深水油藏窄密度窗口气井固井动态仿真模拟研究与应用

Research and Application of Dynamic Gas Well Cementing Performance Simulation within Narrow Density Window in Deep-Water Reservoir

针对中国南海西部油田固井施工过程中存在的井筒内温差大、密度窗口窄等复杂问题,考虑温度、压力对固井流体密度及流变性的影响,建立了固井动态注替模型,并依据瞬态加速度法得到了井内实际流量计算方法,基于测井数据、井身结构参数、固井泥浆性能参数及固井施工参数等,计算了固井过程中各地层薄弱点的当量循环密度及各阶段的井内动态参数。通过对南海西部油田LD1-X井的固井实例,提出了提高深水油藏窄密度窗口气井安全高效固井的技术措施:合理的浆柱结构设计、变排量顶替技术、注水泥全阶段的仿真模拟等。现场应用结果表明,以上技术措施可有效解决大温差窄密度窗口气井的安全固井问题。该研究对南海西部油田的固井施工具有重要指导意义。

In order to improve the large wellbore temperature difference,narrow density window and other complex problems for the cementing process in the western South China Sea Oilfield,a dynamic cementing model was established by considering the effects of temperature and pressure on cementing fluid density and rheology.The actual flow rate calculation was gained according to the transient acceleration method.The equivalent circulation density of weak points in various wellbore sections and the dynamic well parameters in each stage during the cementing process were calculated based on logging data,wellbore casing program,cementing slurry performance parameters,cementing operation parameters,etc.The technical measures for improving the gas well cementing operation safety and efficiency with narrow density window in deep-water reservoir were proposed,including reasonable design of slurry column structure,displacing with variable displacement,whole simulation process of cementing slurry injection,etc.Field application indicates that the above technical measures can effectively improve the cementing operation with large temperature difference and narrow density window.This research could provide certain guidance for the cementing operation in the western South China Sea Oilfield.