Practical guide for testing and maintenance of high temperature drilling fluids during drilling, coring, logging, and cementing wellbores.

摘要

Control of mud weight, fluid rheology, and loss of fluids from the mud system are the most important parameters that must be monitored and controlled during any drilling operation on a mud system. Also, alkalinity control is of paramount importance of systems where the pH is kept below 10.0 because of the differences in the chemical reactions on clays and precipitation of carbonates. Ideally, one must be able to duplicate down-hole conditions of temperature, pressure, shear stress and differential pressure between the column of fluid and the formation. Unfortunately, the instrumentation for monitoring the above is either very scarce, nonexistent, or does not completely duplicate downhole conditions. Therefore, a thorough working knowledge and understanding of chemical reactions from laboratory studies that will take place in a given system under downhole conditions is helpful. There should be a sound scientific foundation established for any phenomenon before attempting to apply it in field procedures and utilization. During the past several years the authors have conducted detailed research on a variety of clay minerals for use as a primary viscosifier for water base drilling fluids. The following is a review of their findings. 6 refs., 6 figs., 3 tabs.