Abstract: A method of controlling bottom hole pressure in a wellbore, including pumping drilling mud into the wellbore, estimating the annular friction pressure in the wellbore, and measuring the pressure of the drilling mud exiting the wellbore. The method includes measuring the flow rate of the drilling mud exiting the wellbore, and, based on the pressure of the drilling mud exiting the wellbore, the flow rate of the drilling mud exiting the wellbore, expected annular friction pressure in the wellbore, and rotational speed of drill string in the wellbore, controlling the flow rate of drilling mud exiting the wellbore to achieve a specified bottom hole pressure.

Abstract: A method of pumping material from a sea floor to a vessel on a sea surface, including the steps of collecting material from the sea floor using a production tool, connecting the production tool to the vessel with a riser including a riser transfer pipe, and pumping the material from the production tool to the vessel using a subsea slurry lift pump positioned between the production tool and the vessel and attached to the production tool by the riser transfer pipe. The method further includes backflushing the riser transfer pipe by running seawater through the slurry lift pump into the riser transfer pipe toward the production tool.

Abstract: A method of controlling bottom hole pressure in a wellbore, including pumping drilling mud into the wellbore, estimating the annular friction pressure in the wellbore, and measuring the pressure of the drilling mud exiting the wellbore. The method includes measuring the flow rate of the drilling mud exiting the wellbore, and, based on the pressure of the drilling mud exiting the wellbore, the flow rate of the drilling mud exiting the wellbore, expected annular friction pressure in the wellbore, and rotational speed of drill string in the wellbore, controlling the flow rate of drilling mud exiting the wellbore to achieve a specified bottom hole pressure.

Abstract: A method of pumping material from a sea floor to a vessel on a sea surface, including the steps of collecting material from the sea floor using a production tool, connecting the production tool to the vessel with a riser including a riser transfer pipe, and pumping the material from the production tool to the vessel using a subsea slurry lift pump positioned between the production tool and the vessel and attached to the production tool by the riser transfer pipe. The method further includes backflushing the riser transfer pipe by running seawater through the slurry lift pump into the riser transfer pipe toward the production tool.

Abstract: A solar powered roof ridge vent apparatus is provided for actively conducting warm air from an attic space of a home or building to the ambient environment. The roof ridge vent apparatus includes a series of electrically powered axial fans fastened to openings formed in a laterally flexible main panel which is installed at the ridge opening of a roof on a home or building. The laterally flexible main panel seals to the roofline. The series of fans are protected from the elements by a shroud. The shroud is fastened to the laterally flexible main panel and forms a cavity surrounding the fans in which the fan drawn air is first introduced prior to passing through a vent to the ambient environment. The fans are powered using electricity generated by a solar panel, which is mounted to the main panel. A thermostat is employed to deactivate the electrical fans at lower ambient temperatures when attic ventilation is undesirable. The apparatus can be installed as a single unit to the exterior of the home.