SU1680921A1 - Underwater drilling rig - Google Patents

Abstract

The invention relates to the mining industry and can be used for underwater drilling. The goal is to increase the reliability of work. The installation for underwater drilling consists of a sealed body (GC) 3 connected to the support base 1 by means of a hinge 4, in which a set of drilling equipment with a drive is installed. GK 3 is made in the form of a multilayer shell having an outer 6 and an inner 7 shell, which form the inner 11 and outer 9 cavities associated respectively with a gas L O O O O GO

Description

21 and a liquid 22 cavity of a hydrocompensator 20 installed on the outer surface of the Ledger 3. Before the unit is lowered to the bottom, the inner 11 and the outer 9 cavities are filled with gas and liquid under preliminary excessive pressure, the value of which depends on the depth of the installation, and is calculated with

taking into account the equality of the stresses in each of the layers of the shell b and 7. When the installation is operated at different depths, the latter are connected to the gas 21 and liquid 22 cavities of the hydrocompensator 20 to self-regulate the overpressures in the inner 11 and outer 9 cavities. metal consumption. 1 il.

The invention relates to the mining industry, in particular to installations for underwater drilling.

The purpose of the invention is to increase reliability in operation.

The drawing shows schematically an installation for underwater drilling, a longitudinal section.

The installation comprises a base 1, in which a casing 3 of a hinge 4 consisting of two parts interconnected by means of a flange connection 5 is installed in the bushing 2. On the hinge 4 a hermetic casing is mounted in the form of a multilayer shell.

The multilayer shell is made, for example, a two-layer one and consists of the outer 6 and inner 7 shells, which are located relative to each other equidistantly. The outer 6 and inner 7 shells have a horizontal connector connected by a flange connection 8. The outer 6 and inner 7 shells have an external cavity 9,

The upper and lower parts of the external cavity 9 communicate with each other through holes 10 made in flange tides of the inner shell 7. A complex of drilling equipment is placed in the internal cavity 11 of the housing: drilling tool 12, swivel rotator 13 moving along rails 14 with a drive, as well as a flush pump with a drive (not shown).

The metal construction of the rack and pinion mechanism, which serves to move the rotator 13 while supplying the drilling tool 12 along the axis of the well, is at the same time a stiffening element that prevents deformation of the inner 7 and outer 6 shells along the vertical axis.

The withdrawal of the drilling tool 12 from the device casing is made through the sealing elements 16 and the centering bearings 17. After installation of the drilling complex in the internal cavity

and

11, the housing is assembled and installed through the hinge 4 onto the support base 1. Before the device is lowered to the bottom of the sea, the inner 11 is filled

5 outer 9 cavities through fittings 18 and 19 with compressed air and oil, respectively, under preliminary overpressure. The magnitude of the overpressure depending on the depth of installation at the bottom

10, the mor is calculated in such a way as to ensure that the stresses in each of the layers of the casing shell are equal with regard to their geometric size. Therefore, each of the hull shells experiences

15 equal in magnitude to the pressure difference, the magnitude of which is three times less (with a two-layer shell) the hydrostatic pressure of seawater outside the shell.

20 When operating the unit at different depths of the sea with a wide range of their changes, in order to self-regulate the values of excess pressure of compressed air in the internal cavity 11 and oil in the intermediate cavity 9 depending on the depth of installation, it is advisable to use a multi-stage hydraulic compensator 20, a gas cavity 21 which through fittings 18 is connected with the internal 30 cavity 11, the liquid cavity 22 through the connector 19 - with the external cavity 9,

Hydropneumatic compensator 20 is equipped with differential pistons 23 and 24 whose diameters are chosen so that the pressures of the media on the pistons on their both sides are mutually balanced at the selected ratio of pressures in the cavities of the device housing. Part of the differential piston 23 of smaller diameter

40 has a free exit and absorbs the force from the hydrostatic pressure of the sea wave. This force through a larger diameter piston and oil in the fluid cavity 22 is transmitted to

45 differential piston 24, part of which is larger in diameter in the gas cavity 21. Due to different diameters

the differential pistons 23 and 24, when perceived by the first force from the hydrostatic pressure of seawater, create corresponding pressures of the oil in the fluid cavity 22 and compressed air in the gas cavity 21.

The use of a piston hydro-pneumatic compensator 20 not only allows you to automatically maintain the required pressures of oil and compressed air in the cavities of the device body, depending on the depth of its installation, but also eliminates the need to create high pressures in these cavities on land before descending .

Reactive moment during rotation of the drill string in the drilling process is perceived by the support base 1 through the pin 25, pressed into the housing 3, the free part of which is located in the groove 26 of the hinge 4,

Using a flexible power connection in the form of a cable-rope 27 with hermetic inlet into the hull, electric power was supplied to the drives of the drilling complex units and connected to the base carrier vessel (not shown). In order to eliminate the possibility of additional stresses due to deformation of the casing shells, the pipeline connecting the gas cavity of the hydro-pneumatic compensator 20 to the internal cavity 11 of the casing and the cable-rope 27 between the casing shells are installed with an overlap.

The installation works as follows.

Before the unit is lowered to the seabed in the inner 11 and outer 9 cavities through the hydropneumatic compensator 20 and fittings 18 and 19, they create preliminary excess pressures of compressed air and oil before the calculated value. Installation on the seabed from the base carrier vessel is lowered onto the cable-rope 27. As the installation descends, the hydrostatic pressure of seawater increases, and the pressures of compressed air in the internal cavity 11 and oil in the external cavity 9 increase accordingly. the cable-rope 27 is slightly loosened, which ensures that the gravity of the device is perceived by the supporting base of 1 part. The magnitude of the axial load on the rock cutting tool during drilling is determined by the mass of the device and the degree of loosening of the cable-rope 27.

In the case of an inclined bottom surface of the sea, the hinged connection of the installation casing with the support base 1 ensures the safety of the vertical position of the casing, which ensures the verticality of the borehole.

Claims (1)

Claims An underwater drilling rig, comprising a set of drilling equipment with a drive mounted on a supporting base and connected by a flexible power link with the vessel, characterized in that, in order to increase the reliability of operation, it is equipped with a hydropneumatic compressor and has a hinged link with the support base is a hermetic case in which a complex of drilling equipment with a drive is placed, while the hermetic case is made in the form of a multilayer shell, the inner and outer cavities of which are respectively are associated with liquid and gas cavities gidropnevmokompensatora mounted on the outer surface of the hermetic housing.