Deep Western Riverbed Sand And Gravel Layer Drilling, Coring Technology Research,

This thesis is based on the item of Chengdu Hydroelectric Investigation & Design Institute of SPC, Research of core-drilling exploration in sandy pebble layers. The main contents of this thesis are the research of simultaneous casing & coring method by pneumatic Down-the-Hole (DTH) hammer drilling and the innovation of a novel vegetable-gum drilling fluid.The DTH hammer has the advantage of fast drilling; casing while drilling can protect the borehole well. By combining these methods together and optimizingdesign, we made a new method of drilling--the technology of simultaneous casing& coring by pneumatic DTH hammer drilling. Drill tools, coring bit and casing bit have been designed and a complete set of equipments and tools have been formed. Rules of operation have been made to operate these equipments more proficiently. The aims of good coring quality, high drilling efficiency and simultaneous casing have been achieved. The needs of geological exploration for project in sandy pebble and drift boulder covered layers are satisfied.A new kind of vegetable-gum, which accords with the demands of environmental protection and has good qualities with proper price and wide source, has been found through investigation and research. A scheme of improving the performance of vegetable-gum has been made. We studied the rheology of vegetable-gum and tested its toxicity. With regard to its field drilling applications, the Vegetable-gum drilling fluid showed itself with excellent rheological behaviors in its abilities of lubrication, plugging holes, suspension and removal of debris, anti-shear shinning, and high coring rates. The main materials of this novel vegetable-gum can automatically degrade into no-harm substances with no environment pollution.