胜利油田樊142块特低渗透油藏 CO2驱油储层压力动态变化研究

摘要

To study the dynamic changes during CO2 flooding in reservoir formations and to evaluate the progress of the miscible front in the oil reservoir in Block Fan 142 which possesses extremely low per‐meability ,and to clarify phases and flooding performances in such reservoirs ,dynamic changes in pressures were reviewed .Comprehensively using geologic data ,production data ,downhole pressure monitoring and reservoir numerical simulation techniques allowed the analysis of patterns in pressure changes and pressure build‐up after CO2 injection in the Well Cluster F142 7 X4 .Research results showed that formation pres‐sures decreased quickly in stages with development by using natural energy .During pressure build‐up with closed producers and injected CO2 ,the formation pressures in Well F142 7 3 and Well F142 8 3 of F142 7 X4 Cluster restored slowly ,whereas pressures in the other the 4 wells was quickly restored .Considering analyses related to minimum miscible pressure front and CO 2 concentration front both vertically and hori‐zontally ,the progres of miscible zones may be determined to establish the method to clarify the CO 2 misci‐ble zones .Research results demonstrate that the dynamic tracking of pressures might provide a reliable foundation to determine the volume and timing of CO 2 injection .In addition ,these results may provide ef‐fective ways to determine phases in CO2 flooding and to clarify boundaries of miscible regions .%为了解胜利油田樊142块特低渗透油藏注CO2驱油时的油层压力动态和混相前缘推进特征，确定油藏中的相态和驱油效果，进行了储层压力动态变化研究。运用地质资料和生产资料分析、井下压力监测和油藏数值模拟相结合的方法，研究了该区块F1427 X4井组自投产以来油层压力的变化规律以及注入CO2后油层的压力恢复特征。研究结果显示，依靠天然能量开采阶段地层压力衰减迅速；在关闭采油井注CO2压力恢复阶段， F1427 X4井组中的F14273井和F14283井地层压力恢复缓慢，其余4口井地层压力恢复较快；实测与数值模拟的油层压力基本一致，可用模拟结果进行相关分析。基于模拟结果，结合油层剖面和平面上的最小混相压力前缘和CO2浓度前缘分析，明确了混相区的推进特征，建立了确定CO2混相区域的方法。研究表明，压力动态跟踪结果可为确定CO2注入量和开机时机提供可靠的依据，为判断CO2驱油相态和确定混相区域提供有效手段。