A completion system comprises tubular components coupled together to form a completion string. In-flow control devices are provided to permit selective fluid communication between an internal bore of the completion string and the annulus. A reaming tool is provided at a leading end of the completion string and the reaming tool is run into the borehole with the completion string. The reaming tool comprises a fluid-powered drive unit, a reaming body and a reaming nose. In use, the completion string is located in the borehole and fluid is directed to the reaming tool to facilitate reaming of the borehole. A second tubular in the form of a washpipe may extend through an internal bore of the completion string for providing fluid to the reaming tool. The reaming tool is operable at a fluid pressure below a pressure which would activate the in-flow control devices.

A rock housing for horizontal directional drilling machine includes a cylindrical housing body with walls defining a longitudinal cavity. A bearing assembly is provided as a part of the housing and is located above a bit box region of the housing. The bearing assembly is lubricated by drilling mud which flows through the drill string of the drilling machine. A portion of the drilling mud is diverted and passes through a gap formed between the bearing races of the bearing assembly, the gap being sized so as to create the necessary back pressure to divert the needed flow of drilling mud to the assembly. In some cases, an additional flow restrictor can be provided in the gap between the bearing races when needed, as when the driller is using a very low viscosity drilling fluid.

A rock housing for horizontal directional drilling machine includes a cylindrical housing body with walls defining a longitudinal cavity. A bearing assembly is provided as a part of the housing and is located above a bit box region of the housing. The bearing assembly is lubricated by drilling mud which flows through the drill string of the drilling machine. A portion of the drilling mud is diverted and passes through a gap formed between the bearing races of the bearing assembly, the gap being sized so as to create the necessary back pressure to divert the needed flow of drilling mud to the assembly. In some cases, an additional flow restrictor can be provided in the gap between the bearing races when needed, as when the driller is using a very low viscosity drilling fluid.

A shank adapter, rock drilling machine and method of mounting a shank adapter of a rock drilling machine inside a slide bearing element. The shank adapter includes a coupling head and a rotation portion at its opposite ends, and a flushing portion located therebetween. Outer diameters of the coupling head and the rotation portion are both greater than outer diameters of portions of the shank adaptor located therebetween.

A shank adapter, rock drilling machine and method of mounting a shank adapter of a rock drilling machine inside a slide bearing element. The shank adapter includes a coupling head and a rotation portion at its opposite ends, and a flushing portion located therebetween. Outer diameters of the coupling head and the rotation portion are both greater than outer diameters of portions of the shank adaptor located therebetween.