渤海油田腐蚀垢卡油管打捞工艺技术——以绥中36-1A井为例

Salvage Technology of Corroded and Scale-Stucked Tubing in Bohai Oilfields:Taking SZ 36-1A Well as an Example

渤海油田稠油资源丰富,稠油区块注水注聚驱动开发策略已实施多年,油藏采收率大幅提高。然而,注水注聚井油管腐蚀、井内污垢积聚以及聚合物垢卡等问题日益突出,导致注采量下降,严重影响油田的正常生产和经济效益。位于渤海油田绥中区块的36-1A井长期注水注聚,井下管柱腐蚀垢卡严重,防砂管柱内径较小而无法套铣,在前期应用"MPC(Mechanical Pipe Cutter)切割+震击倒扣打捞"工艺遭遇瓶颈后,通过应用"机械内切割+震击倒扣打捞交替+磨铣解卡"工艺,最终成功捞获井内全部中心管,并由此得出宝贵经验:针对井内积聚大量聚合物垢,首先应用小油管彻底通井冲洗,同时洗井液中添加合适的除垢剂;针对腐蚀、垢卡且不能套铣的中心管,在震击倒扣打捞手段无效后,应遵循切割为主、钻磨为辅的处理原则;钻磨作业期间,应遵循高转速、低钻压磨铣思路,避免产生大块铁屑,谨防卡钻。本文系统总结了打捞过程及技术要点,为今后渤海油田同类作业提供了指导性建议。

Bohai oilfield is rich in heavy oil resources. The strategy of water flooding and polymer flooding driven development in heavy oil blocks has been implemented for many years, and oil recovery has been greatly improved. Nevertheless, tubing corrosion, clingage accumulation and polymer scale stuck problems lead to injected volume and output quantity reduction, which have severely influenced the normal production and economic benefits. SZ 36-1A well located in Bohai oilfields and had carried out watering - polymer combined flooding for many years, which resulted in string corrosion and polymer scale stuck seriously. Meanwhile, the inside diameter of sand control pipe was so small that it could not carry out wash over operation. When it encounted bottleneck by adopting MPC cutting and back - off fishing technologies, the field engineers adopted decidedly the inner mechanical cutting, milling and back-off fishing. Finally, it salvaged all the fish and valuable experience was obtained as follow: a. in order to accumulate a large amount of polymer scale in the well, firstly apply a small oil pipe to thoroughly flush the well, and add a suitable descaling agent to the well washing liquid at the same time;b. as for tubing corrosion and scale - stucked wells, it should be treated by means of mechanical cutting dominated and milling assisted;c. during the milling period, it should maintain higher RPM and lower weight on bit, avoiding producing bigger metal debris and being alert of tool sticking. This paper systematically summarizes the salvage process, technical points and provides guiding suggestions for similar operations in Bohai oilfield in the future.