Patent Application
20180120240
Deep water oil and gas pipes are an important means of transporting oil and natural gas. Such pipes are built to withstand high internal pressures as well as high external hydrostatic pressures. For example, at a depth of 3 km, a deep water pipe must withstand more than 300 times atmospheric pressure.
Many deep water pipes are between 400 mm and 600 mm in diameter and have a steel wall with a thickness ranging from 20 mm to 35 mm. Many deep water pipes also have a thermal insulation layer to prevent oil from waxing in the pipe (and hence constricting flow), a steel coating for the insulator, and also a cement protective layer.
Over time, erosion and corrosion may develop both inside and outside the deep water pipe. Any of the aforementioned layers may become cracked and threaten the integrity of the deep water pipe.
X-ray radiography is a known method to conduct inspection of large objects for cracks and the like. X-ray systems are used, for example, to inspect cargo, engine blocks, and even rocket engines. Unfortunately, the various components that comprise a typical x-ray imaging system are configured and designed to operate on land in an open air environment and are not well suited to the multiple significant challenges presented in a deep-water setting.
The above needs are at least partially met through provision of the method and apparatus for facilitating deep water radiography described in the following detailed description, particularly when studied in conjunction with the drawings, wherein:
Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions and/or relative positioning of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of various embodiments of the present teachings. Also, common but well-understood elements that are useful or necessary in a commercially feasible embodiment are often not depicted in order to facilitate a less obstructed view of these various embodiments of the present teachings. Certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required. The terms and expressions used herein have the ordinary technical meaning as is accorded to such terms and expressions by persons skilled in radiography except where different specific meanings have otherwise been set forth herein.
This disclosure relates generally to radiography and more specifically to radiography of a submersed object. Generally speaking, the various embodiments described herein provide an apparatus having a submersible, hollow, closed container and an x-ray imaging system radiation source disposed within that container. For a typical application setting the submersible container is configured to withstand at least an external pressure of 150 standard atmospheres (atm) which permits submerging the container to at least 10 meters (m) and also to a depth of at least 1.5 kilometers (km) in a liquid (such as an open body of water) without undergoing permanent deformation. (One standard atmosphere can also be represented as 9.8692×10−6 Pascals (Pa), 0.9678411 bars, or 6.8046×10−2 pounds per square inch (psi).) The x-ray imaging system radiation source is configured to selectively direct x-rays towards an object under inspection that is external to the submersible container. Such an object may be disposed, for example, upon (or within) a sea bed or deep lakebed.
By one approach at least one thermal management component can be included to dissipate heat generated by the x-ray imaging system radiation source. By one approach this thermal management component comprises heat fins that are thermally coupled to the submersible hollow and closed container such that at least some heat generated by the x-ray imaging system radiation source is conducted via the heat fins to the surrounding open body of water.
By another approach, in lieu of the foregoing or in combination therewith, the at least one thermal management component can include a selectively circulating liquid coolant that moves heat from at least a part of the x-ray imaging system radiation source to a wall of the container and then to the surrounding open body of water.
By one approach the submersible hollow and closed container is formed at least in part of steel and has an at least substantially convex shape (such as a spherical shape or an ellipsoidal shape). By one approach, the container also includes a relatively small concave portion configured to accommodate a cylindrically-shaped object (such as a deep water pipe) under inspection in close proximity. In addition, the container can be filled with an essentially oxygen-free gas such as nitrogen gas.
By one approach the aforementioned submersible hollow and closed container also houses the x-ray detector components that are configured to detect x-rays that pass through the object under inspection. By another approach, the apparatus includes a second submersible hollow and closed container that includes the x-ray detector components.
By one approach, in a typical application setting a power source and at least some control circuitry is disposed on a surface platform (such as a surface ship or an oil drilling platform) and/or in a remotely operated underwater vehicle (ROV).
So configured, the x-ray imaging system radiation source and its corresponding detector components can be safely submerged to the deep water location of an object, such as a deep water pipe, to be examined with x-ray imaging. Such an apparatus makes possible the use of known examination techniques in an application setting that has been, to date, hostile to such methodologies.
