Patent Description:
In addition to the complexities of the field itself, ongoing management and periodic interventions may be particularly sophisticated undertakings. For example, it is not uncommon for a variety of different wells at a given field to require a variety of different applications and servicing at the same time and throughout production. This may include the simple opening and closing of different valves or a more rigorous undertaking such as the installation of monitoring equipment or the conducting of a cleanout application, just to name a few examples.

Given the amount of monitoring, management and interventions that may take place throughout the oilfield over time, subsea control modules (SCM's), housing any number of subsea electronic modules (SEM's), may be positioned at the seabed. The SEM's themselves may house electronics for interfacing with a variety of different application tools. In line with the examples above, the SEM and SCM package may be used to direct the opening or closing of different valves, obtain readings from different sensors for relay and use in guiding equipment installation or a cleanout. Of course, these tasks are merely exemplary and the package may be used to support countless other operations. Thus, the SEM itself may be similar to a sizeable mainframe computer or server accommodating a host of printed circuit boards (PCB's) and related electronics within the SCM.

Given the expense and importance of the SEM and SCM hardware, a variety of measures are undertaken to help assure safe and intelligent installation is achieved. For example, the outfitted SCM will generally be installed at larger hardware locations or platforms such as at a manifold or Christmas tree site. In this way, the SCM is afforded additional support rather than relying solely on its own frame for long-term structural support at the seabed. In addition to strategic placement for added support, the SEM design itself must undergo shock testing before being used in the field. Specifically, an industry standard API 17F rating is generally required before an SCM with SEM therein may be utilized at an oilfield. This includes directly subjecting the SEM to hours of random vibration testing and evaluating performance thereafter. Only where no detectable performance issues are presented will the model be qualified for use in the field.

Qualifying an SCM for field use as described above is understandable. Apart from the expense and the importance of the equipment, it is employed within a subsea oilfield environment. This means that it will be delivered to a seabed location potentially several thousand feet below surface and installed with heavy equipment where tight precision and delicacy are a challenge to maintain. Even after the likely natural blows of installation, ongoing operations present continued potential shocks and vibrations to the SCM and internal SEM, particularly in the case of gas production. Additionally, whether for an SCM directed activity or otherwise, interventions that includes various equipment being brought to the manifold or other SCM mounting site may be common, each with the potential to physically impact the assembly. Furthermore, the natural ebbs and flows of subsea currents present continual movement and vibration occurrences to the SCM/SEM.

Presently, measures to safeguard the SEM from the shock related realities of the environment include designing a structure in which printed circuit boards and other electronics are located within nitrogen filled compartments. A host of these compartments are assembled and encased for durability and shock-resistance. Unfortunately, many SEM designs also requires the use of several heat sinks which add weight to the unit rendering it more prone to fail the qualification process. In fact, even for an SEM qualified for use at the subsea oilfield, it is generally understood that the SEM is unlikely to withstand the rigors of the environment for the entirety of the life of the field.

<CIT> describes an electronic component cooling system including a dielectric fluid contained in a vessel, the vessel including a heat-conductive hull at least partially submerged in a heat sink fluid, where heat generated by an electronic component of the system is transferred into the dielectric fluid. <CIT> describes a marine subsea data vessel including a plurality of server boards coupled with a heat exchanger that operates to extract heat and transfer the heat to seawater entirely surrounding the marine subsea data vessel. <CIT> describes a cooling system for cooling of a heat generating electrical component having a coolant liquid to absorb excess energy from the heat generating electrical component, the coolant liquid having an energy input threshold above which chemical breakdown of the coolant liquid occurs. <CIT> describes an immersion cooled electronics arrangement includes a sealed housing, a coolant contained within the sealed housing, and an electronic device disposed within the sealed housing. The sealed housing has a variable-volume alterable between at least a first volume and a second volume in response to changes in pressure within the sealed chamber to reduce the rate of pressure change in the sealed housing over time form heating of the coolant.

