Patent ID: 8813873

Claim:
A process for drilling a wellbore with a drillbit on the end of a drillstring with minimal loss of drilling fluid and minimal casing operations, where the process comprises: a) providing a drilling fluid with granular lost circulation material wherein the lost circulation material comprises particles for accomplishing enhanced smear fracture plugging where the particles have a particle size distribution from about 50 microns to about 4000 microns with substantial populations of particles throughout the entire range of the particle size distribution and further wherein the particles of the lost circulation material are in the drilling fluid in a range from at least 0.5 pound per barrel up to 15 pounds per barrel to flow with the drilling fluid and also to form plugs at any lost circulation areas at the periphery of the wellbore and form a filter cake at such lost circulation areas and block or reduce fluid flow from the wellbore into the lost circulation areas, where the lost circulation areas include openings and fissures in the wellbore walls; b) providing a drillstring having at least one smear tool along a portion of the perimeter of the drillstring to smear filter cakes of lost circulation material into lost circulation areas and compress the lost circulation material into more secure plugs to enhance the performance of the lost circulation material at the lost circulation areas, said smear tool from about 5 to 60 feet long containing a helical trowel with a small front nose ( 21 ), a capture surface ( 25 ), a broader smear surface ( 26 ), and a trailing end ( 22 ), where the radial distance of the small front nose ( 21 ) is less than the radial distance of the trailing end ( 22 ) from a main body of the smear tool, and the capture surface ( 25 ) is shaped to capture the particles along the wall of the wellbore and direct the flow of mud and cuttings between the tool and the wellbore, where the smear tool does not scrape or scratch the inside surface of the wellbore, where the smear tool has a smear surface that has an effective diameter of at least about 75% of the diameter of the wellbore and smears the walls of the wellbore as the drill string rotates; and c) rotating the drillstring to drill the wellbore further into the earth and turn the smear tool so that the smear surface smears along the inside surface of the wellbore and especially press the lost circulation materials into a plug of more dense mass of particles and condition the lost circulation areas to reduce lost circulation, pipe sticking, and spalling.