NO20231271A1 - External, removable cementing adapter for managed pressure cementing and a method of managed pressure cementing - Google Patents

Description

EXTERNAL, REMOVABLE CEMENTING ADAPTER FOR MANAGED PRESSURE CEMENTING AND A METHOD OF MANAGED PRESSURE CEMENTING

Technical Field

[0001] The present invention relates to offshore wells cementation typically to produce hydrocarbons in the technical field of oil and gas well development, to facilitate broader functionality and re-use of equipment.

[0002] More specifically the invention relates to so-called tophole Managed Pressure Cementing (MPC), used to control the well bore pressure within operational pressure windows during cementing operations for tophole applications. Tophole refers to operations prior to installing the high-pressure wellhead.

Background Art

[0003] MPC is used to control pressure during cementing operations. Most often to mitigate annular friction pressure and increased static pressure during cement displacement.

[0004] MPC enables cementing in over-pressurized wells and for cementing in tight/narrow pressure windows, which would be challenging with conventional technology.

[0005] During MPC, pressure control is achieved by introducing an adapter on the outside of the cement ports in the conductor housing. A subsea pump is fluidly connected to the adapter which enables regulation of the pressure in the well during cementing. Control of the pressure ensures the integrity of the cement on the outside of the casing, by keeping the pressure within the operational pressure window from when the cement is first pumped until it is cured or hardened.

Pressure can either be increased, typically in curing, or reduced, typically when displacing.

[0006] The main benefits of MPC, in addition to improving cement integrity, are that it reduces cost by improving casing running and cementing conditions, such as increased flow capacity and reduces the need for additional cement “top-ups” and hence time.

[0007] MPC is for instance disclosed in US 9,249,646, describing a method of cementing a tubular string in a wellbore. The cement slurry is pumped through the tubular string and into an annulus formed between the tubular string and the wellbore. Flow of fluid displaced from the wellbore is controlled by the cement slurry to control pressure of the annulus.

[0008] During MPC operations, MPC equipment is fluidly connected to the cement ports on a low-pressure wellhead. MPC operations to date have mainly been performed in connection with Riserless Mud Recovery. Pressure integrity of the fluid path from the cement ports on the low-pressure wellhead to the pump, has either been achieved by pre-attaching fixtures to the outside of the cement ports topside, or by using a sleeve arrangement on the bottom of the Suction Module (SMO) used for RMR (Riserless Mud Recovery). The two setups result in different challenges.

[0009] Referring to the above, challenges with having pre-attached cement ports are e.g., that it requires machining and assembly on the conductor housing prior to installation and that a substantial amount of hardware is installed and left on the subsea infrastructure after the cementing job has finished, resulting in MPC being cost intensive both in operational time and hardware cost.

[0010] Referring to the above, challenges with having cement ports as part of the SMO is that the cement ports need to be sealed above and below the outer radius of the Well Head (WH) to prevent leaks between the SMO and the conductor housing. As the SMO is installed vertically onto the WH, and the seals need to seal axially against the outer surface of the conductor housing, several challenges occur in order to have a seal that is leak tight once installed; in a first aspect, to create a seal between the SMO and the WH it is required to have a very smooth surface on the WH. This requires pre-installation machining of the conductor housing surface; in a second aspect, the surface can be damaged during handling; in a third aspect, there can be particles or biological substances growing on the surface, rendering the smoothness to be insufficient; in a fourth aspect, the O-ring seals that are used in the prior art application are sensitive and easily damaged, especially as the adapter at the bottom of the SMO is sliding onto the WH, with the O-rings being scratched against the WH surface during the vertical movement.

[0011] When using an MPC system with O-rings, there is an uncertainty whether the seal integrity is intact after installation as there is no way of testing it without pressurizing the bore itself.

[0012] There is a wide range of variants and dimensions of conductors and wellheads, leading to a wide range of unique designs of MPC equipment to fit to each variant.

[0013] When the cement is circulated in place in the well, it is required to flush the MPC system immediately to prevent the cement from curing in the equipment. Depending on the formation characteristics, it might be desired to have either higher or lower than ambient pressure in the cementing port annulus during the flushing operation, to achieve optimal conditions for the cement as it settles.

Ambient pressure refers to the sea-water pressure at the outside of the cement ports. This cannot be achieved with today’s MPC technology for retrievable adapters, where only ambient pressure can be achieved.

Summary of invention

[0014] It is a purpose of the present invention to maintain all the benefits of ordinary MPC while reducing the hardware cost by increasing the flexibility and allowing the hardware to be removed and reused.

[0015] It is an aim with the present invention to fit several different variants of conductors and wellheads by providing expanding seals that are flexible and that do not interface directly with cement ports of the conductor housing.

[0016] It is also an objective to provide a cementing adapter adopted for well head surfaces and conductor housings which are not necessarily prepped for MPC.

[0017] It is also an objective to be able to flush MPC hardware clear of cement whilst maintaining a pressure at the top of the well that is lower or higher than ambient pressure, for MPC operations where it is desired to let the cement cure with a pressure at the top of the cement that is higher or lower than ambient pressure.

