US 20100116507 A1
A mobile equipment for riserless drilling, well intervention, subsea construction and the like from a dynamic positionable vessel having a moonpool (8) is comprising two masts (1) situated at the moonpool (8), a yoke (6) extending between and is movably arranged on the masts, a hydraulic topdrive (7) mounted to the yoke, and a drillfloor (3, 4) mountable in connection with the moonpool (8).
1. Mobile equipment for use during riserless drilling, well intervention, subsea construction and the like from a dynamically positionable vessel with a moonpool, wherein the equipment comprises two masts which are located at the moonpool, a yoke extending between and movably arranged on the masts, a hydraulic top drive mounted on the yoke, and a drill floor mountable in connection with the moonpool.
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The present invention relates to mobile equipment, and more particularly to the composition thereof, for use during riserless drilling, well intervention, subsea construction and the like from a dynamically positionable vessel having a moonpool.
Today, a number of the processes relating to offshore oil and/or gas exploration or production are carried out from specially designed drilling vessels or platforms that have a fixed derrick for use in this connection. In addition, various other vessel types must be hired in, such as platform supply vessels (PSV), anchor handling vessels (AHV) and multipurpose vessels (MPV). These additional vessels are generally dynamically positionable and have moonpools.
It would of course be cost-effective if the last-mentioned vessel types also could be used, for example, in connection with the actual drilling during hydrocarbon exploration. This could mean increased utilisation of a hired vessel for the operator and at the same time a reduction in the need to use different vessel types during the overall process.
Accordingly, one of the main objects of the present invention is to reduce the use of such costly drilling vessels or platforms during hydrocarbon exploration or production, so that riserless drilling, well intervention, subsea construction and the like can be carried out from, for example, already existing dynamically positionable vessels having a moonpool. This object is achieved with mobile equipment of the type mentioned in the introduction, the equipment comprising, as disclosed in the characterising clause of claim 1, two masts located at the moonpool, a yoke extending between and movably arranged on the masts, a hydraulic top drive mounted on the yoke, and a drill floor mountable in connection with the moonpool. It is also desirable to have economy of space on and a minimum weight increase of the vessel in question, and that the mobile equipment can be mounted without major changes to and conversion of the vessel, and also to have a low centre of gravity.
Compared with a specially designed drilling vessel with fixed derrick, the low centre of gravity means that the equipment is lowered considerably, as about 85% of its total weight is lower than four metres from the main deck of the vessel, and also as the drill floor itself is only built to a level within one metre from the main deck. The space requirement is reduced also in relation to a derrick of standard type.
The respective mast can be mounted on a base, preferably of the prefabricated type, and can be laid down on the vessel deck using at least one hydraulic cylinder. Thus, only minor vessel-specific adaptations are required for the vessel in question in relation to the base work and the folding down of the masts. Furthermore, the yoke may be designed to be width-adjustable, thereby permitting alternative positioning of the mast bases. The folding down of the masts with mounted yoke and top drive to a position on the vessel deck provides obvious advantages during relocation from one location to another, and during maintenance and mounting or dismantling of the equipment.
The drill floor can be formed so as to be splittable and have a cut-out in the centre for the installation of slips. This permits easy displacement of the drill floor, for example, when the drill floor must be removed to gain access to the whole of the moonpool. The cut-outs otherwise form a through-opening in the drill floor, for example, for passing through a drill string. An iron roughneck can be provided on the drill floor, which is movably arranged thereon, and likewise an air winch, a hydraulic manipulator arm and the like. It will be appreciated that the low overall height of the drill floor gives advantages when devices of this type are to be brought onto the drill floor. Moreover, the mast base can act as a guide for the splittable drill floor.
Reference is now made to the attached drawings which show a preferred embodiment of the invention, in which
As already mentioned above, the present invention is intended for use on existing PSVs, AHVs, MPVs and similar vessels that are dynamically positionable and have a moonpool. However, this does not prevent the equipment from being equally suited to be put into service on newly built vessels. Another condition that applies, for example, during drilling and well intervention, is that the vessels have sufficient storage tank capacity for drilling mud, bulk barite/bentonite and bulk cement. This is in addition to the need for accommodation for drill personnel, for example, 15 beds. The bed requirement is slightly smaller in connection with subsea construction operations only.
The equipment according to the invention is specifically intended to be used during riserless drilling, well intervention, subsea construction and the like from a dynamically positionable vessel with a moonpool 8. The main components of the equipment are two masts 1 that are located on either side of the moonpool 8, a yoke 6 extending between and movably arranged on the masts, a hydraulic top drive 7 mounted on the yoke and a drill floor 3, 4 that is positionable over the moonpool 8.
Each individual mast 1 is of any suitable design known in the field having sufficient height and load capacity. The mast height is selected for the handling of, for example, drill pipes having a length of 9-13 metres. The lower end of the mast is attached to a mast base 2. The base is dimensioned for distribution of the load from the mast in a way that does not result in overloading and resultant damage to the vessel deck 9 and its underlying supporting structure. The base is attached by welding or bolting.
To permit the masts and the equipment located thereon to be laid down in a horizontal position on the vessel deck 9, see
The yoke 6 is of any suitable type and is, as mentioned above, arranged for movement up and down along the masts 1 during the actual working procedures. Such a movement along the masts is well known in the field and may be effected (not shown in the drawings) in that the respective mast is in the form of a separate hydraulic mast cylinder, is formed having a chain drive, a rack drive and the like. It is in addition assumed that the yoke is of a width-adjustable type, which, for example, may mean variable positioning of the mast bases 2.
A hydraulic top drive 7 is mounted on the yoke 2. Moreover, as shown in
The drill floor 3, 4 is advantageously splittable, which means that the whole moonpool 8, when required, can be uncovered by pushing the drill floor halves apart without first optionally removing, for example, the drill string. It will be understood that the drill floor halves can be supported displaceably on the mast bases 2. Each drill floor half is made having a cut-out 12. Thus, a through-opening is formed in the drill floor when positioned over the moonpool. A standard drill floor usually has a maximum opening of about 1.32 metres. Slips (not shown) are also mounted in the drill floor opening in the respective half 3, 4 of the drill floor. Otherwise, the drill floor comprises an iron roughneck 5. The iron roughneck is advantageously movably arranged on the drill floor, for example, using non-illustrated rails. As the drill floor is at a level close to the vessel deck 9, this allows easy handling of other tools (not shown in the drawings) such as a manipulator arm, an air winch and others, on the drill deck, for example, using a skid.
Apart from the components of the equipment according to the invention as discussed above, it may briefly be mentioned that there is, for example, a need for a hydraulic unit, a power generator if the vessel lacks capacity, an operator cabin, a ramp for handling pipes between the equipment and the vessel deck, a movable pipe handling crane for lifting pipes between storage site on the vessel deck and ramp, equipment containers, a ROV unit, and during drilling and well intervention, mud pumps, and a mobile cement mixer.
The aim is that the vessel's own systems should be used as much as possible so as not to unnecessarily take up deck space on board the vessel. The equipment according to the invention also requires only a minimum of adaptations of the vessel itself, normally solely in connection with the mast bases.
A drilling procedure that is the most demanding of the processes involving use of the mobile equipment according to the invention, can, for example, be carried out in the following way: