Effects of Temperature on the Viscosity of Some Gulf Coast Drilling Muds

Abstract

With the introduction of rotary drilling in the Gulf Coast area, somethirty-two years ago, and its subsequent spread to other producing localitiesin the United States, there has been a constant change in the design ofequipment. Only the general features remain, namely the rotating drill stem andthe circulating mud. Only recently have the properties of mud and theirbehavior received attention from petroleum engineers, but circulating problemsin present deep drilling demand further study and understanding. It is the purpose of this investigation to determine the relative changes inthe apparent viscosity of muds with changes in temperature and to discoverother physical effects due to heat. Very little information has been published regarding the effects of temperatureon the viscosity of drilling muds. Maust states: "The viscosity of mostmuds is decreased on heating, but the interesting thing is that the degree offlocculation is also increased on heating. There will be a greater tendency toseal off formations at high temperatures than at low temperatures." Withregard to the effect of temperature on viscosity and yield point, Herrickstates: "The variation of yield point and viscosity of mud with temperature….. is not very clearly brought out by the data available. Both appear todecrease slightly with increasing temperature up to 2000 F." Theexperimental results presented in this paper further emphasize thispoint. Two types of viscosimeters are available for measuring the apparent viscositiesof drilling muds: the efflux tube type as used by Herrick and Marsh, and thetorsional type such as the McMichael or the Stormer viscosimeters.