[0018] In the context of this patent, an energized seal is defined as a seal that can either be expanded from energy added inside the seal, or a seal that can be deformed from an external force.

[0019] The present invention thus concerns an external, removable cementing adapter for MPC of wells. The adapter includes at least one external cementing adapter with an inside and an outside. The at least one external cementing adapter is adapted to surround a conductor housing with conductor housing ports. At least one first cementing port and at least one second cementing port are formed in the at least one external cementing adapter. At least one of a lower seal and an upper seal is adapted to seal between the external cementing adapter and the conductor housing with conductor housing ports. A radial seal pressure mechanism includes at least one of a force applying brace and at least one expanding seal.

[0020] At least one upper seal may be located above the conductor housing ports and at least one lower seal may be located below the conductor housing ports.

[0021] The least one of the upper seal and the lower seal may be an energized expanding seal.

[0022] The at least one energized seal may be an inflatable seal.

[0023] When the radial seal pressure mechanism includes at least a force applying brace, may the force applying brace include at least two parts.

[0024] The at least one energized seal may be a seal that seals by compression, where the compression comes from an external force on the at least one cementing adapter.

[0025] The external, removable cementing adapter may include at least two energized upper seals above the conductor housing ports and at least two energized lower seals below the conductor housing ports. A first seal integrity port may be located between the two upper seals above the conductor housing ports, and a second seal integrity port may be located between the at least two lower seals below the conductor housing ports whereby the seal integrity of each pair of seals above and below the conductor housing ports may be tested by applying pressure to the seal integrity ports.

[0026] The at least one of a lower seal, and an upper seal may be adapted to seal between the external cementing adapter and a conductor housing with an outer diameter within a range, allowing the external, removable cementing adapter to be used for a range of conductor housings.

[0027] The external, removable cementing adapter may be a cementing seal brace including a plurality of individual brace elements, whereof at least two brace section elements include a cementing port with a cementing port flange, a brace element seal surrounding a brace element cavity of each of the at least two brace section elements with a cementing port adapted to surround conductor housing ports of a conductor housing.,.

[0028] Each brace element may be hinged to an adjoining brace element with a hinge, and at least one of the hinges may be releasable, forming a brace locking element.

[0029] The at least one inflatable seal may include an expandable and inflatable sealing ring with an inner cavity, which may have a rear seal base side and a front, ribbed, lip element opposing the rear seal base side.

[0030] The expandable and inflatable sealing ring may include a cross-section configured to adopt a folded, uninflated, retracted configuration and an unfolded, inflated expanded configuration, whereby the shape of the cross-section transforms in the transition between the retracted configuration and the expanded configuration.

[0031] At least one first cementing port may be connected to at least one first cementing port valve and a source of flushing fluid, and at least one second cementing port may be is connected to at least one second cementing port valve, whereby the adapter is adapted to allow flushing of a cavity between the external cementing adapter and the conductor housing, through the at least one first cementing port and the at least one second cementing port.

[0032] The external, removable cementing adapter may furthermore include a pressure control unit that in combination with the pumps allows for controlling the pressure and the flow rate of the flushing fluid inside the cement adapter.

[0033] The pressure control unit may include pressure drop element.

[0034] The pressure drop element may include at least one of a nozzle, a choking arrangement, a set of valves in a manifold that allows varying between pipes with equal or varying diameters and a length of hose or pipe.

[0035] The pump arrangement may include a valve and pipe arrangement to allow flushing both in the direction from the WH towards the pump and in the opposite direction, from the pump towards the WH.

[0036] Furthermore, the invention relates to use of the external, removable cementing adapter as described above on one of a subsea well and a land based well.

[0037] Furthermore, the invention concerns a method of performing managed pressure cementing of a well with an external, removable cementing adapter for MCP as described above. The method includes the steps of installing the at least one external cementing adapter onto the conductor housing with the conductor housing ports, connecting the at least one first cementing port to at least one first cementing port valve, connecting the at least one second cementing port to at least one second cementing port valve, cementing the well while managing the pressure in the at least one external cementing adapter, flushing the at least one external cementing adapter with a flushing fluid from a source of flushing fluid connected to the at least one first cementing port valve while managing the pressure in the at least one external cementing adapter to remove cement; and removing the external, removable cementing adapter.

[0038] The method of cementing a well may further include installing the removed the external, removable cementing adapter onto a new conductor housing and repeating the steps described above.

Brief description of drawings

Figure 1 is a schematic representation of a prior art setup of an MPC system where the cement ports are permanently attached to the WH;

Figure 2 is a schematic representation of a prior art setup of an MPC system where the cement ports are part of the SMO assembly;

Figure 3 is a schematic representation of a setup of an MPC system including the invention;

Figure 4a shows a detailed schematic of inflatable seals and WH surfaces;

Figure 4b shows detailed cross-sections of an inflatable seal in different stages;

Figure 4c shows a first detailed embodiment of an inflatable seal arrangement;

Figure 4d shows a second detailed embodiment of an inflatable seal arrangement;

Figure 4e shows a third detailed embodiment of an inflatable seal arrangement;

Figure 5a shows a detailed schematic of an inflatable seal arrangement where the seal inflation energy source is part of the seal module;

Figure 5b shows a detailed schematic of an inflatable seal arrangement where the seal inflation energy source is external to the seal module;

Figure 6 shows a cross-sectional view of a cementing adapter assembled to a WH.

