Underwater well structure

Claim 2

A WELLHEAD CAISSON FOR SUBMERGED OIL AND GAS WELLS COMPRISING A SUBSTANTIALLY CYLINDRICAL CONTAINER HAVING OPPOSITE ENDS ONE OF WHICH IS AT LEAST PARTIALLY CLOSED AND THE OTHER OF WHICH IS OPEN, THE CONTAINER HAVING AN OPEN INTERIOR SIZED TO RECEIVE THEREIN THROUGH THE OPEN END OF THE CONTAINER A BLOWOUT PREVENTER AND ASSOCIATED EQUIPMENT, CUTTING MEANS CARRIED BY THE ONE END OF THE CONTAINER OPERABLE UPON ROTATION OF THE CONTAINER ABOUT ITS AXIS TO PENETRATE A CONSOLIDATED EARTH FORMATION AND THE LIKE ENGAGED THEREBY, MEANS FOR ROTATING THE CONTAINER ABOUT ITS AXIS, AND MEANS FOR CIRCULATING FLUID UNDER PRESSURE THROUGH THE ONE END OF THE CONTAINER FOR REMOVING CUTTINGS FROM THE CUTTING MEANS.

Claim 3

Apparatus according to claim 1 including means disposed circumferentially of the container intermediate the ends thereof for discharging fluid along the exterior of the container toward the ends thereof.

Claim 4

Apparatus according to claim 1 including means rigidly mounted within the container coaxially thereof for releasably receiving an elongate rotatable torque transmitting member engaged therewith through the container open end and for transmitting to the container torque applied thereto.

Claim 5

Apparatus according to claim 3 wherein the rigidly mounted means provide a bayonet-type releasable connection to the torque transmitting member.

Claim 6

Apparatus according to claim 3 wherein the rigidly mounted means is disposed adjacent said one end of the container and is arranged to receive and support a blowout preventer assembly.

Claim 7

Apparatus according to claim 3 wherein the rigidly mounted means comprises an open-ended tubular sleeve disposed coaxially within the container adjacent the one end thereof, means cooperating between the sleeve and the container defining a circulating fluid chamber within the container adjacent the one end thereof, and fluid passage means communicating from the chamber in association with the cutting means.

Claim 8

Apparatus according to claim 6 wherein said one end of the container is of conical configuration concentric to said axis to provide an upwardly and outwardly sloping container lower end surface.

Claim 9

Apparatus according to claim 7 wherein said cutting means comprise a plurality of drag teeth projecting from the container lower end surface.

Claim 10

Apparatus according to claim 6 wherein the cutting means comprise a plurality of rotatable cutter cones rotatably mounted to the one end of the container and effectively distributed over the closed area of said one end.

Claim 11

Apparatus according to claim 9 including an opening defined through the one end of the container and centered on the container axis, the cutter cones effectively covering the one end of the container about the opening.

Claim 12

Apparatus accorDing to claim 10 including door means for closing the opening, cutting means carried by the door means, and means for releasably securing the door means in closure relation to the opening.

Claim 13

Apparatus according to claim 6 wherein the means for rotating the container includes said elongate rotatable torque transmitting member and said member comprises a length of hollow drill pipe, connector means carried by the drill pipe for releasably connecting the drill pipe to the sleeve, and means for communicating the interior of the drill pipe to the circulating fluid chamber.

Claim 14

Apparatus according to claim 12 wherein the torque transmitting member is arranged to extend through the one end of the container to an end thereof when the connector means is coupled to the sleeve, and cutting means carried by the end of the torque transmitting means.

Claim 15

Apparatus according to claim 3 including means releasably engageable to the container open end for cooperating with an elongate torque transmitting member engaged with the container to maintain a coaxial relation between the container and the torque transmitting member.

Claim 16

Apparatus according to claim 14 wherein means engageable to the container open end is arranged to cooperate with the torque transmitting member for transmitting torque from said member to the container.

Claim 17

In a wellhead for a submerged arctic oil well and the like installed in an earth formation underlying a body of water, the combination of a. a hollow container substantially wholly disposed in the earth formation adjacent the upper extent thereof for receiving a blowout preventer wholly therein, b. cement securing the container in the earth formation, and c. a protective shield for the container, the shield being of selected thickness and extending radially from the container over the earth formation around the container, the shield and the container cooperating for support of the container in the formation independently of the cement.

