ROP improvement technologies used in the deep igneous formation of Huizhou Block

The Pre-Paleogene in Huizhou block of eastern South China Sea is an igneous formation. Its rock strength is high and formation drillability is poor, which leads to low rate of penetration (ROP), short bit footage and serious wear. In order to improve the drilling efficiency in the igneous formation, this paper carried out rock mechanical analysis based on logging data, by analyzing stratigraphic and lithologic characteristics and evaluating bit wear situations. In addition, strong-aggression ROP improvement tool and bit were designed to improve the ROP, the high impact resistance bit with axed-shape teeth and the bit with double-row teeth were adopted to increase the footage, and the strength at the central part of the bit was increased to reduce the wear. ROP improvement technologies have been successfully applied in Well D of Huizhou Block. Compared with Well A of early stage in Huizhou Block, the bit ROP in Pre-Paleogene diorite and granite is increased by 88% and 69%, respectively, the average footage of each bit in the section of igneous rock is increased by 31.5% and the ascent bit is less worn. In conclusion, these technologies better solve the difficulty of low drilling efficiency in the igneous formation of Huizhou Block and explore the solution to ROP and efficiency improvement in igneous formations.