Figure 7a shows a conceptual representation of the assembly of a external, removable cementing adapter split into separate parts in the open position;

Figure 7b shows a conceptual representation of the assembly of an external, removable cementing adapter split into separate parts in the closed position;

Figure 8a shows a conceptual representation of the assembly of an external, removable cementing adapter split into individually hinged parts in the open position;

Figure 8b shows a conceptual representation of the assembly of an external, removable cementing adapter split into individually hinged parts in the closed position;

Figure 8c shows a design example of an external, removable cementing adapter with individually hinged parts;

Figure 9 is a schematic representation of a setup of valves and flow path to enable flushing of an external, removable cementing adapter with reduced pressure in the annulus; and

Figure 10 is a schematic representation of a setup of valves and flow path to enable flushing of an external, removable cementing adapter with increased pressure in the annulus.

Detailed description of drawings

[0039] Figures 1 and 2 show the prior art.

[0040] Figure 1 shows a combined Riserless Mud Recovery (RMR) and MPC system where the first cement port 38 and second cement port 39 are permanently attached to the conductor housing 1. There may be one or more first cement port(s) 38 and one or more second cement port(s) 39 for operational purposes. In a setup with more than one first cement port 38, they are typically joined to each other with a piping arrangement on the outside of the WH to allow for different flow paths in case of clogging of any of the ports. The same applies in case of one or more second cement port(s) 39. An inner annulus 10 between typically a 91,5cm (36”) conductor housing 1 and a 63,5cm (25”) surface casing 25 may be cemented while the cementing pressure is managed by using a pump 20. The applied pressure at top of the annulus 10 while running the cement job may be above or below the ambient pressure, depending on the operational conditions. The conductor housing 1 has conductor housing ports 2 which allow fluid to flow from the inner annulus 10 and out through the first cementing port 38. The cementing port valves 40 and 41 are typically 15cm (6”) ball valves. The SMO 11 together with the line 12 and isolation valve 54 are only used in RMR operations and are not relevant for this invention. The first cementing port valve 40 and the first cementing port 38 are in fluid communication with the pump 20 through a suction hose 17. A pressure transmitter 55 measures the pressure at the outlet. A seal 26 (Fig. 2) seals between the conductor housing 1 and the surface casing 25. A return conduit 21 reaches from the pump 20 to a topside arrangement (not shown) to allow drilling mud and cement to return to the surface. A pump inlet line 19 connects the suction hose 17 to the pump 20. An isolation valve 57 on the pump inlet line 19 allows control of fluid going into the pump 20. A pressure transmitter 60 measures the pressure in the Pump inlet line 19 going into the pump 20. A pressure transmitter 67 measures the pressure in the pump outlet line 22. A valve arrangement 61 and 66 allows for selection of fluid return either to topside via a return hose 21 or to sea via a separate outlet 65.

[0041] Figure 2 shows a version of MPC where the SMO 111 is equipped with an additional MPC cementing adapter underneath. There may be a flange between the SMO 111 and the MPC cementing adapter, or they may be one unit. The sealing assembly consists of a lower O-ring 68 and an upper O-ring 69, together with two cement port isolation valves 40, 41. As the SMO 111 is landed on top of the WH 13 (see fig.3), the MPC sealing assembly slides onto the outside of the conductor housing 1, ending up in a position where the lower O-ring 68 is below the conductor housing ports 2 in the conductor housing 1, and the upper O-ring 69 is above the conductor housing ports 2. The upper O-ring 69 and the lower O-ring 68 form a barrier between the cement port annulus 14 and the surrounding water, ensuring that there is no mud or cement leakage to sea. The weldment 16 in the conductor housing is pre-machined to sufficient surface smoothness for the O-ring seals to seal.

