# US 12,006,789 B2 · Float valve assembly for drilling and workover operations > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,006,789 B2 - Document ID: US12006789B2 - Status: Granted - Kind: B2 - Application number: 17/686,175 - Filed: 2022-03-03 - Published: 2023-09-07 - Granted: 2024-06-11 - Earliest claimed: 2022-03-03 - Assignees: Saudi Arabian Oil Company - Applicants: Saudi Arabian Oil Company - Inventors: Naif Mohsen Mosleh Alharbi; Mohammed A. Jathmi - Web page: https://patentgrep.com/patent/US12006789B2 ## CPC - E21B 34/10: operated by control fluid supplied from outside the borehole - C09D 5/00: Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced {(electrically insulating plastics, resins or waxes H01B3/30)}; Filling pastes - C09D 7/67: {Particle size smaller than 100 nm} - E21B 21/10: Valve arrangements in drilling-fluid circulation systems - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS - C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D) ## Abstract A float valve assembly is configured to be positioned within in a central bore of a tubular string disposed in a wellbore drilled into a subterranean zone. The float valve assembly includes a valve main body and a plunger, and the plunger is biased by a spring towards a closed position and is configured to open in response to a fluid pressure in a downhole direction. The surface of the plunger main body includes a plurality of substantially flat lateral faces forming a pyramid. A hydrophilic nano-coating comprising particles with sizes of between 1 and 100 nanometers is disposed on at least a portion of the surface of the plunger main body. ## Claims ### Claim 1 A float valve assembly configured to be positioned within in a central bore of a tubular string disposed in a wellbore drilled into a subterranean zone, the float valve assembly comprising: a valve main body comprising: an outer surface substantially cylindrical in shape; a valve flow passage defined in part by an inner surface of the valve main body and configured to be fluidically connected to the central bore; and a circumferential inner sealing surface formed on a portion of the inner body surface; and a plunger positioned within the valve main body and axially moveable therein, the plunger comprising: a circular base; a seal ring disposed circumferentially about the circular base; and a plunger main body disposed on the circular base, a surface of the plunger main body comprising a plurality of substantially flat lateral faces forming a pyramid; and wherein: the plunger is biased, by a spring, towards a closed position in which at least a portion of the seal ring is in contact with the circumferential inner sealing surface, thereby preventing a flow of fluid in an uphole direction through the valve flow passage; the plunger is configured to, in response to a fluid pressure in a downhole direction overcoming a biasing force of the spring, move to an open position in which the seal ring is not in contact with the circumferential inner sealing surface, thereby permitting a flow of fluid in a downhole direction through the valve flow passage; and a hydrophilic nano-coating comprising particles with sizes of between 1 and 100 nanometers is disposed on at least a portion of the surface of the plunger main body. ### Claim 2 (depends on 1) The float valve assembly of claim 1, wherein the hydrophilic nano-coating is further disposed on at least a portion of the circumferential inner sealing surface. ### Claim 3 (depends on 1) The float valve assembly of claim 1, wherein the hydrophilic nano-coating is further disposed on at least a portion of the inner surface of the valve main body other than the circumferential inner sealing surface. ### Claim 4 (depends on 1) The float valve assembly of claim 1, wherein the hydrophilic nano-coating is further disposed on at least a portion of the outer surface of the valve main body. ### Claim 5 (depends on 1) The float valve assembly of claim 1, wherein the surface of the main body comprises four substantially flat lateral faces forming an orthogonal pyramid. ### Claim 6 (depends on 1) The float valve assembly of claim 1, wherein the surface of the main body comprises five substantially flat lateral faces forming a pentagonal pyramid. ### Claim 7 (depends on 1) The float valve assembly of claim 1, wherein the surface of the main body comprises six substantially flat lateral faces forming a hexagonal pyramid. ### Claim 8 (depends on 1) The float valve assembly of claim 1, wherein the surface of the main body comprises more than six substantially flat lateral faces forming a polygonal pyramid. ### Claim 9 (depends on 1) The float valve assembly of claim 1, wherein the hydrophilic nano-coating comprises a non-stick coating. ### Claim 10 (depends on 1) The float valve assembly of claim 1, wherein at least a portion of the circumferential inner sealing surface is shaped so as to conform to the surface of the main body when the valve is in the closed position. ### Claim 11 (depends on 1) The float valve assembly of claim 1, further comprising one or more outer seals disposed on, and circumferentially about, the outer surface and configured to sealingly engage with an inner surface of the tubular string. ### Claim 12 (depends on 1) The float valve assembly of claim 1 wherein the