PDC钻头钻进的岩石可钻性研究

STUDY ON ROCK-DRILLABILITY FOR PDC BIT DRILLING

用微型PDC试验钻头模拟全尺寸PDC钻头的切削破岩方式在岩样上钻孔,测定了石油钻井所遇地层岩心的微PDC钻头可钻性指数(PDT).研究了微PDC钻头可钻性指数和微牙轮钻头可钻性指数(UDT)的关系.研究表明,基于牙轮钻头钻进特点的油矿地层可钻性分级.同样适用于PDC钻头钻井.在岩石可钻性方面.PDC钻头对地层的适应性较差.PDC钻头钻进时,存在着极限等级值和有效等级值.当地层等级值大于极限等级值时。其破岩效果差,当等于或小于有效等级值时,效果最好.

Drillability tests were made on core samples from the formations encountered during drilling. Rock cutting and rolling-crushing were simulated by using micro PDC bits and the drillability indexes of core samples were measured. The relationship of drillability indexes for micro PDC bit and those for micro roller cone bit was analyzed. The result showed that the formation drillability classification for the roller cone bit was also suitable for the PDC bit. However, the PDC bit is less adaptable to various formations than the roller cone bit. During drilling with the PDC bit, there exists a maximum and an effective value of drillability. When the value is larger than the maximum, the drilling effect is the worst. The drilling is satisfactory when the value is equal to or smaller than the effective value.