Development and Testing of a New Type of Diamond-Impregnated Bits

New type of diamond-impregnated bits were developed to solve the problem that PDC bit is not compatible and cone bits have shorter drilling life, less footage and lower ROP in thin sand shale interbed. Diamond concentration was determined to be 80% by drilling tests. Two formulae of diamond granularity were adopted, with 40/45-mesh coarse grain diamond taking up 65%, which was used to crush rocks to improve ROP, and 70/80-mesh fine grain diamond accounting for 35%, which was used to improve the abrasive resistance and service life of drill bits. By testing the mechanic performances of different formula matrices, the D-6 matrix formula was selected, in which tungsten carbide took up 24%, skeleton material 22%, and adhesive 54%. A new type of anti-hollow, high quality structured diamond-impregnated bits were developed ,which had "B"-shaped crown, and 140° inner cone angle, 20° back dip angle, and seven φ16mm diamond grains. The bits were tested in the Yuanba Gas Field. The field test result showed that the average footage was increased by 484.7% and the average rate of penetration was increased by 150.8% compared with other bits in same well sections. The successfully developed new type diamond-impregnated bits are new rock crushing tools with high efficiency for drilling in deep thin sand-shale interbeds.