Patent Application
20250004151
Embodiments of the subject matter disclosed herein generally relate to methods and systems for seabed seismic data acquisition, and more particularly, to an ocean bottom node that uses a quick latch mechanism for attaching two metallic housings to each other for forming a closed casing for hosting electronics to be used for seismic data acquisition underwater.
Seismic data acquisition and processing may be used to generate a profile (image) of geophysical structures under the ground (subsurface). While this profile does not provide an accurate location for oil and gas reservoirs, it suggests, to those trained in the field, the presence or absence of such reservoirs. Thus, providing a high-resolution image of the subsurface is important, for example, to those who need to determine where the oil and gas reservoirs are located.
For marine acquisition, such a high-resolution image may be obtained with a seismic acquisition system as now discussed with regard to
The traditional ocean bottom nodes are designed based on the water depth at which they operate and the required autonomy. Generally speaking, a lower autonomy is required for shallow water depth. However, a long autonomy node is required for deep water applications where the nodes are generally deployed and positioned by ROV so they need more battery capacity. To address these two divergent requirements, most of the existing nodes have been designed to have two different configurations, one for shallow water and one for deep water, which involves different battery capacity, size and volume. For deep water seismic acquisition (from 100 meters to 3,000 meters), the casing for the node also needs to be pressure resistant and robust due to the exerted pressure and duration of the stay in place. Such OBN are generally made of titanium material to avoid corrosion and casing deformation due to the high hydrostatic pressure. The node design is also oversized by the use of reinforcement elements for resisting the high pressure. Thus, such nodes are very expensive.
For shallow water depth (less than 100 meters), the use of the titanium material and an oversized shape is not necessary. Thus, because an OBN for shallow water depth is deployed at a lower depth and for a shorter time operation, it is possible to use cheaper materials for the casing, for example, a polymeric material. Some deep water OBN could also benefit from this choice of material, if only moderate depth is foreseen, e.g., for a depth use up to 300 meters. However, it was observed that even for a deployment depth of less than 200 m, the polymeric casing deforms and water seeps inside the casing, compromising the hosted electronics. In addition, under some circumstances, the weight of the polymeric casing is too light, and the shallow OBN might not achieve a good contact with the seabed. Thus, a solution has been proposed in International Patent Application WO2021/224683, assigned to the assignee of this application, for using an outer metal housing in addition to the polymeric material housing (which is now used as an inner housing), to seal the two halves of the polymeric material housing together.
However, the inventors have observed that for intermediate depths, for example, between 300 and 700 m, the OBN with double housing (the polymer inner housing and metal outer housing) may still leak while the OBN with the titanium housing is too expensive. Thus, there is a need to design a different OBN for medium depth water operations (e.g., between 100 and 700 m) with a better compromise between the weight, cost, compacity, and reliability. While various ranges of depths were mentioned above, e.g., shallow water, medium depth, intermediate depths, etc., it is noted that the effective depths associated with these ranges are different from operator to operator and thus, the various embodiments discussed herein are not limited to the numbers provided herein. The operator of the seismic survey will decide, based on the conditions in which the seismic survey is operated, which depth range is suitable and which node is appropriate for the selected depth range. In other words, the nodes discussed later are not limited to the depth ranges defined herein, but may be used as seen fit by the operator of the seismic survey at any desired depth.
According to an embodiment, there is an ocean bottom node for recording seismic waves, and the ocean bottom node includes a casing made of a battery housing and an electronics housing, both made of metal, electronics located inside the casing, a seismic sensor connected to the electronics and configured to detect the seismic waves, a battery located inside the casing and configured to supply power to the seismic sensor, and a latching mechanism configured to hold the battery housing in direct contact with the electronics housing, free of screws extending between the battery housing and the electronics housing.
According to another embodiment, there is an ocean bottom node for recording seismic waves, and the ocean bottom node includes a casing made of a battery housing and an electronics housing, both made of metal, a seismic sensor connected to the electronics and configured to detect the seismic waves, a latching mechanism configured to hold the battery housing in direct contact with the electronics housing with no screw extending between the battery housing and the electronics housing.
According to yet another embodiment, there is a method for assembling an ocean bottom node, and the method includes placing a battery inside a battery housing of a casing, placing electronics inside the electronics housing of the casing, directly contacting the battery housing with the electronics housing to form a sealed inner chamber, attaching a latching mechanism to the battery and electronics housings, and securing the latching mechanism with corresponding screws to the battery and the electronics housings. Each of the battery housing and the electronics housing is made of metal.
For a more complete understanding of the present invention, reference
is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
The following description of the embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to a middle depth ocean bottom node that records seismic data. However, the embodiments to be discussed next are not limited to a middle depth ocean bottom node that records seismic data, but may be applied to other nodes that collect different data.
Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first object or step could be termed a second object or step, and, similarly, a second object or step could be termed a first object or step, without departing from the scope of the present disclosure. The first object or step, and the second object or step, are both, objects or steps, respectively, but they are not to be considered the same object or step.
The terminology used in the description herein is for the purpose of describing particular embodiments and is not intended to be limiting. As used in this description and the appended claims, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Further, as used herein, the term “if” may be construed to mean “when” or “upon” or “in response to determining” or “in response to detecting,” depending on the context.
According to an embodiment, a novel, middle depth, ocean bottom node that is configured to record seismic data has most of its electronics housed in an aluminum casing. Other, preferably inexpensive, metals may be used for the casing. The aluminum casing is made from two or more parts and these parts are configured to fit together to form an inner chamber that is watertight. In this way, for the 100 to 700 m depth range, which is traditionally served by expensive titanium nodes, the present configuration achieves the desired structural integrity with no water leak at an affordable price. To ensure that the water tightness is maintained between the parts of the casing and also to ensure a quick and reliable connection between the parts of the casing, a quick latch mechanism is employed. The various parts are assembled together and maintained as a single unit with screws. If the casing is made of aluminum, the metal screws need only to keep the parts together, and do not need to have a high strength as the high sealing of the casing is achieved with the latching mechanism. This moreover also contributes to maintaining a lower cost of the product, since no re-design of the classical screws used for closing a casing (like in e.g., with a titanium case as disclosed in WO2020/208424) needs to be made for compatibility of the screws with the aluminum casing in marine environment.
A middle depth OBN 200 is illustrated in
Regarding the casing 202 of the OBN 200,
To withstand the ambient pressure between 100 and 700 m depth in the ocean, and also to prevent rust, casing 202 is entirely made in this embodiment of aluminum. As noted above, other inexpensive metals may be used for the casing. Note that as the node moves to depths higher than 100 m, up to 700 m, the ambient pressure is high enough to press the two halves 230 and 232 making up the casing 202, toward each other with enough force to achieve a tight water seal between them if the facing surfaces are machined enough. In other words, because of the pressure difference between the inner chamber 410 (see
Moreover, preferably, a kind of vacuum is established within the housing, so that the ambient pressure also achieves the tight water seal for the casing when the node 200 is on board of the vessel. In one embodiment, the pressure in the casing is around 0.5 bar. This also avoids condensation inside the housing and allows protection against corroding the electronic components.
The two halves 230 and 232 are configured to be secured to each other by a latching mechanism 240, as shown in
Each latch is made of a solid body 244 made of aluminum, or another material, which is compatible with housing 202 of the node. The solid body 244 has a flat side 244A, as shown in
Casing 202 is shown in
The other half 232 is configured to hold the electronics of the node, and for this reason it is also called the electronics housing 232. While previous implementations of an OBN used to have a strength plate between the various parts forming the casing of the node, in this embodiment, there is no strength plate located between the battery housing 230 and the electronics housing 232. The electronics housing 232 might be configured to hold a pinger 210, as shown in
Chamber 410 is configured to house the electronics 620, as illustrated in
The protective cover 204 may have a first half bumper 650A that is configured to conform over the first half 230 and also a second half bumper 650B, which is configured to conform over the second half 232. The protective cover 204 may be made of an elastic material, for example, thermo-polyurethane (TPU) material. The reason for having this elastic material over the housing is, as noted above, to protect the MEMS sensor 626 from unwanted shocks. Also, the clock of the electronics 620 is very sensitive and needs protection from shock. A shock can happen when the node is deployed in the water, as the node falls freely to the ocean bottom. The elastic material is configured to absorb part of the shock. Note that in one embodiment, the node 200 has no protective cover. This might happen if no MEMS sensors are used, or if the MEMS sensor and the clock are designed to not be affected by the impact with the ocean bottom. If protective cover 204 is present, then it may be attached with screws 660 to the corresponding halves 230 and 232, as illustrated in
The lips 230A and 232A, when placed together, form a partial recess 710, 712 for receiving a neck 720 of the connecting mechanism 220, as also shown in
A method for assembling the ocean bottom node 200 in anticipation of acquiring seismic data is now discussed with regard to
The disclosed embodiments provide an aluminum housing ocean bottom node that is configured to collect seismic data when deployed in a middle depth zone, i.e., a zone where the depth of the ocean bottom is between 100 and 700 m. A quick latching mechanism is used to connect the halves of the housing to each other. No screw is extending from one half to the other half for holding together the two halves. This configuration is preferred in view of the low cost of aluminum, but the housing can be made of any other suitable metal, with corresponding choices for the quick latching mechanism.
Although the term “ocean” is used in this application, one skilled in the art would understand that the OBN can be deployed in a lake, pond, brackish water, river, etc., i.e., any body of water. It should be understood that this description is not intended to limit the invention. On the contrary, the embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.
Although the features and elements of the present embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein.
This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.
