NO347421B1

NO347421B1 - A deep-sea underwater drilling system for drilling and core sampling on a seabed

Info

Publication number: NO347421B1
Application number: NO20211220A
Authority: NO
Inventors: Roger Andersen
Original assignee: Atlantic Geodrill As
Priority date: 2021-10-12
Filing date: 2021-10-12
Publication date: 2023-10-23
Also published as: NO20211220A1

Description

Field of the invention

The present invention relates to a deep-sea underwater drilling system for drilling and core sampling on a seabed according to the preamble of claim 1. The invention also relates to a method for deep-sea underwater drilling and core sampling on a seabed according to the preamble of claim 10.

Background of the invention

There has been scientific exploration related to the potential deep-sea minerals in the North Atlantic ridge mainly performed by UIB (University in Bergen) since 1999. The results from this scientific work have given more questions to explore the possibility to extract rock samples in deeper segments in the areas of interest. Large surveys and seabed mapping have been done with high survey grade sensors. Sampling of stone and rock elements has been collected, but only shallow and surfaces of the seabed.

In 2018 the Norwegian Petroleum Directorate started to collect data for further analysis to determine volumes and to understand the potential for Norwegian interest. The Norwegian government as well as industry is working towards a possible further exploration and exploitation. To understand the geological and geotechnical conditions in the seafloor sulphides and crusts, extensive sampling is required in the years to come.

Prior art

WO 2004/018826 A1 discloses a drilling module for use in drilling of oil and gas wells, where the drilling module is placed directly on the seabed with energy and control cables supplied from a light surface vessel on the surface of the sea. This is realised by constructing a drilling derrick structure on a frame structure having buoyancy elements arranged in each corner, and with anchors against a frame structure positioned on the seabed. On the drilling derrick are arranged hoisting machinery and a drilling machine for hoisting and rotating the drill string. Pipe stands used to assemble a drill string are placed in pipe cassettes that can be transported between the surface and the drilling module. Cassettes of pipe stands are inserted into guide elements on the drilling module. A pipe handling device consisting of a vertical structure with gripping means is provided to facilitate handling of pipe stands between the pipe cassette and the drilling machine. The structure is fixed to the frame with guide elements.

US 2015/0197989 A1 discloses an underwater drilling rig assembly includes a hull anchored to a sea floor with at least one anchoring component. Also included is a rig assembly disposed on the hull. Further included is a mast unit of the rig assembly. Yet further included is a pipe handling unit configured to maneuver a drill pipe into operative communication with the mast unit. Also included is a drill bit assembly operatively coupled to the mast unit. Further included is a control unit positioned proximate the sea floor and in operative communication with a plurality of components of the underwater drilling rig assembly, the control unit operatively coupled to at least one surface vessel for remote control of the underwater drilling rig assembly.

US 2009/0178848 A1 discloses a subsea drilling system includes a drilling module having a tool carousel being removable and replaceable in or out of water, a skid module and an ROV to be connected to and disconnected from the skid module in or out of water, for operating the subsea drilling system with the ROV. A method for operating a subsea drilling system includes removing a tool carousel from a drilling module and replacing the tool carousel with another tool carousel, in or out of water. An ROV is connected to a skid module and disconnected from the skid module in or out of water. The subsea drilling system is operated with the ROV.

Domangue, R. J. “Design and Installation of a Subsea Multiwell Drilling Template at Garden Banks Block 189”, SPE-20821-PA, September 1991, pages 177–181, is a paper that describes the economics, design, and installation of a simple drilling template that was used to retain or save subsea exploratory and delineation wells in Garden Banks Block 189 (GB 189) in the Gulf of Mexico.

Objects of the present invention

An object of the invention is to provide a deep-sea underwater drilling system and a method to drill geotechnical core samples from the seabed, for instance for collecting rock samples.

The invention is specifically aiming at solving the above-mentioned challenges.

It is further an object to provide a modular design, giving a drilling system that makes it possible to abandon the drilling hole and to come back later to commence drilling.

Summary of the invention

According to the invention, a deep-sea underwater drilling system for drilling and core sampling on a seabed is provided, the drilling system comprises a drilling rig with a support skid equipped with extendable support legs, a drill rod magazine and a drilling machinery, and an anchoring base frame arranged to be preinstalled on the seabed, said base frame having one or more drilling apertures, wherein the drilling rig is mountable on the base frame preinstalled on the seabed and with the drilling machinery aligned with an inline drilling aperture in the base frame. The base frame comprises several spaced apart inline drilling apertures, wherein the drilling rig is rotatable to align the drilling machinery of the drilling rig with a first inline drilling aperture in the base frame and with a second or third inline drilling aperture in the base frame.

The base frame can comprise a docking point connecting the drilling rig and the base frame.

