RU2712857C1 - Mechanism for rigid attachment of underwater column heads system - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to means of connection of a conductor column with a column of direction for underwater wells. Disclosed is a mechanism for rigid attachment of a system of underwater column heads, comprising an end part of a conductor column and an end part of a column for connecting to each other; group of ratchets with free running, installed on end external part of conductor column and representing split rings with toothed profile. At that, the end internal part of the direction column is made in form of a gear surface for engagement with ratchets; external part of the conductor column and inner part of the directional column have each first, second, third and fourth conical surfaces. Taper of first conical surfaces and second conical surfaces is at angle of 1° relative to the conductor column longitudinal axis; taper of third conical surfaces is at angle of 19° relative to the conductor column longitudinal axis; taper of fourth conical surfaces is at angle of 30° relative to the lengthwise axis of the conductor column. At initial contact of the first conical surface of the conductor column with the first cone surface of the direction column and the second conical surface of the conductor column with the second conical surface of the column of direction between the third conical surface of the conductor column and the third conical surface of the direction column, as well as between the fourth conical surface of the conductor column and the fourth conical surface of the directional column there are maintained gaps, the value of which is calculated for bearing capacity of contact of the first and second conical surfaces.

EFFECT: technical result is maintaining fit with tension in a rigid joint when moving the column of the conductor up, including as a result of thermal expansion of the column of the conductor.

5 cl, 6 dwg

Description

FIELD OF THE INVENTION

The present invention relates to the field of underwater hydrocarbon production, in particular, to subsea wells and means for connecting a conductor column to a directional column.

BACKGROUND

The prior art anti-rotation device designed to prevent rotation of the casing of the conductor column inside the casing of the direction, disclosed in the source US 6695059 B2 (published on 02.24.2004). The specified device is equipped with a variety of anti-rotation mechanisms between the casing of the conductor column and the column direction. These mechanisms are directed towards the casing column housing and are placed at a distance from each other around the circumference on the inner part of the directional column housing between the two thrust shoulders. The anti-rotation device further includes a plurality of corresponding grooves located on the outside of the conductor column housing. Many anti-rotation mechanisms are provided with springs, while these mechanisms protrude radially from the surface of the housing of the direction column in a protruding position. When placing the conductor column housing in the directional column housing, the conductor column housing presses the anti-rotation mechanisms of the directional column into a folded position. Then, when the conductor column body is rotated inside the direction column body until the anti-rotation mechanisms are placed opposite the corresponding grooves, these anti-rotation mechanisms again move to the protruding position in the grooves of the direction column housing.

In addition, the prior art source US 5029647, publ. 07/09/1991, revealing the connection node of the conductor column and the directional column, in which the outer part of the conductor column is wedged relative to the inner part of the directional column to create a preliminary tension between said bodies. Jamming is carried out using the upper and lower conical sections, spaced axially relative to each other and formed on the outer part of the conductor column and the inner part of the direction column, respectively. These conical sections are reduced in diameter at a slight angle relative to the longitudinal axis. The sections have such dimensions that when lowering the inner case into the outer case, it is wedged. The known joint is also provided with means for fixing the inner part of the column of direction relative to the outer part of the column of the conductor after the upper and lower conical surfaces are fully engaged with each other. The locking means include a locking ring with a gear profile and a ratchet in the form of a split gear ring having mating teeth providing engagement with the locking ring. To install the conductor column, a tool is used that requires the application of the force necessary and sufficient to push the conductor column into the direction column, ensuring that the conductor column is wedged into the direction column. The devices disclosed in US 6695059 B2 and US 5029647 counteract significant bending loads exerted on the conductor column housing caused, in particular, by the rotational force transmitted from the floating drilling vessel. Advantageously, the adhesion counteracts these forces due to the frictional forces of the landing collars of the inner shell and the outer shell. If the rotational forces are strong enough to cause the rotation of the inner casing inside the outer casing, one of the casing joints below the inner casing may begin to unscrew, which, in turn, will lead to serious problems in operation.

