Effects of Temperature and Pressure on Shale Cuttings Dispersion in Water Based Mud WBM Using NACL, CACL2, KCL Salts as Primary Inhibiting Agents and Polymer XCD Xanthan Gum as Secondary Inhibiting Agent

Abstract

Abstract The primary cause of wellbore instability is the interaction of water based mud with shales which usually involves the movement of water and ions into or out of shale thereby causing alterations in mechanical property of the shale resulting in dispersion of shale particles into the mud. This work involves experiments to analyze the effects of chemical osmosis, diffusive flow prior to shale hydration and inhibition, determination of the effects of salt addition on pH and density of mud and also determination of the effect of Temperature and pressure other than just temperature on dispersion of shale cuttings into water based mud. It also shows the behaviour of shale in various inhibitive agents e.g NaCl, KCl, CaCl2 and Polymer XCD when being hot rolled. Results from experiment performed in this work confirmed that osmosis and ionic diffusion play a great role in shale hydration and dispersion. It also showed that subjecting the system to temperature and pressure conditions other than just temperature caused more dispersion of shale into mud. KCl was the best inhibitive agent as more shale cuttings were recovered from the mud while the least shale recovery was from CaCl2/salt formulation. A further experiment was performed by adding polymer XCD to the Salt/mud formulations so as to investigate its inhibitive capability; result showed that more shale cuttings were recovered as compared to when only Salt/mud was used.