Displacement efficiency calibration collar

Abstract

A system displacing cement in an annulus of a well is disclosed. The system includes a casing string with a casing outer circumferential surface, wherein the casing outer circumferential surface delineates a boundary of the annulus and a wiper plug, wherein the wiper plug is placed to follow the displacement of the cement in the annulus. Further, the system includes a float collar, having an outer circumferential surface delineated by the inner circumferential surface of the casing string, configured to allow the cement to pass downward with respect to a surface, and a displacement efficiency calibration collar, having an outer circumferential surface delineated by the inner circumferential surface of the casing string, configured to control volume of the cement displaced in the annulus, wherein the displacement efficiency calibration collar includes a calibration shearing disc.

What is claimed is: 
     
         1 . A system for displacing cement in an annulus of a well, the system comprising:
 a casing string with a casing outer circumferential surface, wherein the casing outer circumferential surface delineates a boundary of the annulus;   a wiper plug, having an outer circumferential surface delineated by an inner circumferential surface of the casing string, wherein the wiper plug is placed to follow the displacement of the cement in the annulus,   a float collar, having an outer circumferential surface delineated by the inner circumferential surface of the casing string, configured to allow the cement to pass downward with respect to a surface, and   a displacement efficiency calibration collar, having an outer circumferential surface delineated by the inner circumferential surface of the casing string, configured to control volume of the cement displaced in the annulus,   wherein the displacement efficiency calibration collar includes a calibration shearing disc.   
     
     
         2 . The system of  claim 1 , wherein the displacement efficiency calibration collar is located above the float collar, at distance equal to 10% of a casing string depth. 
     
     
         3 . The system of  claim 1 , wherein the calibration shearing disc of the displacement efficiency calibration collar is compatible with an outer profile of the wiper plug. 
     
     
         4 . The system of  claim 1 , wherein the calibration shearing disc is compatible with the float collar. 
     
     
         5 . The system of  claim 1 , wherein an outer profile of the displacement efficiency calibration collar is a pup joint. 
     
     
         6 . The system of  claim 1 , wherein the displacement efficiency calibration collar comprises shear pins that break under a predetermined pressure. 
     
     
         7 . The system of  claim 6 , wherein when the shear pins break under pressure exerted by the cement and the wiper plug, the wiper plug latches to the calibration shearing disc and travels to the float collar. 
     
     
         8 . The system of  claim 1 , wherein the wiper plug comprises collapsible fins disposed around a solid core. 
     
     
         9 . The system of  claim 1 , wherein the cement is displaced by pumping drilling fluid on top of the wiper plug. 
     
     
         10 . A method for displacing cement in an annulus of a well, the method comprising:
 providing a casing string having a casing outer circumferential surface that delineates a boundary of the annulus within the casing string, wherein the casing string further comprises a cement displacement control apparatus;   pumping drilling fluid into the casing string until a displacement efficiency calibration collar reaches a predetermined distance from a float collar;   pumping a predetermined volume of the cement into the casing string while running the casing string into the well;   placing a wiper plug into the casing string and displacing the wiper plug, using the drilling fluid, until the wiper plug latches to the displacement efficiency calibration collar;   measuring a number of strokes of the drilling fluid pumped into the casing string needed to achieve latching the wiper plug to the displacement efficiency calibration collar; and   calculating the number of strokes of the drilling fluid pumped into the casing string needed push the wiper plug and the displacement efficiency calibration collar to the float collar.   
     
     
         11 . The method of  claim 10 , wherein measuring the number of strokes is performed manually or automatically. 
     
     
         12 . The method of  claim 10 , wherein calculating the number of strokes pumped into the casing string needed push the wiper plug and the displacement efficiency calibration collar to the float collar is performed by a computer processor based on a formula. 
     
     
         13 . The method of  claim 10 , wherein determining a location the displacement efficiency calibration collar is based on a distance equal to 10% of a casing string depth above the float collar. 
     
     
         14 . The method of  claim 10 , wherein when performing latching of the wiper plug to a calibration shearing disc, the calibration shearing disc is compatible with an outer profile of the wiper plug. 
     
     
         15 . The method of  claim 10 , wherein when performing latching of the displacement efficiency calibration collar to the float collar, an outer profile of the displacement efficiency calibration collar is compatible with an inner profile of the float collar. 
     
     
         16 . The method of  claim 14 , wherein the displacement efficiency calibration collar comprises shear pins that break under a predetermined pressure. 
     
     
         17 . The method of  claim 16 , wherein when performing latching, the shear pins break under pressure exerted by the cement and the wiper plug, the wiper plug latches to the calibration shearing disc and travels to the float collar. 
     
     
         18 . The method of  claim 10 , wherein the cement is displaced by pumping the drilling fluid on top of the wiper plug. 
     
     
         19 . A displacement efficiency calibration collar for displacing cement in an annulus of a well, the displacement efficiency calibration collar comprising:
 a housing that extends horizontally over a casing string, the housing comprising a rounded profile component;   a calibration shearing disc structured to be compatible with a wiper plug, the wiper plug latching to the calibration shearing disc;   an outer profile structured to be compatible with a float collar, the outer profile latching to the float collar,   a plurality of shear pins, coupled to the calibration shearing disc and the outer profile, configured to break when a predetermined pressure is exerted on the plurality of shear pins.   
     
     
         20 . The displacement efficiency calibration collar of  claim 19 , wherein the outer profile of the displacement efficiency calibration collar is a pup joint.