Patent Application
20200393584
Techniques for marine surveying include marine seismic surveying, in which geophysical data may be collected from below the Earth's surface. Marine seismic surveying has applications in mineral and energy exploration and production to help identify locations of hydrocarbon-bearing formations. Marine seismic surveying typically may include towing a seismic source below or near the surface of a body of water. One or more streamers may also be towed through the water by the same or a different vessel. The streamers are typically cables that include a plurality of sensors disposed thereon at spaced apart locations along the length of each cable. Some seismic surveys locate sensors on ocean bottom cables or nodes in addition to, or instead of, streamers.
The sensors may be configured to generate a signal that is related to a parameter being measured by the sensor. At selected times, the seismic source may be actuated to generate, for example, acoustic energy that travels downwardly through the water and into the subsurface formations. Acoustic energy that interacts with interfaces, generally at the boundaries between layers of the subsurface formations, may be returned toward the surface and detected by the sensors on the streamers. The detected energy may be used to infer certain properties of the subsurface formations and interfaces, such as structure, mineral composition and fluid content, thereby providing information useful in the recovery of hydrocarbons.
These drawings illustrate certain aspects of some of the embodiments of the present disclosure and should not be used to limit or define the disclosure.
Embodiments may be directed to acoustic projectors and associated methods. At least one embodiment may be directed to an acoustic projector operable in a monopole mode and a dipole mode.
As illustrated, the survey vessel 102 may tow sensor streamers 112. The sensor streamers 112 may be towed in a selected pattern in the body of water 104 by the survey vessel 102 or a different vessel. As illustrated, the sensor streamers 112 may be laterally spaced apart behind the survey vessel 102. “Lateral” or “laterally,” in the present context, means transverse to the direction of the motion of the survey vessel 102. Towing equipment 116 may be used spread the sensors streamers 112 laterally apart from one another. Suitable towing equipment 116 may include trawl doors or other suitable device for providing spreading force when towed through the body of water 104. The sensor streamers 112 may each be formed, for example, by coupling a plurality of streamer segments (none shown separately). The sensor streamers 112 may be maintained in the selected pattern by towing equipment 116, such as paravanes or doors that provide lateral force to spread the sensor streamers 112 to selected lateral positions with respect to the survey vessel 102. The sensor streamers 112 may have a length, for example, in a range of from about 2,000 meters to about 12,000 meters or longer. The configurations of the sensors streamers 112 on
The sensor streamers 112 may include seismic sensors 114 thereon at spaced apart locations. The seismic sensors 114 may be any type of seismic sensors known in the art, including hydrophones, geophones, particle velocity sensors, particle displacement sensors, particle acceleration sensors, pressure gradient sensors, or combinations thereof, for example. By way of example, the seismic sensors 114 may generate response signals, such as electrical or optical signals, in response to detecting acoustic energy emitted from the acoustic projector 110 after the energy has interacted with the subsurface formations (not shown) below the water bottom. Signals generated by the seismic sensors 114 may be communicated to the recording system 106. While not illustrated, the seismic sensors 114 may alternatively be disposed on ocean bottom cables or subsurface acquisition nodes in addition to, or in place of, sensors streamers 112.
In accordance with example embodiments, a geophysical data product indicative of certain properties of the one or more subsurface formations (not shown) may be produced from the detected acoustic energy. The geophysical data product may include acquired and/or processed seismic data and may be stored on a non-transitory, tangible, computer-readable medium. The computer-readable medium may include any computer-readable medium that is tangible and non-transitory, including, but not limited to, volatile memory, such as random access memory (RAM) and non-volatile memory, such as read-only memory (ROM), flash memory, hard disc drives, optical disks, floppy discs, and magnetic tapes. The geophysical data product may be produced offshore (e.g., by on a vessel) or onshore (e.g., at a facility on land) either within the United States and/or in another country. Specifically, embodiments may include producing a geophysical data product from at least the measured acoustic energy and storing the geophysical data product on a non-transitory tangible computer-readable medium suitable for importing onshore. If the geophysical data product is produced offshore and/or in another country, it may be imported onshore to a facility in, for example, the United States or another country. Once onshore in, for example, the United States (or another country), further processing and/or geophysical analysis may be performed on the geophysical data product. According to some embodiments, reflected sound waves may comprise at least a portion of the first sound wave and/or the second sound wave. The sound waves that are reflected from a subsurface interface are then processed to produce a seismic image.
