渤海A3井弃井技术及重晶石塞的应用

Well Abandonment Technology and Application of Barite Plug in Bohai Well A3

注水泥塞弃井作业是油气田勘探开发中较为常见的作业,当需要侧钻、回填及最终弃井时都需要注水泥塞。注水泥塞质量的好坏直接影响安全和环保,"压得稳、封得住"是其基本要求。渤海油田某A3井钻进至5 046m发生卡钻和底部钻具落井事故,打捞未成功后,注水泥回填弃井侧钻。该井井底温度达到100℃以上,地层孔隙压力1.52g/cm3,钻进过程出现较好的气测显示,同时又属于低孔低渗油藏。本区块在该弃井层位存在极高的气全量,前期作业时频繁出现注水泥无法封隔气层的问题。鉴于此,通过G级水泥+漂珠+胶乳聚合物体系+重晶石塞的组合以及加压候凝措施的配合,精确计算附加量,优化候凝方式,最终成功封隔气层,有效保证了井控安全及后续作业。

Cementing plugging is a common operation in oil and gas field exploration and development,usually used in side tracking,backfilling and well abandonment.The quality of cementing plugging directly affects safety and environmental protection,with the basic requirement known as＂pressing stably,sealing reliably＂.The well A3 is a deep well in the Bohai Oilfield.During the drill process,drilling tool sticking and dropping occurred when the drilling depth reached 5 046 m.After the failure of fishing,the only choice was well abandonment and side tracking.At that time,the bottom temperature exceeded 100 ℃,and the pore pressure was 1.52 g/cm3.There is a high total gas amount at this depth,and this well belongs to the low porosity and low permeability reservoir.Considering the failure of gas blocking by cementing plugging in previous operations,the combination of cement,floating beads,latex polymer and barite plug was proposed to block the gas. With the help of pressure waiting-on-cement,gas blocking was finally achieved,which guaranteed the safety of well control and subsequent operations.