Patent ID: 11905791
Assignee: SAUDI ARABIAN OIL COMPANY
Field: Civil engineering (Other fields)
Classification: CPC E | IPC E

Claim 11:
12. A method comprising:
before a tubular string is lowered into a wellbore into a subterranean zone;
attaching a landing sub to a bottom end of one of a plurality of tubular segments of the tubular string, the landing sub comprising a landing sub central bore and a landing sub locking profile on an inner surface of the landing sub central bore; and
installing a primary check valve assembly in the tubular string below the landing sub, the primary check valve assembly configured to allow the flow of fluids in the downhole direction and to prevent the flow of fluids in the uphole direction in the tubular string;

lowering the tubular string into the wellbore;
pumping, by a flow of fluid through the tubular string, a secondary check valve assembly in a downhole direction through the tubular string until the secondary check valve assembly lands within the landing sub central bore and valve body setting dogs positioned on an outer surface of a main body of the secondary valve assembly lock into the landing sub locking profile, the secondary check valve assembly operable to prevent the flow of fluids in the uphole direction in the tubular string in the event of a failure of the primary check valve assembly, the secondary check valve assembly comprising:
a flapper configured to pivot between an open position and a closed position, wherein in the closed positon the flapper seals against a flapper seat and blocks fluid from flowing in an uphole direction through the valve central bore;
a rupture disc positioned in the valve central bore and configured to rupture in response to an application of a predetermined fluid pressure and to block fluid from flowing through the valve central bore when in an unruptured state; and
increasing a fluid pressure of the fluids in the tubular string until the rupture disc ruptures.