CPC E21B 34/10 (2013.01) [C09D 5/00 (2013.01); C09D 7/67 (2018.01); E21B 21/10 (2013.01)] | 23 Claims |
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.
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