RU2819216C1 - Set of tools for suspension of pipes of drill string at mouth of underwater well - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: set of tools for suspension of pipes of a drill string in the mouth of an underwater well includes an adapter pipe, a housing, two-sided lower and upper subs, as well as a lowering element and an extraction element having a through channel. Adapter pipe, housing and lower sub are connected in series to each other, and the extraction element has a freely rotating axial position stabilizer with protrusions on the outer surface. Housing in lower part is made of stepped shape for installation on mating projection of block of valves of X-mas tree. Adapter pipe is made with a head part having a mounting surface for installation on the preventer unit, located in its lower part, and two coaxially located seats with differently directed threads for the lowering element and the extraction element. Each of lowering and extraction elements is made with possibility of connection with adapter pipe and upper sub, wherein lowering element and extraction element have oppositely directed threads for connection with appropriate seat of adapter pipe.

EFFECT: proposed solution makes it possible to provide disconnection of part of pipes of drill string from drilling rig with reduction of time for disconnection and return of pipes of drill string into operation, as well as reliable retention of part of pipes of drill string at wellhead.

6 cl, 8 dwg

Description

The technical field to which the invention relates.

The invention relates to the oil industry, namely to equipment used in drilling underwater wells and can be used for the safe suspension of drill string pipes at the mouth of a gas-condensate underwater well during its construction.

State of the art.

Due to the depletion of gas and oil fields in accessible land and coastal regions, solutions related to subsea hydrocarbon production, in particular, subsea drilling and operation of subsea wells at relatively great depths, are becoming increasingly important. The increased complexity of using drilling methods at sea is due to a number of reasons, in particular, the pitching and drift of a floating drilling rig, the location of the bottom wellhead out of sight of the driller and the resulting difficulties, increased wear of drilling equipment and tools due to work in an aggressive environment. The problem of ensuring reliability is one of the most important when using underwater drilling technology, since inspection of underwater equipment is difficult, and its maintenance and (or) replacement is expensive. In addition, failure of subsea equipment directly affects the environment. To minimize costly subsea operations, it is important to ensure subsea equipment components are retrievable for inspection, repair or replacement. In many offshore drilling areas, such as the North Sea, environmental conditions often become so severe that excessive movement of the floating drilling rig relative to the wellhead occurs and operations have to be stopped for safety reasons. These harsh environmental conditions often develop very quickly, requiring a means to quickly disconnect portions of the drill string tubing.

A device is known from the prior art for quickly separating a floating platform from its casing when a storm approaches. The body of the device surrounds the casing for part of its length at a depth below the sea surface and defines a chamber, inside of which there is a blade, the cutting edge of which is adjacent to the well casing. The explosive charge located opposite the blade is electrically coupled to sensors at the wellhead. When the sensor detects an unsafe condition, an explosive charge is initiated, which passes the blade through the casing without seriously destroying it (US 3766979 A, publ. 10/23/1973, E21B29/08, 6 l.).

The known device has a number of disadvantages, in particular, the activation of the emergency device does not exclude damage to the equipment and requires labor-intensive diving work to restore it. In addition, the effectiveness of this solution sharply decreases as the strength of the cut pipes increases. At the same time, the use of explosives creates additional difficulties and risks.

It should also be noted that due to the high costs of operating an offshore drilling rig, it is desirable that well downtime be kept to a minimum. Thus, the use of destructive means to separate part of the drill string is not advisable. In this regard, there is a problem of creating non-destructive means of disconnecting the drill string, which contribute to the return of this string to work in the shortest possible time.

A set of tools for hanging a drill string at the mouth of an underwater well is known from the prior art, including basic elements, namely a series-connected adapter pipe and a housing. There is also a descent element and an extraction element. In this solution, the transition pipe has seats for the descent element and the extraction element. The body is made in a stepped shape for installation on the block of valves of the Christmas tree valves (see US 4116272 A, published 09/26/1978, E21B 33/035, 18 l.).

This solution discloses a means of allowing a portion of the drill string to be temporarily detached from a surface tower if necessary. At the same time, when operating such a solution at depth with a large length of the descending part, a number of difficulties arise. In particular, when lowering part of the drill string to the main elements of the tool kit, deviations of this part from its calculated axis may be observed. This is due to the movement of a long and relatively thin drill string within the water column. As a result, its connection to the hanger tool kit adapter pipe, which is placed on the seabed, invariably remains an operation that limits the time frame for bringing the drill string into operation.

Disclosure of the invention.