The base frame functions as an anchoring weight providing downward directed force on the drilling rig when mounted to the base frame.

The base frame can comprise several spaced apart inline drilling apertures.

The base frame comprises preferably on its underside adjustable cones or feet for level adjustment and grip on the seabed.

Operation of the drilling rig can be assisted and controlled by an adjacent ROV.

The ROV can optionally be docked to the drilling rig during operation, and be arranged to supply pressure and return hydraulics, as well as communication to sensors and actuators on the drilling rig.

The ROV can optionally be floating adjacent the drilling rig during drilling, and arranged to supply pressure and return hydraulics, as well as communication to sensors and actuators on the drilling rig through flying lead connections.

The drill rod magazine can be interchangeable, in a complete drill rod magazine can be lifted to surface and be exchanged by a new prearranged magazine that is to be deployed to the seabed, assisted by the ROV and mounted onto the drilling rig.

According to the invention, a method for deep-sea underwater drilling and core sampling on a seabed is also provided, comprising the steps:

- deploying a base frame in the sea at a preassigned location,

- landing the base frame on the seabed,

- adjusting the position of the base frame on the seabed,

- deploying a drilling rig in the sea,

- landing and docking the drilling rig on the base frame, wherein the base frame acts as an anchoring weight for the drilling rig, and

- connecting an ROV to the drilling rig, to assist and control the drilling rig and supplying pressure and return hydraulics, as well as communication to sensors and actuators on the drilling rig, wherein

the method further comprises the steps of orientating the drilling rig such that a drilling machinery of the drilling rig is aligned with a first inline drilling aperture in the base frame, and rotating the drilling rig such that the drilling machinery of the drilling rig is aligned with a second or third inline drilling aperture in the base frame.

The method may further comprise the step of docking the ROV on the drilling rig during the drilling operation.

Alternatively, the method may further comprise the step of placing the ROV floating adjacent the drilling rig, and to connect the ROV using flying lead connections.

The drilling rig may comprise an interchangeable drill rod magazine, and the method may further comprise the step of lifting a completed drill rod magazine to the surface and to exchange with a new prearranged drill rod magazine, which then is deployed to the drilling rig on the seabed.

The design according to the invention has a flexible modularity, which allows the operators to consolidate or segregate the process in several steps of the drilling process. The invention also provides a solid base frame, as the invention can use a standalone base frame with interface adaptor to latch into the drilling skid. This establish a firm platform for the operation. The base frame can be designed in several shapes, and various volume/weight engineered depending on scope of work. For deeper planned boreholes the larger base frame. In addition, supporting legs can be extended to increase the footprint and stabilize the unit further. The base frame has several optional apertures to select drilling hole. This gives the operator opportunity to change position, in the event a drill hole is fractured, and drilling needs to be aborted for any reason. The operator can orientate the machinery to next selected apertures and commence drilling operation. A drilled hole can be blanked off with a blind cap for later selection of continued drilling. This will only be possible as the base frame is installed, and consequently the ROV will be able to revisit the location for continued drilling. This opportunity is not possible for a random drilled hole in the seabed as inclination of drilling head is critical for repositioning and debris will fall into the well over time.

Description of the figures

Embodiments of the present invention will now be described, by way of example only, with reference to the following figures, wherein:

Figure 1 shows a base frame (top view) for use in a deep-sea underwater drilling system according to the invention.

Figure 2 shows the base frame (side view) on a seabed.

Figure 3 shows the base frame attached to a cable for deployment from a vessel.

Figure 4 shows a ROV (side view) assisting in positioning the base frame. Figure 5 shows a drilling rig (side view) according to the invention docked to the base frame.

Figure 6 shows the drilling rig (top view) docked to the base frame.

Figure 7 shows the ROV (side view) undocked for drilling, with the ROV and the drilling rig separated.

Figure 8 shows the ROV (side view) docked to the drilling rig, for drilling with the ROV attached to the drilling rig.

Figure 9 shows the ROV (top view) docked to the drilling rig.

Figure 10 shows the ROV (front view) docked to drilling rig, and with support legs extended to the seabed.

Figure 11 shows a drill rod magazine being lifted by a vessel assisted by the ROV.

Description of preferred embodiments of the invention

Item list - Figure 1 to figure 11

10: Base frame

12: Drilling apertures

14: Docking point

16: Adjustable cones

18: Lift line

20: Seabed

30: ROV

40: Drilling rig

42: Support skid

44: Support legs

46: Drill rod magazine

48: Drilling machinery

50: Hydraulic cylinder

The present invention related to a deep-sea underwater drilling system for drilling and core sampling on a seabed 20, wherein the drilling system comprises a drilling rig 40 with a support skid 42 equipped with extendable support legs 44, a drill rod magazine 46 and a drilling machinery 48. The drilling system further comprises an anchoring base frame 10 arranged to be preinstalled on the seabed 20, wherein said base frame 10 has one or more drilling apertures 12.

