Enhanced smear effect fracture plugging process for drilling systems

Abstract

This invention relates to drilling a well, particularly an oil or gas well, where casing or liner will be installed to stabilize the wellbore. The present invention is intended to permit more drilling and longer lengths of casing or liner to be installed at one time. The present invention includes a combination of a smear tool and specially sized granular lost circulation material solids in the drilling mud which work together to close and seal leaking formations and fractures whether pre-existing or induced by drilling. By the natural collection of the inventive solids along with the conventional particles in the drilling mud to form a filter cake at the problem areas along the wall of the wellbore and the smear tool arranged to compress the filter cake into the problem areas, lost circulation is minimized Maintaining circulation naturally allows for longer drilling cycles and potentially fewer liner joints in the well. As such, larger diameter boreholes are located in the hydrocarbon bearing formation and less time is spent installing casing or liner pipe.

1 . A smear tool comprising a smooth trowel surface to smear filter cake, cuttings, or lost circulation material (LCM) into the wellbore wherein said trowel comprises:
 a leading edge,   a capture surface,   a smear surface, and   a trailing edge   wherein said smear tool is at least 10 feet in length, said smooth trowel covers up to 95 percent of the smear tool length, said smear tool smooth trowel diameter is at least 75% of the nominal hole diameter (NHD), and said smooth trowel compresses particles into the wellbore while drilling, and   wherein said leading edge has a radial distance that his less than the radial distance of the trailing edge from the tool body.   
     
     
         2 . The smear tool of  claim 1  comprising a straight trowel or a helical trowel. 
     
     
         3 . The smear tool of  claim 1  wherein said smear tool smooth trowel surface is at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 feet or 3, 5, 7, 10, 12, 15, 20, 25, 30 meters in length. 
     
     
         4 . The smear tool of  claim 1  wherein said smear tool trowel diameter is 75, 80, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent of the NHD. 
     
     
         5 . The smear tool of  claim 1  comprising one trowel surface, two trowel surfaces, three trowel surfaces, four trowel surfaces, five trowel surfaces, six trowel surfaces, or more that are distributed around the smear tool to provide a consistent smear effect. 
     
     
         6 . A trowel tool comprising a smooth trowel surface attached to a tool body, wherein said smooth trowel surface is at least 3 meters or 10 feet in length, said smooth trowel surface covers up to 95 percent of the trowel tool length, said trowel tool diameter is at least 75% of the nominal hole diameter (NHD), and said smooth trowel compresses particles into the wellbore while drilling. 
     
     
         7 . The smear tool of  claim 6  wherein said trowel tool smooth trowel surface is at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 feet or 3, 5, 7, 10, 12, 15, 20, 25, 30 meters in length. 
     
     
         8 . The smear tool of  claim 6  wherein said trowel tool smooth trowel surface diameter is approximately 75, 80, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent of the NHD. 
     
     
         9 . A process for drilling a wellbore comprising:
 determining a rate of progress (ROP) for a drill string, placing at least 0.5 meter of smooth trowel surface per each meter per hour of ROP,   drilling a wellbore using a smooth trowel surface to increase compaction of solids into fissures and decrease lost circulation,   wherein said smooth trowel surface is at least 10 feet in length, said smooth trowel surface covers up to 95 percent of the tool length, said tool diameter is at least 75% of the nominal hole diameter (NHD), said smooth trowel surface has a leading edge with a radial distance that his less than a radial distance of a trailing edge from the tool body, and said smooth trowel surface compresses particles into the wellbore.   
     
     
         10 . The process for drilling a wellbore according to  claim 9 , wherein said smooth trowel surface is at least 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 feet or 3, 5, 7, 10, 12, 15, 20, 25, 30 meters in length. 
     
     
         11 . The process for drilling a wellbore according to  claim 9 , wherein said smooth trowel surface diameter is approximately 75, 80, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99 percent of the NHD. 
     
     
         12 . The process for drilling a wellbore according to  claim 9 , comprising two, three, four, five, or more smooth trowel surfaces in the drill string to provide a consistent smear effect. 
     
     
         13 . The process for drilling a wellbore according to  claim 9 , comprising a combination of an eccentric smear tool and a concentric smear tool, a smooth trowel tool, or both. 
     
     
         14 . The process for drilling a wellbore according to  claim 9 , wherein a lost circulation material including materials selected from the group consisting of: ground nut shells; calcium carbonate; graphite; coke; carbon; sulfur; plastic; resins; sand; crushed rock; metal particles; ceramic particles; glass beads; expanded perlite particles; hard rubber compound particles; urethane particles; crushed cement; crushed coal and combinations of one or more such materials is circulated.