[0042] Figure 3 shows a schematic of an MPC system including an embodiment of the present invention. The SMO 211 has a modular design, allowing for a separate, removable cementing adapter 109 to be attached to the SMO 211 via an SMO cementing adapter interface 18 if needed. The cementing adapter 109 may also be used without the SMO 211. A first cement port 3 and a second cement port 4 allow flow in and out of the cementing port annulus. There may be one or more first cement port(s) 3 and one or more second cement port(s) 4 for operational purposes. In a setup with more than one first cement port 3, they are typically joined to each other with a piping arrangement on the outside of the cementing adapter 109 to allow for different flow paths in case of clogging of any of the ports. The similar applies in case of one or more second cement port(s) 4. At least one first cement port valve 5 is located on the line from the first cementing port 3 and at least one second cement valve 6 is located on the line from the cementing port 4. An upper seal 8 and a lower seal 7 are inflatable and ensure sealing integrity of the cement port annulus 14. A pressure transmitter 56 is connected to the cement port line 23, reading the pressure at the outlet of the cement port annulus 14. Pressure transmitters 55 and 56 are used to measure the difference in pressure in the cement port line 23 depending on the position of the first cement port valve 5. A pressure transmitter 51 is connected to the cement port line 53, reading the pressure just outside the cement port annulus 14. Another pressure transmitter 50 is connected to the cement port line 53, on the opposite side of the second cement port valve 6 in relation to the pressure transmitter 51. Pressure transmitters 50 and 51 are used to measure the difference in pressure in the cement port line 53 depending on the position of the second cement port valve 6. A pressure control unit 42 is connected to the cement port line 53. A flushing water inlet/outlet 46 is connected to the pressure control unit 42. A seal energizing unit 52 is connected to the cementing adapter 109. The combination of the seal energizing unit 52 and the inflatable seals 8, 7 form the radial seal pressure mechanism. On the outside surface of the conductor housing 1 there is normally a taper 73 where the conductor housing 1 OD goes from larger in the upper part of the conductor housing 1 to smaller in the lower part of the conductor housing 1. A back flush loop line 63 is connected between the pump outlet line 22 and the pump inlet line 19. An isolation valve 62 allows the back flush loop line 63 to be open or closed. A sea water inlet line 59 is connected to the Pump inlet line 19 via an isolation valve 58, to allow sea water to be pumped for flushing purposes. On the pump outlet line 22 there is a sensor unit 64, which may be a flow meter, PH meter or any other type of sensor.

[0043] Figure 4a shows a cementing adapter 109 mounted to a conductor housing 1. The cementing adapter 109 has an upper dual upper seal 81 and a lower dual upper seal 82 in position above the conductor housing ports 2. An upper dual lower seal 71 and a lower dual lower seal 72 are in a position below the conductor housing ports 2. A first alternative position for the lower dual lower seal is shown as 72a where it is in a position on the taper 73 on the conductor housing 1. A second alternative position for the lower dual lower seal is shown as 72b where it is in a position below the taper 73 on the conductor housing 1, where the OD of the conductor housing 1 is smaller than above the taper 73. A seal energizing unit 52 is connected to the cementing adapter 109.

[0044] Figure 4b shows an example of cross-sections of an expandable and inflatable sealing ring 30. A folded, uninflated, retracted configuration 30a and an unfolded, inflated and fully expanded configuration 30c are shown. When energized, the shape of the cross-section transforms from the retracted configuration 30a to the expanded configuration 30c. An intermediate stage is also shown 30b.

[0045] Figure 4c shows a detailed example of the above-described inflatable seal profiles where the four seals 81, 82, 71 and 72 are attached to a cementing adapter 109 with a cement port line 53. The cementing adapter 109 is mounted to a conductor housing 1 on the outside of surface casing 25. All four seals 81, 82, 71 and 72 seal against the same conductor housing 1 OD. Dual seals are created both above and below the conductor housing ports 2. All four seal profiles are shown as partly inflated 30b.

[0046] Figure 4d shows a detailed example of such above-described inflatable seal profiles where the four seals 81, 82, 71 and 72a are attached to a cementing adapter 109 with a cement port line 53. The cementing adapter 109 is mounted to a conductor housing 1. Both upper dual seals 81 and 82 and the upper dual lower seal 71 seal against the same conductor housing 1 OD. The lower dual lower seal 72a seal against a taper 73 on the conductor housing 1. Three seal profiles are shown as partly inflated 30b and one seal profile is shown as fully inflated 30c. Dual seals are created both above and below the conductor housing ports 2.

[0047] Figure 4e shows a detailed example of such above-described inflatable seal profiles where the four seals 81, 82, 71 and 72 are attached to a cementing adapter 109 with a cement port line 53. The cementing adapter 109 is mounted to a conductor housing 1. Both upper dual seals 81 and 82 and the upper dual lower seal 71 seal against the same conductor housing 1 OD. The lower dual lower seal 72b seal against a surface below the taper 73 on the conductor housing 1. The conductor housing 1 OD is smaller than above the taper 73. Three seal profiles are shown as partly inflated 30b and one seal profile is shown as fully inflated 30c. Dual seals are created both above and below the conductor housing ports 2.

[0048] Figure 5a shows an example of an inflation/deflation arrangement where there is a seal energizing power source 524 that does not require ROV intervention. The seal energizer power source 524 may e.g., be an accumulator or an umbilical to surface. Both dual upper seals 81 and 82 and both dual lower seals 71 and 72 have ports 532a-d in the cementing adapter 109. Each port 532a-d is connected to a line 533a-d, which is fitted with a pressure transmitter 522a-d and an isolation valve 521a-d. Each isolation valve 521a-d is connected to the seal energizer line header 544. The seal energizer power source 524 is connected to the seal energizer line header 544 via a line 528 which is fitted with a pressure transmitter 523 and a valve 525. Between the dual upper seals 81 and 82 an upper dual seal cavity 526 is formed towards the conductor housing 1. Between the dual lower seals 71 and 72 a lower dual seal cavity 527 is formed towards the conductor housing 1. The upper dual seal cavity 526 and the lower dual seal cavity 527 have ports 532e-f in the cementing adapter 109. Each port 532e-f is connected to a line 533e-f, which is fitted with a pressure transmitter 522e-f and an isolation valve 521e-f. Each isolation valve 521e-f is connected to the seal energizer line header 544. The isolation valves 521a-f can be manipulated to pressurize each individual seal or seal cavity as desired. The pressure transmitters 522a-f are used to monitor each line individually. The pressure transmitter 523 shows available pressure in the seal energizer power source 524.