These and other benefits may become clearer upon making a thorough review and study of the following detailed description. Referring now to the drawings,
The container 101 can be at least substantially formed of steel, titanium, acrylic resins, or some other suitably strong material, including composite materials (such as metal matrix composites (MMC) and reinforced plastics or polymer matrix composites (PMC0)). The steel can include high-strength alloyed steel or stainless steel, which is resistant to corrosion. By one approach the container 101 has an at least substantially convex shape (where the expression “substantially” will be understood to refer to at least 80 percent surface area). By one approach the container 101 is generally symmetrical in shape and may comprise, for example, a sphere or an ellipsoid. That said, these teachings will readily accommodate nonsymmetrical shapes as desired.
X-rays are a type of ionizing radiation. Accordingly, when x-rays interact with ordinary air the interaction produces a significant amount of ozone (especially in front of the x-ray source head). Generally speaking, each 100 electron volts (eV) of radiation energy that interacts with pure oxygen produces approximately 13 ozone molecules while each 100 eV of radiation energy that interacts with ordinary air produces approximately 7 to 10 ozone molecules. Ozone is a strong oxidant. Unfortunately, as little as one part per million ozone concentration can lead to significant material degradation and/or oxidation that results in damaged equipment, hoses, and/or cables. With the foregoing in mind, by one approach the container 101 is filled with an essentially oxygen-free gas (0.1% oxygen or less), such as nitrogen gas (where commercially-available nitrogen gas usually has less than 2 parts per million (ppm) of oxygen and less than 2 ppm water). In another example, essentially oxygen-free gas is less than 0.01% oxygen. By one approach the internal atmospheric pressure is regulated to around 1.0 atm (for example, within 1%, 2%, 3%, 4%, or 5% as desired) to accommodate the design specifications of typical x-ray equipment. For example, internal atmospheric pressure can be between 0.99 atm and 1.01 atm, 0.98 atm and 1.02 atm, 0.97 atm and 1.03 atm, and 0.96 atm and 1.04 atm, or 0.95 atm and 1.053 atm. In an example, the internal atmospheric pressure is regulated by a pressure regulator (not shown).
Using dry nitrogen gas provides another benefit as well; internal humidity problems are essentially eliminated. As a result, essentially no condensation within the container 101 occurs as the container 101 raises and lowers within an open body of water and experiences corresponding significant changes in temperature.
By one approach the container 101 can also include some flotation components (not shown) affixed, for example, to an upper surface thereof. For many application settings it will be useful if the overall weight of the container 101 and its contents approximate that of the volume of water that the container 101 displaces so the container 101 can be raised and lowered efficiently in the water. The center of gravity can be separate from and, for example, lower than the center of flotation for increased stability. Such design concerns are understood in the art and require no further elaboration here. In another approach the container 101 can be moved by an underwater propulsion or navigation system (not shown). Such underwater propulsion or navigation systems are understood in the art and require no further elaboration here.
The container 101 has an x-ray imaging system radiation source 102 (“x-ray source”) disposed therein. This x-ray source 102 is generally configured to selectively direct x-rays towards an object 103 under inspection that is external to the container 101. The x-ray source 102 can comprise, for example, a radio-frequency (RF) linear particle accelerator-based (linac-based) x-ray source, such as the Varian Linatron M9. The linac is a type of particle accelerator that greatly increases the kinetic energy of charged subatomic particles or ions by subjecting the charged particles to a series of oscillating electric potentials along a linear beamline, which can be used to generate ionizing radiation (e.g., X-rays) and high energy electrons.
For the sake of an illustrative example this description presumes that the object 103 comprises a deep water pipe, a deep water pipe valve, a deep water blowout preventer, or the like. It will be understood that no particular limitations are intended in these regards and that the described apparatus 100 may be successfully deployed with other underwater objects of choice.
A power distribution component 203 distributes power received from externally-provided electrical power 202 to this accelerator assembly 201 and to a pulse modulator 204. (The power distribution component 203 can distribute electrical power as appropriate to the other components as well, though
The pulse modulator 204 generates narrow high-voltage and high power electric pulses. These pulses typically represent several kilowatts (kW) of average power and several megawatts (MW) of peak power during each pulse period of a few microseconds. Pulse repetition frequency is usually a few hundred pulses per second.
