Abstract: A vibrating screen used for the fine screening of solids from a slurry containing solids includes a base, a screen box having feed end and discharge end with said screen box being resiliently supported on the base, and a drive for vibrating said screen in a generally longitudinal direction. The screen includes at least two overlying layers of relatively fine mesh screen cloth. A tensioning device is connected to one end of the screen cloth for tensioning the screen cloth in a direction parallel to the direction of motion of the screen cloth.

Abstract: Gas laden drilling mud is effectively handled by a centrifugal pump system which allows the flow of released gases from the drilling mud to move in the same axial direction as the mud flow through the pump; whereupon the released gases may be conducted to safe disposal areas. A hollow-centered impeller is driven by a hollow shaft through which the gases may be withdrawn. A prerotation chamber and impeller shroud below the impeller admit drilling mud into the impeller housing, providing the drilling mud with initial rotational velocity through a reduced radius, and further establishing a central opening through which gases escaping from the drilling mud will be released due to centrifugal forces on the mud. Released gases may then be removed through the central passage in the hollow shaft, which shaft may be provided with external means for preventing upward flow of fluid therearound.

Abstract: A gas bubble is circulated from a well by a system that maintains the well and bottom hole pressure substantially constant by progressively increasing the casing pressure as needed to maintain the drill pipe pressure substantially constant. An incrementally increasing casing pressure reference signal is produced by detecting each occurrence of the drill pipe pressure falling a predetermined amount below a drill pipe pressure reference signal. The casing pressure reference signal is compared with the actual casing pressure. A throttling valve is closed a corresponding amount if the acutal casing pressure is less than the casing pressure reference signal. The throttling valve is opened a corresponding amount if the actual casing pressure is greater than the casing pressure reference signal.

Abstract: An improved rotary drill head is provided having two lip seals installed in a seal cavity to provide a long lasting dynamic seal. The first lip seal is installed with the heel first and the second lip seal is installed with the lip first. Lubricant is maintained between the two seals at a pressure greater than the operating pressure of the rotary drill head. The lubricant pressure energizes the two lip seals. The abrasive fluid from the borehole is prevented from leaking past the seals because of the pressure differential. An infinitesimal amount of lubricant will leak past the lips of the seals thereby lubricating the seal.

Abstract: A unique degasifying system for removing entrapped gas bubbles from a viscous drilling fluid utilizes a hollow shaft pump having a hollow impeller, with a prerotation chamber and impeller shroud below the impeller; a spray vessel having a continuous sheet radial spray head and vacuum creating means therein; a vacuum conduit connecting the vacuum creating means to the hollow shaft of the pump; and an enclosed degasifying trough connected to the spray vessel and having fluidic seal means at each end, with a gas exhaust conduit connected thereto.

Abstract: A system is disclosed for removing gas from drilling mud without allowing the gas to escape to the atmosphere before the gas is treated to prevent contamination. The system includes a mud-gas separator vessel with a drilling mud inlet, means for maintaining a minimum mud level in said mud-gas separator vessel, a separator vessel gas outlet, and a separator vessel drilling mud outlet. A degassing means includes a drilling mud inlet located in a position higher than said minimum mud level. Enclosed conduit means connects the separator vessel drilling mud outlet to said degassing means drilling mud inlet.