An invert emulsion drilling fluid, and a method for the use thereof in drilling wellbores, with good rheological properties at high temperatures and pressures. One embodiment of the drilling fluids is free of organophilic clays and lignites, free of calcium chloride, and comprises glycerol in the internal phase, and a suspension agent comprising a combination of a fatty dimer diamine and a short chain acid, such as citric acid. In one embodiment, the base oil for the emulsion is a paraffin and/or mineral oil. The drilling fluids provide good rheological properties including good suspension of drill cuttings.