Nevertheless, the stresses arising in the process of laying the flow line from the wellbore can cause, in addition to significant bending, also significant shear loads at the wellhead. The effect of thermal elongation or contraction of the casing pipes in the well and attached flow lines, as well as additional loads due to the possible deviation of the well axis from a vertical position, should also be taken into account.

Therefore, a design is needed in which the best stress distribution will be ensured when the conductor string is installed in the direction string and the loads created by the drilling platform and thermal expansion of the casing are transferred from the conductor string to the direction string and further into the sea soil.

SUMMARY OF THE INVENTION

According to the present invention, there is provided a mechanism for rigidly mounting a system of underwater column heads comprising:

the end of the conductor column and the end of the direction column for connection with each other;

a group of ratchets with a free wheel mounted on the end outer part of the conductor string and consisting of split rings with a gear profile;

while the end inner part of the column direction is made in the form of a gear surface for engagement with ratchets;

the outer part of the conductor column and the inner part of the direction column each have first, second, third and fourth conical surfaces;

moreover, the first conical surface of the column of the conductor is made with the possibility of contact with the first conical surface of the column of direction, and the second conical surface of the column of the conductor is made with the possibility of contact with the second conical surface of the column of direction, while the taper of the first conical surfaces and second conical surfaces is at an angle of 1 ° relative to the longitudinal axis of the conductor column;

the third conical surface of the conductor column is configured to contact the third conical surface of the direction column, while the conicity of the third conical surfaces is at an angle of 19 ° relative to the longitudinal axis of the conductor column;

the fourth conical surface of the column of the conductor is made with the possibility of contact with the fourth conical surface of the column of direction, while the taper of the fourth conical surfaces is at an angle of 30 ° relative to the longitudinal axis of the column of the conductor;

in this case, at the initial contact of the first conical surface of the conductor column with the first conical surface of the conductor column and the second conical surface of the conductor column with the second conical surface of the conductor column between the third conical surface of the conductor column and the third conical surface of the conductor column, and also between the fourth conical surface of the conductor column and the fourth conical surface of the directional column gaps are maintained while maintaining the bearing capacity of the contact of the first and W conical surfaces.

The technical result of the claimed invention is to maintain an interference fit in a rigid connection when moving the conductor column up, including as a result of thermal expansion of the conductor column.

In addition, by means of the claimed invention, an increase in the efficiency of moment transmission through the connection of the conductor column and the direction column is achieved with an increase in the load on the connection, an increase in the operating life of the system of underwater column heads to fatigue fracture, and also the activation of the mechanism of rigid fixation of the system of underwater column heads with minimal axial force.

The technical result is achieved through the use of four conical surfaces located on the outer part of the column of the conductor, and four conical surfaces placed on the inside of the column of direction.

The first and second conical surfaces of the conductor column and the direction column have a taper angle of 1 ° relative to the longitudinal axis of the conductor column. These conical surfaces first come into contact when the conductor column is installed in the direction column.

Due to the small angle of inclination, low contact stiffness is ensured with relative movement of the conductor column in the direction column.

During thermal expansion of the casing strings, a force arises which acts on the conductor string and tends to push it upward from the direction string. To prevent loss of contact between the columns and, accordingly, reduce lateral stiffness and fatigue endurance of the compound, ratchet mechanisms are used. Ratchets have a free play, determined by the pitch of the thread, with a maximum value of 7 mm.

Thus, the conductor column can be displaced relative to the direction column in the vertical direction by the amount of free play without resistance from the ratchet. The relative displacement of the initial installation of the conductor column in the directional column exceeding the free movement of ratchets makes it possible to have residual contact pressure on the first and second conical surfaces (with a taper angle of 1 °) as with the relative rise of the conductor column relative to the directional column by the value of the ratchet free play.

Third conical surfaces with a taper angle of 19 ° transmit weight loads exceeding a minimum installation force of 200 tons, as well as bending moment from the drilling platform. The fourth conical surfaces with a taper angle of 30 ° are safety belts for the transfer of weight loads, the value of which exceeds the design values, as well as, partially, the bending moment.

