Systems and methods for protecting drill blades in high speed turbine drills

A drilling assembly in an elongated hole comprising:

• a housing defining an interior;
• a plurality of motor stages in the interior, each motor stage having at least one blade with supporting platform surfaces;
• a casing within the interior and surrounding the plurality of motor stages, the casing defining an annular flowpath with the housing and at least one offtake passage adjacent each motor stage;
• a shielding fluid passing through the annular flowpath and, in turn, the at least one offtake of each motor stage to coat and protect the at least one blade and supporting platform surfaces;
• and
• a driving fluid passing through the casing for propelling the at least one blade of each motor stage.

A method for drilling using a turbine assembly in an elongated hole comprising the steps of:

• providing a housing that defines an interior;
• mounting a plurality of motor stages in the interior, each motor unit having at least one blade;
• surrounding the plurality of motor stages with a casing within the interior, wherein the casing defines an annular flowpath with the housing and at least one offtake passage adjacent each motor stage;
• passing a shielding fluid through the annular flowpath and, in turn, the at least one offtake of each motor stage to coat and protect the at least one blade;
• and
• passing a driving fluid through the casing for propelling the at least one blade of each motor stage.