OFFSHORE METHOD
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.
The present invention relates to an offshore method for preparing a well for production of hydrocarbon-containing fluids from a wellbore. The invention also relates to a downhole system derived from the method according to the present invention.
The Deepwater Horizon oil spill, also referred to as the oil spill in the Gulf of Mexico or the Macondo blowout, is an oil spill which flowed unabated for three months in 2010. This blowout is considered one of the largest accidental marine oil spills in the history of the petroleum industry, and the spill stemmed from a sea-floor oil gush which was a result of the 20 Apr. 2010 explosion of the Deepwater Horizon rig which drilled on the Macondo Prospect. It is believed that one of the primary reasons for the cause of the blowout was a defective cement job during completion of the well. Cement is used to seal between a first tubular and a borehole wall and between the first tubular and the next tubular. The cement is injected, and for some reason, the cement settles in the intended space. During this process, unwanted pockets are formed in the cement, or the cement disappears in an unexpected fracture in the formation. If the cement does not sufficiently fill the annular space, e.g. between the first tubular and the borehole wall, the oil may leak during production and gush through the cement or along the tubular, and an oil spill disaster may be a consequence of this.
After the Macondo blowout, ensuring well integrity has been an increased focus of governments around the world, and thus also of the oil industry. To this effect, the downhole barrier systems incorporated in the well completion designs have been brought into focus to improve the well integrity.
Due to the low price on an oil barrel, the recent focus has been on costs and how the wells can be completed at a lower cost, in order that the oil production can give return on investment at an earlier stage.
It is an object of the present invention to wholly or partly overcome the above disadvantages and drawbacks of the prior art. More specifically, it is an object to provide an improved offshore method providing a less expensive way of drilling and completing a well without jeopardising the safety and thus still ensuring well integrity.
The above objects, together with numerous other objects, advantages and features, which will become evident from the below description, are accomplished by a solution in accordance with the present invention by an offshore method for preparing a well for production of hydrocarbon-containing fluids from a wellbore, comprising:
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- 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, 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.
In known completion methods, the drilling rig is maintained on top of the well until production or at least early production is initiated. By installing the plug after the annular barriers have been expanded, the drilling can be disconnected earlier than in known solutions saving a lot of rig time and thereby minimising costs when making new wells. After the plug is installed, the BOP (blow-out preventer) is disconnected and the production tree or Christmas tree is connected, and then the drilling rig is disconnected. Then, the production testing or production is initiated without having the drilling rig.
Furthermore, the drilling rig may be disconnected after the expandable metal sleeves of the annular barriers have been expanded before production is initiated.
The offshore method as described above may further comprise circulating cleaning fluids.
The offshore method as described above may further comprise circulating cleaning fluids before expansion of the expandable metal sleeves of the annular barriers for cleaning the wellbore from drilling mud.
Also, the installation of the production casing may be performed by means of a drill pipe connected to the first end part of the production casing.
Moreover, the production casing may comprise at least one valve arranged between two annular barriers, the valve being closed when disconnecting the drilling rig.
In addition, the production casing may comprise at least one valve arranged between two annular barriers, the valve being closed when disconnecting the drilling rig, providing a well integrity barrier.
The offshore method as described above may further comprise installation of a downhole safety valve which is closed when disconnecting the drilling rig.
Moreover, the offshore method as described above may further comprise installation of a downhole safety valve which is closed when disconnecting the drilling rig, providing a well integrity barrier.
Additionally, the production casing below the plug may be filled with liquid when disconnecting the drilling rig.
Furthermore, the production casing below the plug may be filled with liquid when disconnecting the drilling rig, providing a well integrity barrier.
Also, the production casing above the plug may be filled with liquid when disconnecting the drilling rig.
Also, the production casing above the plug may be filled with liquid when disconnecting the drilling rig, providing a well integrity barrier.
The liquid may be sea water or brine.
The offshore method as described above may further comprise cementing an annulus between the production casing and an inner face of the wellbore.
