Drilling system with annular flush separation device and method

A method of drilling a wellbore, comprising the steps of:

• a) providing a drilling system comprising:
• a driving device and a separation device disposed upstream of the driving device and including an external housing, the external housing including a sidewall;
• the driving device configured to convert hydraulic or pneumatic horsepower into mechanical horsepower;
• the separation device including a filter flow path and a flush flow path;
• wherein the flush flow path extends to a flush outlet on an outer surface of the separation device, the flush outlet being in direct fluid communication with a section of an annulus between the outer surface of the separation device and the wellbore, the flush outlet of the separation device comprising a port extending through the sidewall of the external housing of the separation device;
• b) drilling the wellbore in a subterranean formation with the drilling system;
• c) flowing a drilling media through the filter flow path of the separation device to filter at least a portion of any solids within the drilling media;
• wherein any filtered solids are retained within the separation device;
• d) flowing the drilling media to the driving device;
• and
• e) activating the separation device to flow the drilling media through the flush flow path of the separation device to flush at least a portion of the filtered solids through the flush flow path and through the flush outlet and into the section of the annulus.