[0049] Figure 5b corresponds to fig.5a, with the only difference that the seal energizing power source to form a part the radial seal pressure mechanism is part of an ROV. An ROV stab receptacle 529 is connected to the line 528. An ROV 531 with an ROV stab 530 provides seal energizing power by engaging the ROV stab 530 in the ROV stab receptacle 529.

[0050] In an alternative embodiment (not shown) may each of the lines 533a-f be connected to individual ROV ports.

[0051] Figure 6 shows a cross-section of a cementing adapter 109 in position on a conductor housing 1. An inner annulus 10 is formed between the surface casing 25 and the conductor housing 1. The conductor housing has four conductor housing ports 2a-d which connect the inner annulus 10 with the cement port annulus 14. The cement port annulus 14 is formed between the conductor housing 1, the cementing adapter 109, an upper seal (not seen in this cross-section) and a lower seal (not seen in this cross-section). The cementing adapter 109 has two cementing ports 3, and 4.

[0052] Figure 7a is a schematic representation of a split version of a cementing adapter 209 in open position with split section elements 132 and 136. A split version of a cementing adapter 209 may have two or more split sections elements 132 and 136. There may be one or more split section seal elements 135 and 137 to seal towards the casing housing 1. Two or more split section locking elements 134 and 138 are used to lock the split section elements 132 and 136 to each other in position on the casing housing 1.

[0053] Figure 7b shows the split version of a cementing adapter 209 as described above, but in closed position.

[0054] Figure 8a is a schematic representation of a brace version of an external, removable cementing adapter 309 in an open position. The cementing adapter includes brace elements. A brace version of the cementing adapter 309 may have two or more brace sections elements 32 and 36. The brace section elements 32 and 36 are joined together by one or more hinges 33. There may be one or more brace section seal elements 35 and 37 to seal towards the casing housing 1. One or more brace section locking elements 34 are used to lock the brace section elements 32 and 36 to each other in position on the casing housing 1. The radial seal pressure is provided by imposing a force on the brace section elements 32 and 36 when they are locked in position on the casing housing 1

[0055] Figure 8b shows the brace version of a cementing adapter 309 as described above, but in closed position.

[0056] Figure 8c shows an example of an external, removable cementing adapter in the form of a brace 409 of a further embodiment of the invention. Each of four arch shaped individual brace section elements 32 include a cementing port with a cementing port flange 37 and a brace element seal 35 surrounding a brace element cavity adapted to surround conductor housing ports. The brace element cavities are arch shaped and are formed between each arch shaped individual brace element seal 35 and the outer surface of the conductor housing when the removable cementing adapter in the form of a cementing seal brace 409 is installed. A brace locking element 34 is used to lock the two ends of the interjoined hinged brace section elements 32 to each other. When the cementing seal brace 406 is installed on a conductor housing, the brace elements seals 35 form a fluid tight seal between the individual brace section elements 32 and the conductor housing outer surface.

[0057] Figure 9 shows a setup of the invention as shown in Figure 3, allowing pressure in the cement port annulus 14 to be reduced below ambient. For clarity, only selected relevant items are shown with item numbers. Isolation valves 54, 58, 62 and 66 are shown as closed. Isolation valves 5, 6 and 61 are shown as open. The flow path is visualized by a fat line and arrows show the flow direction.

[0058] Figure 10 shows a setup of the invention as shown in Figure 3, allowing pressure in the cement port annulus 14 to be increased above ambient. For clarity, only selected relevant items are shown with item numbers. Isolation valves 54, 57, 61 and 66 are shown as closed. Isolation valves 5, 6, 58 and 62 are shown as open. The flow path is visualized by a fat line and arrows show the flow direction. A line 63 from the outlet side of the pump 20 to the inlet side allows fluid to be pumped back towards the cementing port annulus 14. A sea water inlet line 59 allows water to be sucked into the pump 20.

Detailed description of the invention

[0059] In a first aspect of the invention as shown in Figure 3, the removable cementing adapter 109 is a separate unit that may be assembled separately on the WH 13. The SMO 211 is present in the setup, but the invention is also relevant for solutions without a SM 211. The removable cementing adapter 109 may be installed on the conductor housing 1 prior to the subsea installation of the conductor housing 1 on the seabed. Alternatively, the cementing adapter 109 may be installed in situ in many ways, such as with an ROV in the event of a subsea installation. Alternatively, the cementing adapter 109 may be a modular assembly which may be part of the SMO 211 and installed onto the WH 13 together with the SMO 211. The upper seal 8 and the lower seal 7 in the cementing adapter 109, together with the conductor housing 1, form a cement port annulus 14. See Figure 6 for a cross-sectional view of how the inner annulus 10 and the cement port annulus 14 are formed.