The technical problem solved by the invention is to ensure the possibility of protecting a floating drilling rig and preventing breakage of drill string pipes in the event of unfavorable conditions, such as weather, and resuming drilling with minimal time.

The technical result consists in providing the ability to disconnect part of the drill string pipes from the drilling rig while reducing the time spent on disconnecting and returning the entire drill string to operation, as well as reliably holding part of the drill string pipes at the wellhead.

To achieve a technical result, a set of tools is proposed for hanging drill string pipes at the mouth of an underwater well, including a transition pipe, a housing, double-sided lower and upper subs, as well as a lowering element and an extraction element having a through channel. The adapter pipe, body and bottom sub are connected in series. The extraction element has a freely rotating axial position stabilizer with protrusions on the outer surface. The housing in the lower part is made in a stepped shape for installation on the counter protrusion of the christmas tree valve block. The transition pipe is made with a head part having a seating surface for installation on the preventer block, located in its lower part, and two coaxially located seats with multidirectional threads for the descent element and the extraction element. Each of the lowering and retrieving elements is configured to be connected to the transition pipe and the top sub, and for connection to the corresponding seat of the transition pipe, the lowering element and the retrieving element have multidirectional threads.

Preferably, recesses are provided on the outer surface of the housing to allow passage of liquid.

Preferably, the transition pipe, housing, release element and extraction element are made of structural alloy chrome vanadium steel, in particular hypoeutectoid, low alloy, medium carbon steel.

Preferably, a phosphate coating is applied to the transition pipe, housing, release element and extraction element.

Preferably, the axial position stabilizer has projections in the form of wings.

It should be noted that the presence of a landing surface at the head of the transition pipe for installation in the preventer block, in addition to the stepped shape of the lower part of the body, provides an additional safety mechanism for the suspended part of the drill string. This is due to the fact that if tight contact with the body of the tool kit is not ensured, for example, in the event of destruction or wear of the supporting surface of the protrusion of the christmas valve block, then the suspension is carried out by means of the preventer block and the head part of the transition pipe. As a result, this arrangement helps to securely hold part of the drill string pipes.

In addition, the presence of two coaxially located seats with multidirectional threads for the lowering element and the extraction element makes it possible to facilitate and reduce the time of lowering and lifting operations. Due to the fact that the descent element must be unscrewed under water, the use of, for example, a left-hand thread for it, opposite to the threads on the extraction element and drill pipes, will allow such an operation to be carried out by rotating the drill string and without unscrewing its other components. In this case, the presence of a seat with opposite threads allows the extraction element to be screwed into the transition pipe by the same rotation of the drill string. As a result, there is no need to use additional technological means or reconfigure existing drilling equipment to disconnect and connect lowering and retrieving elements, which in turn reduces the time of lowering and lifting operations.

Also, the presence on the extraction element of a freely rotating axial position stabilizer, which preferably contains stabilizing protrusions in the form of wings, ensures axial alignment and centering of a portion of the drill string pipes running from the drilling rig to the transition pipe. This is due to the fact that such a stabilizer interacts with its protrusions, for example, wings, with the water column, which provides resistance from the water during the angular deviation of the extraction tool from the calculated axis of the drill string and thereby makes it possible to maintain its axial position and center the lowered part of the drill string. As a result, the probability of successful tightening of the retrieval element increases, and, consequently, the time required to retrieve part of the hanger tool kit placed at the wellhead is reduced.

Thus, the proposed solution makes it possible to disconnect part of the drill string from the drilling rig, as well as reduce the time spent on disconnecting and returning the entire drill string to operation. In addition, reliable retention of part of the drill string pipes is ensured using the proposed set of tools.

Additionally, it should be noted that structural alloy chrome vanadium steel, in particular hypoeutectoid, low-alloy, medium-carbon steel, has an excellent combination of ductility, strength and ability to resist abrasion. This allows the material to perform well under dynamic loads. This steel also has high corrosion resistance, which allows it to be used when working in marine conditions and low temperatures. In this case, phosphating is used for additional protection against corrosion, improving hardness, wear resistance, and increasing the electrical insulating properties of the base coating.

Brief description of the drawings.

The claimed invention is illustrated by the following figures:

Fig. 1 - shows a set of tools for hanging drill string pipes assembled with a running element (isometric).

Fig. 2 - shows a set of tools for hanging drill string pipes assembled with a retrieval element (isometric).

Fig. 3 - shows a set of tools for hanging drill string pipes assembled with a running element.

