Abstract: There is disclosed an improved downhole steerable motor assembly (5) and related method. A problem in known assemblies is that the distance from a bent housing bend axis to the face of a drill bit needs to be kept relatively short resulting in the length of the bearing package and its thrust capacity being restricted. Accordingly, the invention provides a downhole motor assembly (5) comprising a motor (115), at least one thrust bearing (116) and a bent portion (117), the assembly (5) having a first end (135) and a second end (140), the first end (135) being closer to surface than the second end (140), in use, wherein the bent portion (117) is closer to the second end (140) than is the at least one thrust bearing (116).

Abstract: The invention relates to stabilisation devices for down-hole drill motors and provides such a device comprising a tubular motor body portion (18) adapted for rotational movement on a selective basis to provide a steering capability, a motor shaft (16) passing through the body portion (18). A lower end portion of the shaft provides an end surface (20) for attachment of a tool (32) by a bit attachment means (28, 30) provided within a lower end of the shaft. The lower end of the shaft (16) has an external diameter less than the internal diameter of the motor body portion so as to be either completely or partially received within the body portion to enable the overhang distance between the operating faces of the bit and the stabiliser on the bearing housing to be as short as possible. Alternatively the end face (20) of the shaft may project slightly (.ltoreq.5 cm) from the end face (22) of the motor body portion (18).