Development of rheological models depending on the time, temperature, and pressure of wellbore cement compositions: a case study of southern Iran’s exploratory oilfields

Abstract

One of the significant challenges in cementing operations is the ability to predict the rheological behavior of wellbore cement under bottom-hole conditions. Therefore, developing advanced fluid mechanics models is necessary to predict the rheological behavior of wellbore cement. This study focused on wellbore cement compositions in southern Iran’s exploratory oilfields, considering time, temperature, pressure, and cement stability during drilling and production operations. The proper exploratory and development oil wells’ cement formulation of the area shall be prepared according to the geological characteristics and static and circulation temperature at the beginning and end of the formation. It requires conducting various tests, such as compressive strength, free water, and thickening time, in the studied formations. Optimal compaction should be produced according to the amount of allowed slurry and comparing the data obtained from the tests. The values obtained from different formations were compared with those obtained from Bingham’s plastic and power fluids theories, and the very low deviation of the shear stress calculated at different radii of the rotary viscometer was compared. It was concluded that Bingham’s plastic model is the appropriate rheological model that describes the slurry’s rheological properties, such as plastic viscosity, shear stress, shear rate, and density. The novelty aspects of this work include a rheology modeling error range of 0.11 to 0.95% for wellbore cement compositions and the accurate representation of these cement’s rheological behavior. If this model is used to predict the rheological behavior of wellbore cement compositions before casing cementing, it can save drilling operations costs and time. It will also cause a correct evaluation of the reservoir layers and increase the production rate.