增刊):120-123.SONG Huaming,CHEN Shuyang,ZHANG Yun,et al. Study on cy-clic gas injection technology for development of Dalaoba condensatefield in Tarim basin[J]. Oil Drilling&Production Technology,2010,32(Supp.):120-123.
[7]焦玉卫,李保柱,王博,等.凝析气藏循环注气驱替机理研究[J].新疆石油天然气,2010,6(4):63-66.JIAO Yuwei,LI Baozhu,WANG Bo,et al. Research on mechanismsof cycling reinjection in gas-condensate reservoir[J]. Xinjiang Oil&Gas,2010,6(4):63-66.
[8]陈文龙,廖发明,吕波,等.牙哈凝析气藏注气开发过程反蒸发动态相态特征[J].天然气工业,2012,32(8):67-70.CHEN Wenlong,LIAO Faming,LüBo,et al. Retrograde vaporiza-tion dynamic phase behaviors in gas injection development of theYaha condensate gas reservoir[J]. Natural Gas Industry,2012,32(8):67-70.
[9]宋文杰,江同文,冯积累,等.塔里木盆地牙哈凝析气田地质特征与开发机理研究[J].地质科学,2005,40(2):274-283.SONG Wenjie,JIANG Tongwen,FENG Jilei,et al. Geological fea-tures and exploitation mechanism of the Yaha condensate gas fieldin the Tarim basin[J]. Chinese Journal of Geology,2005,40(2):274-283.
[10]朱卫红,张芬娥,唐明龙,等.牙哈凝析气田循环注气延缓气窜的方法[J].天然气工业,2008,28(10):76-77.ZHU Weihong,ZHANG Fen’e,TANG Minglong,et al. Methods ofcyclic gas injection to retard gas channeling in the Yaha conden-sate gas field[J]. Natural Gas Industry,2008,28(10):76-77.