Flat Rheology Water Based Mud for Deepwater Drilling Operation

Non-aqueous Fluid (NAF) or Synthetic Based Mud (SBM) has always been the default selection when it comes to deep water drilling due to its high Rate of Penetration (ROP) and enhanced wellbore stability. However, the use of NAF always lead to large downhole losses when the Equivalent Circulating Density (ECD) window is narrow and the rheology of fluid increases at low temperature. Therefore, since 2004, Flat Rheology Non-aqueous Fluid (FR NAF) has been developed to overcome the problems faced by conventional NAF when drilling in deep water. Although better rheological performance is observed for FR NAF, there is still an extent for its application due to its compressibility and gas solubility issue. An alternative method is to revert back to the usage of an Aqueous Fluid (AF) such as FR WBM with the addition of Kinetic Hydrate Inhibitors (KHI) to overcome the problems that arises due to the usage of NAF in deep water drilling operations. From the experiments conducted it is observed that the formulated FR WBM (mud #1) do possess a flat rheology which is independent of temperature both before and after the hot roll process.