The pulse modulator 204 provides these pulses to an RF generator and RF network 205. The RF generator converts the pulsed electric power into RF power for the same duration (e.g., a few microseconds). The RF network delivers the RF power to the accelerator assembly 201 to power the aforementioned electron acceleration. The RF generator can comprise, for example, a magnetron or alternatively a solid-state oscillator followed by a klystron. The magnetron is a high-powered oscillator that can use, for example, a vacuum tube that can generate microwaves using the interaction of a stream of electrons with a magnetic field while moving past a series of open metal cavities (also referred to as cavity resonators or RF cavities). By another approach a solid-state oscillator uses a solid state circuit to produce high quality small signals that can then be amplified by a solid state amplifier. The klystron is a high-power amplifier such as a high RF amplifier (e.g., microwave amplifier), where an electron beam generated by an electron gun interacts with radio waves as the electron beam passes through cavity resonators (or RF cavities) along a length of a tube (e.g., drift tube).
The power distribution component 203 and/or the pulse modulator 204 can provide power to the electron source as comprises a part of the accelerator assembly 201 as described above. A frequency servo 207 can serve to sense changes in resonance frequency of the RF cavities and adjust the RF generator frequency accordingly. Additional components, such as coils to generate a magnetic field for various purposes, may also be included depending on system design.
A controller 208 operably couples to many (or all) of the aforementioned elements and serves to coordinate the actions of these various components. This controller 208 can also serve to communicate with appropriate external elements as desired. By one approach the controller 208 comprises a control circuit and therefore comprises structure that includes at least one (and typically many) electrically-conductive paths (such as paths comprised of a conductive metal, such as copper or silver) that convey electricity in an ordered manner, which path(s) will also typically include corresponding electrical components (both passive (such as resistors and capacitors) and active (such as any of a variety of semiconductor-based devices, like transistors and diodes) as appropriate) to permit the circuit to effect the control aspect of these teachings.
Such a control circuit can comprise a fixed-purpose hard-wired hardware platform (including but not limited to an application-specific integrated circuit (ASIC) (which is an integrated circuit that is customized by design for a particular use, rather than intended for general-purpose use), a field-programmable gate array (FPGA), and the like) or can comprise a partially or wholly-programmable hardware platform (including but not limited to microcontrollers, microprocessors, and the like). These architectural options for such structures are well known and understood in the art and require no further description here. This control circuit is configured (for example, by using corresponding programming as will be well understood by those skilled in the art) to carry out one or more of the steps, actions, and/or functions described herein.
By one approach the control circuit operably couples to a memory. This memory may be integral to the control circuit or can be physically discrete (in whole or in part) from the control circuit as desired. This memory can also be local with respect to the control circuit (where, for example, both share a common circuit board, chassis, power supply, and/or housing) or can be partially or wholly remote with respect to the control circuit (where, for example, the memory is physically located in another facility, metropolitan area, or even country as compared to the control circuit).
This memory can serve, for example, to non-transitorily store the computer instructions that, when executed by the control circuit, cause the control circuit to behave as described herein. (As used herein, this reference to “non-transitorily” will be understood to refer to a non-ephemeral state for the stored contents (and hence excludes when the stored contents merely constitute signals or waves) rather than volatility of the storage media itself and hence includes both non-volatile memory (such as read-only memory (ROM) as well as volatile memory (such as an erasable programmable read-only memory (EPROM), random-access memory (RAM; e.g., static or dynamic RAM), or non-volatile RAM (NVRAM) or flash memory).
A typical x-ray imaging system can consume a high level of electrical power and can generate almost as much corresponding heat. Some components of the system (such as, for example, the aforementioned RF cavities and an RF circulator that can comprise a part of the aforementioned RF network) are typically designed to work at a constant temperature. Accordingly, the container 101 can also include a thermal management system 209 to manage the heat and control the temperature of components within the container 101. Further examples and descriptions in these regards are provided further below.
