Reduced differential sticking drilling collar

Abstract

Systems and methods for drilling a subterranean well include a reduced differential sticking drilling collar. The reduced differential sticking drilling collar is an elongated tubular member having a minimum outer diameter at an uphole end and at a downhole end. A collar body is located between the uphole end and the downhole end. The collar body has a cross section of alternating lobes and troughs. The collar body has a maximum outer diameter that is larger than the minimum outer diameter. A taper section extends from the minimum outer diameter to the maximum outer diameter. The lobes of the collar body wind along an entire axial length of the collar body in a spiral pattern.

What is claimed is: 
     
         1 . A system for drilling a subterranean well, the system including:
 a reduced differential sticking drilling collar, the reduced differential sticking drilling collar being an elongated tubular member having:
 a minimum outer diameter at an uphole end and at a downhole end; 
 a collar body located between the uphole end and the downhole end, the collar body having a cross section of alternating lobes and troughs, the collar body having a maximum outer diameter that is larger than the minimum outer diameter; and 
 a taper section extending from the minimum outer diameter to the maximum outer diameter; where 
   the lobes of the collar body wind along an entire axial length of the collar body in a spiral pattern.   
     
     
         2 . The system of  claim 1 , where the taper section includes reaming elements, the reaming elements extending radially outward from the taper section. 
     
     
         3 . The system of  claim 1 , where the taper section includes cutting elements, the cutting elements extending obliquely radially outward from the taper section. 
     
     
         4 . The system of  claim 1 , where an angle of the taper section relative to a central axis of the reduced differential sticking drilling collar is in a range of 10 to 30 degrees. 
     
     
         5 . The system of  claim 1 , where a number of lobes of a cross section of the collar body is at least three. 
     
     
         6 . The system of  claim 1 , where the lobes of the collar body wind around no more than one half of a circumference of the collar body over an entire axial length of the lobes. 
     
     
         7 . The system of  claim 1 , where the lobes of the collar body and the troughs of the collar body are curved in shape. 
     
     
         8 . The system of  claim 1 , where an outermost surface of the lobes is parallel to a central axis of the reduced differential sticking drilling collar. 
     
     
         9 . A system for drilling a subterranean well, the system including:
 a rotating drilling string formed of a plurality of tubular drill string joints, each of the plurality of tubular drill string joints having a joint outer diameter,   a reduced differential sticking drilling collar secured in-line with the plurality of tubular drill string joints, the reduced differential sticking drilling collar having:
 a minimum outer diameter at an uphole end and at a downhole end; 
 an uphole connector operable to secure the uphole end to an uphole adjacent drill string member; 
 a downhole connector operable to secure the downhole end to a downhole adjacent drill string member; and 
 a collar body located between the uphole end and the downhole end, the collar body having a cross section of alternating lobes and troughs, the collar body having a maximum outer diameter that is larger than the minimum outer diameter and larger than the joint outer diameter; where 
   the lobes of the collar body wind along an entire axial length of the collar body in a spiral pattern.   
     
     
         10 . The system of  claim 9 , further including a taper section extending from the minimum outer diameter to the maximum outer diameter, where an angle of the taper section relative to a central axis of the reduced differential sticking drilling collar is in a range of 10 to 30 degrees. 
     
     
         11 . The system of  claim 9 , where the lobes of the collar body wind around no more than one half of a circumference of the collar body over an entire axial length of the lobes. 
     
     
         12 . A method for drilling a subterranean well, the method including:
 providing a reduced differential sticking drilling collar, the reduced differential sticking drilling collar being an elongated tubular member having:
 a minimum outer diameter at an uphole end and at a downhole end; 
 a collar body located between the uphole end and the downhole end, the collar body having a cross section of alternating lobes and troughs, the collar body having a maximum outer diameter that is larger than the minimum outer diameter; and 
 a taper section extending from the minimum outer diameter to the maximum outer diameter; where 
 the lobes of the collar body wind along an entire axial length of the collar body in a spiral pattern; 
   securing the reduced differential sticking drilling collar in line with a plurality of tubular drill string joints to form a drilling string; and   rotating the drilling string to form the subterranean well.   
     
     
         13 . The method of  claim 12 , where the taper section includes reaming elements extending radially outward from the taper section, and the method further includes reaming within a wellbore of the subterranean well with the reaming elements. 
     
     
         14 . The method of  claim 12 , where the taper section includes cutting elements extending obliquely radially outward from the taper section, and the method further includes cutting within a wellbore of the subterranean well with the cutting elements. 
     
     
         15 . The method of  claim 12 , where an angle of the taper section relative to a central axis of the reduced differential sticking drilling collar is in a range of 10 to 30 degrees. 
     
     
         16 . The method of  claim 12 , where a number of lobes of a cross section of the collar body is at least three. 
     
     
         17 . The method of  claim 12 , where the lobes of the collar body wind around no more than one half of a circumference of the collar body over an entire axial length of the lobes. 
     
     
         18 . The method of  claim 12 , where the lobes of the collar body and the troughs of the collar body are curved in shape. 
     
     
         19 . The method of  claim 12 , where an outermost surface of the lobes is parallel to a central axis of the reduced differential sticking drilling collar.