Study On The Core Drilling In The Jiujiang-Ruichang Ore Concentration Area

Core drilling is an important means to acquire geological data. With the development of the national economy and the science and technology, the depth and the bore diameter of core drilling are improved continually, more complicated geologic condition has to be faced, increased the chances of an accident and the varieties of accidents, the complexity of accidents are continuously growing. Jiujiang and Ruichang ore concentration area is one of the five key exploration districts of middle to lower Yangtze mineralizing belt, as an important Cu (Au) poly metallic metallogenic belt of China. During the core drilling construction in the Jiujiang and Ruichang ore concentration area, stratum in which core drilling accidents are easily happens, mainly as fragile and loose strata、deflecting formation、karst fracture formation、deep hard slipping formation. According to the summary and the research of the core drilling accidents happend in Jiujiang and Ruichang ore concentration area, the main results achieved and understanding are as follows:(1) This paper, analysis on the geologic feature、the causes and the classification of accidents and measures of prevention and management in the Jiujiang and Ruichang ore concentration area. At the meanwhile, it is point out that choosing the rope coring drilling technology, preparing multistage aperture rope and applying sodium modified bentonite to drilling, all of which are better to increase drilling efficiency, reduce drilling strength and prevent some accidents to happen.(2) Limestone in Aoxia mining area of Ruichang is wildly distributed, when construct drilling, not only cave can be encountered in superficial layer, but also large-scale cave could be encountered in deep layer. Dealt with deep and large krast are rather difficult, choosing filling and protect drilling such traditional method to drilling, the economy or the effect maybe worse.(3) Through analysis on the deep and large krast drilling difficulties and technical points, this research adopt sodium to the leak、high-level cement to fix the location、oxygen free welding to the bottom of the drill rope、double wire-line drill pipes stagger drilling to construct and make it succeed.(4) Within the deep Aoxie mining area of Ruichang, exist in hard slipping layer, namely hard granite layer, drilling inefficiency and drilling bite wear obvious often occursin this layer, when facing with deep hard rock simply by raised bit pressure and improve frictional force won’t work out, and accidents are easily happened, such as drilling bite wearing serious、drilling pipe fracture and sticking, the effort by increased face height are not obvious.(5) By analyze the factor and the correlation of impact on deep and hard slipping layer drilling, this paper put forward a new bite, which takes diamond quality of the drilling bite、matrix hardness、lip sharp、diamond concentration and working lining thickness into consideration and make it succeed.