A centralizer with low friction buttons and method of fabrication thereof

Abstract

A centralizer with low friction buttons comprising a plurality of collars including a first collar and a second collar; a plurality of bow springs, each bow spring having a first end and a second end; and a plurality of low friction buttons. The plurality of bow springs extend between the first and second collar such that the first and second end of each bow spring is connected to the first and second collar respectively; the plurality of low friction buttons are mounted on the bow springs such that they act as the only point of contact between the centralizer and borehole during movement of the pipe casing while getting it to the total depth during drilling operation, said buttons being of the type whose coefficient of friction is lesser than the rest of the body of the centralizer.

I claim: 
     
         1 . A centralizer provided for lowering friction comprising:
 a plurality of collars including a first collar and a second collar; and   a plurality of bow springs, each bow spring having a first end and a second end; wherein   a plurality of buttons are mounted on said plurality of bow springs such that the first and second end of each bow spring is connected to the first and second collar respectively;   the plurality of buttons are mounted on the bow springs such that at least one button from any plurality of bow springs is in contact with the borehole wall and act as the only/preferable point of contact between the centralizer and borehole; and   said low friction buttons having low coefficient of friction than the rest of the body thus reducing torque and drag, thereby increasing the longevity of the centralizer.   
     
     
         2 . The centralizer as claimed in  claim 1 , wherein the low friction buttons are mounted on the bow springs such that they constitute the air gaps between borehole wall and the centralizer, thereby allowing said low friction buttons to touch on the borehole wall during run in the hole, providing minimum loss of the applied torque and high running force to the centralizer. 
     
     
         3 . The centralizer as claimed in  claim 1 , wherein said low friction buttons are composed of metal alloy. 
     
     
         4 . The centralizer as claimed in  claim 3 , wherein said metal alloy is preferably stainless steel. 
     
     
         5 . The centralizer as claimed in  claim 1 , wherein said centralizer is designed for open-hole and cased-hole logging applications. 
     
     
         6 . The centralizer as claimed in  claim 1 , wherein the coefficient of friction of said low friction buttons in water-based mud ranges from 0.10-0.15. 
     
     
         7 . The centralizer as claimed in  claim 1 , wherein the coefficient of friction of said low friction buttons in oil-based mud ranges from 0.05-0.10. 
     
     
         8 . The centralizer as claimed in  claim 1 , wherein the buttons are fitted in holes punched on centralizer. 
     
     
         9 . The centralizer as claimed in  claim 8 , wherein the holes are preferably oval with transverse diameter in range of 11-17 mm and longitudinal diameter in range of 13-15 mm.