为提高PDC钻头在研磨性硬地层中的机械钻速、延长钻头寿命，研制了特种孕镶块加强PDC钻头。该钻头以PDC切削齿为主切削元件，天然金刚石孕镶块为副切削元件，既具有常规PDC钻头破岩效率较高的特点，又具有孕镶金刚石钻头在研磨性硬地层寿命长的特点。在钻头开始工作时，主要为 PDC切削齿“犁切”式破岩，当PDC切削齿磨损到一定程度后，天然金刚石开始磨削岩石，形成“犁沟”，有助于 PDC切削齿吃入并切削岩石。该钻头在东北金山气田金古11HF水平井基底花岗岩硬地层进行了现场试验，平均机械钻速达到4.46 m／h ，是同井同地层常规PDC钻头机械钻速的1.5倍，是2口邻井同井段牙轮钻头和常规PDC钻头机械钻速的2倍以上，其使用寿命也达到2口邻井同井段牙轮钻头和常规PDC钻头的2倍以上，取得了良好的现场应用效果。特种孕镶块加强PDC钻头的成功研制，为钻进强研磨性硬地层提供了一种新的高效破岩工具。%To further enhance the rate of penetration and life of a PDC bit in abrasive and hard formations ,a new type of PDC bit enhanced by a special diamond‐impregnated section was developed .It adopted PDC cutting teeth as the main component and the impregnated natural diamond as subsidiary parts .At the beginning of drilling , the bit breaks rock mainly in the form of“Plough Cutting”by the teeth ,but the natural diamonds start to grind the formations into“Plough Furrows”after the teeth have been worn to a certain degree ,which allows the teeth to pene‐trate the formations and cut them efficiently .This kind of bit combined PDC composite cutting teeth with diamond‐impregnated segment ,possess the properties of high formation cutting efficiency and long life w hich is necessary for abrasive and hard formations .The application in the deep hard granite formation of horizontal well Jingu 1 1HF in North‐East Jinshan gas field indicated that the average ROP was 4.46 m/h ,which was 1.5 times of the ROP got by regular PDC bit in the same formation ,and more than 2 times of that produced by roller bit and PDC bit in the same formation of two offset wells ,proving it has very good potential for application .The successful development of the new diamond‐impregnated PDC bit could provide new rock crushing tools with high efficiency for drilling ab‐rasive and hard formations .
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