The present invention resides in a subsea electronic assembly for positioning in an oilfield environment as defined in claim <NUM> and a method of managing operations at an oilfield as defined in claim <NUM>.

In the following description, numerous details are set forth to provide an understanding of the present disclosure. However, it will be understood by those skilled in the art that the embodiments described may be practiced without these particular details. Further, numerous variations or modifications may be employed which remain contemplated by the embodiments as specifically described.

Embodiments are described with reference to certain subsea operations. For example, operations in which a cluster of wells at a seabed are each fluidly coupled to manifolds is described. In the embodiment shown, equipment cooperation is guided by an SCM which accommodates one or more SEM's and other features directed at helping to electronically facilitate operations where possible. However, a variety of different layouts may take advantage of the concepts detailed herein. For example, a variety of different electronic components for use with a host of different types of equipment and functions may take advantage of the architecture and techniques described. These may be referred to generally as electronic assemblies or modules, though the specific illustrative example of an SEM within an SCM is detailed herein. Indeed, so long as a unique configuration of a housing containing an electronic component with shock absorbing liquid is utilized in a subsea environment, appreciable benefit may be realized.

Referring now to <FIG>, a front view of an embodiment of a subsea electronic assembly is shown in the form of an SEM <NUM>. However, in other embodiments, the assembly may be an electronic actuator, a subsea sensor, a remote operated vehicle (ROV), an autonomous underwater vehicle (AUV) or a variety of other electrical tools or even communications equipment. Regardless, the illustrated SEM <NUM> houses a variety of electronic components such as multi-chip modules or the PCB's <NUM>, <NUM> shown. Once more, the SEM <NUM> includes an outer housing <NUM> which may be of aluminum or other suitable material for the environment that is substantially filled with a shock-absorbing liquid <NUM>. That is, the internal support structure <NUM> along with the accommodated PCB's <NUM>, <NUM>, <NUM> and other SEM features may take up a good portion of the area within the outer housing <NUM>. Of the remaining space, for the embodiment shown, most is filled with the noted liquid <NUM> while the remainder constitutes a circulation space <NUM> with air or an inert gas such as nitrogen. More specifically, in the embodiment shown, the fill level <NUM> is in excess of about <NUM>% the noted remaining space with the rest constituting the circulation space <NUM>. As detailed below, the circulation space <NUM> may allow for a boiling of the shock-absorbing liquid, condensation thereof and eventual recirculation.

In the example embodiment noted above, the entirety of the SEM <NUM> interior of the housing <NUM> is made up of either structural hardware that includes the PCB's <NUM>, <NUM>, <NUM> (and other electronic and non-electronic features) or the noted circulation space <NUM>. It is suggested that the circulation space may be less than about <NUM>% of the remaining space that does not include the structural hardware. Of course, in other embodiments, the circulation space may be much less or even much greater. Furthermore, in one embodiment, shock and heat resistance for the SEM <NUM>, which are facilitated by the shock-resistant liquid <NUM>, are notably enhanced so long as the fill level <NUM> is above the height of the PCB's <NUM>, <NUM>, <NUM> and/or a majority of the electronic components of the SEM <NUM>. Thus, the size of the circulation space <NUM> in terms of percentage volume of the "remaining space" may fluctuate greatly depending on the architectural layout of the SEM <NUM>. So long as sufficient circulation space <NUM> is provided to allow for circulation as illustrated in <FIG> is provided, appreciable benefit from the use of the shock-absorbing liquid <NUM> may be realized.

As detailed further below, the shock-absorbing liquid <NUM> is selected to dampen shock and vibration that may be inherent in the installation of the SEM <NUM>, production and other oilfield environment variables or even the effect of periodic interventions. The dampening of any vibrations inherent in the subsea environment may be of benefit to the long term performance of the SEM <NUM>. Further, the liquid <NUM> should be of a dielectric variety given the prominent presence of electronics within the SEM <NUM>.

