Matching Technologies and Their Application for Increasing Drilling Speed in Deep Exploratory Well in East China Sea

The oil and gas exploration in the East China Sea has changed gradually into the deep depth, and the drilling depth of exploratory well is increasing constantly. Therefore, it is necessary to optimize the original casing program. The casing program has changed, with 444.5 mm large size hole deepen to 2400 m, and the rock hardness and strength in deep well increase. Thus, the formation drillability became poor, which leaded to a decreasing obviously in drilling rate, a long drilling cycle and high drilling cost. Therefore it is urgent to conduct a study on the technology for increasing drilling speed and its application. To overcome these difficulties, by optimizing bit, drilling method and improving the drilling fluid, the fast drilling technology has been developed for the upper 444.5 mm hole section. In the lower hole section, intelligent logging real-time monitoring technology has been used to optimize and adjust timely the drilling parameters and the torsional drilling tool was chosen to increase drilling speed, which formed matching technology for increasing drilling speed in the lower section of hole. The field application results indicated that the drilling rate was speeded up significantly. The large size composite drilling technology, torsional drilling tool, and intelligent borehole logging technology for monitoring drilling parameters can be fully applied in the area.