Abstract: 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 penetrate 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 which 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 abrasive and hard formations.