Fig. 4 - shows a tool kit for hanging drill string pipes assembled with a retrieval element.

Fig. 3 - shows the housing installed in the block of Christmas tree valves.

Fig. 6 - shows the head of the transition pipe in the preventer block.

Fig. 7 - cross-section of the head part of the transition pipe.

Fig. 8 shows the head of the transition pipe in connection with the lowering and retrieving elements.

Implementation of the invention.

In fig. 1-2 shows a set of tools for hanging drill string pipes assembled with a lowering element (Fig. 1) or an extraction element (Fig. 2). The set of tools allows you to lower part of the drill string pipes when using the running element and carry out lifting operations when using the extraction element. In each of the options, the set of tools includes an adapter pipe 1, a housing 2, double-sided lower 3 and upper 4 subs, as well as a lowering element 5 (Fig. 1, 3) or an extraction element 6 (Fig. 2, 4). Each of these parts of the tool kit has a through channel. In this case, the extraction element 6 has a freely rotating axial position stabilizer 12 having protrusions on its outer surface (Fig. 4).

The lower 3 and upper 4 subs are used to connect the tool set to adjacent pipes of the drill string.

The housing 2 in the lower part is made in a stepped shape 17 for installation on the counter protrusion 16 of the block 8 of the Christmas tree valves. The transition pipe 1 is made with a head part 9, which has a landing surface 14 in the lower part for installation on the preventer block 15 (Fig. 6). Also, the transition pipe 1 has two coaxially displaced axially located seats 10, 11 with multidirectional threads for the descent element 5 and the extraction element 6 (Fig. 7).

Each of the lowering elements 5 and extracting 6 is designed to be connected to the transition pipe 1 and the upper sub 4. To connect to the corresponding seat of the transition pipe, the lowering element 5 and the extraction element 6 also have multi-directional threads, for example, the lowering element 5 has a left-hand thread, and the extraction element 6 has a right-hand thread.

The tool kit is designed to ensure safe suspension of drill string pipes at the head of a subsea well. The presented set of tools allows you to close pipe rams, including the top ones, to prevent blowout on the drill string pipe. In this case, the housing 2 prevents the ejection of the Xmas tree head in the protective sleeve, and the upper head part 9 of the transition pipe 1 in the preventer block 15.

The drill string pipes are connected to two-way subs - with the lower 3 and upper 4. In this case, the upper 4 sub is connected, respectively, to the lowering element 5 or the extraction element 6, depending on the operation performed with the drill string pipes.

The material of the parts from which the transition pipe 1, body 2, descent element 5 and extraction element 6 are made is structural alloyed chrome vanadium steel, which helps ensure strength characteristics and resistance to various types of corrosion. Coating of these parts using phosphating technology is also provided. Structural alloy chrome vanadium steel is a hypoeutectoid, low alloy, medium carbon steel. It is distinguished by an excellent combination of ductility, strength and ability to resist abrasion, which allows the material to perform well under dynamic loads. This steel has high corrosion resistance, which allows it to be used when working in marine conditions and low temperatures. Phosphating is used for additional protection against corrosion, improving hardness, wear resistance, and increasing the electrical insulating properties of the base coating.

The proposed set of tools is used as follows. If there is a risk of breakage of drill string pipes that pass through the water column, for example, as a result of deteriorating weather conditions or for other reasons, drilling operations are stopped. At the same time, in order not to remove the entire length of the pipes, including the part that is located in the well, the proposed set of tools is used. To do this, the pipes together with the preventer block 15 are first lifted upstairs, where they are disconnected and the lower 3 sub, the housing 2, the transition pipe 1, the lowering element 5 and the upper 4 sub are installed in the place of the connector. After which the pipes are lowered to the bottom along with installed tools using the descent element and a preventer. Next, after the body 2 comes into interaction with the block 8 of the Christmas tree valves, the descent element 5 is unscrewed (since it has, for example, a left-hand thread) and is lifted onto the drilling rig along with the upstream pipes.

In this case, the housing 2, which provides suspension of the drill string pipes, is fixed in the block 8 of the Christmas tree valves, namely in the protective sleeve of the column head. The housing 2 in the lower part has a stepped shape in response to the protrusion 15 of the valve block 8 (Fig. 5), which allows it to be securely fixed and thereby suspend the associated part of the drill string pipes.