Moreover, the installation of the production casing may comprise a rotation of the production casing.
In addition, cleaning fluid, such as acid, may be circulated out of the second end part of the production casing while installing the production casing.
Further, cleaning fluid, such as acid, may be circulated out of the second end part of the production casing while installing the production casing for cleaning the wellbore from drilling mud.
A dart may be circulated to the second end of the production casing, landing and closing the second end part before expansion of the expandable metal sleeves of the annular barriers.
The offshore method as described above may further comprise hanging off the production casing in a liner hanger or in a wellhead.
Also, the production casing may have a receptacle at the first end.
Furthermore, the production casing may comprise gas lift valves.
Moreover, the liquid above the plug may be brine.
The plug may be a glass plug.
Finally, the present invention also relates to a downhole system derived from the offshore method as described above.
The invention and its many advantages will be described in more detail below with reference to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments and in which:
All the figures are highly schematic and not necessarily to scale, and they show only those parts which are necessary in order to elucidate the invention, other parts being omitted or merely suggested.
In
Then, a production casing 10 is installed, as shown in
The expandable metal sleeve 22 is configured to expand, e.g. by pressurised fluid from within the production casing 10, as shown in
In
In
When having the plug installed, the wellbore is sealed off, and the drilling blowout preventer can safely be disconnected from the top 8 of the surface casing 6, as shown in
After disconnecting the drilling blowout preventer and the drilling rig 4 and after connecting the production tree 19, the plug is removed and production of hydrocarbon-containing fluid is initiated, e.g. early production or straight to production, as shown in
Before expanding the expandable metal sleeves of the annular barriers, cleaning fluid, such as acid, is circulated out of the second end 12 of the production casing 10, e.g. while installing the production casing, to clean the wellbore from drilling mud. When inserting the production casing, a rotation of the production casing may be performed to ease the insertion of the production casing into the wellbore. The plug may be a glass plug or a similar plug.
In
The liquid below or above the plug may be sea water or well fluid, and the liquid may also be brine so that the liquid can always be circulated if needed before production.
The offshore method as described in relation to describing the above figures may also comprise cementing an annulus 55 between the production casing and an inner face of the wellbore, as shown in
The valves of the production casing 10 may be opened e.g. by applying acid to dissolve an acid-dissolvable plug or they may be opened by an intervention tool, such as a key tool engaging e.g. grooves in a sliding sleeve.
By well fluid is meant any kind of fluid that may be present in oil or gas wells downhole, such as natural gas, oil, oil mud, crude oil, water etc. By gas is meant any kind of gas composition present in a well, completion or open hole, and by oil is meant any kind of oil composition, such as crude oil, an oil-containing fluid etc. Gas, oil and water fluids may thus all comprise other elements or substances than gas, oil and/or water, respectively.
By an annular barrier is meant an annular barrier comprising a tubular metal part mounted as part of the well tubular metal structure and an expandable metal sleeve surrounding and connected to the tubular part defining an annular barrier space.
By a production casing, intermediate casing, surface casing or well tubular metal structure is meant any kind of pipe, tubing, tubular, liner, string etc. used downhole in relation to oil or natural gas production.
In the event that the tool is not submergible all the way into the casing, a downhole tractor can be used to push the tool all the way into position in the well. The downhole tractor may have projectable arms having wheels, wherein the wheels contact the inner surface of the casing for propelling the tractor and the tool forwards in the casing. A downhole tractor is any kind of driving tool capable of pushing or pulling tools in a well downhole, such as a Well Tractor®.
Although the invention has been described in the above in connection with preferred embodiments of the invention, it will be evident for a person skilled in the art that several modifications are conceivable without departing from the invention as defined by the following claims.
Claims
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.
Type: Application
Filed: Mar 5, 2019
Publication Date: Sep 12, 2019
Inventor: Christian KRÜGER (Allerød)
Application Number: 16/292,516