As illustrated in
In some embodiments, the control system 108 may operate the acoustic projector 110. Those of ordinary skill in the art, with the benefit of this disclosure, should be able to select an appropriate frequency for operation of the acoustic projector 110. The control system 108 may include hardware and software that operate to control acoustic projector 110. For example, control system 108 may include a processor (e.g., microprocessor), memory, and interfaces, among other components. In some embodiments, processor may include any type of computational circuit, such as a microprocessor, a complex instruction set computing (CISC) microprocessor, a reduced instruction set computing (RISC) microprocessor, a very long instruction word (VLIW) microprocessor, a digital signal processor (DSP), or any other type of processor, processing circuit, execution unit, or computational machine. It should be understood that embodiments of the control system 108 should not be limited to the specific processors listed herein. In some embodiments, the control system 108 uses iterative learning control characterizations to control a phase, generate a repeatable signal, and reduce unwanted harmonics on an arbitrary signal.
The first and second bender plates 202 and 204 may be based on generation of acoustic energy through mechanical vibration of a flexible disc, also referred to as a flexural disc projector. Additionally, a driver 208 may be affixed to the second bender plate 204 and disposed within the cavity 206, such that the first and second bender plates 202 and 204 can oscillate to generate an acoustic wave. As shown, the driver 208 may comprise a stator 210, an actuator 212, a permanent magnet 214, and voice coil 216. By way of example, the stator 210 may be attached to one of the bender plates (e.g., second bender plate 204) and the voice coil 216 may be attached the other of the bender plates (e.g., first bender plate 202). When current is flowed through the voice coil 216, the two parts of the actuator 212 may be attracted or repelled causing the first and second bender plates 202, 204 to bend inwards and outwards at the same time. Accordingly, embodiments may use an alternate current to generate a monopole wavefield in the surrounding medium. While not illustrated, springs and mass elements may be attached to the first and second bender plates 202 and 204 as desired for a particular application. When current is applied to driver 208, driver 208 may then apply a force to a corresponding transmission element. In some embodiments, the first and second bender plates 202 and 204 may be generally planar. In particular embodiments, the first and second bender plates 202 and 204 may each be in the form of a flexible disk. In some embodiments, the first and second bender plates 202 and 204 may each be in the form of flat, circular disks having substantially uniform thickness (i.e., disk thickness varies by no more than 10%), and include both axially-symmetric and axially-asymmetric configurations as may be suitable for particular applications.
By way of example, the first and second bender plates 202 and 204 may be rectangular, square, elliptical, or other suitable shape for providing the desired pressure waves. The first and second bender plates 202 and 204 may be made from any of a variety of materials including materials comprising metal, metal alloy, steel, aluminum, titanium, stainless steel, a copper alloy, glass-fiber reinforced plastic (e.g., glass-fiber reinforced epoxy), one or more composite materials, carbon fiber reinforced or other suitable flexible spring material. Examples of suitable copper alloys may include brass, beryllium, copper, phosphor bronze, or other suitable copper alloy. In some embodiments, the first and second bender plates 202 and 204 may comprise aluminum or be made from the same or a different material. In particular embodiments, the first and second bender plates 202 and 204 may have a thickness from about 1 millimeter to about 12 millimeters or even greater. However, dimensions outside these ranges may be suitable for a particular application, as desired by one of ordinary skill in the art with the benefit of this disclosure. In general, the first and second bender plates 202 and 204 may be configured of a thickness that allows sufficient deformation but can withstand expected differential static pressures.
It will be appreciated that, according to other embodiments of the present disclosure, acoustic energy may be generated by acoustic source via other means including a flextensional shell. While not illustrated, the flextensional shell may be formed, for example, by two shell side portions that may be mirror images of one another and operable to be driven in phase, or out of phase with respect to one another. Additionally, flextensional shell may be elliptical in shape or may be any other suitable shape, including convex, concave, flat, or a combination thereof.