[0060] In a second aspect of the invention, as shown in Figure 4a, the cementing adapter 109, is a part of the SMO 211. The cementing adapter may also be a separate unit. In fig.4a, the cementing adapter has dual upper seals 81 and 82 instead of a single upper seal and dual lower seals 71 and 72 instead of a single lower seal. The dual upper seals 81 and 82 and the dual lower seals 71 and 72 may all be inflatable. The dual upper seals 81 and 82 and the dual lower seals 71 and 72 may alternatively compressible. The dual upper seals 81 and 82 and the dual lower seals 71 and 72 may be energized/de-energized using a seal energizing unit 52. A first benefit of using inflatable seals is that the surface of the actual seal can be in a retracted position when the cementing adapter 109 is moved into position, hence reducing the risk of the seals being damaged from interaction with objects such as e.g., the conductor housing 1. A second benefit is that inflatable seals can seal against a wider range of conductor housing ODs, as a sealing effect is achieved both when the seal is partly inflated as well as when it is fully inflated. This is useful as the same cementing adapter 109 can be used on different diameter WHs, reducing the need for unique designs of MPC equipment. A third benefit is that inflatable seals are less sensitive for the surface smoothness on the outer surface of the conductor housing 1, removing the requirement for conductor housing surface machining which is necessary for the prior art system.

[0061] An additional benefit from the ability to seal against a range of conductor housing ODs is that it becomes less sensitive to where on the conductor housing outside surface the seals engage. As shown in Figure 4a, a conductor housing 1 normally has a taper 73 where the OD goes from a larger dimension to a smaller dimension further down towards the seabed. This taper can be in different positions depending on the design of each conductor housing 1. If a seal is in a position e.g., where there is a taper 73, or below a taper 73, where the conductor housing 1 OD is smaller than above the taper 73, it would still be able to create a seal. Figure 4d shows a schematic representation of a scenario where the design of the conductor housing 1 is such that the lower dual lower seal ends up in a position 72a on the taper 73 while both dual upper seals 81 and 82 and the upper dual lower seal 71 are in a position above the taper 73. Similarly Figure 4e shows a schematic representation of a scenario where the design of the conductor housing 1 is such that the lower dual lower seal ends up in a position 72b below the taper 73 where the conductor housing OD is smaller than above the taper 73, while both dual upper seals 81 and 82 and the upper dual lower seal 71 are in a position above the taper 73. Due to the inflatable design of the seals, they will make a leak tight seal regardless of whether it is towards a cylindrical surface or towards a taper 73.

[0062] Figure 5a shows a setup that may be used to achieve the second aspect of the invention. To energize e.g., the upper dual upper seal 81, isolation valves 521b-e are closed. Isolation valves 521a and 525 are opened to let fluid pass from the seal energizing power source 524 into the upper dual upper seal 81. When a defined pressure is read on the at least one pressure transmitter 522a, the seal is fully energized. To test the integrity of the upper dual upper seal 81 inflation itself, isolation valve 521a is closed and pressure transmitter 522a is monitored to see if the pressure falls or not. Similarly, the other seals 82, 71 and 72 can be pressurized and integrity tested by opening/closing isolation valves 521b-d while monitoring pressure transmitters 522b-d. A pressure transmitter 523 shows what pressure is available in the power source 524. As shown in Figure 5a the space between the dual upper seals 81 and 82 form an upper dual seal cavity 526 the space between the dual lower seals 71 and 72 form a lower dual seal cavity 527. A benefit having dual upper seals and dual lower seals is that the integrity of the upper seal cavity 526 and the lower dual seal cavity 527 can be tested. To test the integrity of the upper dual seal cavity, isolation valves 521a-d and isolation valve 521f are closed. Isolation valve 521e is opened to let fluid pass from the seal energizing power source 524 into the dual upper seal cavity 526. When the desired pressure is read on pressure transmitter 522e, the isolation valve 521e is closed and pressure can be monitored on pressure transmitter 522e to see if the pressure falls or not. Similarly, the lower dual seal cavity can be pressurized, and integrity tested by opening/closing isolation valve 521f while monitoring pressure transmitter 522f. The energizing medium can be gas, water, or any other suitable fluid. The energizing power source 524 may be e.g., an accumulator, a pump, or an umbilical to topside. Pressure transmitters 522a-f may be one or more pressure transmitters.

[0063] Figure 5b shows a different example of an inflation/deflation arrangement. The difference from Figure 5a is that the energizing unit 531 is a non-stationary unit such as e.g., an ROV that is be equipped with an energizing unit such as a pump, utilizing a medium e.g., sea water or a reservoir with a desired fluid or gas to energize/de-energize and test the inflatable seals 81, 82, 71 and 72 and to test the dual seal cavities 526 and 527. The ROV may interface the seal energizing line header 544 via a stab 530/stab receptacle 529 interface. The functionality is as described above in Figure 5a with the only difference that the energizing unit is located in an ROV. A person skilled in the art recognizes that the stab arrangement and the isolation valves as shown in Figure 5a and Figure 5b can be combined to guide flow to different parts of the system.

