Patent Application
20210231249
This disclosure relates generally to subsea oil and gas production facilities, and particularly to interconnecting conduits extending between subsea components. The disclosure further relates to thermal management of such interconnecting conduits.
The production of hydrocarbons from offshore oil and gas reservoirs requires the transportation of production fluids from the reservoirs to subsea facilities for processing. Three phases, i.e., oil, gas and water, may be included in the production fluids. Subsea developments increasingly must accommodate high temperature production fluids that need to be safely transported to the production facility. The high temperature of the production fluids can have several undesirable effects. Special grade subsea and pipeline materials, extensive qualifications of insulation coating and expensive modifications topsides may be required to handle the high temperature of the product. For instance, water cooled heat exchangers may be used topsides on an offshore platform to reduce the temperature of production fluids, e.g., from around 400° F. to a temperature below 250° F., involving weight, space, cost, etc. In the subsea facility, the high temperature of the product may undesirably result in the occurrence of upheaval buckling, lateral buckling and pipeline walking in flowlines carrying the product. The temperature may also undesirably accelerate corrosion and therefore reduce the life of the flowlines. Attempts have been made at providing a subsea cooling system for use with gas production. No established oil or three phase subsea cooling system is available in the industry.
There exists a need for cost-effective subsea cooling systems and methods that can be applied to subsea flowlines or interconnecting conduits such as jumpers that carry three-phase production fluids to enable the development of high temperature subsea fields without the disadvantages of known systems.
In general, in one aspect, the disclosure relates to a system for thermal management of a subsea conduit that carries oil and/or gas produced from a subsea well in a subsea production facility located on a seabed. The system includes an interconnecting conduit circuit for carrying production fluids between subsea components. The circuit has two ends for connecting to the subsea components, a first conduit section, and a second conduit section in parallel with respect to one another, wherein the first and second conduit sections have different heat transfer with respect to the surrounding seawater. The system also includes valving to direct the production fluids through the first conduit section and/or second conduit section such that heat transfer from the production fluids to seawater surrounding the interconnecting conduit circuit can be controlled by adjusting the valving.
In another aspect, the disclosure can generally relate to a method for thermal management of the subsea conduit in the subsea production facility. The method includes transmitting production fluids between subsea components in the interconnecting conduit circuit; and controlling the valving to direct the production fluids through the first conduit section and/or second conduit section such that heat transfer from the production fluids to seawater surrounding the interconnecting conduit circuit is adjusted as desired.
These and other objects, features and advantages of the present invention will become better understood with reference to the following description, appended claims and accompanying drawings. The drawings are not considered limiting of the scope of the appended claims. Reference numerals designate like or corresponding, but not necessarily identical, elements. The drawings illustrate only example embodiments. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Additionally, certain dimensions or positionings may be exaggerated to help visually convey such principles.
Referring to
In one embodiment, referring to
Valving 4 is provided to direct the production fluids flowing in the jumper circuit 2 through the first jumper section 2C and/or second jumper section 2D as desired. For example, by adjusting the valving 4, production fluids can be directed solely through section 2C, solely through section 2D, or partially through each of sections 2C and 2D. Since the sections 2C and 2D have differing heat transfer coefficients, the heat transfer from the production fluids to the seawater surrounding the jumper circuit 2 can be controlled by adjusting the valving 4 as desired.
In one embodiment, each of the jumper sections 2C and 2D includes multiple jumper segments changing in direction, e.g., zig-zagging, and sloping downward such that flow of fluid in the jumper segments is assisted by gravity thereby ensuring self-draining of the fluid independent from fluid pressure in the jumper circuit. An example of such a configuration is shown in
In one embodiment, the valving 4 can be controlled responsive to a control system 6 based on a predetermined fluid temperature and/or flow rate of production fluids flowing through the jumper circuit 2. A temperature sensor 8 such as a phase change thermostat, for example, can be used for continuously monitoring an internal fluid temperature of fluid in the jumper circuit 2. A flow rate sensor 9 can be used for continuously monitoring an internal fluid flow velocity of fluid in the jumper circuit 2. A flying lead or umbilical 10 can be used for transmitting temperature and/or flow rate data from the temperature sensor 8 and/or the flow rate sensor 9, respectively, to a processor 11. The processor 11 is configured or set to determine whether to activate an alarm based on the temperature and/or flow rate information. The alarm indicates the need to adjust the valving 4. Operating personnel can act on the alarm by adjusting the valving 4 manually using an ROV. The processor 11 of the control system 6 can also be configured to automatically adjust the valving 4 based on the temperature and/or flow rate information.
In one embodiment, during routine or early-life production of oil and/or gas from a subsea well, the valving 4 is set to direct produced fluid flow through the one of the jumper sections 2C and 2D having the greater amount of heat transfer (i.e., the greater heat transfer coefficient) with respect to the surrounding seawater to aid in cooling of produced fluid in the jumper circuit 2. Likewise, in one embodiment, during shutdown or late-life production from the subsea well, the valving 4 is set to direct produced fluid flow through the one of the jumper sections 2C and 2D having the lesser amount of heat transfer (i.e., the lower heat transfer coefficient) with respect to the surrounding seawater to aid in retaining heat and thus maintaining produced fluid temperature above hydrate formation and wax formation temperatures.
It should be noted that only the components relevant to the disclosure are shown in the figures, and that many other components normally part of a subsea oil and gas field are not shown for simplicity.
For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present invention. It is noted that, as used in this specification and the appended claims, the singular forms “a,” “an,” and “the,” include plural references unless expressly and unequivocally limited to one referent.
Unless otherwise specified, the recitation of a genus of elements, materials or other components, from which an individual component or mixture of components can be selected, is intended to include all possible sub-generic combinations of the listed components and mixtures thereof. Also, “comprise,” “include” and its variants, are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that may also be useful in the materials, compositions, methods and systems of this invention.
