Choosing Drilling Fluid for Carbonaceous Slate
April 2013, hard difficulties had been met in Zhouqu drilling project. Formations in the region give priority to
brown yellow and grey sandstone slate, limestone and black carbonaceous slate. Slate is a metamorphic rock which
is low grade metamorphic rocks metamorphosed from clay, siltstone or slightly acidic tuff, and has significant platy
structure. In the mining area, there is mainly sandy slate and carbonaceous slate with limestone. These slate and
limestone are integrated, occasionally including no more than 10cm quartz veins. The low metamorphosed
carbonaceous shale slate is relatively fractured, partially high oxidated, and 1-5mm particles. The formation is a