Pump-down pressure plug

Abstract

A pressure plug system comprising a pressure plug with a tapered section, a receiving landing receptacle having a tapered section with substantially the same tapering angle as tapered section of the pressure plug, and tapering angle being less than the friction angle corresponding to the coefficient of friction between the pressure plug and the landing receptacle. The pressure plug engages the receiving landing receptacle providing reliable seal and locking the plug against landing receptacle preventing axial movement under cycling pressure and rotation of the plug during drillout.

1 . A pressure plug system comprising:
 a pressure plug comprising a first tapered section with a first tapering angle;   a landing receptacle comprising a second tapered section with a second tapering angle substantially equal to the first tapering angle of the first tapered section of the pressure plug;   whereby the first tapered section of the pressure plug is adapted to engage in the second tapered section of the landing receptacle; and   whereby the first tapering angle of the pressure plug is less than a friction angle corresponding to a coefficient of friction between the first tapered section of the pressure plug and the second tapered section of the landing receptacle.   
   
   
       2 . The pressure plug system of  claim 1 , wherein the tapering angle is in the range of substantially from 0.5 to 6 degrees. 
   
   
       3 . The pressure plug system of  claim 1 , wherein the tapering angle is in the range of substantially from 1 to 3 degrees. 
   
   
       4 . The pressure plug system of  claim 1 , wherein the ratio of the length to the diameter of the tapered section of the pressure plug is substantially from 1 to 6. 
   
   
       5 . The pressure plug system of  claim 1 , wherein the ratio of the length to the diameter of the tapered section of the pressure plug is substantially from 2 to 4. 
   
   
       6 . The pressure plug system of  claim 1  comprising a cylindrical section of constant diameter, wherein the cylindrical section of the pressure plug having at least one groove with elastomeric ring adapted to sealingly engage in a cylindrical section of the landing receptacle. 
   
   
       7 . The pressure plug system of  claim 1  comprising at least one elastic cup extending outwardly and rearwardly. 
   
   
       8 . A method of providing a pressure containment comprising:
 providing a pressure plug system comprising a pressure plug with a tapered section, a receiving landing receptacle having a tapered section with substantially the same tapering angle as said tapered section of the pressure plug, and said tapering angle being less than the friction angle corresponding to the coefficient of friction between the pressure plug and the landing receptacle;   pumping said pressure plug down through the drill pipe and landing pressure plug in receiving landing receptacle;   applying pressure not less than maximum expected back pressure.   
   
   
       9 . The method of providing a pressure containment of  claim 8 , wherein said applied pressure is approximately twice higher that the expected maximum back pressure.