Claim 18

In a wellhead for a submerged arctic oil well and the like installed in an earth formation underlying a body of water, the combination of a. a hollow container substantially wholly disposed in the earth formation adjacent the upper extent thereof for receiving a blowout preventer wholly therein, b. cement securing the container in the earth formation, and c. a protective shield for the container, the shield being of selected thickness and extending radially from the container over the earth formation around the container, the shield and the container cooperating for support of the container in the formation independently of the cement.

Claim 19

A wellhead according to claim 16 wherein the shield extends radially from the container over the formation for a distance substantially greater than the radius of a zone in the formation circumferentially of the container subject to thermal influence in response to operations performed in or through the container.

Claim 20

A wellhead according to claim 16 wherein the margins of the shield remote from the container are sloped upwardly and inwardly.

Claim 21

A wellhead according to claim 16 wherein the shield is defined integral with the cement and is provided in the wellhead in conjunction with providing said cement.

Claim 22

A wellhead according to claim 16 wherein the container is installed in the formation through the shield.

Claim 23

A wellhead according to claim 20 wherein the shield is prefabricated.

Claim 24

A wellhead according to claim 21 wherein the shield is comprised of a plurality of interlocking slab-like sections.

Claim 27

The method of claim 23 including circulating fluid through the one end of the container and upwardly along the exterior of the container during the rotating and further lowering steps.

Claim 28

The method of claim 23 wherein the rotating and lowering steps are effective to define an annular space around the container in the earth formation, and the securing step is performed by disposing cement in said space.

Claim 29

The method of claim 25 wherein the cement is disposed in the space by pumping cement through the one end of the container.

Claim 30

The method of claim 23 including forming a protective cement shield for the container to a desired depth over the earth formation and for a desired distance laterally around the container.

Claim 31

The method of claim 27 including forming the shield after termination of the lowering step.

Claim 32

The method of claim 28 including forming the shield by flowing cement through the one end of the container, upwardly along the exterior of the container through the earth formation, and over the formation.

Claim 35

A method according to claim 30 wherein the earth formation includes a stratum of permafrost, and including providing the shield to extend radially over said stratum from the location of the container for a distance substantially greater than the radius from the container in the stratum of a zone of significant thermal influence associated with operations performed in or through the container.

Claim 38

The method of claim 32 including coating the exterior of the skirt before forming the shield with a material to which the cement does not securely bond.

Claim 41

In a wellhead caisson for submerged oil and gas wells in which the caisson includes a substantially cylindrical container adapted to be substantially wholly disposed in an earth formation under a body of water and having opposite ends one of which is at least partially closed and the other of which is open, the container having an open interior sized to receive wholly therein through the open end of the container a blowout preventer and associated equipment, the caisson also including means for circulating fluid under pressure through the one end of the container, the improvement comprising cutting means carried by the one end of the container over the closed area thereof operable in response to rotation of the container about its axis to penetrate a consolidated earth formation and the like engaged thereby, the cutting means being disposed in association with the fluid circulating means for removal of cuttings from the cutting means by fluid circulated through the one end of the container, and means for rotating the container about its axis including means rigidly mounted within the container coaxially thereof for releasably receiving an elongate rotatable torque transmitting member engaged therewith through the container open end and for transmitting therefrom to the container sufficient torque to produce effective operation of the cutting means on a consolidated earth formation, the fluid circulating means including the rigidly mounted means.

Claim 42

In a wellhead caisson for submerged oil and gas wells in which the caisson includes a substantially cylindrical container adapted to be substantially wholly disposed in an earth formation under a body of water and having opposite ends one of which is at least partially closed and the other of which is open, the container having an open interior sized to receive wholly therein through the open end of the container a blowout preventer and associated equipment, the caisson also including means for circulating fluid under pressure through the one end of the container, the improvement comprising cutting means carried by the one end of the container over the closed area thereof operable in response to rotation of the container about its axis to penetrate a consolidated earth formation and the like engaged thereby, the cutting means being disposed in association with the fluid circulating means for removal of cuttings from the cutting means by fluid circulated through the one end of the container, and means for rotating the container about its axis including means rigidly mounted within the container coaxially thereof for releasably receiving an elongate rotatable torque transmitting member engaged therewith through the container open end and for transmitting therefrom to the container sufficient torque to produce effective operation of the cutting means on a consolidated earth formation, the fluid circulating means including the rigidly mounted means.