Abstract: A method for assembling a marine drilling riser includes assembling a predetermined number of sections of the marine drilling riser and extending them into a body of water from a drilling platform. The assembling including affixing a selected number of external line guides to the riser at selected longitudinal positions. The line guides are initially closed to be substantially at most equal a diameter of buoyancy devices on the riser. The line guides are subsequently opened to extend beyond the buoyancy device diameter. A predetermined length of fluid external line is moved to adjacent the assembled riser and the fluid conduit is coupled to the external line guides. The external line guides are locked and assembly of the riser is completed and tension is applied thereto.

Abstract: A subsea mudlift pump includes a pressure sealed housing disposed in a body of water in which a wellbore is being drilled by a drilling rig disposed above the surface of the body of water. A motor (44) is configured to generate linear motion is coupled to at least one piston (46) disposed within the housing such that operation of the motor causes linear motion of the piston within the housing. One side of the piston is within a pumped fluid chamber that changes volume when the piston is moved within the housing.

Abstract: A method for inhibiting an explosive atmosphere in a wellbore drilling system, including a riser (12) connected to a wellbore above a top thereof wherein the riser has a fluid outlet (17) below a surface of a body of water in which the wellbore is drilled, and wherein the fluid outlet is connected to a subsea pump to return drilling fluid to a drilling platform on the water surface and wherein a space in the riser (12) above the drilling fluid level filled with air includes pumping drilling fluid into a drill string (15) extending from the drilling platform into the wellbore. Fluid (27) is introduced proximate an upper end of the riser (12). A rate of introducing the fluid (27) is selected to inhibit an explosive atmosphere in the space in the riser above the drilling fluid level. The subsea pump to remove fluid from the riser outlet is operated at a rate selected to maintain the fluid level or to maintain a selected wellbore pressure.

Abstract: An impeller for a centrifugal pump for pumping fluid containing solid particles includes: a rear side wall; a front side wall; a plurality of vanes located between the rear side wall and the front side wall, each vane having an outer edge and a vane width in an axial direction of the impeller. At least one of a periphery of the rear side wall or a periphery of the front side wall projects by a radial distance beyond the outer edges of the vanes, the radial distance being at least 0.5 times the vane width.

Abstract: There is provided a device and method for control of return flow from a borehole (18) where drill fluid is supplied from a surface rig (16) via a multi section drill string (4) to a bottom hole assembly (18), the drill pipe sections (6) having tool joints (8) that include an enlarged outer diameter portion (9), and where an annulus (12) is formed between a pipe (2) and the drill string (4), and where the annulus (12) is in fluid communication with or forms part of a return path (40) for the drill fluid, and where a choke (1) is positioned in the annulus (12), and where the length (L) of the choke (1) exceeds the distance (M) between the enlarged outer diameter portion (9) of two adjacent tool joints (8).

Abstract: Boost system and method for dual gradient drilling where a marine riser (1) has a mud return line (14) connected at a first connection position (18) below the lowest foreseeable mud level (12) in the marine riser (1), and where a mud return pump (16) is connected to the mud return line (14), and where a recirculation line (20) that has a recirculation pump (22), is connected to the marine riser (1) at a second connection position (24) below the lowest foreseeable mud level (12) in the marine riser (1), and at a third connection position (26) on the marine riser (1) below said second connection position (24).

Abstract: A method and a device for enabling the use of riserless drilling fluid recovery from a seabed-based borehole (1) which is to be drilled by means of a casing (26), the casing (26) being provided with a drill bit (28) at its lower portion and with an inner wellhead (30) at its upper portion, and there being a conductor casing (6), which has an outer wellhead (8), in the seabed (2), the method including: —providing a suction module (12) with a dividable adapter (16) which fits complementarily in the outer wellhead (8); —drilling a length of the borehole (1) by means of the casing (26) extending through the suction module (12), while, at the same time, drilling fluid is flowing via the suction module (12) from the borehole (1); —subsequently pulling the adapter (16) up from the outer wellhead (8) and dividing the adapter (16); and—lowering the casing (26) with the inner wellhead (30) through the suction module (12) and the adapter (16) to its position in the outer wellhead (8).

Abstract: A method and device for establishing a borehole (26) in the seabed (4), comprising setting of a conductor (1), wherein the method is characterized in that it comprises:—providing the conductor (1) with a suction module (6);—then lowering the conductor (1) down to the seabed (4); and—displacing the conductor (1) down into the seabed (4).

Abstract: Boost system and method for dual gradient drilling where a marine riser (1) has a mud return line (14) connected at a first connection position (18) below the lowest foreseeable mud level (12) in the marine riser (1), and where a mud return pump (16) is connected to the mud return line (14), and where a recirculation line (20) that has a recirculation pump (22), is connected to the marine riser (1) at a second connection position (24) below the lowest foreseeable mud level (12) in the marine riser (1), and at a third connection position (26) on the marine riser (1) below said second connection position (24).

Abstract: A method and a device for enabling the use of riserless drilling fluid recovery from a seabed-based borehole (1) which is to be drilled by means of a casing (26), the casing (26) being provided with a drill bit (28) at its lower portion and with an inner wellhead (30) at its upper portion, and there being a conductor casing (6), which has an outer wellhead (8), in the seabed (2), the method including:—providing a suction module (12) with a dividable adapter (16) which fits complementarily in the outer wellhead (8);—drilling a length of the borehole (1) by means of the casing (26) extending through the suction module (12), while, at the same time, drilling fluid is flowing via the suction module (12) from the borehole (1);—subsequently pulling the adapter (16) up from the outer wellhead (8) and dividing the adapter (16); and—lowering the casing (26) with the inner wellhead (30) through the suction module (12) and the adapter (16) to its position in the outer wellhead (8).

