Abstract: A method of intervention on the seabed (F) using a free end of one riser (24) originating from a semi-submersible platform (10) designed for producing oil from a deposit, at a number of distinct intervention points (30, 32), includes the following successive steps: tethering the platform (10) to immobilize it in a position floating over the deposit; installing the riser (24) connecting the floating platform (10) to the seabed (F) for intervention at a first intervention point (30); carrying out an intervention at the first intervention point (30); disengaging the free end of the riser (24) from the first intervention point (30), while keeping this end submerged; moving the free end of the riser (24) with respect to the seabed (F) towards a second intervention point (32), while keeping the floating platform (10) in place; and carrying out an intervention at the second intervention point (32).

Abstract: An apparatus and method are provided for controlling hydrostatic pressure in drilling fluid in a subsea well. A main pump forces drilling fluid down the drill pipe, out of the end of the drill pipe, and upward in an annulus surrounding the pipe. A rotating drilling head is attached to a wellhead assembly at the sea floor. The drilling head has an inner body rotatably carried in an outer body landed in a bore of a housing. An energizable gripper in a bore of the inner body grips an outer surface of the drill pipe. The drilling head diverts the drilling fluid into a lateral passage in the sidewall of the housing. An auxiliary pump forces seawater through a venturi into a conduit, creating a lower pressure to draw drilling fluid into the conduit to be carried back to the surface vessel. Pressure and flow rate measurements are sent to a control system that modulates the speed of each pump to control hydrostatic pressure.

Abstract: An undersea drilling template adapted to be lowered onto a seabed by a drillpipe. The template comprises a template base and at least one arm having a releasable clamping assembly for releasably connecting the template to the drillpipe. The clamping assembly is adapted to be clamped to the drillpipe during lowering of the template and release from the drillpipe when the lowering is completed.

Abstract: A floating rig or structure for drilling in the floor of an ocean using a rotatable tubular includes a seal housing having a rotatable seal connected above a portion of a marine riser fixed to the floor of the ocean. The seal rotating with the rotating tubular allows the riser and seal housing to maintain a predetermined pressure in the system that is desirable in underbalanced drilling, gas-liquid mud systems and pressurized mud handling systems. The seal is contemplated to be either an active seal or a passive seal. A flexible conduit or hose is used to compensate for relative movement of the seal housing and the floating structure because the floating structure moves independent of the seal housing. A method for use of the system is also disclosed.

Abstract: A method for assembling and delivering a drivepipe to a drill site, the method having the following steps: assembling the drivepipe and driving mechanism at a shoreline assembly station; attaching floatation devices to the drivepipe and floating the drivepipe in the ocean; towing the drivepipe with tow vessels to a drill site; delivering the drivepipe in a horizontal orientation to a drilling vessel at the drill site; attaching a upper end of the drivepipe to the drilling vessel and detaching the tow vessels from the drivepipe; pivoting the drivepipe about its point of attachment to the drilling vessel until the drivepipe is vertically oriented; deactivating the buoyancy function of the floatation devices attached to the drivepipe; removing the floatation devices from the drivepipe; and lowering the drivepipe with a running string from the drilling vessel to the sea bed.

Abstract: A method for drilling and completing oil wells of small intermediate diameter, in particular for application in ultra deep water. The method includes two drilling and running stages. The first stage of drilling and running provides for drilling the well and running at least first and second casings. The second stage provides for drilling and running at least two and more preferably three suspended liners.

Abstract: A drilling head used to seal around a drill pipe while drilling is employed in a subsea location. The drilling head has an inner body located within an outer body. At least one bearing is located between the outer body and the inner body for facilitating the rotation of the inner body relative to the outer body. A seal mounted to a lower portion of the inner body seals around the outer surface of the drill pipe. While lowering the drilling head to the wellhead, a support attached to the drill pipe is inserted into a skirt which surrounds a portion of the seal. The skirt and support are releasably connected using a J-slot mechanism. An inner annulus and an outer annulus are located between the inner and outer bodies, the annuluses containing a lubricating fluid. Helical vanes are located within the inner annulus and affixed to the inner body. The vanes rotate with the inner body for circulating the fluid through the inner and outer annuluses.

