Volumetric piezoelectric seismic wave source and related methods

• US 8,973,702 B2
• Filed: 08/21/2013
• Issued: 03/10/2015
• Est. Priority Date: 09/26/2012
• Status: Active Grant

• Current Assignee: Cgg Services Sa (CGG)
• Original Assignee: Cgg Services Sa (CGG)
• Inventors: Gresillon, Francois-Xavier
• Primary Examiner(s): San Martin, Edgardo
• Application Number:
  US13/972,183
• Publication Number:
  US 20140086012A1
• Time in Patent Office: 566 Days
• Field of Search: 181/104, 181/106, 181/111, 367/189, 367/159, 367/157
• US Class Current: 181/104
• CPC Class Codes: G01V 1/159 using piezoelectric or magnetostrictive driving means generating mechanical vibrations by using piezoelectric or magnetostrictive effect in general, B06B1/06, B06B1/08
• CPC Class Codes: G01V 1/40 specially adapted for well-logging

Abstract

Seismic wave sources and related methods are provided. A seismic wave source includes a housing, plural pillars and an excitation system. The housing is split in two halves along a plane including a longitudinal axis of the housing. The plural pillars are made of piezoelectric elements and are positioned inside the housing to have one end in contact with a semi-cylindrical middle portion of one half of the housing and another end in contact with a semi-cylindrical middle portion of the other half of the housing. The excitation system connected by wires to the plural pillars and is configured to provide electrical signals to the piezoelectric elements. Upon receiving the electrical signals from the excitation system, the pillars generate forces on the housing thereby generating seismic waves.

Claims

1. A seismic wave source for generating seismic waves, comprising:

a housing split in two halves along a plane including a longitudinal axis of the housing, wherein one of the two halves is separated along the entire longitudinal axis from another one of the two halves by a predetermined distance so that ends of the two halves move one relative to another;

plural pillars made of piezoelectric elements and positioned inside the housing to have one end in contact with a semi-cylindrical middle portion of one of the two halves of the housing and another end in contact with a semi-cylindrical middle portion of the other one of the two halves of the housing; and

an excitation system connected by wires to the plural pillars and configured to provide electrical signals to the piezoelectric elements,

wherein upon receiving the electrical signals from the excitation system, the pillars generate forces on the housing thereby generating the seismic waves.

2. The source of claim 1, wherein each of the pillars is made of a sequence of piezoelectric elements and electrodes.

3. The source of claim 2, wherein the piezoelectric elements have substantially the same shape.

4. The source of claim 3, wherein the shape of the piezoelectric elements is one of a disk, a ring or a rectangle.

5. The source of claim 1, wherein a volume inside the housing is filled with polyurethane.

6. The source of claim 1, wherein the pillars are arranged at substantially equal distances along the longitudinal axis.

7. The source of claim 1, wherein elongation axes of at least two of the pillars have an angular offset there-between in a plane perpendicular to the longitudinal axis.

8. The source of claim 1, wherein the excitation system generates signals having a predetermined frequency.

9. The source of claim 1, wherein the excitation system generates signals sweeping a predetermined range of frequencies.

10. The source of claim 1, wherein the excitation system generates trains of signals at predetermined time intervals.

11. The source of claim 1, wherein the housing has at least one end tapering off along the longitudinal axis into a conical shape.

12. A method for generating seismic waves in a formation, the method comprising:

placing a seismic wave source inside a hole drilled in the formation, the source including (A) a housing split in two halves along a plane including a longitudinal axis of the housing, wherein one of the two halves is separated along the entire longitudinal axis from another one of the two halves by a predetermined distance so that ends of the two halves move one relative to another, (B) plural pillars made of piezoelectric elements and positioned inside the housing to have one end in contact with a semi-cylindrical middle portion of one of the two halves of the housing and another end in contact with a semi-cylindrical middle portion of the other one of the two halves of the housing, and (C) an excitation system connected by wires to the pillars and configured to provide electrical signals to the piezoelectric elements, wherein the longitudinal axis of the housing is substantially parallel to a drilling direction of the hole;

filling a volume around the housing with a coupling material; and

providing electrical signals to the piezoelectric elements, wherein upon receiving the electrical signals from the excitation system, the pillars generate forces on the housing thereby generating the seismic waves.

13. The method of claim 12, wherein the coupling material is cement.

14. The method of claim 12, wherein the piezoelectric elements have substantially the same shape which is one of a disk, a ring or a rectangle.

15. The method of claim 12, wherein a volume inside the housing is filled with polyurethane.

16. The method of claim 12, wherein elongation axes of at least two of the pillars have an angular offset there-between in a plane perpendicular to the longitudinal axis.

17. The method of claim 12, wherein the excitation system generates a signal having a predetermined frequency or sweeping a predetermined range of frequencies, or generates trains of signals at predetermined time intervals.

18. The method of claim 12, wherein the housing has at least one end tapering off along the longitudinal axis into a conical shape.

19. The method of claim 12, further comprising:

placing a plurality of seismic wave detectors at various positions relative to the source;

acquiring reflections of seismic waves in the plurality of seismic wave detectors; and

extracting information about structure of the formation based on the acquired reflections.

20. A seismic wave source configured to be inserted in a well comprises:

a housing split in two halves along a plane including a longitudinal axis of the housing, wherein one of the two halves is separated along the entire longitudinal axis from another one of the two halves by a predetermined distance so that ends of the two halves move one relativet to another; and

a plurality of piezoelectric elements arranged at multiple locations along an insertion direction to generate forces in a plane substantially perpendicular to the insertion direction.