近平衡正压射孔与负压返涌联作技术在海上油田的应用

疏松砂岩油藏储层岩石强度较低,若采用负压射孔完井方式容易造成地层出砂,甚至砂卡射孔枪;且负压射孔由于工艺限制不能一次射开大跨度的多个层位。针对海上疏松砂岩油藏,储层射孔段跨度比较大的难点,提出了近平衡正压射孔与负压返涌联作技术。由于海上作业平台的局限性,过大的返涌液如不能及时处理只能排入海中,将会对环境造成严重污染;因此在射孔作业前需对返涌量进行定量计算。根据不稳定渗流理论和负压返涌工艺,推导出了负压返涌量的数学模型,利用计算机编程、迭代求解,并分析表皮系数和返涌负压差对返涌量及返涌时间的影响。该技术已在海上油田现场应用,效果良好。

Application of combination technology of perforating with near-balanced pressure and induced flow with negative pressure in offshore oilfield

Negative pressure perforation completion, incapable of perforating multiple layers of large span because of its technical limits, is likely to trigger formation sand and even plug the perforating gun due to the low rock strength in unconsolidated sandstone reservoir. This paper presents a joint technology of perforating with near-balanced pressure and induced flow with negative pressure aimed at the difficulty of large perforating span in offshore unconsolidated sandstone reservoir. Because of the limitation of offshore working platform, a large sum of induced flow liquid, if not processed timely, can only be discharged into the sea, which will cause serious environmental pollution, so we need to calculate the volume of induced flow before perforating. Based on unstable seepage theory and the technics of induced flow with negative pressure, a mathematical model of induced flow is established. Then computer programming and iteration methodology are used to solve the volume of induced flow, and the effect of skin factor and induced flow negative differential pressure on the volume and time of induced flow is analyzed. This technology has been applied to offshore oilfield and yielded good results.