The present disclosure relates generally to an apparatus for providing storage of fluids, solids or liquids. In particular, the present disclosure relates to a polygonal shaped vessel. More particularly, the present disclosure relates to a plurality of polygonal shaped vessels for saving space on an offshore oil rig.
Oil rigs, particularly off-shore rigs, need to utilize all available space efficiently due to the number of processes that are performed and the limited amount of space provided. Most off-shore oil rigs include numerous levels or platforms and utilize gravity to move fluids between the levels, minimizing the number of pumps on the oil rig.
Various fluids (“well fluids”) may be used on the oil rig and may include both solids and liquids. Common uses for well fluids include: lubrication and cooling of drill bit cutting surfaces while drilling generally or drilling-in (i.e., drilling in a targeted petroleum bearing formation), transportation of “cuttings” (pieces of formation dislodged by the cutting action of the teeth on a drill bit) to the surface, controlling formation fluid pressure to prevent blowouts, maintaining well stability, suspending solids in the well, minimizing fluid loss into and stabilizing the formation through which the well is being drilled, fracturing the formation in the vicinity of the well, displacing the fluid within the well with another fluid, cleaning the well, testing the well, implacing a packer fluid, abandoning the well or preparing the well for abandonment, and otherwise treating the well or the formation.
Since space is a priority on an oil rig, the storage of fluids must be done efficiently. These fluids include various components that may be recycled and re-used or may be treated prior to disposal. Between the various operations, these fluids may be temporarily stored in a tank system. For example, when a wellbore fluid brings cuttings to the surface, the mixture is typically subjected to various mechanical treatments (shakers, centrifuges, etc) to separate the cuttings from the recyclable wellbore fluid. However, the cuttings may need to be treated or the recyclable wellbore fluid may need to be stored until it is used again.
Typically, storage vessels are provided on a lower level of the platform and gravity is used to provide the fluids to them. Circular cross-section vessels are easy to clean but are an inefficient use of space. Rectangular (or square) cross-section vessels are an efficient use of space but are difficult to clean. Accordingly, there exists a need for a tank system which efficiently uses space, maintains the integrity of the vessels and is easy to clean.
In one aspect, embodiments disclosed herein relate to a vessel that includes an inlet to receive fluids; at least five side walls configured in a polygonal shape; a lower angled section having an angle selected to enable mass flow of fluids coupled to the side walls; and an outlet coupled to the lower angled section.
In another aspect, embodiments disclosed herein relate to a system of vessels comprising at least two vessels of polygonal shape and having at least one common side wall between adjacent vessels.
Other aspects and advantages of the invention will be apparent from the following description and the appended claims.
In one aspect, embodiments disclosed herein relate to a vessel. More specifically, embodiments disclosed herein relate to a system of vessels for storing fluids on an oil rig.
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Due to the angle of the lower section 20c being less than a certain value, the material flow out of the vessel is of the type known as mass flow and results in all of the material exiting uniformly out of the vessel. In the case of mass flow, fluid in the vessel descends or moves in a uniform manner towards the outlet, as compared to funnel flow (a central core of material moves, with stagnant materials near the hopper walls). It is known that the critical hopper angle (to achieve mass flow) may vary depending upon the material being conveyed and/or the vessel material. In various embodiments, the angle (from the vertical axis) for mass flow to occur may be less than 40°. One of ordinary skill in the art would recognize that in various embodiments the lower section 20c may be conical or otherwise generally pyramidal in shape or otherwise reducing in nature, e.g., a wedge transition or chisel, to promote mass flow. In a particular embodiment, the lower angled section has a minimum discharge dimension of at least 12 inches (300 mm). The lower section 20c of the vessel 20 may be round and provide a round discharge 25.
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The discharge 25 of the vessels 20 may be connected to a discharge valve 125b, which is further connected to a pipe 125. A filling pipe 122 extends into the vessel 20f via an inlet valve 122a. Also extending into vessel 20f may be a secondary filling pipe 124. The filling pipe 122 or secondary filling pipe 124 may extend into any of the vessels 20 and may in fact extend into all vessels 20. In other embodiments, the vessels 20 may be manufactured to provide a shared discharge and a shared length of pipe.
In some embodiments, also extending into the vessel 20 may be an automatic tank cleaning system (ATC) 128, such as those manufactured by MI-SWACO, LLC of Houston, Tex. Not every vessel 20 includes the ATC 128, the ATC 128 may be optional for the vessels 20 and may not be provided for all vessels 20 on the rig 10.
The polygonal shape of the vessels 20 provides an efficient, space-saving design. By manufacturing the tank system 40 to have vessels 20 with a common side wall, less material may be used while providing a rigid vessel.