Continuing with reference to <FIG>, other features of the SEM <NUM> are illustrated given the subsea environment in which it is to be utilized. For example, with added reference to <FIG>, an SCM <NUM> which securely accommodates the SEM <NUM> at couplings <NUM> may be positioned at a seabed platform <NUM>. These couplings <NUM> may help ensure the SEM <NUM> remains in place and also provide a route for supplying communications and/or power to the SEM <NUM> even from an external location even beyond the SCM <NUM>. Regardless, as detailed further below, subsea operations facilitated through communications with the SEM <NUM> may be reliably ensured over a longer period due to the unique shock-resistance of the SEM <NUM> as detailed herein.

Referring now to <FIG>, an enlarged partial top view of a PCB <NUM> of the SEM <NUM> of <FIG> is shown disposed within the shock absorbing liquid <NUM>. In the embodiment shown, the PCB <NUM> is outfitted with different electronic communications <NUM> and power supply <NUM> lines. As noted above, the prominence of the liquid <NUM> in the area of the PCB <NUM> and various electronic components may be of benefit to the PCB <NUM> in terms of shock absorbance. However, the presence of electronics means that the liquid <NUM> is a dielectric fluid. That is, just as dielectric materials are found within the PCB <NUM> itself, to help isolate conductive lines and other PCB electronic features, a similar dielectric fluid about the PCB <NUM> may similarly be of benefit. Liquid fluorinated ketones and fluorocarbons, such as commercially available <NUM> products, Novec® and Fluorinert®, respectively are good choices, although other dielectric fluids may be employed as well.

In addition to the shock absorbing nature of the liquid <NUM>, as well as the electrical compatibility with the PCB <NUM>, utilizing a dielectric form of the liquid may also provide additional benefits. For example, in addition to communications <NUM> and power <NUM> lines, the PCB <NUM> also includes a fair amount of other components <NUM> that tend to generate heat. These may include transistors, resistors, capacitors and a host of other conventional PCB features. Generally, managing this generated heat involves the use of heat sinks throughout the PCB <NUM>. However, where the shock-absorbing liquid <NUM> is a compatible dielectric liquid, heat may be absorbed and circulated away from the PCB <NUM> in a manner that minimizes or even eliminates the use of such heat sinks. Indeed, with the liquid <NUM> in direct contact with the entire exposed surface area of the PCB <NUM>, it may serve as a more effective heat dissipator than employing conventional heat sinks.

The effect of the shock-absorbing liquid <NUM> in substantially eliminating potentially damaging hot spots provides another advantage. That is, the reduction or elimination of heavy heat sinks changes the layout of the PCB <NUM> and may lead to a more compact designed subsea electronic assembly. This, in turn, may reduce installation costs with smaller ROV's or smaller installation delivery vessels being utilized. More specifically, the PCB <NUM> layout will be a lighter configuration. Thus, the PCB <NUM> may be even further resistant to shock induced damage. In other words, the introduction of the liquid <NUM> not only directly protects the PCB <NUM> but may also allow for a naturally more shock resistant PCB <NUM> configuration. Once more, this will also allow for the development of a more compact PCB <NUM> that does not need to account for as many heat sink locations. Thus, a higher performance may be expected from the same size PCB <NUM>.

Similar to the substantial elimination of heat sinks, the PCB <NUM> may also forego the use of conventional conformal coatings that are often utilized to seal over the exposed surface of the PCB <NUM>. Thus, the PCB <NUM> may advantageously be further lightened. Further, even without such a coating, the liquid <NUM> may also serve to help avoid dewing and corrosion at the surface of the PCB <NUM>.

