Application of Multi-process Drilling Technology to the Hot Dry Rock Well GH-03 in Gonghe Basin, Qinghai Province

GH-03 well is a hot dry rock production well deployed by China Geological Survey. Its target layer is granite, which is characterized by high hardness, strong abrasiveness, poor drill ability, low ROP and bit life. In order to achieve high efficiency drilling in high temperature hard rock, based on the investigation of the existing drilling technologies, conventional rotary table drilling, PDM compound drilling, turbo drill with impregnated diamond bit compound drilling and rotary-impact drilling are applied. Some of these technologies have achieved good results, especially the PDM compound drilling and rotary-impact drilling, which can increase the drilling speed by 52%–103% and extend the bit life by 104%–252% compared with the adjacent wells. These results can greatly improve the drilling efficiency of hot dry rock wells in Gonghe basin and also provide experience for high temperature hard rock construction.