[0064] In a third aspect of the invention, as shown in principal sketches in Figures 7a (open position) and 7b (closed position), a cementing adapter 209 may as a first version be split, to allow it to be mounted to the conductor housing 1 radially. There may be two or more elements comprising the split version cementing adapter 209. Each split element may have at least one seal above the conductor housing ports and at least one seal below the conductor housing ports. The split version cementing adapter 209 is mounted to the conductor housing 1 so that the sealing elements 135 and 137 are surrounding the conductor housing ports 2, each creating a cement port annulus 14 (see fig.6). A split design includes seals that may be inflatable, or they may be compressible. In the split version, a cementing adapter 209 design with compressible seals, makes it possible to use a wider range of materials, compared to the O-rings currently used in the prior art, which are quite rigid to seal towards the same surface as they are slid over when the SMO including seals is mounted axially onto the WH. As the split version cementing adapter 209 can be applied a radial force when closing the split parts, the sealing function can easier be controlled and can seal on rough surfaces. To close the split version cementing adapter 209, the split brace section elements 132 and 136 are moved towards each other with the conductor housing 1 in between. The split section locking elements 134 and 138 are used to lock the split brace section elements 132 and 136 to each other. The split section seal elements 135 and 137 create a seal towards the conductor housing 1.

[0065] In a second embodiment of the third aspect of the invention, as shown in in the schematic representation of fig.8a (open position) and 8b (closed position), the cementing adapter 309 is hinged to allow it to be mounted to the conductor housing 1 radially. The individual parts and functionality of a hinged version cementing adapter 309 may be similar to the split version cementing adapter 209, the main difference being that two or more hinged brace section elements 32 and 36 are pre-connected to each other through one or more hinges. The hinged version cementing adapter 309 is mounted to the conductor housing by using a brace element locking element 34 to lock the open end of the hinged section elements to each other with the conductor housing 1 in between. Figure 8c shows an embodiment of such a hinged version cementing adapter 409.

[0066] A fourth aspect of the invention as shown in Figure 9. When the cement is in place in the well, the MPC equipment needs to be flushed with sea water to remove all remaining cement inside the MPC equipment to prevent occurrence of cured cement inside the equipment. The different components of the invention can be configured so that it is possible to achieve a pressure lower that ambient pressure when flushing the components after cementing. This is important as it may be desired to keep a pressure below ambient pressure until the cement has cured. A pressure control unit 42 is connected to the cement port line 53 coming from the cementing port 4. The main purpose of the pressure control unit 42 is to create a pressure lower than ambient pressure when pumping to flush the MPC equipment in the direction shown in Figure 9. This functionality enables operational conditions that are beneficial to the cement curing process in certain well conditions, compared to what is achievable in the prior art. To achieve the desired flow path, isolation valves 54, 58, 62 and 66 are closed while isolation valves 5, 6, 57 and 61 are opened. When using the pump 20 with this valve setup, the pressure control unit 42 acts like a restriction, making the pressure drop in the cement port annulus 14. Such pressure control unit 42 includes flow control elements with at least either valves, nozzles, flow restrictions and/or pumps. In a simple form the pressure control unit 42 is a piece of hose/pipe to create a pressure drop when operating the pump to create suction in the cement port 3. The flushing water inlet 46 would then be the inlet of the hose/pipe. Alternatively, a choke or valve manifold may be used to produce a pressure drop and to form the pressure control unit 42. The pressure control unit 42 may thus be a fixed unit controlling the pressure drop typically as a function of flow rate or it may be an active control unit allowing controlled variations in the pressure drop. The pressure control unit 42 may even include a pressure increasing device such as a pump for special situations. During flushing, the flow rate and pressure are controlled by manipulating the pump 20 and the pressure control unit 42 to maintain the required flow rate and pressure. The expelled water quality may be monitored with a sensor unit 64 to ensure that the flushing is maintained until the cementing adapter is sufficiently flushed.

[0067] A fifth aspect of the invention is shown in Figure 10. By having isolation valves 54, 61 and 66 closed while having isolation valves 5, 6, 59 and 62 open, sea water can be pumped from the pump 20 into the cementing port annulus 14 and further out through the pressure control unit 42. Compared to in Figure 9, the water passes through the pressure control unit 42 in the opposite direction. As the pressure control unit 42 acts as a restriction when pumping, pressure will increase to above ambient pressure in the cement port annulus 14 and the desired operational conditions can be achieved.

Claims (19)

1. An external, removable cementing adapter for Managed Pressure Cementing (MPC) of wells comprising:

at least one external cementing adapter (109, 209, 309) with an inside and an outside, wherein the at least one external cementing adapter is adapted to surround a conductor housing (1) with conductor housing ports (2);

at least one first cementing port (3) and at least one second cementing port ( 4) in the at least one external cementing adapter (109, 209, 309);

at least one of a lower seal (7), and an upper seal (8), adapted to seal between the external cementing adapter and the conductor housing (1) with conductor housing ports (2); and

a radial seal pressure mechanism including at least one of a force applying brace and at least one expanding seal.