While not illustrated, according to some embodiments of the disclosure, one or more of first and second bender plates 202, 204 may include a hinge to generate a secondary acoustic energy resonance output. Generation of a secondary acoustic energy output may be useful to the system output.
As illustrated, a first driver 208A may be affixed to a portion of one side of the fixed plate 218 in the first cavity 206A. The first driver 208A may comprise stator 210A, permanent magnet 214A, actuator 212A, and voice coil 216A. As illustrated, a second driver 208B may be affixed to a portion on the side of the fixed plate 218 in the second cavity 206B. The second driver 208B may comprise stator 210B, permanent magnet 214B, actuator 212B, and voice coil 216B. It will be appreciated, that, while first driver 208A and second driver 208B are shown, according to other embodiments, other driver types may be used such as a bi-directional driver, in which both parts of the driver may be controlled individually. As shown, first and second drivers 208A, 208B are affixed to opposite sides of the fixed plate 218. The first and second drivers 208A, 208B of the acoustic projector 110 are operable to act upon the first bender plate 202 and the second bender plate 204 independently in response to in-phase or out-of-phase current. As shown, the first driver 208A may be coupled to the first bender plate 202, and the second driver 208B may be coupled to the second bender plate 204. It will be appreciated that current may be controlled in a number of ways including in response to signal communication from one or more sources such as control system 108 as shown and described with respect to
As illustrated, a first driver 208A may be affixed to a portion of one side of the fixed plate 218 in the first cavity 206A. As illustrated, a second driver 208B may be affixed to a portion on the side of the fixed plate 218 in the second cavity 206B. As shown, first and second drivers 208A, 208B are affixed to opposite sides of the fixed plate 218. The first and second drivers 208A, 208B of the acoustic projector 110 are operable to act upon the first bender plate 202 and the second bender plate 204 independently in response to in-phase or out-of-phase current. As shown, the first driver 208A may be coupled to the first bender plate 202, and the second driver 208B may be coupled to the second bender plate 204. It will be appreciated that current may be controlled in a number of ways including in response to a signal from one or more sources such as control system 108 as described with respect to
As shown, each cavity 206A, 206B also features one or more endcaps 220A, 220B. Endcaps 220A, 220B may seal one or more ends of fixed plate 218 and the first and second bender plates 202, 204 to form cavities 206A, 206B. While acoustic projector 110 is shown with endcaps 220A, 220B, according to alternate embodiments, each cavity 206A, 206B does not require endcaps. With additional reference to
In some embodiments, the acoustic projector 110 may further include first and second sensors 222A, 222B. A first sensor 222A may be placed on or coupled to the first bender plate 202. A second sensor 222B may be placed on or coupled to the second bender plate 204. The first and second sensors 222A, 222B may be any type of particle motion sensor, for example geophones or accelerometers. First and second sensors 222A, 222B may be used for a control feedback loop to control the operation each bender plate 202, 204 of the acoustic projector 110 via interaction with control system 108 as shown in
While not illustrated, electrical connections may be made to the acoustic projector 110 and components thereof, including the first and drivers 208A, 208B via cable 118 as shown in
The particular embodiments disclosed above are illustrative only, as the described embodiments may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Although individual embodiments are discussed, the disclosure covers all combinations of all those embodiments. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. All numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. Moreover, the indefinite articles “a” or “an,” as used in the claims, are defined herein to mean one or more than one of the elements that it introduces. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Furthermore, the word “may” is used throughout this application in a permissive sense (i.e., having the potential to, being able to), not in a mandatory sense (i.e., must). The term “include,” and derivations thereof, mean “including, but not limited to.” The term “coupled” means directly or indirectly connected. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents that may be incorporated herein by reference, the definitions that are consistent with this specification should be adopted for the purposes of understanding this disclosure.
The present application claims the benefit of U.S. Provisional Application No. 62/860,141, filed Jun. 11, 2019, entitled “Mono and Dipole Acoustic Projector,” the entire disclosure of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62860141 | Jun 2019 | US |