Abstract: A method and apparatus for temporarily storing the lower portion of a string of drill pipe in a well which has a cased portion wherein a packer, installed between a storm valve located below the packer and an actuator located above the packer, is set in the annulus between the drill pipe and the well casing, the actuator being designed to close the valve upon initial axial movement of the upper portion of the drill pipe, and then to become disengaged from the lower portion of the set drill pipe allowing the remaining surface suspended drill pipe and actuator to be retrieved as in the case of a floating drill ship or set aside for reconnection and reopening of the storm valve after a storm has passed.

Abstract: A subsea wellhead assembly located at the sea floor that includes a subsea wellhead and a stationary blowout preventer mounted to the subsea wellhead for controlling a well during drilling. A drill pipe defines an annulus within the stationary blowout preventer. The drill pipe extends to a rotational drive mechanism on a drilling rig at the surface. A drilling head forms a seal against a drill pipe with a rotatable inner portion. The rotatable inner portion rotates with the drill pipe and prevents drilling fluid returns from flowing up the annulus around the drill pipe and prevents drilling fluid returns from discharging onto the seabed. The drilling head is mounted on top of the stationary blowout preventer. A riser extends upward from the drilling head and extends to a floating drilling rig. The riser has a lower end that connects into the drilling head below the drill pipe seal for receiving mud-returns flowing up around the annulus of the drill pipe.

Abstract: There are disclosed a wellhead system and a method for use in drilling a subsea well from a jackup platform which includes a wellhead housing which is installed on a surface casing of a subsea well. A first riser having a connector on its lower end is lowered over the upper end of the housing as the connector to land on the housing, and a second riser is lowered through the first riser and connector over and onto the upper end of the wellhead housing to form an upward continuation of the bore of the housing. The connector has locking parts which are movable between outer unlocking position to permit the second riser to be lowered onto and raised from the wellhead housing, and inner positions for locking engagement with the upper end of the housing and lower end of the second riser. A casing hanger is lowered through the second hanger and into landed position within the housing bore for suspending an inner casing string within the surface casing.

Abstract: A facility or platform (11) having a limited number of circular well-drilling slots (3) is converted to provide additional well-drilling locations on the platform (11) while protecting the platform (11) from the hoisting and lowering loads normally required to drill deep water wells. The additional well-drilling locations are provided by placing multiple wells in individual slots (3). Load protection is accomplished by transferring such loads to a underwater competent earth formation (15) with a thick-walled shroud (12). The shroud (12) surrounding the multiple wells carries at minimum by a plurality of internal centers through which the wells pass for assuring separation of the multiple wells and transmitting loads to the shroud (12).

Abstract: Apparatus and a method for killing a live well after activation of a well blowout preventer is described. This is achieved by providing apparatus in the form of a shear or kill sleeve (34) in a string (26) above a sub-sea test tree and which is located between the pipe rams (22, 24) and shear rams (18) of a blowout preventer (12). In the event that the shear rams (18) are activated and seal the string above the kill sleeve (34), the sleeve includes a pressure sensitive valve (84) which may be opened, by pressurising between the blowout preventer rams (18, 22), to permit fluid to be pumped from the blowout preventer (12) through the valve (84) and into the string (40), to choke or kill the well. After the well has been killed, the blowout preventer (12) may be opened to permit removal of the well tools. Embodiments of the invention are described.

Abstract: A method and apparatus for drilling and completing a bore hole is disclosed. Generally, the method comprises the steps of positioning a workstring in the well, with the workstring having attached thereto a bottom hole assembly. The bottom hole assembly may contain a bit for rotary drilling a bore hole; and, a drilling motor, operably associated with the bit, for effecting rotation to said drilling means. The method further includes the steps of circulating a fluid in the workstring so that the motor effects rotation of the bit means; and, drilling the bore hole through a target reservoir. In one embodiment, the workstring string is a production string, and the production string is attached to an isolation safety valve member for isolating the well and the bore hole from pressure.

Abstract: The present invention relates to an arrangement to be used when drilling oil/gas wells, especially deep water wells, and the invention gives instructions for how to utilise the riser pipe as part of a high pressure system together with the drilling pipe, namely in that the arrangement comprises a surface blowout preventer (SURBOP) which is connected to a high pressure riser pipe (SR) which in turn is connected to a well blowout preventer (SUBBOP), and a circulation/kill line (TL) communicating between said blowout preventers (SURBOP, SUBBOP), all of which being arranged as a high pressure system for deep water slim hole drilling.