2. The external, removable cementing adapter (109, 209, 309) of claim 1, including at least one upper seal (8) above the conductor housing ports (2) and at least one lower seal (7) below the conductor housing ports (2).

3. The external, removable cementing adapter (109, 209, 309) of claim 2, wherein at least one of the upper seal (8) and the lower seal (7) is an energized expanding seal.

4. The external, removable cementing adapter (109, 209, 309) of claim 3, wherein the at least one energized expanding seal (7, 8) is an inflatable seal.

5. The external, removable cementing adapter (109, 209, 309) of claim 1, wherein the force applying brace includes at least two parts.

6. The external, removable cementing adapter (109, 209, 309) of one of claims 1-4, comprising:

at least two upper seals (81, 82) above the conductor housing ports (2) and at least two lower seals (71, 72) below the conductor housing ports (2);

a first seal integrity port between the at least two upper seals (81, 82) above the conductor housing ports (2); and

a second seal integrity port between the at least two lower seals (71, 72) below the conductor housing ports (2), whereby the seal integrity may be tested by applying pressure to the seal integrity ports.

7. The external, removable cementing adapter (109, 209, 309) of one of claims 1-6, wherein the at least one of a lower seal (7), and an upper seal (8) is adapted to seal between the external cementing adapter and a conductor housing (1) with an outer diameter within a range, allowing the external, removable cementing adapter to be used for a range of conductor housings (1).

8. The external, removable cementing adapter (109, 209, 309) of claim5, wherein the force applying brace is a cementing seal brace (31) including:

a plurality of arch shaped individual brace section elements (32) whereof at least two brace section elements include a cementing port with a cementing port flange (37); and

a brace element seal (35) surrounding a brace element cavity of each of the at least two brace section elements with a cementing port, adapted to surround conductor housing ports (2) of a conductor housing (1).

9. The external, removable cementing adapter (109, 209, 309) of claim 8, wherein each brace section element (32) is hinged to an adjoining brace section element (32) with a hinge (33), and wherein at least one of the hinges is releasable, forming a brace locking element (34).

10. The external, removable cementing adapter (109, 209, 309) of claim 4, wherein the at least one inflatable seal includes an expandable and inflatable sealing ring (30) with an inner cavity, a rear seal base side (49) and a front, ribbed, lip element (29) opposing the rear seal base side (49).

11. The external, removable cementing adapter (109, 209, 309) of claim 10, wherein the expandable and inflatable sealing ring (30) includes a cross-section configured to adopt a folded, uninflated, retracted configuration and an unfolded, inflated expanded configuration, whereby the shape of the cross-section transforms in the transition between the retracted configuration and the expanded configuration.

12. The external, removable cementing adapter (109, 209, 309) of any of the preceding claims, wherein;

at least one first cementing port (3) is connected to at least one first cementing port valve (5) and a source of flushing fluid; and

at least one second cementing port (4) is connected to at least one second cementing port valve (6), whereby the adapter is adapted to allow flushing of a cavity between the external cementing adapter and the conductor housing (1), through the at least one first cementing port (3) and the at least one second cementing port (4).

13. The external, removable cementing adapter (109, 209, 309) of claim 12, further including a pressure control unit (42) controlling the pressure and the flow rate of a flushing fluid from the source of flushing fluid.

14. The external, removable cementing adapter (109, 209, 309) of claim 13, wherein the pressure control unit (42) includes a pressure drop element (27).

15. The external, removable cementing adapter (109, 209, 309) of claim 14, wherein pressure drop element (27) includes at least one of a nozzle, a choking arrangement, a set of valves in a manifold that allows varying between pipes with equal or varying diameters and and a length of hose or pipe.

16. Use of the external, removable cementing adapter (109, 209, 309) of any of the preceding claims on a subsea well.

17. Use of the external, removable cementing adapter (109, 209, 309) of any of the preceding claims on a land-based well.

18. A method of performing managed pressure cementing of a well with the external, removable cementing adapter of claim 1, comprising the steps of:

installing the at least one external cementing adapter (109, 209, 309) onto the conductor housing (1) with the conductor housing ports (2);

connecting the at least one first cementing port (3) to at least one first cementing port valve (5);

connecting the at least one second cementing port (4) to at least one second cementing port valve (6);

cementing the well while managing the pressure in the at least one external cementing adapter (109, 209, 309);

flushing the at least one external cementing adapter (109, 209, 309) with a flushing fluid from a source of flushing fluid connected to the at least one first cementing port valve (5) while managing the pressure in the at least one external cementing adapter (109, 209, 309) to remove cement; and

removing the external, removable cementing adapter (109, 209, 309).

19. The method of performing managed pressure cementing of a well of claim 18, further including installing the removed external, removable cementing adapter (109, 209, 309) onto a new conductor housing and repeating the steps.