Also selected are the gaps between the third conical surfaces with a taper angle of 19 ° and the fourth conical surfaces with a taper angle of 30 °, which are available at the initial contact of the conical surfaces with a taper angle of 1 °. These gaps determine the magnitude of the load, after which the contact vertical stiffness increases significantly. In this case, the conical surfaces with a large angle of inclination begin to perceive the main part of the vertical load. The gaps are selected so that the loads do not exceed the bearing capacity of the conical surfaces with a smaller angle of inclination until the moment of the complete selection of the gaps and, accordingly, the redistribution of loads on the conical surfaces with a large angle of inclination.

The conductor column and the direction column are made of heat-resistant relaxation steel.

The conductor column and the direction column may have at least one anti-friction coating layer on their conical surfaces. Ratchets can be made of structural alloy steel. The ratchet material preferably has a minimum tensile strength of 700 MPa and a minimum hardness of 35 HRC.

In the context of the present description, the words “first”, “second”, etc. used in the form of adjectives solely to distinguish the nouns to which they relate, but not to describe any specific connection between these nouns.

BRIEF DESCRIPTION OF THE DRAWINGS

The above advantages of the invention will become more apparent from the following description of a preferred embodiment, given with reference to the accompanying drawings, in which:

- in FIG. 1 shows a longitudinal section of a directional column with a conductor column installed therein in accordance with a preferred embodiment of the invention,

- in FIG. 2 shows a mechanism for rigidly fastening a system of underwater column heads in accordance with a preferred embodiment of the invention;

- in FIG. 3 is an enlarged view A of a rigid attachment mechanism of an underwater column head system in accordance with a preferred embodiment of the invention;

- in FIG. 4 is a detailed view of the conical surfaces of the hard mount mechanism of the underwater column head system in accordance with a preferred embodiment of the invention;

- in FIG. 5 is an enlarged view of the Third and fourth conical surfaces of the hard mount mechanism of the underwater column head system in accordance with a preferred embodiment of the invention;

- in FIG. 6 shows an enlarged view of a ratchet in the recess.

DETAILED DESCRIPTION OF THE INVENTION

Next, with reference to the accompanying drawings, a mechanism for rigidly attaching a system of underwater column heads in accordance with a preferred embodiment of the invention is described.

In FIG. 1 shows a longitudinal section of a direction column 1 in which a conductor column 2 is placed. The mechanism of rigid fastening of the system of underwater column heads according to the claimed invention is intended to connect the column 1 direction with column 2 of the conductor. The conductor column 2 has an end outer part on which a group of ratchets is mounted.

In FIG. 2, it is illustrated that in the end inner part of the direction column 1, recesses 3 and 4 are made for engaging with ratchets. In FIG. 3 in more detail than in FIG. 2, it is shown that the outer part of the conductor column 2 has a first conical surface 5 and a second conical surface 6, and the inner part of the direction column 1 has a first conical surface 7 and a second conical surface 8, while the first conical surface 5 of the conductor column 2 contact with the first conical surface 7 of the column 1 direction, and the second conical surface 6 of the column 2 of the conductor is made with the possibility of contact with the second conical surface 8 of the column 1 direction.

Also in FIG. 3, it is illustrated that the outer part of the conductor column 2 has a third conical surface 9 and a fourth conical surface 10, and the inner part of the direction column 1 has a third conical surface 11 and a fourth conical surface 12, while the third conical surface 9 of the conductor column 2 is contactable with the third conical surface 11 of the column 1 direction, and the fourth conical surface 10 of the column 2 of the conductor is made with the possibility of contact with the fourth conical surface 12 of the column 1 direction.

According to a non-limiting embodiment, these conical surfaces are solid conical surfaces extending over the entire circumference of the columns. In place of the first conical surfaces 5, 7, the diameter of the outer part of the conductor column 2 decreases in the direction of its end part so that when the conductor column 1 is placed in the direction column 2, a pre-tension is formed, i.e. preload. The taper of the first conical surfaces 5, 7 is at an angle of 1 ° relative to the longitudinal axis of the conductor column 2. Similarly, the second conical surfaces 6, 8 have the same taper as the first.

The first and second conical surfaces are abutment and, when installed, create a preload between the housing of the column 1 of the direction and the housing of the column 2 of the conductor.