spring is a coil spring and the coil spring is partially or fully disposed within a helical passageway of a flexible spring sheath. ### Claim 13 (depends on 12) The float valve assembly of claim 12, wherein the helical passageway is a sealed volume, and wherein the sealed volume is at least partially filled with an inert hydrostatic buffer material. ### Claim 14 (depends on 1) The float valve assembly of claim 1, wherein the tubular string is a drill string, and wherein the fluid is a drilling fluid. ### Claim 15 (depends on 14) The float valve assembly of claim 14, further comprising a bottomhole assembly connected to the drill string, the bottomhole assembly comprising a drill bit and configured to further drill the wellbore into the subterranean zone. ### Claim 16 A well system, comprising: a tubular string positioned in a wellbore drilled into a subterranean zone and comprising a plurality of tubular segments and a central bore; and a float valve assembly configured to be positioned within the central bore, the float valve assembly comprising: a valve main body comprising: an outer surface substantially cylindrical in shape; a valve flow passage defined in part by an inner surface of the valve main body and configured to be fluidically connected to the central bore; and a circumferential inner sealing surface formed on a portion of the inner body surface; and a plunger positioned within the valve main body and axially moveable therein, the plunger comprising: a circular base; a seal ring disposed circumferentially about the circular base; and a plunger main body disposed on the circular base, a surface of the plunger main body comprising a plurality of substantially flat lateral faces forming a pyramid; and wherein: the plunger is biased, by a spring, towards a closed position in which at least a portion of the seal ring is in contact with the circumferential inner sealing surface, thereby preventing a flow of fluid in an uphole direction through the valve flow passage; the plunger is configured to, in response to a fluid pressure in a downhole direction overcoming a biasing force of the spring, move to an open position in which the seal ring is not in contact with the circumferential inner sealing surface, thereby permitting a flow of fluid in a downhole direction through the valve flow passage; and a hydrophilic nano-coating comprising particles with sizes of between 1 and 100 nanometers is disposed on at least a portion of the surface of the plunger main body. ### Claim 17 (depends on 16) The well system of claim 16, wherein the spring is a coil spring and the coil spring is partially or fully disposed within a helical passageway of a flexible spring sheath. ### Claim 18 (depends on 17) The well system of claim 17, wherein the helical passageway is a sealed volume, and wherein the sealed volume is at least partially filled with an inert hydrostatic buffer material. ### Claim 19 (depends on 16) The well system of claim 16, wherein the tubular string is a drill string, and wherein the fluid is a drilling fluid. ### Claim 20 A method comprising: (a) positioning a float valve assembly within a central bore of a tubular string, the float valve assembly comprising: a valve main body comprising: an outer surface substantially cylindrical in shape; a valve flow passage defined in part by an inner surface of the valve main body and configured to be fluidically connected to the central bore; and a circumferential inner sealing surface formed on a portion of the inner body surface; and a plunger positioned within the valve main body and axially moveable therein, the plunger comprising: a circular base; a seal ring disposed circumferentially about the circular base; and a plunger main body disposed on the circular base, a surface of the plunger main body comprising a plurality of substantially flat lateral faces forming a pyramid; and wherein: the plunger is biased, by a spring, towards a closed position in which at least a portion of the seal ring is in contact with the circumferential inner sealing surface, thereby preventing a flow of fluid in an uphole direction through the valve flow passage; and a hydrophilic nano-coating comprising particles with sizes of between 1 and 100 nanometers is disposed on at least a portion of the surface of the plunger main body; (b) lowering the tubular string into a wellbore drilled into a subterranean zone; (c) sufficiently increasing a fluid pressure of the fluids in the tubular string uphole of the float valve assembly to overcome a biasing force of the spring, thereby causing the plunger to move to an open position in which the seal ring is not in contact with the circumferential inner sealing surface; and (d) flowing a fluid in a downhole direction through the valve flow passage. ### Claim 21 (depends on 20) The method of claim 20, wherein the spring is a coil spring and the coil spring is partially or fully disposed within a helical passageway of a flexible spring sheath. ### Claim 22 (depends on 21) The method of claim 21, wherein the helical passageway is a sealed volume, and wherein the sealed volume is at least partially filled with an inert hydrostatic buffer material. ### Claim 23 (depends on 20) The method of claim 20, wherein the tubular string is a drill string, and wherein the fluid is a drilling fluid.