Specific heat capacity of xanthan gum/PAC polymer-based drilling fluids: An experimental and correlation study

Abstract

The accurate prediction of wellbore thermal profile is essential to ensure the success of any drilling operation. Currently, the heat capacity values used for predicting the thermal behavior of oil and gas wells assume the heat capacity of the drilling which leads to errors. Thus, determining the heat capacities of drilling mud systems would aid to efficiently predict the thermal distribution of wells. In this study, the heat capacities of fresh and aged mud samples of 0.8 wt% xanthan gum water-based mud and 0.8 wt% polyanionic cellulose (PAC) water-based mud and their blend system (0.4 wt% xanthan gum + 0.4 wt% PAC) were measured using a differential scanning calorimetry (DSC) from 5 to 100 °C. The new and aged samples represent testing the mud as fresh samples and over time (1–3 days). The result shows that the specific heat capacity values of the drilling muds differ from the heat capacity of water (which is generally used for drilling-related heat transfer modeling and simulations). High heat capacity values were observed for the 0.8 wt% xanthan gum mud system compared with the 0.8 wt% PAC mud system. However, the blend of 0.4 wt% xanthan gum + 0.4 wt% PAC exhibited the highest heat capacity values. In both fresh and aged samples, the heat capacity of 0.8 wt% xanthan gum mud was in the range of 3.805–4.287 J/g.oC. While 0.8 wt% PAC mud and 0.4 wt% xanthan gum + 0.4 wt% PAC mud system were within 0.7635–1.1329 J/g.oC, and 4.134–4.324 J/g.oC, respectively. These experimental heat capacity values are recommended for accurate oil & gas well heat transfer behavior modeling and simulation predictions and related studies.