Offshore method

Abstract

The present invention relates to an offshore method for preparing a well for production of hydrocarbon-containing fluids from a wellbore, comprising installation of a drilling rig for drilling at least part of the wellbore, drilling a first part of the wellbore, installation of a surface casing, connecting a drilling blowout preventer with a top of the surface casing, e.g. via a wellhead, i.e. directly or indirectly via a wellhead, drilling a second part of the wellbore, installation of a production casing having a first end part being closest to the top of the surface casing and a second end part, the production casing comprising a plurality of annular barriers, each annular barrier having a tubular metal part mounted as part of the production casing and an expandable metal sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing an inner face of the wellbore of the well, each end of the expandable metal sleeve being connected with the tubular metal part, and an annular space between the inner face of the expandable metal sleeve and the tubular metal part, the expandable metal sleeve being configured to expand, expanding the expandable metal sleeves of the annular barriers in order that the expandable metal sleeves abut the inner face of the wellbore, installation of a plug in the first end part of the production casing sealing off an inside of the production casing, disconnecting the drilling blowout preventer from the top of the surface casing, connecting a production tree with a wellhead, disconnecting the drilling rig from the well, removing the plug and initiating production. The invention also relates to a downhole system derived from the method according to the present invention.

1 . An offshore method for preparing a well for production of hydrocarbon-containing fluids from a wellbore, comprising:
 installation of a drilling rig for drilling at least part of the wellbore,   drilling a first part of the wellbore,   installation of a surface casing,   connecting a drilling blowout preventer with a top of the surface casing, e.g. via a wellhead,   drilling a second part of the wellbore,   installation of a production casing having a first end part being closest to the top of the surface casing and a second end part, the production casing comprising a plurality of annular barriers, each annular barrier having:
 a tubular metal part mounted as part of the production casing, 
 an expandable metal sleeve surrounding the tubular metal part and having an inner face facing the tubular metal part and an outer face facing an inner face of the wellbore of the well, each end of the expandable metal sleeve being connected with the tubular metal part, and 
 an annular space between the inner face of the expandable metal sleeve and the tubular metal part, the expandable metal sleeve being configured to expand, 
   expanding the expandable metal sleeves of the annular barriers in order that the expandable metal sleeves abut the inner face of the wellbore,   installation of a plug in the first end part of the production casing sealing off an inside of the production casing,   disconnecting the drilling blowout preventer from the top of the surface casing,   connecting a production tree with a wellhead,   disconnecting the drilling rig from the well,   removing the plug, and   initiating production.   
     
     
         2 . An offshore method according to  claim 1 , wherein the drilling rig is disconnected after the expandable metal sleeves of the annular barriers have been expanded before production is initiated. 
     
     
         3 . An offshore method according to  claim 1 , further comprising circulating cleaning fluids. 
     
     
         4 . An offshore method according to  claim 1 , wherein the installation of the production casing is performed by means of a drill pipe connected to the first end part of the production casing. 
     
     
         5 . An offshore method according to  claim 1 , wherein the production casing comprises at least one valve arranged between two annular barriers, the valve being closed when disconnecting the drilling rig. 
     
     
         6 . An offshore method according to  claim 1 , further comprising installation of a downhole safety valve which is closed when disconnecting the drilling rig. 
     
     
         7 . An offshore method according to  claim 1 , wherein the production casing below the plug is filled with liquid when disconnecting the drilling rig. 
     
     
         8 . An offshore method according to  claim 1 , wherein the production casing above the plug is filled with liquid when disconnecting the drilling rig. 
     
     
         9 . An offshore method according to  claim 7 , wherein the liquid is sea water. 
     
     
         10 . An offshore method according to  claim 1 , further comprising cementing an annulus between the production casing and an inner face of the wellbore. 
     
     
         11 . An offshore method according to  claim 1 , wherein the installation of the production casing comprises a rotation of the production casing. 
     
     
         12 . An offshore method according to  claim 1 , wherein a cleaning fluid, such as acid, is circulated out of the second end part of the production casing while installing the production casing. 
     
     
         13 . An offshore method according to  claim 1 , further comprising hanging off the production casing in a liner hanger or in a wellhead. 
     
     
         14 . An offshore method according to  claim 1 , wherein the plug is a glass plug. 
     
     
         15 . A downhole system derived from the method according to  claim 1 .