Method and apparatus for installing casing in a borehole

Abstract

An apparatus and method for installing casing into a wellbore is provided. The apparatus includes a piston assembly which is engagable with a casing string to be installed into a wellbore. The piston assembly works in conjunction with a previously installed section of casing in the wellbore to create a hydraulic piston system to aid in the installation of the casing string to which the piston assembly is attached into a wellbore. More particularly, the piston assembly in conjunction with an intermediate casing is used to aid in the installation of a casing string comprising production casing. A method of operating the piston assembly is also provided.

1 . A method of running in casing into a borehole having a previously installed section of casing is provided, the method including the steps of: 
 (i) providing a piston assembly;    (ii) engaging the piston assembly with a casing string to be installed into the borehole;    (iii) inserting the casing string with the engaged piston assembly into the previously installed section of casing; and    (iv) pressurizing the previously installed section of casing above the piston assembly with a fluid such that the piston assembly engaged with the casing string is forced to translate within the previously installed section of casing causing the casing string to be pressed into the borehole.    
   
   
       2 . The method as recited in  claim 1 , further comprising the steps of: 
 (v) equalizing pressure across said piston assembly; and    (vi) backing off said piston assembly from the casing string.    
   
   
       3 . The method as recited in  claim 2 , wherein said fluid is drilling fluid.  
   
   
       4 . The method as recited in  claim 2 , said piston assembly includes: 
 a piston body having a forward end including an adaptor sub and an opposite rearward end, the piston body defining a longitudinal bore formed axially therethrough;    a mandrill, said mandrill is slidably received within said longitudinal bore through said rearward end and is slidable within said longitudinal bore to a first forward position and to a second rearward position;    said piston body having a radial shoulder surface of a diameter to correspond to an interior diameter of the previously installed casing, such that when said piston body is positioned within the previously installed casing a sealing contact is made between said radial shoulder surface of the piston body and the interior surface of the previously installed casing; and    said piston body further defining at least one blind port hole formed therethrough from an exterior surface forward of said radial shoulder surface to said longitudinal bore, and defining at least one annulus port hole formed therethrough from an exterior surface rearward of said radial shoulder surface to the longitudinal bore.    
   
   
       5 . The method as recited in  claim 4 , wherein during said step (v) equalizing pressure across said piston assembly, said mandrill is moved from said first forward position to said rearward position establishing fluid communication between said blind port hole and said annulus port hole.  
   
   
       6 . The method as recited in  claim 1 , wherein said casing string includes at least one centralizer engaged therewith.  
   
   
       7 . The method as recited in  claim 1 , wherein said casing string is a production casing string.  
   
   
       8 . An apparatus for running in a casing string into a borehole having a previously installed section of casing is provided, the apparatus comprising: 
 a piston body having a forward end including an adaptor sub and an opposite rearward end, the piston body defining a longitudinal bore formed axially therethrough;    a mandrill, said mandrill is slidably received within said longitudinal bore through said rearward end and is slidable within said longitudinal bore to a first forward position and to a second rearward position;    said piston body having a radial shoulder surface of a diameter to correspond to an interior diameter of the previously installed casing, such that when said piston body is positioned within the previously installed casing a sealing contact is made between said radial shoulder surface of the piston body and the interior surface of the previously installed casing; and    said piston body further defining at least one blind port hole formed therethrough from an exterior surface forward of said radial shoulder surface to said longitudinal bore, and defining at least one annulus port hole formed therethrough from an exterior surface rearward of said radial shoulder surface to the longitudinal bore.    
   
   
       9 . The apparatus of  claim 8 , wherein said radial shoulder surface includes a wear surface and a radial seal.  
   
   
       10 . The apparatus of  claim 9 , wherein said longitudinal bore defines a threaded section approximate said forward end of said piston body and further wherein said mandrill includes a threaded forward end which is adapted to be threadably engaged with said threaded section.  
   
   
       11 . The apparatus of  claim 10 , further comprising: 
 at one least projection extending into said longitudinal bore approximate said rearward end of said piston body, said at least one projection is adapted to be received by a cooperating slot formed longitudinally along an exterior surface of said mandrill.    
   
   
       12 . The apparatus of  claim 11 , wherein said cooperating slot is formed along said exterior surface of said mandrill such that when said mandrill is positioned in the first forward position the projection is free from engagement with said slot and such that when said mandrill is positioned in the second rearward position said projection is engaged with said slot.  
   
   
       13 . The apparatus of  claim 8 , further comprising: 
 a one-way valve positioned within a channel that is formed longitudinal through said radial shoulder.    
   
   
       14 . The apparatus of  claim 8 , further comprising: 
 at least one o-ring seal positioned in said longitudinal bore to provide sealing contact between said mandrill and the sidewall of said longitudinal bore.    
   
   
       15 . An apparatus for use in running in production casing in a borehole having an intermediate casing already installed therein, the apparatus being adapted to be engaged inline with a production casing string comprising, the apparatus comprising: 
 a piston body having a forward end and an opposite rearward end, the piston body defining a longitudinal bore formed axially therethrough;    an adapter sub threadably received by said forward end of said piston body;    a mandrill having a first end and an second end, said mandrill is slidably received within said longitudinal bore through said rearward end of said piston body, and is slidable within said longitudinal bore to a first forward position and a second rearward position, said first end of said mandrill is adapted to be threadably coupled to said adapter sub when said mandrill is in the first forward position;    said piston body having a radial shoulder of a diameter corresponding to an interior diameter of the intermediate casing, such that when said piston body is positioned within the intermediate casing a sealing contact is made between said radial shoulder surface of said piston body and the interior surface of the intermediate casing;    said piston body further defining at least one blind port hole formed therethrough from an exterior surface forward said radial shoulder surface to said longitudinal bore, and defining at least one annulus port hole formed therethrough from an exterior surface rearward of said radial shoulder surface to said longitudinal bore; and wherein fluid communication is established between said at least one blind port hole and said at least one annulus port hole when said mandrill is positioned in said second rearward position.    
   
   
       16 . The apparatus of  claim 15 , further comprising: 
 at least one projection extending inward into said longitudinal bore approximate said rearward end and which is adapted to be received by a cooperating slot formed longitudinally along an exterior surface of said mandrill.    
   
   
       17 . The apparatus of  claim 16 , wherein said cooperating slot is formed along said exterior surface of said mandrill such that when said mandrill is positioned in the first forward position the projection is free from engagement with said slot and such that when said mandrill is positioned in the second rearward position said projection is engaged with said slot.  
   
   
       18 . The apparatus of  claim 17 , further comprising: 
 at least one o-ring seal positioned in said longitudinal bore to provide sealing contact between said mandrill and a sidewall of said longitudinal bore.    
   
   
       19 . The apparatus of  claim 18 , further comprising: 
 a one-way valve positioned within a channel that is formed longitudinal through said radial shoulder.    
   
   
       20 . The apparatus of  claim 15 , wherein said radial shoulder includes: 
 a wear surface; and    a sealing member.