A backup protection is also provided (Fig. 6), which is located in the upper section of the transition pipe 1 on its head part 9, which will operate in the event of a loose fit of the housing 2 in the block 8 of the Christmas tree valves. For this purpose, the head part 9 has a seating surface 14 located in its lower part. In this case, the transition pipe 1, and, consequently, the pipes of the drill string will hang on the preventer bushing through the surface 14 of the head part 9. Thus, in the event of emergency situations with the suspension of the Christmas tree valves on the block, the transition pipe 1 will hang on the counter protrusions of the block preventer, which additionally insures this structure and ensures reliable retention of part of the drill string pipes.

As shown above, the head part 9 of the transition pipe has two axially displaced coaxially located seats with multi-directional threads for the descent element 5 and the extraction element 6, which, respectively, also have multi-directional threads (Fig. 7). To install the tool kit, a lowering element 5 is used, which has, for example, a left-hand thread for connection with the corresponding seat of the transition pipe 1, which also has, for example, a left-hand thread, which allows it to be unscrewed under water, after installing the tool kit by rotating the drill string in which pipes with right-hand threads are used. In this case, the extraction element 6 is screwed into the transition pipe 1 when it is already installed together with the housing 2 under water in the christmas tree valve block and is designed to lift the pipes together with the preventer block 15 from the bottom. To connect to the corresponding seat of the transition pipe 1, the extraction element 6 has a thread opposite to the thread of the descent element 5, for example, a right-hand thread. As a result, to install the extraction element 6 on the adapter pipe 1, a seat with a corresponding thread, for example, a right thread, is used (Fig. 8). This implementation makes it possible to facilitate and reduce the time of lowering and lifting operations by combining seats for lowering and extraction elements on one head part 9 of the receiving pipe 1.

The extraction element 6 is also equipped with a freely rotating axial position stabilizer 12, which contains stabilizing protrusions, preferably in the form of wings (Fig. 2, 4). These projections serve to stabilize and axially align the column. In particular, the freely rotating “shirt” with the wings of the stabilizer 12 allows you to center the trigger element when trying to screw into the thread at depth, due to interaction with the aquatic environment. The size and dimensions of the wings, as well as their shape, are selected experimentally for each standard size of the drill string pipe used. As a result, this implementation ensures axial alignment and centering of part of the drill string pipes descended from the drilling rig to the head part 9 of the transition pipe 1.

Each of the elements included in the set of tools has a through channel, which, if connected to each other, form a common channel 13 (Fig. 3, 4). Such channel 13 provides the ability to pump out some of the media that may have accumulated in the drill string pipes while the drill string was disconnected. In this regard, before removing the drill string pipes, to ensure safety, it is necessary to carry out actions to pump out the possibly remaining medium through the body of the tool kit elements. To do this, by means of a pump, the medium is pumped out through the upper 4 sub, which is connected to the extraction element 5, the transition pipe 1, the housing 2 and the lower 3 sub, and only after this the drill string pipes are removed.

In accordance with the above, the use of the proposed solution makes it possible to disconnect part of the drill string pipes from the drilling rig, as well as reduce the time spent on disconnecting part of the pipes and returning the drill string to operation. In addition, reliable retention of part of the drill string pipes at the wellhead is ensured.

Claims (9)

1. A set of tools for hanging drill string pipes at the mouth of an underwater well, including a transition pipe, a housing, double-sided lower and upper subs, as well as a running element and an extraction element having a through channel, while the transition pipe, housing and lower sub are connected in series between itself, and the extraction element has a freely rotating axial position stabilizer with protrusions on the outer surface, the housing in the lower part is made in a stepped shape for installation on the counter protrusion of the christmas tree valve block, the transition pipe is made with a head part having a seating surface for installation on the preventer block, located in its lower part, and two coaxially located seats with multidirectional threads for the descent element and the extraction element, each of the lowering and retrieving elements is configured to be connected to the transition pipe and the top sub, and for connection to the corresponding seat of the transition pipe, the lowering element and the retrieving element have multidirectional threads. 2. A set of tools according to claim 1, characterized in that there are recesses on the outer surface of the housing to allow the passage of liquid. 3. A set of tools according to claim 1, characterized in that the adapter pipe, body, descent element and extraction element are made of structural alloy chrome vanadium steel. 4. A set of tools according to claim 3, characterized in that the structural alloy chrome vanadium steel is a hypoeutectoid, low-alloy, medium-carbon steel. 5. A set of tools according to claim 3, characterized in that a phosphate coating is applied to the adapter pipe, housing, descent element and extraction element. 6. A set of tools according to claim 1, characterized in that the axial position stabilizer has protrusions in the form of wings.