Abstract: The present invention relates to a method and to a system for producing hydrocarbons from marginal offshore fields. The invention includes a baseplate (2) fastened to the bottom and a small-size floating support (9) anchored to the baseplate by tendons (10). The baseplate comprises locations (31) for wellheads (7,8) and at least one receptacle (22,32) for a pumping device (21). The floating support comprises hoisting device allowing workover operations in the wells and maintenance operations on the pumping device to be performed.

Abstract: A method and apparatus for drilling and completing a bore hole are disclosed. The method comprises positioning a work string in the well, with a bottom hole assembly attached. The bottom hole assembly can include a drill bit, a drilling motor, orientation instrumentation, and a completion assembly. A fluid is circulated to drive the drill bit to drill the well to a target formation. Then, the completion assembly is used to produce fluids from the formation. Gravel packing can also be performed with the bottom hole assembly.

Abstract: A method and assembly for completing a well is disclosed. Generally, the method comprises the steps of positioning a stationary string in the well at a first position. The stationary string will have connected thereto a completion device for completing the well to a reservoir and a detachment apparatus for detaching the completion device from the stationary string. The method further comprises the steps of positioning a secondary string in the well, with the secondary string having a cooperating detachment apparatus for detaching the completion member from the stationary string. Next, the completion member is detached from the stationary string and attached to the secondary string, and the completion member is positioned at a second position which corresponds to a hydrocarbon zone. In one embodiment, the stationary string is a production tubing string, and the production tubing is attached to an isolation safety valve member for isolating the well from pressure.

Abstract: A dual string high pressure riser system is disclosed for use in drilling a deepwater well through a subsea wellhead. An outer riser extends from the surface and sealingly engages the wellhead and an inner riser extends from the surface downwardly, concentrically through the outer riser to communicate with the well. A surface BOP provides well control at the top of the dual high pressure riser. In another aspect of the present invention, a method is disclosed for conducting deepwater drilling operations in which a surface BOP and a lightweight outer riser are installed in communication with a subsea wellhead and a first interval is drilled through the outer riser. Casing is run through the outer riser into the first interval, cemented within the borehole and sealed at wellhead.

Abstract: An improved subsea template system. A drilling template is adapted to rest on the seafloor. The drilling template includes at least one conductor guide through which a well is drilled. An alignment structure is attached to the top of the conductor guide and fits within a conductor guide of a production template. The production template includes at least one conductor guide more than the drilling template. Once engaged, the alignment sleeve serves to coaxially align the conductor guide of the drilling template with a corresponding conductor guide of the production template.

Abstract: An integrated oil drilling and producing base includes a single guiding funnel for guiding a wet Christmas tree into the proper position on a high pressure well head. The single guiding funnel has a cylindrical downcomer for resting directly on the high pressure well head, at least one cradle on the guiding funnel and at least one pipeline terminal hingedly mounted on said at least one cradle. The guiding funnel has a plurality of slits for allowing passage of a plurality of pipelines therethrough for connection to a respective terminal on the funnel and for connection of each terminal to the wet Christmas tree.

Abstract: A system for turning a swivel aboard a vessel for oil extraction at sea includes a stationary swivel part connected to a rotary drilling rig on the vessel and one or more rotating parts connected to the vessel. The rotating swivel parts are connected to a torsionally rigid vertical frame structure via a drive mechanism which transmits rotary motion between the vessel and the swivel without angular displacement or significant reactive forces in the frame structure. The vertical frame structure includes four walls where one of the walls forms a gate for the insertion and removal of an entire swivel or parts of a swivel. The frame structure is attached to an overhead frame that extends across the diameter of the rotary drilling rig and is secured to the hull of the vessel.

Abstract: A well system, and a method for installing the well system, for use in producing hydrocarbons from a subterranean reservoir located beneath a body of water is disclosed. The well system is intended for use in conjunction with a bottom-founded offshore platform. The inventive well system eliminates the conductors traditionally used in offshore platform well systems. According to the invention, a subsea guide template and an outer casing string extending downwardly from the guide template to a first predetermined depth less than the depth of the reservoir are installed prior to installation of the offshore platform. Thereafter, the platform and the first intermediate casing string are installed, in either order. Drilling for the first intermediate casing string takes place in the open hole defined by the outer casing string with all returns of drilling fluid and drill cuttings occurring at the seafloor.

