Method for multiple suppression based on phase arrays

• US 20020114218A1
• Filed: 11/16/2001
• Published: 08/22/2002
• Est. Priority Date: 12/20/2000
• Status: Active Grant

• Current Assignee: Exxonmobil Upstream Research Company (Exxon Mobil Corporation)
• Original Assignee: Exxonmobil Upstream Research Company (Exxon Mobil Corporation)
• Inventors: Lee, Paul J., Zhang, Michael M., Angevine, Doug, Heiney, Steve E., Yaung, John V., Ross, Warren S.
• Granted Patent: US 6,606,278 B2
• Time in Patent Office: Days
• US Class Current: 367/140
• CPC Class Codes: G01V 1/38 specially adapted for water-covered areas G01V1/28 takes precedence

Abstract

An apparatus and method for suppressing multiples in the collection of marine seismic data comprises at least one source positioned in the body of water; at least one receiver positioned in the body of water below the air-water interface and near the sources; a bubble diffuser positioned in the body of water so that the bubbles emitted by the bubble diffuser are positioned between the receivers and the air-water interface, wherein the emitted bubbles provide high acoustic reflection and substantially suppress specular reflection of seismic waves; and a control for activating the bubble diffuser during the collection of seismic data by the sources and receivers.

Claims

1_9. ] An apparatus for suppressing multiples in the collection of seismic data in a body of water with an air-water interface, comprising:

at least one source positioned in the body of water;

at least one receiver positioned in the body of water below the air-water interface and near the sources;

a bubble diffuser positioned in the body of water so that the bubbles emitted by the bubble diffuser are positioned between the receivers and the air-water interface, wherein the emitted bubbles provide high acoustic reflection and substantially suppress specular reflection of seismic waves; and

a control for activating the bubble diffuser during the collection of seismic data by the sources and receivers.

2_9. ] The apparatus of claim 1, further comprising:

a support positioned in the body of water below the air-water interface and near the receivers and attached to the bubble diffuser; and

a towing line attached to the support for the bubble diffuser for positioning the emitted bubbles between the receivers and the air-water interface.

3_9. ] The apparatus of claim 1, further comprising:

a compressed air hose for supplying compressed air to the bubble diffuser sufficient to emit bubbles providing high acoustic reflection.

4_9. ] The apparatus of claim 1, wherein the bubble diffuser comprises a plurality of diffuser elements.

5_9. ] The apparatus of claim 4, wherein the diffuser elements are ceramic stone air diffusers.

6_9. ] The apparatus of claim 4, wherein the diffuser elements are porous hose air diffusers.

7_9. ] The apparatus of claim 4, wherein the diffuser elements comprise a plurality of porous hose air diffusers wrapped around the support.

8_9. ] The apparatus of claim 4, wherein the plurality of diffuser elements are positioned in a vertical orientation to increase bubble emission.

9_9. ] The apparatus of claim 4, wherein the plurality of diffuser elements are positioned in a horizontal orientation to increase bubble emission.

10_9. ] The apparatus of claim 9, wherein the plurality of diffuser elements comprise trailing porous air hoses.

11_9. ] The apparatus of claim 4, wherein the bubble diffuser comprises diffuser elements positioned in a vertically oriented phase grating.

12_9. ] The apparatus of claim 11, wherein the phase grating is focussed on a range of distances to the sources and receivers.

13_9. ] The apparatus of claim 11, wherein the diffuser elements of the phase grating are positioned according to a discrete number sequence.

14_9. ] The apparatus of claim 13 wherein the discrete number sequence is a primitive root sequence.

15_9. ] The apparatus of claim 11, wherein the diffuser elements of the phase grating are positioned in a generally concave upward shape.

16_9. ] The apparatus of claim 15, wherein the diffuser elements of the phase grating are positioned substantially in a wedge shape.

17_9. ] A method for suppressing multiples in the collection of seismic data in a body of water with an air-water interface, comprising the steps of:

positioning at least one source and at least one receiver in the body of water, wherein the receivers are positioned below the air-water interface;

positioning a bubble diffuser in the body of water so that the bubbles emitted by the bubble diffuser are positioned between the receivers and the air- water interface, wherein the emitted bubbles provide high acoustic reflection and substantially suppress specular reflection of seismic waves; and

activating the bubble diffuser during the collection of seismic data by the sources and receivers.

18_9. ] The method of claim 17, wherein the emitted bubbles are of sufficiently small size so that the bubbles rise slowly in the body of water.

19_9. ] The apparatus of claim 17, wherein the diffuser elements comprise a plurality of porous hose air diffusers wrapped around the support.

20_9. ] The apparatus of claim 17, wherein the plurality of diffuser elements are positioned in a vertical orientation to increase bubble emission.

21_9. ] The apparatus of claim 17, wherein the plurality of diffuser elements are positioned in a horizontal orientation to increase bubble emission.

22_9. ] The apparatus of claim 21, wherein the plurality of diffuser elements comprise trailing porous air hoses.

23_9. ] The method of claim 17, wherein the bubble diffuser comprises diffuser elements positioned in a vertically oriented phase grating.

24_9. ] The method of claim 23, wherein the phase grating is focussed on a range of distances to the sources and receivers.

25_9. ] The method of claim 23, wherein the diffuser elements of the phase grating are positioned according to a discrete number sequence.

26_9. ] The method of claim 25 wherein the discrete number sequence is a primitive root sequence.

27_9. ] The method of claim 23, wherein the diffuser elements of the phase grating are positioned in a generally concave upward shape.

28_9. ] The method of claim 27, wherein the diffuser elements of the phase grating are positioned substantially in a wedge shape.