Abstract: A method for removing a fluid influx from a subsea wellbore drilled using a pump to return fluid from the wellbore to the surface. The method includes detecting the influx when a rate of the return pump increases. Flow from the wellbore is diverted from the return pump to a choke line when the influx reaches the wellhead. A choke in the choke line is operated so that a substantially constant bottom hold pressure is maintained while drilling fluid continues to be pumped through the drill sgring. Fluid flow from the wellbore is redirected to the return pump inlet when the influx has substantially left the well.

Abstract: A method for inhibiting an explosive atmosphere in a wellbore drilling system, including a riser (12) connected to a wellbore above a top thereof wherein the riser has a fluid outlet (17) below a surface of a body of water in which the wellbore is drilled, and wherein the fluid outlet is connected to a subsea pump to return drilling fluid to a drilling platform on the water surface and wherein a space in the riser (12) above the drilling fluid level filled with air includes pumping drilling fluid into a drill string (15) extending from the drilling platform into the wellbore. Fluid (27) is introduced proximate an upper end of the riser (12). A rate of introducing the fluid (27) is selected to inhibit an explosive atmosphere in the space in the riser above the drilling fluid level. The subsea pump to remove fluid from the riser outlet is operated at a rate selected to maintain the fluid level or to maintain a selected wellbore pressure.

Abstract: A pump module for a drilling riser includes at least one pump mounted to a frame, the frame including features to couple the frame to a segment of riser. A fluid inlet is affixed to the frame. The fluid inlet is in fluid communication with an intake of the at least one pump. The fluid inlet has features to make fluid tight hydraulic connection to a fluid outlet of the riser segment when the frame is coupled thereto.

Abstract: A subsea mudlift pump includes a pressure sealed housing disposed in a body of water in which a wellbore is being drilled by a drilling rig disposed above the surface of the body of water. A motor (44) is configured to generate linear motion is coupled to at least one piston (46) disposed within the housing such that operation of the motor causes linear motion of the piston within the housing. One side of the piston is within a pumped fluid chamber that changes volume when the piston is moved within the housing.

Abstract: An outer rotor of a progressive cavity pump includes at least one inner helical rotor with Z external thread starts and at least one adapted outer rotor with a helical cavity with Z+1 internal thread starts. The at least one outer rotor is assembled from several concentric rotor inserts axially following closely one after another, with helical cavities and Z+1 internal thread starts. Each rotor insert is closely surrounded by and concentrically fixed in a common rigid rotor sleeve. There is detachably connected to the rotor sleeve at least one removable end piece with a principally concentric hollow axially extending through it. The through hollow of the end piece or end pieces forms a gradual transition between a principally circular cross section furthest out and a cross section adapted to the helical cavities of the rotor inserts nearest to them.

Abstract: A particle collector for a dynamic cyclone placed on the ocean bottom for separation of particles in a fluid is described, where the dynamic cyclone comprises a tank (2) which is equipped with an upper inlet opening (25) and an upper and lower outlet opening (26, 32) for outflow of fluid and particles, respectively. Furthermore, the tank comprises a shaft (5) which is equipped with a number of vanes or blades (6) and which is arranged to be driven by an adjoining motor (1), where a centrally placed piece of pipe (4) with a number of slits is arranged around the shaft (5).

Abstract: A progressing cavity pump adapted for pumping of compressible fluids may include an inner rotor having a number of thread-starts together with an adapted stator or outer rotor provided with one extra thread-start. A number of closed pump cavities are formed which are moved, during fluid conveyance, from the inlet side of the pump to the outlet side of the pump, at which position they become open outlet cavities exposed to the fluid pressure in a downstream pipeline. At least one passage is disposed between the outlet side and the closed pump cavity defined closest to the outlet side. The passage is structured for intentional fluid back-flow from the outlet side in a measured and approximately constant volume.

Abstract: A progressive cavity pump includes at least one inner rotor with Z external threads and at least one outer rotor with Z+1 internal threads. The outer rotor has radial bearings at both ends, whereas the inner rotor has a radial bearing only on one side, preferably the inlet side. There is arranged, on the same side as the bearing of the inner rotor, a conventional gear, for example a wheel gear, for maintaining a stable ratio between the rotational speeds of the inner and outer rotors exactly equal to (Z+1)/Z.

Abstract: A method for removing a fluid influx from a subsea wellbore drilled using a pump to return fluid from the wellbore to the surface. The method includes detecting the influx when a rate of the return pump increases. Flow from the wellbore is diverted from the return pump to a choke line when the influx reaches the wellhead. A choke in the choke line is operated so that a rate of fluid pumped into the wellbore is substantially equal to a flow rate through the choke line. Fluid flow from the wellbore is redirected to the return pump inlet when the influx has substantially left the well.

Abstract: A progressing cavity pump comprises at least an inner pump rotor enclosed by at least an outer pump rotor so as to collectively form one or more, in principle, separate pump cavities which, according to known geometric principles, will be moved axially through the pump upon bringing the rotors into coordinated rotation. At least two pump sections are disposed therein, each of which comprises one outer pump rotor and one adapted inner pump rotor. The outer pump rotors of all pump sections are fixedly supported and arranged along the same axis, wherein all the inner rotors are supported in fixed positions relative to a pump casing of the pump. The outer rotors of all pump sections are driven by the same motor via at least one differential arranged to allow each pump section to rotate at a mutually different rotational speed.