Abstract: A steerable motor system with integrated formation evaluation logging capacity is presented. The device comprises a housing, a formation resistivity logging tool, a surface signaling device, a density logging tool, a porosity logging tool and a downhole motor and drill. The formation resistivity logging tool is located below the downhole motor and is mounted within the housing wherethrough a drive shaft, extending from the downhole motor, is disposed. Power and signal cables are located within an outer shell of the housing and connect the surface signaling device with the resistivity logging tool. In an alternate embodiment, the resistivity logging tool is located between a motor stabilizer and the drill bit. The present invention allows for increased drill angle during wellbore drilling and formation evaluation.

Abstract: A method of drilling a subsea well involves partial drilling of several wells within a cluster. A base such as a template will have a receptacle. A gimbal mounts to a latching mechanism which in turn releasably latches an outer wellhead housing. The latching mechanism has an upward facing guide funnel. After setting conductor pipe, the well is drilled to a selected depth, an inner wellhead housing and a first string of casing are lowered through the funnel. The running tool for the inner wellhead housing has a funnel retriever which latches to the funnel. After the casing has been cemented, upward movement of the running tool will pull the funnel, latching mechanism and gimbal to the surface.

Abstract: There is disclosed a system for use in drilling subsea wells from platforms wherein drilling fluids may be diverted at either of two levels beneath the rotary table of the platform.

Abstract: A method for drilling offshore wells in deep water with greater safety and with fewer casing strings, maintaining a maximum diameter wellbore in the early stages of drilling to facilitate casing operations in and beyond deviated sections, and providing full well control while setting surface casing. This method utilizes a two-riser system for drilling in which the surface casing interval is run and set within a large diameter, light duty riser. Thereafter, drilling proceeds with a heavy duty riser.

Abstract: A spar-buoy type boring device including a main pipe and a central pipe installed in the main pipe. The main pipe, which has a service deck at the top and a float near the top so that the float stays underneath the water, is anchored at the bottom to a sinker which is placed on the seabed, and the central pipe with the bottom end opening in the sea is used for guiding boring equipments to the seabed and collecting samples from the seabed.

Abstract: A floating/tensioned production system for use in deepwater drilling and production operations generally combining a relatively small tension leg platform with a semisubmersible platform. The semisubmersible platform is provided with a working deck supported above the water surface so that an air gap exists between the working deck and the water surface. The tension leg platform provides a heave-restrained production deck for near-surface wellhead equipment. The production deck is supported above the drill site but beneath the water surface by buoyancy members and held in place by one or more tethers. Most other drilling and production equipment is located on the semisubmersible working deck. A caisson, surrounding the production deck, is used to provide a substantially dry working area. In one embodiment, the caisson is retractably attached to the production deck.

Abstract: Apparatus for performing drilling operations and for servicing an underwater well from a surface installation comprises a main string that is removable from the top of the wellhead in a way that is totally independent of auxiliary hoses which are hoses suspended from the surface installation independently of the main string and at a distance from it, from separate elements making possible the continuous advance of the hoses. The length of the hoses is adjusted in service so that they form, in the water, a plurality of catenaries supported by the surface installation and connected to the top of the wellhead with interposition of curvature-limiting elements.

Abstract: A system is disclosed which may alternatively be used as a diverter or as a blowout preventer for a drilling rig. The system comprises a blowout preventer attached above a spool having a hydraulically driven sleeve/piston. An outlet flow passage in the spool, which may be connected to a vent line, is closed off by the sleeve wall when the spool piston is at rest.Hydraulic ports are connected above and below the blowout preventer annular piston and above and below the spool annular piston. The ports below the blowout preventer piston and above the spool piston are in fluid communication with each other. A hydraulic circuit is provided having two valves between a source of pressurized hydraulic fluid and a drain.

