Drilling occurred at the depth 7 km. The required bottom-hole pressure at this depth to keep the wellbore stable 100 MPa. The drilling mud is made of water, polymer and barite. 2 kg of polymer is added per 1 m of water to ensure that the fluid is viscous enough to suspend the barite particles. 400 tonnes of barite is available for the mud. Take the acceleration due to gravity as g = 9.81 m/s. Densities: Barite - 4200kg/m Polymer - 2000kg/m Water - 1000kg/m a) (2 marks) Calculate the density of mud needed to keep the borehole stable. b) (4 marks) Calculate the amount of water needed to achieve the required mud density to keep the borehole open.