Density Measurement of Vegetable and Mineral Based Oil Used in Drilling Fluids

Abstract

Abstract Normally, calculated frictional pressure losses do not match actual frictional losses recorded during drilling operation. Discrepancies between calculated and measured pressure losses are more severe in operations where synthetic based drilling fluids are used because synthetic based drilling fluids density and rheology varies with changes in down-hole conditions. In order to deal with this phenomenon, a comprehensive experimental study was performed to predict the densities of vegetable base oil (derivative of ester), mineral base oil (commercially used in the formulation of drilling fluids) and their blend at elevated pressure and temperature. In the experiments, the temperature ranged between 80F-300F degrees F and the pressure ranged between 50psi- 5000psi. The data showed that when the pressure increased at the constant temperature conditions, the volume of the based oil reduced. The data analysis also shows the importance of introducing the effect of pressure and temperature on the density of the based oil for the pressure loss calculation during drilling activities. The blend of vegetable based oil with mineral based oil showed more tolerance in High Pressure High Temperature (HPHT) down-hole conditions. In addition to that, part of the study focused on developing an empirical linear equation that related density change in pressure and temperature. Liner regression technique was used in this purpose. It was found that the empirical equation was accurate in estimating the experimental result. On the other hand, it was observed that the mineral based oil sample was more compressible and subject to higher thermal expansion than the vegetable based oil and their blend.