复合钻杆胶塞解决超深井尾管固井碰压问题

How to Judge Whether the Cement Is in Place for Liner Cementing by Combined Drill Pipe Plug in a Ultra Deep Well

为了解决塔河油田尾管固井由于不能确保碰压而采用平衡法固井留水泥塞过长的问题,设计了一种分体式复合钻杆胶塞。该胶塞由上胶塞(φ127mm、空心)、下胶塞(φ89mm)、密封圈、销钉、导向头及卡簧组成,上胶塞与下胶塞通过销钉连接在一起。上胶塞针对φ127mm钻杆内钻井液的顶替,下胶塞针对φ89mm钻杆内钻井液的顶替。替浆时,复合胶塞在φ127mm和φ89mm钻杆连接处分离,下胶塞继续在φ89mm钻杆内运行,直至与尾管挂处的套管胶塞复合。现场试验表明,采用复合胶塞固井能够确保碰压,缩短水泥塞,从而减少了扫水泥塞时间(由过去的平均50h缩短到现在的不到10h),而且改善了固井质量。

In the Tahe Oilfield, because when the cement is in place cannot be known while cementing liners run in the Ardovician system, the balance cementing method is employed, and then a long cement plug is got. Regarding such scenario, a kind of knockdown complex drill pipe plug is designed. The plug consists of a hollow top plug of 127mm diameter, a bottom plug of 89mm diameter, O-rings, pins, guide head, and snaprings. The top plug is connected with the bottom plug by a pin. The top plug is suitable for drill pipes of 127mm diameter, and the bottom plug for 89mm drill pipe. While cementing, the complex plug is separated in the crossover sub connecting 127mm drill pipe and 89mm one, and then the bottom plug will not go down in 89mm drill pipes until it settle on the casing plug situated in liner hanger. Field tests show that a complex plug ensures cement to be displaced in place, shortens cement plug, and reduces time of drilling out of it from 50h to less than 10h, and improves cementing quality.