Drilling technology difficulties and countermeasures for ultra-low permeability gas pools in Ordos Basin

In line with formation characteristics and downhole complicated conditions like old age of formations in development wells for ultra-low permeability gas pools in Ordos, poor drill ability of sandy conglomerate and quartz sandstone, strong abrasion, too many interbeds, high heterogeneity, high effective stress, hole deviation, lost circulation, unstable wellbore, blowout, stuck pipe, bit bouncing, etc., analysis of technical difficulties during drilling was conducted in terms of geology and engineering, and technical countermeasures and measures were proposed regarding optimized BHA, optimized bit types, optimized drilling fluid, optimized completion fluid for gas reservoir protection and prevention of drill string failure. The field application shows that these measures have effectively solved the drilling difficulties in development well of Shanxi well group in Ordos Basin, and the drilling cycle of this well was reduced by 30% and drilling rate up by 10%, providing technical reference for effective drilling of ultra-low permeability gas pool by development wells and reservoir protection in Ordos Basin.