Pressure Variation in a Fluid at Rest 1. In April 2010, the Deepwater Horizon drilling rig experienced a severe explosion and fire and sank off the coast of Louisiana. Eleven persons died, and 17 others were injured. The resulting uncontrolled oil release from the damaged well being drilled persisted for almost 4 months. The rig was in the process of closing an exploratory oil well in the Gulf of Mexico. The seafloor at the well site was 5,067 ft below the water surface, and the petroleum reservoir was located 18,360 ft below the water surface. One cement plug had been placed at this lower depth, and a second cement plug was being completed at the time of the explosion. A key issue in the investigation of the explosion is the decision to replace drilling fluid (a.k.a. %u201Cdrilling mud%u201D) with seawater in the well pipe prior to installation of the upper cement plug. Drilling fluid is an engineered mixture of water, polymers, clay, and other material that serves a variety of purposes including acting as a dense counterweight to the high pressure of the petroleum reservoir. Some experts have hypothesized that removal of the drilling fluid in favor of less dense seawater allowed a high pressure methane bubble to move up the well pipe (a %u201Cblowout%u201D). Determine the pressure (psi) at the bottom of the well pipe (depth 18,360 ft) if drilling fluid of specific weight 17 lb/gal were left in place between the seafloor and the petroleum reservoir. Remember that pressure at the seafloor would include hydrostatic pressure due to the seawater (\(\gamma=64 lb/ft^3\)). Determine the pressure (psi) at the bottom of the well pipe if all drilling fluid were replaced by seawater.