The taper of the third conical surfaces 9, 11 is at an angle of 19 ° relative to the longitudinal axis of the conductor column 2.

The taper of the fourth conical surfaces 10, 12 is at an angle of 30 ° relative to the longitudinal axis of the conductor column 2. According to the invention, the conductor column 2 is lowered into the direction column 1 under its own weight, in other words, under the influence of gravity. When installing the conductor column 2 in the column 1 of the direction, the first conical surface 5 of the column 2 of the conductor mates with the first conical surface 7 of the column 1 of the direction, and the second conical surface 6 of the column 2 of the conductor mates with the second conical surface 8 of the column 1 of the direction. Thus, the conductor column 2 is supported by its conical surfaces on the conical surfaces of the direction column 1, that is, the conductor column 2 is wedged into the direction column 1. In this case, a preload is created between the conductor column 2 and the direction column 1, and a gap is maintained between the third conical surfaces 9, 11 and the fourth conical surfaces 10, 12, as shown in FIG. 4 and FIG. 5.

When exposed to bending forces acting on the column 2 of the conductor due to waves and currents, it is necessary to ensure maximum transfer of bending forces to the column 1 direction. In this case, these loads, as well as all weight loads exceeding a minimum installation force of 200 tons, are redistributed from the first and second conical surfaces 5, 7, 6, 8 to the third conical surfaces 9, 11 with a large taper angle, the magnitude of which is 19 ° .

The fourth conical surfaces 10, 12 with a taper angle of 30 ° are safety belts and are able to absorb extreme loads, the magnitude of which exceeds the design values. The conductor column 2 and the direction column 1 are made of heat-resistant relaxation steel, for example, AISI 8630 steel having an analogue steel 30XMA, strength category 586 MPa.

The conductor column 2 and the direction column 1 may have at least one anti-friction coating layer on their conical surfaces.

It should be understood that the preferred embodiment of the invention described above by way of example does not limit the scope of the present invention. After reviewing the present description, those skilled in the art can suggest many changes and additions to the described embodiments, all of which will fall within the scope of patent protection of the invention defined by the following claims.

Claims (12)

1. A mechanism for rigidly mounting a system of underwater column heads comprising: the end of the conductor column and the end of the direction column for connection with each other; a group of ratchets with a free wheel mounted on the end outer part of the conductor string and consisting of split rings with a gear profile; while the end inner part of the column direction is made in the form of a gear surface for engagement with ratchets; the outer part of the conductor column and the inner part of the direction column each have first, second, third and fourth conical surfaces; moreover, the first conical surface of the column of the conductor is made with the possibility of contact with the first conical surface of the column of direction, and the second conical surface of the column of the conductor is made with the possibility of contact with the second conical surface of the column of direction, while the taper of the first conical surfaces and second conical surfaces is at an angle of 1 ° relative to the longitudinal axis of the conductor column; the third conical surface of the conductor column is configured to contact the third conical surface of the direction column, while the conicity of the third conical surfaces is at an angle of 19 ° relative to the longitudinal axis of the conductor column; the fourth conical surface of the column of the conductor is made with the possibility of contact with the fourth conical surface of the column of direction, while the taper of the fourth conical surfaces is at an angle of 30 ° relative to the longitudinal axis of the column of the conductor; in this case, at the initial contact of the first conical surface of the conductor column with the first conical surface of the conductor column and the second conical surface of the conductor column with the second conical surface of the conductor column between the third conical surface of the conductor column and the third conical surface of the conductor column, and also between the fourth conical surface of the conductor column and the fourth conical surface of the directional column retains gaps, the value of which is calculated on the bearing capacity of the con tact of the first and second conical surfaces. 2. The mechanism according to claim 1, characterized in that the conductor column and the direction column are made of heat-resistant relaxation steel. 3. The mechanism according to claim 1, characterized in that the conductor column and the direction column have at least one layer of antifriction coating on their conical surfaces. 4. The mechanism according to p. 1, characterized in that the ratchets are made of structural alloy steel. 5. The mechanism according to claim 1, characterized in that the ratchet material has a minimum tensile strength of 700 MPa and a minimum hardness of 35 HRC.

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