The base frame 10 according to the invention is shown in figure 1 and 2, while figure 3 and 4 show deployment of the base frame 10 on the seabed 20.

The base frame 10 is a drilling skid that functions as an anchoring weight providing downward directed force on the drilling rig 40 when mounted to the base frame 10. Hence, the base frame 10 may be rather heavy.

The base frame 10 is in the shown embodiment of triangular shape but may be of any suitable shape.

As shown, a drilling aperture 12 is provided in each corner of the base frame 10. Dependent on the design of the base frame 10, the base frame 10 may thus be equipped with at least one but preferably several spaced apart inline drilling apertures 12. The base frame 10 has on its upper side, i.e. the side facing upward from the seabed 20, a docking point 14 suitable for connecting the drilling rig 40 and the base frame 10. The docking point 14 may be any suitable connection that can be locked to the drilling rig 40, for instance can the docking point be a mushroom hat design with receptacle with latching mechanism in the drilling rig 40, such as on the underside of the support skid 42. The base frame 10 has on its underside, i.e. the side facing the seabed 20, adjustable cones 16 or feet for level adjustment and grip on the seabed 20. The base frame 10 may further comprise logging sensors for seabed and/or downhole well logging.

The base frame 10 is deployed on the seabed 20 from a vessel on the surface and onto a preassigned location using a hoisting or lift line 18, as shown in figure 3. The lifting line 18 is connected to the docking point 14, which then also functions as connection point for the lift line 18. Figure 4 shows an ROV 30 assisting in positioning of the base frame 10 on the seabed 20. By using the adjustable cones 16, the base frame 10 is levelled and seated as desired on the seabed 20.

Figures 4 and 5 show a drilling rig 40 according to the invention deployed to the seabed 20 and mounted on the base frame 10. The drilling rig 40 can be deployed using the lift line 18. The drilling rig 40 comprises a basically flat surfaced support skid 42 equipped with extendable support legs 44. The support legs 44 will when deployed on the seabed 20 support and level the drilling rig 40. The drilling rig 40 further comprises a drill rod magazine 46 and a drilling machinery 48. The drill rod magazine 46 and the drilling machinery 48 are placed next to each other and basically vertically oriented. The angle of the drilling machinery 48 can be adjusted using a hydraulic cylinder 50 connected between the support skid 42 and the drilling machinery 48.

The drilling magazine 46 will be filled up with rods, for instance four to six units, depending on drilling equipment and core sample diameter.

A completed drilling magazine 46 can be lifted by the vessel winch/crane and recovered to surface, as illustrated by figure 11. A new prearranged drilling magazine 46 can then be deployed to the seabed 20, assisted with the ROV 30 and mounted onto the drilling rig 40. The drilling operation will be commenced and no need for repositioning will be needed as the base frame’s integrity has been unchanged. The operation can be additionally supported with a second support ROV, and with the same compatibility to operate the drilling unit.

Once the drilling rig 40 is docked onto the base frame 10, the operator may select two modes for the drilling phase.

1. Drilling with the ROV 30 attached on the drilling rig 40, as shown for instance in figure 8. The units will remain connected together, and drilling will be done with the ROV 30 connected via flying leads. This method can be selected by the operator but will be limited to continue until all drilling pipes from the magazine is consumed and samples need to be brought to surface.

2. Drilling with the ROV released from the drilling rig 40 with flying lead connections between the ROV and the drilling rig, as shown for instance in figure 7 (the lead connections are not shown). Flying leads contain pressure and return hydraulics, as well as communication to sensors and actuators on the drilling rig or the base frame. The ROV 30 will undock after base frame 10 is stabilized, and support legs 44 are extended. Flying leads will remain connected or can be disconnected at the separation. The drilling process starts as the ROV 30 is monitoring the operation. All power and control signals are intact through the flying leads. The operation can be temporarily paused without removing the base frame 10 and drilling rig 40 attached together. The ROV undock the flying leads and return to surface. This will allow the operation to be halted for any unforeseen but also predicted reasons for pausing the operations as weather, service of equipment etc.

By moving the drilling platform to the seabed with power and communication transferred through the ROV umbilical the drilling is projected from the seabed, and not from surface as with traditionally rig/vessel solutions with rigid or flexible pipe/drill string.

The combination of the base frame 10 that will be deployed separately to form a seabed platform with docking towards the drilling rig 40 will solve several challenges.

a) The base frame 10 will act as mass required to push drill string into the seabed

b) Axial and lateral stability

c) Temporary placed platform to perform drilling, interrupted and re-engaged even if drilling have been aborted for hours or months. Re-establishment can be obtained as continued operation can be done with exact same inclination and orientation from last operating position as the base is in the same spot.