In a filling operation, prior to loading fluid into vessel 20, discharge valve 125b is closed. The inlet valve 122a is opened, and the fluids are fed into the vessel 20f. In a preferred embodiment, the vessels 20 may be fluidly connected to provide a mechanism of filling all vessels with only a single filling pipe 122. In some embodiments, the vessels 20 are fluidly connected via one or more apertures in the common wall between adjacent vessels, allowing fluid to flow from one vessel to another through the apertures. Alternatively, the vessels are fluidly connected via the common wall between adjacent vessels, allowing fluid to flow from one vessel to another over the common wall. In order to empty the vessel 20, valve 125b is opened, and gravity forces the fluid out of the vessel 20 and into pipe 125. In an alternate embodiment, if the vessel is pressurized, compressed air or another gas may be used to discharge the fluid from the vessel 20. In a particular embodiment, the compressed gas applied to the pressurized vessel may be within a pressure ranging from about 4 to 8 bar.
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The tank system 50 may include a dedicated tank 20a capable of acting as a multiphase clarifier (MPC). The MPC can be used to drain runoff from the various levels of the offshore rig including the shaker house, rig floor, main deck and, helicopter deck. The MPC provides first-stage separation of waste stream runoff offshore due to waste stream runoff. The MPC may provide for separation of any oil and water-based drilling fluid systems. Further, the MPC has the ability to break the drain runoff from multiple areas such as the rig floor and the shaker deck, into three waste streams, for example, water, mud/base oils, and solids. The waste stream separation may occur without chemical or mechanical assistance. The MPC also may enable automated separation, collection, routing and processing of varying degrees of emulsified mixtures. The MPC is capable of separating solids in heavy fluids/muds, separating water from oil, sending each waste stream to a desired location, and minimizing volumes for post-treatment. Post-treatment processes may include further processing including, but not limited to, shakers, centrifuges, hydrocyclones or the like. Tank 20a also includes a discharge valve 125a. The MPC tank 20a may also be sized for a larger volume as compared to other tanks in the tank system.
The tank system 50 may also include five dedicated tanks 20b for use as shaker pits. These tanks 20b preferably provide storage for the return mud flow. The discharge 25b of the vessels 20b may be connected to a discharge valve 125b, which is further connected to a pipe 135b. The pipe 135b may be connected to an active mud system. An unrestricted overflow pipe 70 may be included in one or more of the tanks 20b. The pipe 70 may be connected to pipe 135b.
The tank system 50 may also include two dedicated completion tanks 20c for completion operations. Completion tanks 20c may be lined/coated for ease of cleaning and resistance to abrasive properties of completion fluids. Tank 20a and tanks 20b may be also lined/coated for ease of cleaning and resistance to abrasive properties of the fluids they may process. The liner of the tanks may be any liner or coating known to one skilled in the art such as, but not limited to, polyurethanes, epoxies, polytetrafluoroethylenes (PTFE) and the like. The discharge 25c of the completion tanks 20c may be connected to a discharge valve 125b, which is further connected to a pipe 145b. The pipe 145b may be connected to an active fluid or completion system.
One skilled in the art will appreciate that a wide variety of discrete subsystems may be combined to form a tank system providing a variety of discrete processes. The discrete subsystems may have varying numbers of associated tanks, dependent upon the requirements of the discrete processes. Discrete processes may include cleaning, storage, processing, completion, workover, production and the like known to one skilled in the art.
One of skill in the art will appreciate that a wide variety of materials may be used in the construction of the above described vessel. In one such illustrative embodiment, a vessel is constructed of welded metal, such as steel, steel alloys, aluminum, aluminum alloys, and the like, which may subsequently be coated with paint, epoxy, thermoplastic and other such protective materials. Alternatively, the vessel may be constructed from composite materials including resin based composites, such as: fiberglass/resin; carbon fiber/resin; metal fiber/resin; combinations of these and the like, thermoplastic composites such as fiberglass/plastic; carbon fiber/plastic; metal fiber/plastic; combinations of these and the like; as well as combinations of various composite materials that are suitable for such applications. Finally it should be noted that one of skill in the art will appreciate that the illustrative vessels may be cast, stamped, forged, or machined from ferrous and non-ferrous metals, plastics, composite materials and the like.
While the present disclosure has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments may be devised which do not depart from the scope of the present disclosure. Accordingly, the scope of the present disclosure should be limited only by the attached claims.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US11/51774 | 9/15/2011 | WO | 00 | 5/23/2013 |
Number | Date | Country | |
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61383121 | Sep 2010 | US |