Annular barrier with an expansion detection device

1. An annular barrier to be expanded in an annulus between a well tubular structure and an inside wall of a borehole downhole, comprising:

a tubular part for mounting as part of the well tubular structure, said tubular part having a longitudinal axis,

an inflatable, expandable sleeve surrounding the tubular part and having an outer face positioned to contact the inside wall, the expandable sleeve being of metallic construction and the outer face having no apertures, each end of the expandable sleeve being fastened to the tubular part by means of a connection part, where at least one of the connection parts is a sliding connection part sliding in relation to the tubular part when the expandable sleeve is expanded,

an annular barrier space between the tubular part and the expandable sleeve,

an aperture in the tubular part for letting fluid into the annular barrier space to expand the sleeve, and

an activatable shut-off valve having an open and a closed position and arranged in the aperture, wherein the annular barrier further comprises a detection device for detecting when the expandable sleeve has been expanded into a contact position in which the outer face of the sleeve contacts the inside wall, and wherein the detection device is adapted to provide a signal to activate the shut-off valve to bring the shut-off valve from the open to the closed position when detecting that the expandable sleeve is in the contact position.

2. An annular barrier according to claim 1 , wherein the detection device comprises a movement sensor for detecting movement of the sliding connection part, and wherein the detection device is adapted to provide a signal to activate the shut-off valve to bring the shut-off valve from the open to the closed position when the movement sensor detects that the sliding connection part has stopped.

3. An annular barrier according to claim 2 , wherein the movement sensor comprises a linear potentiometer for detecting a change in the position of the sliding connection part.

4. An annular barrier according to claim 1 , wherein the detection device comprises an expansion sensor for detecting a material expansion of the expandable sleeve, wherein the detection device is adapted to provide a signal to activate the shut-off valve to bring the shut-off valve from the open to the closed position when the expansion sensor detects that the material expansion of the expandable sleeve has stopped.

5. An annular barrier according to claim 4 , wherein the expansion sensor comprises a strain gauge for detecting expansion of the material of the expandable sleeve.

6. An annular barrier according to claim 2 , wherein the movement sensor is a magnet sensor, an accelerometer, an infrared sensor, a variable reluctance sensor or an inductive magnetic sensor for detecting movement of the sliding connection part.

7. An annular barrier according to claim 1 , wherein the activatable shut-off valve is a solenoid valve adapted to block the flow of fluid into the annular barrier space when power to the soleniod valve is discontinued.

8. An annular barrier according to claim 1 , wherein the detection device comprises a contact pressure sensor provided at the outer surface of the expandable sleeve, the pressure sensor being adapted to measure a contact force between the outer surface of the expandable sleeve and an inner wall of the borehole.

9. An annular barrier according to claim 1 , wherein the detection device comprises a fluid pressure sensor for measuring the fluid pressure inside the annular barrier space.

10. An annular barrier according to claim 1 , wherein the detection device further comprises a distance sensor for measuring a change in a maximum inner diameter of the expandable sleeve.

11. A downhole system comprising a plurality of annular barriers according to claim 1 .

12. A method for expanding an annular barrier according to claim 1 , comprising the steps of:

positioning the annular barrier downhole as part of a well tubular structure,

pressurising the tubular structure from within to expand the expandable sleeve of the annular barrier, and

detecting when the expandable sleeve has been expanded into a contact position.

13. A method according to claim 12 , further comprising the step of activating the shut-off valve to block the flow of fluid into the annular barrier space when the expandable sleeve has been expanded into a contact position.

14. A method according to claim 12 , wherein a contact pressure between the outer surface of the expandable sleeve and the inner wall of the borehole is measured to detect when the expandable sleeve has been expanded into a contact position.

15. A method according to claim 14 , wherein the shut-off valve is activated when the contact pressure between the outer surface of the expandable sleeve and the inner wall of the borehole is in the range of 1,000 psi-2,000 psi.