Separation Device for Material from a Power Tong on a Drilling Rig Situated on the Sea Bed

This invention regards a device for separating material from a coupling unit in a drilling rig situated on the seabed. More particularly, it regards a drilling rig situated on the seabed, where the drilling rig is sealingly enclosed against the surroundings. The pipe coupling unit in the drilling rig is closed, provided with seals against the pipe and connected to a liquid collector and separator.

It is common knowledge that oil and gas deposits in the earth's crust are recovered by drilling holes down to the deposits, to allow oil and gas deposits to be drained to the surface.

The equipment used to drill holes in the earth's crust primarily comprises a drilling derrick formed as a trussed steel structure. In the drilling derrick there is a wireline based drawworks for hoisting and deploying drill pipes. A great deal of auxiliary equipment is also used to handle drill pipes and to set casing in the borehole.

Floating or fixed platforms provided with the required drilling equipment are utilized to recover oil and gas deposits from great depths. These types of platforms are large and expensive structures, as the drilling equipment is large and heavy. In addition to the actual drilling equipment, marine risers must also be used to circulate drilling mud between the platform and the seabed during the drilling operation. Floating platforms also require heave compensation to accommodate wave motion against the platform relative to the seabed.

As an alternative to drilling from floating drilling platforms, the drilling rig may be arranged directly on the seabed, obviating the need for large and expensive platforms.

Today, the oil industry possesses a great deal of advanced equipment developed for remote-controlled subsea operations. This is technology that is available and may be used during a remote-controlled drilling operation where the drilling equipment is situated directly on the seabed.

Furthermore, it is necessary to meet the relatively strict requirements set by the authorities in connection with environmental pollution and the target of zero discharge to the environment.

Prior art does not provide a solution to these problems in connection with drilling rigs situated on the seabed.

The object of the invention is to remedy or reduce at least one of the drawbacks of prior art.

The object is achieved in accordance with the invention, through the features given in the description below and in the following claims.

A drilling rig in accordance with the invention is situated on the seabed, the drilling rig being sealingly enclosed against the surroundings, and it is characterized in that the pipe coupling unit of the drilling rig is closed, provided with seals against the pipe and connected to a liquid collector and separator.

The separator is connected to a circulation system arranged to circulate liquid through the coupling unit, the circulation system comprising a pump and conduits in addition to the separator.

The inlet of the circulation system communicates with one of the upper or lower part of the drilling rig, while the outlet of the circulation system communicates with the other of the upper or lower part of the drilling rig.

Preferably, the hydrostatic pressure inside the drilling rig is lower than that outside the drilling rig, whereby liquid in the drilling rig is prevented from flowing out to the surroundings of the drilling rig.

The separator is connected to e.g. a container for separated material, the container, when filled, may be replaced with a new container and brought up to the surface for further processing of the separated material. The drilling rig may comprise several containers for separated material.

Preferably containers going into and out of the drilling rig are passed through lock arrangements.

A device according to the invention provides a solution for handling e.g. drilling fluid flowing out during disconnection of pipes, the liquid in the coupling unit being circulated through the separator.

The following describes a non-limiting example of a preferred embodiment illustrated in the accompanying drawings, in which:

FIG. 1 is a principle drawing of an enclosed drilling rig with a connection to a surface vessel;

FIG. 2 is a principle drawing of an automated drill floor comprising an enclosed coupling unit for connecting and disconnecting stands;

FIG. 3 shows the enclosed coupling unit for stands;

FIG. 4 is a vertical sectional view through the coupling unit for stands; and

FIG. 5 is a principle drawing of a circulation system for cleaning the liquid-filled coupling unit.

In the drawings, reference number 1 denotes an enclosed drilling rig constructed for placement on the seabed 11. The drilling rig comprises an upper section 12 and a lower section 13, a supporting section 14 being located primarily in the lower section 13.

The drilling rig 1 is controlled from a surface vessel 2 on the surface 5 of the sea. A tubing and cable connection 3 extends between the drilling rig 1 and the surface vessel 2, from a cable drum 4 and down to the drilling rig 1.

The drilling rig 1 is provided with suction anchors 8 which provide anchorage to the seabed 11. The suction anchors 8 are connected to the supporting section 14 via sections 20.

At the top of the drilling rig 1 there is provided a lock cover 10 for a drilling unit (not shown) and lock covers 9 for drill pipe cartridges 7. The drill pipe cartridges 7 are inserted into encased silos 21.

The upper section 12 comprises the drilling unit (not shown) with associated drill pipe handling equipment (not shown), together with several drill pipe cartridges 7.

A circulation system (not shown) for the liquid in the drilling rig 1 is situated in one of sections 20.

The lower section 13 comprises remote-controlled and at least partly automated handling systems, including an coupling unit 24 for connecting and disconnecting pipes 23. The pipes 23 may be e.g. drill pipes or casing.

The entire drilling rig 1 is filled with water at a slight underpressure relative to the surrounding pressure.

The coupling unit 24, which is provided with a liquid inlet 31 and outlet 26 at the bottom and top, respectively, is provided with packing members 25 that encircle the pipe 23, and which are expanded by use of hydrostatic pressure to seal against the pipe 23.

The coupling unit 24 is further provided with the requisite screwing means, comprising clamping jaws 29 and 30 operated by hydraulic cylinders 35, the clamping jaws 29 being rotated about the central axis of the pipe 23 by hydraulic rotary motors 27 via a gear rim 28.

Internal discharges in the coupling unit 24 are circulated through the separator 33 by a pump 32 via a pipe 35 connected to the inlet 31 and a pipe 36 connected to the outlet 26.

Separated substances are removed from the separator 33 in a controlled manner.