A bearing arrangement for a turbine rotor of a turbine is adapted to be mounted in a drill string and to be driven by the flow of drilling fluid. The bearing arrangement includes a turbine chamber surrounding the turbine rotor and having an inflow and an outflow, a stator on which the turbine rotor is rotatably mounted, and a cavity formed between the turbine rotor and the stator and accommodating at least one radial plain bearing and being separated from the turbine chamber by an axial plain bearing constructed as a bearing ring seal and by a conveyor screw which is disposed on the turbine rotor and operates to convey from the cavity to the turbine chamber.