Abstract: A method and apparatus for drilling subsea wells in water depths exceeding 3000 feet (preferably exceeding 4000 feet). Drilling mud returns are taken at the seafloor and pumped to the surface by a centrifugal pump that is powered by a seawater driven turbine. A low-differential pressure rotating head seats in the upper tapered portion of the longitudinal throughbore of an upper stack package which is attached to the top of the blowout preventer stack and seals against the drill string as it is run in and out of the borehole. The method and apparatus of the present invention enable higher mud weights to be used than can be used in conventional techniques which allows kicks to be more easily controlled, fewer casing strings to be run, and overall drilling time reduced by up to 40%.

Abstract: A drilling, production and oil storage caisson for use in deep water offshore well operations in which the caisson has such a deep draft that its bottom end is subject only to minimal excitation forces caused by wave, wind and current acting on the caisson, the caisson including a plurality of oil storage compartments, a plurality of water ballast compartments above said oil storage compartments, a through axial passageway through said compartments; a riser system including a plurality of riser pipes in concentric circular arrangement within the through passageway or center well, each of the riser pipes being supported and tensioned by a buoyant flotation unit connected thereto; a drill string extending axially through said passageway between said riser pipes; and mooring lines connected to the bottom portion of the caisson extending therefrom with relatively low scope of 1:1 or less and providing a small watch circle for anchors for said mooring lines, the mooring lines being tensioned so that the mooring li

Abstract: Conductor guides for use in drilling wells in an offshore body of water wherein the wells are positioned in close proximity one to the other. A first clamping member is removably attached to a well which includes a conductor or well head protruding therefrom. A conductor guide is spaced a predetermined distance from the clamping by means of a connecting beam that extends therebetween. The connecting beam is adjusted to properly position the conductor guide on the ocean floor at a fixed distance and directional relationship with the first conductor.

Abstract: A method for handling an underwater wellhead assembly by means of an offshore jack-up drilling rig or platform wherein the wellhead assembly is prepared on the shore or quay and is carried on the drilling rig to a preselected drilling location and lowered down therefrom to the ocean floor.

Abstract: A method is provided for producing usable hydrocarbon product from an offshore reservoir. The method includes the economically desirable step of producing a valuable hydrocarbon product from the formation, soon after its being discovered. The product is then extracted from its reservoir, long prior to, and during the period when a marine structure is being fabricated and installed to more fully develop the reservoir and to receive a flow of the product.

Abstract: A subsea drilling and production system where the production unit is removably connected onto a drilling template and operatively connected to one or more Christmas trees so that the production unit may be disconnected from the trees and removed from the template without first removing any of the trees and so that any of the trees may be disconnected from the production unit and removed from the underwater site without removing the production unit.

Abstract: A remotely releasable pipe connector is described and comprises a first tubular connector or "pin connector" having at least one laterally extending locking member, and a slotted second tubular connector or "box connector" cooperatively disposable over the first tubular connector with the slots thereof removably engaging the first tubulars connector's locking members. One or more shear plates are attachable to the second tubular connector and are positioned to prevent the release of the locking members from the slots in the second tubular connector until the shear plates are subjected to a force greater than or equal to a predetermined force.

Abstract: The subsea wellhead system includes a wellhead, a housing seat disposed in and connected to the wellhead, a casing hanger supported by the seat, a holddown and sealing assembly in the annulus between wellhead and hanger, a running tool attached to the hanger for lowering it into the well and initially actuating the holddown and sealing assembly, and apparatus for applying hydraulic pressure to further actuate the seal. The housing seat and wellhead are connected by breech block teeth. The seat maintains 360.degree. bearing surface with the hanger. The holddown and seal assembly includes an upper rotating member threadingly engaging the hanger and suspending a lower stationary member. The latter includes a Z-shaped portion having a plurality of frustoconical metal rings positively connected by links. The rings form grooves housing resilient elastomeric members.

Abstract: A development and production facility for an offshore oil or gas field is constructed and drilling of wells is performed using a jack-up drilling platform in an improved manner. The facility is composed of a development well platform and a production platform, each of which is composed of a modular prefabricated unitary deck assembly of substantially turn-key completeness and of a prefabricated jacket or leg assembly to which the deck assembly is matable. Crane or derrick barges are used only to position the deck assemblies on the leg or jacket assemblies after the latter assemblies have been placed erect on and secured to the sea floor by use of the jack-up platform. The development well platform is constructed first so that drilling of development wells can be performed from the jack-up platform through the former platform concurrently with the placement and completion of the production platform.