Electrically isolated streamer section

Patent metadata

Field	Value
Publication number	US-2016109609-A1
Application number	US-201514594389-A
Country	US
Kind code	A1
Filing date	Jan 12, 2015
Priority date	Oct 17, 2014
Publication date	Apr 21, 2016
Grant date	—

Abstract

Aspects described herein provide for a sensor assembly having an electrically isolated cable segment that may be used for geophysical prospecting. The sensor assembly generally includes a first cable segment comprising at least one electromagnetic (EM) sensor, and a second cable segment connected to the first cable segment and electrically isolated from the first cable segment. The second cable segment may be free of electrically conductive components. Alternatively, the second cable segment may have electrically conductive components that are not electrically connected to the first cable segment. The electrically isolated cable segment may reduce or eliminate undesired signal cross-feed from the EM source to the first cable segment, which may aid in maintaining data quality.

First claim

What is claimed is:

1 . An apparatus for marine geophysical surveying, comprising:
a first cable segment comprising at least one electromagnetic (EM) sensor; and a second cable segment connected to the first cable segment and electrically isolated from the first cable segment.

2 . The apparatus of claim 1 , wherein the second cable segment is free of electrically conductive components.

3 . The apparatus of claim 1 , wherein the second cable segment comprises at least one electrically conductive component.

4 . The apparatus of claim 1 , wherein the second cable segment comprises at least one electrically conductive component, wherein the at least one electrically conductive component is not electrically connected to the at least one EM sensor.

5 . The apparatus of claim 1 , wherein the second cable segment is couplable to geophysical surveying equipment of a survey vessel.

6 . The apparatus of claim 5 , wherein the apparatus further comprises a cable termination coupled to an EM field source cable, wherein the cable termination is coupleable to the survey vessel, and wherein a length of the second cable segment is equal to or greater than a length of the EM field source cable.

7 . The apparatus of claim 1 , wherein the first cable segment further comprises at least one seismic sensor.

8 . The apparatus of claim 1 , wherein the second cable segment comprises at least one optical waveguide that optically couples the second cable segment to the first cable segment.

9 . The apparatus of claim 8 , wherein the second cable segment is coupled to an energy source to transfer energy optically to the first cable segment via the at least one optical waveguide.

10 . The apparatus of claim 1 , wherein the first cable segment comprises at least one data storage unit communicatively coupled with the at least one EM sensor.

11 . The apparatus of claim 1 , wherein the first cable segment further comprises a power supply.

12 . The apparatus of claim 11 , wherein the power supply comprises a battery, and wherein the first cable segment further comprises an electronic component coupled to the battery.

13 . The apparatus of claim 11 , wherein the power supply comprises a power harvester and a transducer, wherein the first cable segment further comprises an electronic component, and wherein the transducer couples the power harvester to the electronic component.

14 . The apparatus of claim 13 , wherein the power harvester comprises at least one of: a hydrodynamic generator, a solar power generator, a wind power generator, a vibration power generator.

15 . The apparatus of claim 13 , wherein the power harvester comprises a hydrodynamic generator comprising at least one propeller.

16 . The apparatus of claim 1 , wherein a density of the first cable segment is equal to a density of the second cable segment.

17 . The apparatus of claim 1 , wherein the second cable segment comprises an EM field source.

18 . A marine geophysical survey system, comprising:
a vessel; an electromagnetic (EM) field source cable operable to be disposed in a body of water and coupled to the vessel, wherein the EM field source cable comprises an EM field source that is operable to emit an EM field; a sensor assembly operable to be disposed in the body of water and coupled to the vessel, wherein the sensor assembly comprises:
a first cable segment comprising at least one sensor; and
a second cable segment connected to the first cable segment and electrically isolated from the first cable segment.

19 . The marine geophysical survey system of claim 18 , wherein a length of the second cable segment is equal to or greater than a length of the EM field source cable.

20 . The marine geophysical survey system of claim 19 , wherein the sensor assembly is operable to be disposed in the body of water below and parallel to the EM field source cable, and wherein, when the sensor assembly and EM field source cable are disposed in the body of water, at least a portion of the length of the second cable segment is radially adjacent to the EM field source cable.

21 . The marine geophysical survey system of claim 18 , wherein the sensor assembly is operable to be disposed in the body of water parallel to the EM field source cable, and wherein, when the sensor assembly and the EM field source cable are disposed in the body of water, the second cable segment and the first cable segment are not radially adjacent to the EM field source cable and the second cable segment is between the EM field source cable and the first cable segment.

22 . A method for performing a marine geophysical survey, comprising:
disposing an electromagnetic (EM) field source cable in a body of water, wherein the EM field source cable comprises an EM source that generates an EM field; disposing a sensor assembly in the body of water, wherein the sensor assembly comprises a first cable segment having at least one EM sensor and a second cable segment connected to the first cable segment and electrically isolated from the first cable segment; and measuring the EM field with the at least one EM sensor.

Assignees

• Pgs Geophysical As

Inventors

• Björnemo Lars Erik Magnus
• Lindqvist Ulf Peter

Classifications

• G01V3/02

  operating with propagation of electric current · CPC title

• G01V3/165 Primary

  operating with magnetic or electric fields produced or modified by the object or by the detecting device (with electromagnetic waves G01V3/17) · CPC title

• G01V3/083 Primary

  Controlled source electromagnetic [CSEM] surveying · CPC title