Referring now <FIG>, a side cross-sectional view of the PCB <NUM> of <FIG> is illustrated in a manner revealing a circulation of the shock-absorbing liquid <NUM>. More specifically, notice the upward movement of bubbles <NUM> away from the top surface of the PCB <NUM>. This is indicative of a degree of boiling of the liquid <NUM> in direct contact with the PCB <NUM>. Thus, it is also indicative of the cooling of the PCB <NUM>. That is, heat is being carried away from the PCB <NUM> by the liquid <NUM> which is illustrated in the bubbles <NUM>. Once more, with added reference to <FIG>, the bubbles <NUM> are provided with a place to go at the circulation space <NUM>. Thus, a circulation is provided with heat being carried away from the PCB <NUM> and to this space <NUM>. Furthermore, to the extent that heated condensate of the liquid <NUM> has been brought to the circulation space <NUM>, it may now cool and rejoin the remainder of the liquid <NUM> below which is removed from the location of the PCB <NUM>.

With additional added reference to <FIG>, in one embodiment, the circulation of the liquid <NUM> to the circulation space <NUM> may present an added opportunity for managing the production of particulate in the circulating liquid <NUM>. So, for example, where there has been some degree of corrosion, abrasion or other deterioration of a PCB component, a collector located between the PCB <NUM> and the circulation space <NUM> may be employed. This may include a magnet to attract metal particulate or a mechanical filter to collect any form of minor debris. Thus, the circulating liquid <NUM> has now presented the opportunity to effectively reduce the presence of particulate that might otherwise effect PCB <NUM> performance.

The boiling point for the liquid <NUM> may be tailored to the sought after heat management applied to the PCB <NUM>. For example, in one embodiment, the liquid <NUM> may be selected with a boiling point that is less than about <NUM> to help ensure that PCB components do not sustain excessive heat for extended periods of time.

Continuing with reference to <FIG>, the side cross-sectional view reveals conventional PCB microchip components. These include interconnecting metal line traces <NUM> of copper or other suitable material. These are deposited within an etched dielectric <NUM> at a substrate <NUM>. An electrode <NUM>, otherwise prone to generate a hot spot at the PCB <NUM> is illustrated positioned at a barrier layer <NUM>. Of course, any number of different PCB <NUM> architecture types may be employed which take advantage of effectively being bathed in the indicated shock-absorbing liquid <NUM>.

Regardless of the specific architecture of the PCB <NUM>, the degree of heat maintained at potential hot spots such as the noted electrode <NUM> is dramatically reduced by the surrounding presence of the shock-absorbing liquid <NUM>. Once more, an overall electrical efficiency may be observed with a reduction in power consumption. The bathing presence of the liquid <NUM> may reduce the risk of electrical shorts and allow for reduced clearance and creepage distances. So, for example, just as the dielectric <NUM> isolates the metal line traces <NUM>, so does the liquid <NUM> with respect to such features and others. That is, a new found manner of presenting the benefits of dielectric isolation is provided where the surrounding liquid <NUM> is itself a suitable dielectric.

Referring now to <FIG>, a perspective overview of a subsea oilfield <NUM> is illustrated accommodating the SEM <NUM> of <FIG> within an SCM <NUM> at a secure location with subsea hardware. The SCM <NUM> may include the presence of insulation oil, platform connectors, retrieval architecture and a host of other features. Regardless, for the embodiment shown, the SCM <NUM> is located at a structural platform <NUM>, well suited for securing the SEM <NUM> in position. However, the SCM <NUM> may be located at a variety of suitable hardware locations such as at manifold <NUM>, <NUM> or any number of well Christmas trees <NUM>, <NUM>, <NUM>, <NUM>. Regardless of location, the SCM <NUM> may take advantage of the shock-absorbing and dielectric advantages afforded by the liquid <NUM> employed as described above (see <FIG>).

In this particular layout, multiple well clusters <NUM>, <NUM> are coupled to manifolds <NUM>, <NUM>. This oilfield <NUM> includes a conventional offshore platform <NUM> from which subsea operations, and indeed the SCM <NUM> itself, may be directed. In this particular example, bundled water and production lines <NUM> and bundled electrical/hydraulic lines <NUM> may run along the seabed between the platform <NUM> and the cluster locations.

