In one embodiment, a method for drilling a wellbore includes injecting drilling fluid into a top of a tubular string disposed in the wellbore at a first flow rate. The tubular string includes: a drill bit disposed on a bottom thereof, tubular joints connected together, a longitudinal bore therethrough, and a port through a wall thereof. The drilling fluid exits the drill bit and carries cuttings from the drill bit. The cuttings and drilling fluid (returns) flow to the surface via an annulus defined between the tubular string and the wellbore. The method further includes rotating the drill bit while injecting the drilling fluid; remotely removing a plug from the port, thereby opening the port; and injecting drilling fluid into the port at a second flow rate while adding a tubular joint or stand of joints to the tubular string. The injection of drilling fluid into the tubular string is continuously maintained between drilling and adding the joint or stand to the drill string. The method further includes remotely installing a plug into the port, thereby closing the port. The first and second flow rates may be substantially equal or different.

Methods and apparatus enable reliable and improved isolation between two portions of a bore extending through a casing string disposed in a borehole. A downhole deployment valve (DDV) may provide the isolation utilizing a valve member such as a flapper (1702) that is disposed in a housing of the DDV and is designed to close against a seat (1714) within the housing. The DDV includes an operating mechanism (1703,1704) for opening/closing the DDV. In use, pressure in one portion of a well that is in fluid communication with a well surface may be bled off and open at well surface while maintaining pressure in another portion of the casing string beyond the DDV.

In one embodiment, a method for drilling a wellbore includes injecting drilling fluid into a top of a tubular string disposed in the wellbore at a first flow rate. The tubular string includes: a drill bit disposed on a bottom thereof, tubular joints connected together, a longitudinal bore therethrough, and a port through a wall thereof. The drilling fluid exits the drill bit and carries cuttings from the drill bit. The cuttings and drilling fluid (returns) flow to the surface via an annulus defined between the tubular string and the wellbore. The method further includes rotating the drill bit while injecting the drilling fluid; remotely removing a plug from the port, thereby opening the port; and injecting drilling fluid into the port at a second flow rate while adding a tubular joint or stand of joints to the tubular string. The injection of drilling fluid into the tubular string is continuously maintained between drilling and adding the joint or stand to the drill string. The method further includes remotely installing a plug into the port, thereby closing the port. The first and second flow rates may be substantially equal or different.

Apparatuses useable in drilling installations for adjusting a mud return flow in a mud loop, at a location far from a mud tank are provided. An apparatus includes (1) a sensor located close to a seabed and configured to acquire values of at least one parameter related to a return mud flow, (2) a valve located near the sensor and configured to regulate the return mud flow, and (3) a controller connected to the valve and the sensor. The controller is configured to automatically control the valve to regulate the return mud flow towards achieving a value of a control parameter close to a predetermined value, based on the values acquired by the sensor. Methods of incorporating an apparatus in a drilling installation and retrofitting existing installations are also provided.

A rotating control apparatus, comprising:

an outer member;

an inner member having a first sealing element and a second sealing element; said inner member, said first sealing element and said second sealing element rotatable relative to said outer member;

a first cavity defined by said inner member, said first sealing element and said second sealing element; and

said inner member having a port to said first cavity.

Disclosed is also a method for drilling a wellbore in a formation with a fluid, comprising the steps of:

casing a portion of the wellbore using a casing having a casing shoe;

determining a casing shoe pressure;

determining a formation fracture pressure;

positioning a rotating control device with said casing; and

drilling the wellbore at a fluid pressure calculated using the lesser of the casing shoe pressure and the formation fracture pressure.

Methods and apparatus enable reliable and improved isolation between two portions of a bore extending through a casing string disposed in a borehole. A downhole deployment valve (DDV) may provide the isolation utilizing a valve member such as a flapper that is disposed in a housing of the DDV and is designed to close against a seat within the housing. The DDV includes an operating mechanism for opening/closing the DDV. In use, pressure in one portion of a well that is in fluid communication with a well surface may be bled off and open at well surface while maintaining pressure in another portion of the casing string beyond the DDV.

A float shoe/collar apparatus (14) and method is disclosed for multipurpose use in running a tubular string (11) such as a casing string or liner into a wellbore and for optimizing cementing operations. In one presently preferred embodiment, the present invention permits auto filling of the tubular string (11) as the string (11) is lowered into the wellbore. If desired, circulation can be effected through down jets (30) for washing the wellbore as necessary. After the tubular string (11) is positioned, the down jets (3) can be blocked off and up jets (33) opened to thereby direct cement upwardly to optimize cement placement. Check valves (31) can also be activated in accord with the present invention to prevent flow from the wellbore into the tubular string (11). In one embodiment, the invention comprises an inner member (27) and an outer tubular member (25). The inner member (27) is movable upon release of shear pins (28) to cause longitudinal movement relative to the outer member (25). The movement of the inner member (27) may close a plurality of downward jets (30) and may also open a plurality of upward jets (33) if desired. The apparatus (14) may also be equipped with a set of check valves (31) which can be held open on run in, and subsequently activated to thereby automatically close upon cementing to prevent "u-tubing" of fluids back into the casing (11).