The interior (and/or exterior) of the container 101 may include some x-ray shielding. For example, x-ray shielding in the backward direction can serve to protect sensitive electronics.
It would be possible, of course, to disperse some of the above-described components amongst a plurality of such containers. While there may be some benefit in some application settings to such an architecture, consolidating these components within a single container helps to minimize the need for additional or excessive cabling (including high-voltage cables) to thereby reduce the need for openings through the container wall and additional high-voltage cables between such containers that may increase risk and contribute to deployment challenges.
Referring again to
Referring again to
As mentioned above, the apparatus 100 can include a thermal management mechanism 209. By one approach the thermal management mechanism 209 can include one or more thermal sensors to provide temperature information regarding a local component or local ambient area. Various thermal sensors are known in the art. Accordingly, further elaboration in these regards is not provided here.
In this example a control circuit 504 providing flow rate control serves to actively maintain, for example, the temperature of at least a part of the x-ray source 102 within a predetermined temperature range (such as, for example, +/−1° C.). If desired, one or more flow rate sensors (not shown) can be appropriately located to provide flow rate information to the control circuit 504. In the wall loop, the rate of heat being transferred from the circulating liquid to the container wall is determined by dQ/dt=h*ΔT*A where the heat transfer coefficient h is determined by the turbulence condition (which is in turn determined by material properties, geometry, and flow rate), ΔT represents the difference between wall temperature and the temperature of the bulk liquid, and A represents the contact area between the wall and the circulating liquid. By one approach ΔT would be 26° C. in normal operation when the temperature-sensitive RF components are designed to operate at 30° C. So configured, and based on measured reservoir temperature, the flow rate control circuit 504 can increase or decrease pump flow rates in real time to adjust the amount of heat released into the container wall (and hence the surrounding body of water 402) to thereby maintain the temperature of interest within a small range even without directly measuring that temperature of interest.
As noted above, the object 103 being examined can comprise a pipe. A pipe, of course, has a circular cross-section. If desired, and as shown in
So configured, such a submersible hollow and closed container 101 having an x-ray imaging system radiation source 102 disposed therein can be submersed to a desired depth (such as 1.5 km, 3 km, and so forth) in an open body of water to within some desired distance (such as within at least 0.5 m or less of a submersed object 103) and the radiation source 102 employed to selectively direct x-rays towards the submersed object 103 under inspection. A submersed x-ray detector 104 can be disposed on an opposite side of the object 103 and employed to detect the x-rays to thereby facilitate imaging the object 103.
By one approach the x-ray source 102 and the detectors 104 in their respective containers 101 and 105 can be independently navigated into the aforementioned respective positions (using, for example, on-board or outboard cameras, sonar, or the like). By another approach these two containers 101 and 105 can be physically coupled to one another via a beam or other structure. Such an intervening structure may be rigid and have a fixed length or can be arranged to have a selectively modified length as desired to thereby accommodate variously sized objects.
As yet another example in these regards,
These teachings will accommodate a wide range of methodologies for delivering the above-described components to the object 103 and/or for properly disposing these components with respect to the object 103. For example, these components can each have an independent capability to deliver and position itself or can be delivered and/or positioned by an external mechanism such as a properly-configured ROV.
At block 802 this submersible x-ray imaging system radiation source is submersed at least 10 m in a liquid (such as an open body of water) and, at block 803, is disposed within at least 0.5 m of a submersed object (such as a pipe, valve, or blow-out preventer) under inspection. At block 804 the submersed submersible x-ray imaging system radiation source is then used to selectively direct x-rays towards that submersed object under inspection.
Also-submersed detectors can serve in combination with the submersed submersible x-ray imaging system radiation source to detect such x-rays and thereby provide imaging information regarding the submersed object under inspection.
Depending upon the configuration of the aforementioned components, the system can be used in a same way and considerably greater pressures (such as 150 atm) to thereby obtain image information for objects that are submersed at considerably greater depths (such as 150 m).
Those skilled in the art will recognize that a wide variety of modifications, alterations, and combinations can be made with respect to the above described embodiments without departing from the scope of the invention, and that such modifications, alterations, and combinations are to be viewed as being within the ambit of the inventive concept.
