Abstract: An adjustable bent sub assembly is provided comprising a tubular adaptor for connection with the stator of a downhole motor, a tubular adjusting ring for altering the angular offset of the assembly, and a tubular offset sub for connection with the bearing and bit assemblies. A tubular mandrel is positioned internal of this stack of components. The mandrel is threadably connected at its upper end with the adaptor and at its lower end with the offset sub. The mandrel and ring have a spline connection. The ring and offset sub have disengagable dog clutch means connection them. The mandrel is transversely bent at a point along its length as is the offset sub. The ring has an angled or canted bottom end face. The combination of bending the internal mandrel, bending the offset sub and canting the end face of the ring results in the effective or resultant bend point of the assembly being closer to its lower end.

Abstract: A flow retarder is provided for use in the bearing assembly of a downhole drilling motor. The bearing assembly comprises an inner tubular mandrel and an outer tubular housing. The flow retarder comprises: an inner carbide sleeve connected to the rotating mandrel by a resilient elastomer layer bonded to a driver ring which is locked on the rotating mandrel; an outer carbide sleeve affixed to the stationary tubular housing; the sleeves forming a narrow annular clearance or metering gap between them; a secondary port extending through the mandrel side wall directly above the carbide sleeves; and a housing port extending through the housing side wall below the flow retarder sleeves. Drilling fluid leaks down from the adapter/adjustable housing clearance and passes through the metering gap to lubricate the carbide sleeves. Part of this fluid returns through the secondary port to the main bore of the mandrel.

Abstract: An adjustable bent sub assembly is provided comprising a tubular adaptor for connection with the stator of a downhole motor, a tubular adjusting ring for altering the angular offset of the assembly, and a tubular offset sub for connection with the bearing and bit assemblies. A tubular mandrel is positioned internal of this stack of components. The mandrel is threadably connected at its upper end with the adaptor and at its lower end with the offset sub. The mandrel and ring have a spline connection. The ring and offset sub have disengagable dog clutch means connection them. The mandrel is transversely bent at a point along its length as is the offset sub. The ring has an angled or canted bottom end face. The combination of bending the internal mandrel, bending the offset sub and canting the end face of the ring results in the effective or resultant bend point of the assembly being closer to its lower end.