Method and device to acquire seismic data
View Patent ↗Streamer and method for deploying the streamer for seismic data acquisition related to a subsurface of a body of water. The method includes a step of releasing into the body of water, from a vessel, a body having a predetermined length together with plural detectors provided along the body; a step of towing the body and the plural detectors such that the plural detectors are submerged; and a step of configuring plural birds provided along the body, to float at a predetermined depth from a surface of the water such that a first portion of the body has a curved profile while being towed underwater.
1. A streamer for collecting seismic data related to a subsurface of a body of water, the streamer comprising:
a body having first and second portions;
plural detectors provided along the body; and
plural birds distributed along the first portion of the body,
wherein the plural birds are configured to position the body, when deployed under water, at predetermined depths from a surface of the water to impart to the first portion of the body a predetermined, variable-depth profile while being towed underwater.
2. The streamer of claim 1 , wherein the variable-depth profile is one of a parabola, a circle or a hyperbola.
3. The streamer of claim 1 , wherein the plural birds are also distributed along the second portion to achieve a flat profile of the second portion.
4. The streamer of claim 1 , wherein the non-linear, variable-depth profile is parameterized and described by z(h), which is a depth of a point of the first portion relative to the surface of the water, and satisfies the following equation:
z
(
h
)
=
z
0
+
s
0
h
(
1
-
0.5
(
h
h
c
)
)
for
h
≤
h
c
,
where h is a horizontal distance between the point and a first detector provided on the body, z 0 is a depth of the first detector relative to the surface of the water, s 0 is a non-zero slope of the body at the first detector of the streamer, and h c is a predetermined horizontal distance between the first detector and an end of the non-linear, variable-depth profile.
5. The streamer of claim 4 , wherein the second portion is described by equation z(h)=z 0 +s 0 ·0.5·h c for h>h c .
6. The streamer of claim 4 , wherein a projection of the entire body on a line substantially parallel to the surface of the water is less than h c .
7. The streamer of claim 1 , wherein the non-linear, variable-depth profile stays substantially the same during the towing.
8. The streamer of claim 1 , wherein the plural detectors include hydrophones and accelerometers.
9. A method for seismic data acquisition related to a subsurface of a body of water, the method comprising:
towing a body having plural detectors distributed along the body;
configuring plural birds along a first portion of the body, to position the body at predetermined depths from a surface of the water to impart to the first portion of the body a predetermined, variable-depth profile while being towed underwater; and
recording with the plural detectors the seismic data while towing the body.
10. The method of claim 9 , wherein the profile is a parabola, a circle or a hyperbola.
11. The method of claim 9 , wherein a second portion of the streamer has a flat profile and is connected to the first portion.
12. The method of claim 9 , wherein the non-linear, parameterized, variable-depth profile is described by z(h), which is a depth of a point of the first portion relative to the surface of the water, and satisfies the following equation:
z
(
h
)
=
z
0
+
s
0
h
(
1
-
0.5
(
h
h
c
)
)
for
h
≤
h
c
,
where h is a horizontal distance between the point and a first detector provided on the body, z 0 is a depth of the first detector relative to the surface of the water, s 0 is a non-zero slope of the body at the first detector of the streamer, and h c is a predetermined horizontal distance between the first detector and an end of the non-linear, variable-depth profile.
13. The method of claim 12 , further comprising:
towing a second portion, connected to the first portion, the second portion being described by equation z(h)=z 0 +s 0 ·0.5·h c for h>h c .
14. The method of claim 9 , wherein the plural detectors include hydrophones and accelerometers.
15. A method for processing seismic data acquired with a variable-depth profile streamer, the method comprising:
towing a body having plural seismic detectors;
configuring plural birds along a first portion of the body, to position the body at predetermined depths from a surface of the water, to impart to the first portion of the body a predetermined, variable-depth profile while being towed underwater;
recording with the plural seismic detectors seismic data generated by a seismic source while towing the body; and
processing the seismic data to generate an image of a surveyed subsurface.
16. The method of claim 15 , wherein the variable-depth profile is one of a parabola, a circle or a hyperbola.
17. The method of claim 15 , wherein the plural birds are also distributed along a second portion of the body to achieve a flat profile for the second portion.
18. The method of claim 15 , wherein the non-linear, variable-depth profile is parameterized and described by z(h), which is a depth of a point of the first portion relative to the surface of the water, and satisfies the following equation:
z
(
h
)
=
z
0
+
s
0
h
(
1
-
0.5
(
h
h
c
)
)
for
h
≤
h
c
,
where h is a horizontal distance between the point and a first detector provided on the body, z 0 is a depth of the first detector relative to the surface of the water, s 0 is a non-zero slope of the body at the first detector of the streamer, and h c is a predetermined horizontal distance between the first detector and an end of the non-linear, variable-depth profile.
19. The method of claim 18 , wherein a second portion attached to the first portion is described by equation z(h)=z 0 +s 0 ·0.5·h c for h>h c .
20. The method of claim 15 , wherein the plural detectors include hydrophones and accelerometers.