Abstract: A downhole oil-sealed bearing pack assembly is provided for protecting bearing elements and seals. The bearing pack assembly includes a non-contact flow restrictor for reducing large differential pressures across sealing elements. The non-contact flow restrictor includes an inner restrictive element attached to a rotatable drive shaft and an outer restrictive element secured to a stationary bearing housing. The inner restrictive element can include an outwardly extending ring adjacent to a first land and the outer restrictive element can include an inwardly extending ring adjacent to a second land. During rotation of the drive shaft the inwardly and outwardly extending rings remain a distance from the second and first lands, respectively, thus permitting a fluid to traverse the rings and lands. The invention also provides a wear sleeve for increasing seal and shaft life. The wear sleeve includes a groove cut into a hollow sleeve which is secured to the rotatable driveshaft.

Abstract: Apparatus for sensing the resistivity of geological formations surrounding a borehole includes a tubular body member (1) which is adapted to form a portion of a length of drill string. An antenna (10) is mounted within the body member (1) and the body member (1) has apertures (2) adjacent to the antenna (10) to permit an electro-magnetic signal to pass through the body member (1) after transmission from, or for reception by, the antenna (10).

Abstract: A combination drill motor with measurement-while-drilling sensor apparatus includes a rotor within a stator. The rotor rotates and gyrates in response to fluid flow through the stator. An outer housing assembly having a bearing housing and a sensor housing is connected to the stator. A drive shaft is concentrically located within the bearing housing. A bearing assembly is positioned between the bearing housing and the drive shaft. A sensor cartridge assembly having a longitudinal throughbore is suspended within the sensor housing. A power transmission assembly connects the rotor to the drive shaft. The power transmission assembly includes a shaft assembly extending through the longitudinal throughbore in the sensor cartridge assembly. An annular space is formed in the longitudinal throughbore between the sensor cartridge assembly and the shaft assembly and the fluid flows through the annular space.

Abstract: A downhole tool bearing assembly is provided which utilizes a secondary annular threaded locknut and a compression ring in order to take up tolerance stack-up and to provide supplemental preload through a bearing housing assembly, thus helping to ensure against accidental disassembly during operation. The bearing housing assembly is comprised of a prepackaged subassembly of thrust bearings, sleeves and, optionally, "BELLEVILLE"-type disk springs which can be quickly and easily installed onto a downhole tool drive shaft or other similar apparatus by maintenance personnel having a minimum of training. The bearing housing assembly is designed such that reconfiguration involves little more than removal and reinstallation in the opposite orientation, thereby overcoming the need to reconfigure the bearing assembly one bearing at a time.