Abstract: A water based drilling fluid composition and an additive for water based drilling fluid compositions having as components poly(N-vinyl-2-pyrrolidone/sodium 2-acrylamido-2-methylpropane sulfonate) and ferrous sulfate useful in controlling high temperature water loss in drilling a well to recover oil and gas from a subterranean formation in a hostile environment and their methods of use.

Abstract: A novel organophilic clay suspension medium prepared by admixing an organophilic clay with a hydrocarbon oil and an activator selected from the group consisting of phenyl hydroxyalkyl ethers and phenylalkanols. Optionally water may be added to the admixture for further improving the suspension medium.

Abstract: A drilling fluid additive is disclosed which will prevent water loss into subterranean formations during the drilling of oil and gas wells in hard brine environments. The drilling fluid additive comprises a hydrocarbon, an anionic surfactant, an alcohol, a sulfonated asphalt, a biopolymer, and optionally an organophilic clay, poly(N-vinyl-2-pyrrolidone-co-sodium-2-acryamido-2-methylpropane sulfonate, and water.

Abstract: A controllable power source is suitable for driving one or more electric motors from a low voltage battery. A converter steps up the d.c. voltage to a higher level at which the motors are designed to operate and a power regulator placed between the converter and each motor regulates the power which is drawn at the higher voltage by the motors. A current limit is imposed on the converter which is significantly less than the maximum current handling capabilities of the motors, so that when a motor attempts to draw an excessive current the output voltage of the converter drops accordingly. This enables the overall power handling capability of the converter to be minimize, while still allowing a motor to draw maximum current or maximum voltage, but not both simultaneously.