Abstract: A method is disclosed that affords improved stability to wellbores during drilling in argillaceous formations with water-based drilling fluids. The method comprises adding to the drilling fluid a compound of the invention having the capacity in water to generate a highly efficient membrane on argillaceous materials. The compound is soluble in the drilling fluid at least at the pH at which the compound is added to the drilling fluid or exists in the drilling fluid, but is insoluble in the water in the pores of the argillaceous formations, or at least at the pH of the water in such pores.

Abstract: A method is disclosed that affords improved stability to wellbores during drilling in argillaceous formations with water-based drilling fluids. The method comprises adding to the drilling fluid a compound of the invention having the capacity in water to generate a highly efficient membrane on argillaceous materials. The compound is soluble in the drilling fluid at least at the pH at which the compound is added to the drilling fluid or exists in the drilling fluid, but is insoluble in the water in the pores of the argillaceous formations, or at least at the pH of the water in such pores.

Abstract: A water-based drilling fluid for use in shale formations having a given average pore size has solutes dissolved therein sized so as to allow the pores of the shale formations to at least partially restrict the solutes. For purposes of enhancing the restriction of the solutes by the shale pores, the dissolved solutes may have different radii. Additional solutes, preferably lower molecular weight salts, are dissolved in the drilling fluid to lower the activity of the water in the water-based drilling fluid.The same combination of additives, a first additive of dissolved molecular solutes sized to at least partially block a shale pore space and a second additive of dissolved molecular solutes selected to lower the water activity, are combined in a water-based carrier fluid and used in earth boreholes surrounded by shale formations as either a spotting fluid, or as a lubricant, or as a shale formation strengthener or as a completion fluid.

Abstract: A method for drilling utilizing a composition comprising water, a water-soluble polyalcohol, a water-insoluble alcohol, and drill solids. Also, a composition ideally suited for drilling is provided comprising water, a mixture of water-soluble and insoluble alcohols and drill solids.