Drilling Mud Influence on Sandstone Poroelastic Parameters
Keywords:drilling mud; rock mechanical properties; Biot’s coefficient; acoustic waves; dynamic measurement
Abstract: The most critical challenge faced during drilling operations is related to the stability of the well. Additionally, drilling mud plays a crucial role in wellbore stability, as one of its main uses is to support the wellbore wall during the drilling operation. However, ignorance of the effects of drilling mud on the mechanical properties of rock formation can also lead to well failure. The stability of the wellbore is also influenced by the pore pressure during the drilling process. The analysis of changes in rock poroelastic parameters after drilling mud saturation was found to be a useful research regarding the above mentioned. Therefore, the measurement of the dynamic Young’s modulus, Poisson’s ratio and Biot’s coefficient of sandstone samples was carried out to determine their trends of variations with confining pressure in different conditions such as dry, water and drilling mud filtrate saturation. The findings indicate that both the dynamic Young modulus and the Poisson’s ratio of the sandstone rock increased after saturation with water and drilling mud filtrate, while the Biot’s coefficient was reduced. Furthermore, the velocity of the P wave, the dynamic Young modulus and the dynamic Poisson ratio of the sandstone rock were proportional to the confining pressure, while the Biot’s coefficient were inversely proportional to the confining pressure. The results imply that the effective stress calculation can be influenced by changes in poroelastic parameters established from geophysical measurements, and risk management of wellbore stability stability was increased.