The oilfield <NUM> accommodates the SCM <NUM> to help facilitate and promote production of fluids from the clusters <NUM>, <NUM> of wells <NUM>, <NUM>, <NUM>, <NUM> (see arrow <NUM>). In spite of the potential for vibrations and mechanical disturbances throughout installation of the SCM <NUM> and subsequent production, the SCM <NUM> is particularly suited to avoid damage and maintain long term performance. Indeed, the SCM <NUM> is also resistant to shock that might be initiated by the SCM <NUM> itself. Further, where the shock resistant liquid <NUM> detailed above is tailored with proper dielectric properties, additional electrical component safeguarding may be provided to further extend the life of the SEM <NUM>/SCM <NUM> (see <FIG>).

Referring now to <FIG>, a chart illustrating results of a random vibration test applied to the SEM <NUM> of <FIG> is shown. In this chart, the x-axis represents the frequency of vibrations in Hz applied to the SEM design, whereas the y-axis represents the resultant vibrations that resonate from the SEM in response thereto (again in Hz). This illustration is in contrast to the prior art chart of <FIG> which illustrates the same but without the use of shock absorbing fluid <NUM> included within the SEM <NUM> (see <FIG>).

Looking at the two charts, it is evident that at about <NUM> and again at about <NUM> there are mechanical resonance peaks. Specifically, where <NUM> is applied as noted along the x-axis, a peak <NUM> presents in <FIG> that is notably smaller than the same peak <NUM>' in <FIG>. That is, where the shock-absorbing liquid is utilized, the peak is smaller by a factor of about <NUM>. The same holds true where the <NUM> is applied as noted along the x-axis. Specifically, where <NUM> is applied, a peak <NUM> presents in <FIG> that is again notably smaller than the same peak <NUM>' in <FIG>. Again, where the shock-absorbing liquid is utilized, the peak is smaller by a factor of about <NUM>.

Of course, a variety of different observations may be made from such testing depending on the particular SEM <NUM> design and type of liquid utilized. Furthermore, results may vary depending on the level of vibration applied (e.g. along the x-axis). It may be that a more dramatic damping effect is observed where the vibration levels applied are at lower frequencies. However, it should remain that so long as the liquid is utilized, some degree of dampening should be observed. This may be beneficial in both SEM deployment as use as well as in the initial qualification process.

Referring now <FIG>, a flow-chart summarizing an embodiment of employing a subsea electronic system in a subsea oilfield environment is shown. More specifically, an SEM utilizing a housing with shock absorbing liquid about electronic components is illustrated. As shown at <NUM>, the SEM system is filled with a shock absorbing liquid and qualified for use (see <NUM>). Of course, the use of the liquid is an aid to obtaining qualification. However, as a more practical matter, shock protection may be afforded to the system during deployment to the field as noted at <NUM>. The same holds true for any number of potential shock inducing occurrences given the environment. That is, whether it be the operation of nearby oilfield equipment (<NUM>), the obtaining of production through such equipment (<NUM>) or even manipulation of the equipment with the very same SEM system (<NUM>), the potential for shock is ever present. Nevertheless, protection from the effects of such shock may be afforded to the SEM system, not to mention a host of other electronic efficiencies where the liquid is of a suitable dielectric variety as detailed above.

Embodiments described above provide electronic component architecture particularly configured for a subsea environment. Once more, the component architecture is rendered shock resistant in a manner that may reduce overall weight of structural hardware and may further enhance shock resistance and/or even minimize heat. So, for example, the life of electronic components, such as those of an SEM, may be substantially lengthened.

Claim 1:
A subsea electronic assembly (<NUM>) for positioning in an environment of an oilfield and comprising:
a housing (<NUM>);
an electronic component (<NUM>, <NUM>, <NUM>) disposed within the housing to facilitate electrical coupling with a subsea device at the oilfield; and
a shock absorbing liquid (<NUM>) occupying space within the housing about the electronic component to enhance resistance to shock induced damage from the oilfield environment, wherein the shock absorbing liquid is a dielectric fluid including one of a fluorinated ketone and a fluorocarbon.