Apparatus for receiving and transmitting signals in electromagnetic telemetry system used in a wellbore
AssigneeSchlumberger Technology Corporation
InventorsMatthe Contant, Erwann Lemenager, Yves Mathieu, Juergen Zach
Life of this patent
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Abstract
A downhole electromagnetic telemetry unit for use with a tubing string (5) includes an insulated electrically conductive member (31) and a processing unit (15). The insulated electrically conductive member (31) is electrically coupled to the tubing string (5) at an upper measuring point (23) and a lower measuring point (25). The processing unit (15) is configured to process a voltage difference measured between the upper measuring point (23) and the lower measuring point (25) across the insulated electrically conductive member (31) and to derive therefrom a signal transmitted from a surface location (13).
Claims13
A downhole electromagnetic telemetry unit for use with a tubing string, the downhole electromagnetic telemetry unit comprising:
- an insulated electrically conductive member electrically coupled to the tubing string at an upper measuring point and a lower measuring point;
- and
- a processing unit configured to process a voltage difference measured between the upper measuring point and the lower measuring point across the insulated electrically conductive member and to derive therefrom a signal transmitted from a surface location.
A system for communicating signals between a surface and a downhole electromagnetic telemetry unit in a wellbore having a casing and a tubing string disposed in the casing, the system comprising:
- the downhole electromagnetic telemetry unit comprising:
- an insulated electrically conductive member electrically coupled to the tubing string at an upper measuring point and a lower measuring point;
- and
- a processing unit configured to transmit a signal by applying a voltage difference between the upper measuring point and the lower measuring point across the insulated electrically conductive member;
- an electrically conductive ground member located at a distance from a wellhead disposed above the wellbore;
- and
- a surface processing unit configured to process a voltage difference measured between the wellhead and the electrically conductive ground member and to derive therefrom the signal transmitted from the downhole electromagnetic telemetry unit.
A downhole electromagnetic telemetry unit for use with a tubing string, the downhole electromagnetic telemetry unit comprising:
- an insulated electrically conductive member electrically coupled to the tubing string at an upper measuring point and a lower measuring point;
- and
- a processing unit configured to transmit a signal by applying a voltage difference between the upper measuring point and the lower measuring point across the insulated electrically conductive member.
A method of transmitting a signal between a surface and a downhole tool in a wellbore, the wellbore including a casing and a tubing string disposed in the casing, the method comprising the steps of:
- applying a modulated voltage carrying the transmitted signal from the surface between a surface location and the casing using an electrically conductive ground member located at the surface location at a distance from the casing;
- detecting a voltage difference using an electrically conductive member disposed between at least two measuring points on the tubing;
- and
- processing the detected voltage difference to obtain the transmitted signal.
A method of transmitting a signal between a downhole tool in a wellbore and a surface, the wellbore including a casing and a tubing string disposed in the casing, the method comprising the steps of:
- applying a modulated current carrying the transmitted signal from the downhole tool to an electrically conductive member disposed between at least two measuring points on the tubing;
- detecting a voltage difference between the casing and a surface location at a distance from the casing;
- and
- processing the detected voltage difference to obtain the transmitted signal from the downhole tool.
Dependencies are inferred from the claim text.