A Rheometer for Evaluating Drilling Fluids at Elevated Temperatures

Abstract

American Institute of Mining, Metallurgical and Petroleum Engineers Inc. Abstract The trend toward deeper wells with subsequent higher bore-hole temperatures has increased the need for data on drilling fluid properties at elevated temperatures and pressures. Equipment presently available does not allow direct presently available does not allow direct determination of fluid properties from lower laminar to fully turbulent flow with precision. This paper presents the design precision. This paper presents the design considerations that led to the construction of equipment at the University of Oklahoma to provide high temperature data for drilling fluids and cement slurries and examples of such data for three drilling mud systems. The equipment will operate up to 350 degrees F through flow ranges from lower laminar to turbulent flow with sufficient precision for extrapolation to other precision for extrapolation to other pipe sizes and other geometries of flow pipe sizes and other geometries of flow conduit. It was determined that the equipment was adequate and that the fluid properties of at least some fluid systems properties of at least some fluid systems are highly dependent on temperatures and should be examined by this procedure for critical design programs. Introduction Several investigators have recently been interested in the high temperature behavior of drilling fluids due to the increasing numbers of deep wells and the need to critically control drilling fluid rheology in these wells. The experimental methods and the chosen form of data presentation vary considerably among the presentation vary considerably among the various investigators but all have indicated a deleterious effect on drilling fluid caused by a high temperature environment. Many of the investigators have tried to relate the deleterious effects to measurable chemical or physical changes that occur in clay drilling fluids at elevated temperatures. Most of the previous investigators have chosen to study the rheological properties of drilling fluids at elevated properties of drilling fluids at elevated temperatures with a modified rotational viscometer and report the data considering the fluids as Bingham Plastics.