The drill skid modularity will solve the direct and rigid drill string issue. By ROV operated unit the flexible umbilical will be mitigating the weather dependent surface conditions. As the ROV also can perform modular drilling when the ROV 30 is released from the drill rig 40 the operation can be monitored with connected flying leads to the drilling process, as well as the ROV can release connection to the drilling rig and return to surface and commence operation once back at the seabed. The operation can additionally be executed with two ROV systems where one is backup for the other and continuously drilling can be executed by alternating the two ROV`s

The drill string magazine 46 can be replaced and engaging and disengaging and replacement magazine operation can be done without re-establishing drilling point/inclination.

Claims

1. A deep-sea underwater drilling system for drilling and core sampling on a seabed (20), the drilling system comprises:

a drilling rig (40) with a support skid (42) equipped with extendable support legs (44), a drill rod magazine (46) and a drilling machinery (48), and

an anchoring base frame (10) arranged to be preinstalled on the seabed (20), said base frame (10) having one or more drilling apertures (12),

wherein the drilling rig (40) is mountable on the base frame (10) preinstalled on the seabed (20) and with the drilling machinery (48) aligned with an inline drilling aperture (12) in the base frame (10), characterized in that

the base frame (10) comprises several spaced apart inline drilling apertures (12), wherein the drilling rig (40) is rotatable to align the drilling machinery (48) of the drilling rig (40) with a first inline drilling aperture (12) in the base frame (10) and with a second or third inline drilling aperture (12) in the base frame (10).

2. The underwater drilling system according to claim 1, wherein the base frame (10) comprises a docking point (14) connecting the drilling rig (40) and the base frame (10).

3. The underwater drilling system according to claim 1, wherein the base frame (10) is an anchoring weight providing downward directed force on the drilling rig (40) when mounted to the base frame (10).

4. The underwater drilling system according to claim 1, wherein the base frame (10) comprises logging sensors for seabed and/or downhole well logging.

5. The underwater drilling system according to claim 1, wherein the base frame (10) on its underside comprises adjustable cones (16) for level adjustment and grip on the seabed (20).

6. The underwater drilling system according to claim 1, wherein operation by the drilling rig (40) is assisted and controlled by an adjacent ROV (30).

7. The underwater drilling system according to claim 6, wherein the ROV (30) is docked to the drilling rig (40) during operation, and arranged to supply pressure and return hydraulics, as well as communication to sensors and actuators on the drilling rig (40).

8. The underwater drilling system according to claim 6, wherein the ROV (30) is floating adjacent the drilling rig (40) during drilling, and arranged to supply pressure and return hydraulics, as well as communication to sensors and actuators on the drilling rig (40) through flying lead connections.

9. The underwater drilling system according to claim 1, wherein the drill rod magazine (46) is interchangeable, in that a completed drill rod magazine (46) is adapted to be lifted to surface and to be exchanged by a new prearranged magazine that is to be deployed to the seabed, assisted by the ROV (30) and mounted onto the drilling rig (40).

10. A method for deep-sea underwater drilling and core sampling on a seabed (20), characterized by comprising the steps:

- deploying a base frame (10) in the sea at a preassigned location,

- landing the base frame (10) on the seabed (20),

- adjusting the position of the base frame (10) on the seabed (20),

- deploying a drilling rig (40) in the sea,

- landing and docking the drilling rig (40) on the base frame (10), wherein the base frame (10) acts as an anchoring weight for the drilling rig (40), and

- connecting an ROV (30) to the drilling rig (40), to assist and control the drilling rig (40) and supplying pressure and return hydraulics, as well as communication to sensors and actuators on the drilling rig (40), wherein the method further comprises the steps of orientating the drilling rig (40) such that a drilling machinery (48) of the drilling rig (40) is aligned with a first inline drilling aperture (12) in the base frame (10), and rotating the drilling rig (40) such that the drilling machinery (48) of the drilling rig (40) is aligned with a second or third inline drilling aperture (12) in the base frame (10).

11. The method according to claim 10, comprising the step of docking the ROV (30) on the drilling rig (40) during the drilling operation.

12. The method according to claim 10, comprising the step of placing the ROV (30) floating adjacent the drilling rig (40), and to connect the ROV (30) using flying lead connections.

13. The method according to claim 10, wherein the drilling rig (40 comprises an interchangeable drill rod magazine (46), and the method comprises the steps of lifting a completed drill rod magazine (46) to the surface and to exchange with a new prearranged drill rod magazine, which then is deployed to the drilling rig (40) at the seabed (20).