OBM
OBM is the acronym of Oil Based Mud. Oil-based mud is a drilling fluid composed of oil as the continuous phase and water as the dispersed phase. Additional chemicals are added as needed for achieving desired rheological properties. The oil base can be diesel, kerosene, fuel oil, mineral oil or synthetic oil. Barite is used as weighting agent to increase fluid density and organophilic bentonite is used for providing viscosity. There are two types of Oil Based Mud systems, 'Invert Emulsion Mud' and 'Oil Mud'.
OBM is used to address drilling problems such as, clays in the formation that would react or swell when exposed to water-based drilling fluid. Oil Base Mud also provides higher lubricity and reduces torque & drag downhole. Oil muds have the ability to drill formations where bottom hole temperatures exceed water-based mud tolerances. OBM has been used at temperatures approaching 550°F. Environmentally sensitive location however have strict regulations for disposal of drilling fluid and drilled cuttings. In many offshore locations, drilled cuttings need to be collected and shipped to onshore locations to safely treat and dispose as per environmental regulations.