RU2642580C1 - Drill string filter - Google Patents

Abstract

FIELD: mining engineering.

SUBSTANCE: invention relates to filtering devices for cleaning drilling mud and protecting drilling equipment against the ingress of large mechanical particles. The filter includes a perforated tube installed in axial channel of a hollow body. An adapter provided with a gripping device for removing the filter is mounted on the upper end of the perforated tube. A swirler in the form of a spiral is installed in the axial channel of the adapter. A flow splitter is installed in the middle part of the perforated pipe, perpendicularly to its axis. The flow splitter is in the form of a rod, on which two bevel cuts are made with formation of a triangle in section which is turned with its vertex to the adapter. A bottom with perforation holes and one radial hole is installed on the lower end of the perforated tube for installation of a cable, which upper end is fixed in the hole a supporting ring body rigidly connected to the adapter.

EFFECT: improved reliability by preventing clogging of perforations with slurry, holding filter elements in case of their destruction, reduction of flow rate.

3 dwg

Description

The invention relates to the mining industry, in particular to filtering devices for cleaning flushing fluid when drilling wells and protecting drilling equipment.

The filter design is known (see Akhmadishin F.F. Trial use of the filter on the suction line of mud pumps. / FF Akhmadishin, V.E. Pronin, S.L. Bagnyuk. / Collection of scientific papers TatNIPIneft. Issue No. LXXX. Moscow , 2012, pp. 182-186) installed on the suction or discharge line of mud pumps.

The filter is a perforated pipe equipped with a tip at the lower end and an opening at the upper end to ensure removal of the filter from the installation site. A support ring is mounted on the outer surface of the perforated pipe, with the possibility of support on the inner protrusion in the axial channel of the drill pipe.

The diameter of the perforated holes on the pipe is taken equal to ∅ = 4 ÷ 5 mm, with their staggered arrangement along the body of the pipe.

The disadvantages of the filter design include the low filtration efficiency, with fast clogging of the perforation holes with mechanical impurities, with the formation of arched structures on them, the presence of stagnant zones, and a change in the speed of the filtered mud stream.

A known filter design (V. M. Gavrilko, B. C. Alekseev. Second publishing house. / Moscow, Nedra, 1976, p. 5-8), which is a perforated pipe, the rows of perforations on which are placed in a checkerboard pattern. The upper end of the perforated pipe is equipped with a connecting element, and a stopper plug is fixed to the thread at the lower end. The perforated pipe is installed in the axial channel of the drill pipe string.

Filter operation.

The flow of drilling fluid is fed into the axial channel of the perforated pipe and through the perforations flows into the annular gap between the pipe wall of the drill string and the outer surface of the filter. The arrangement and number of perforations on the pipe body is determined based on the estimated flow rate of the drilling fluid.

Sludge and various mechanical impurities settle over the plug plug in the axial channel of the filter.

The disadvantages of the design include:

- when sludge accumulates in the axial channel of the filter, the living section is blocked by a series of perforation holes, which leads to an increase in the filtration flow rate through the remaining holes. At the same time, the processes of abrasive impact on the filter design are intensified, which reduces the reliability of its operation;

- the presence of a blind plug at the lower end of the filter pipe, determines the presence of a stagnant zone, which affects the operation of the entire filter.

Practice shows that when filtering the drilling fluid through perforations, it is also possible to form arched structures from fine fractions on them, which negatively affects the overall performance of the filter.

A known design of a filter with a bypass assembly (see RF patent No. 2016186, IPC ЕВВ 21/00, published July 15, 1994), which provides for the passage of washing liquid through the filter element, into the annular cavity between it and the housing, with sludge settling in axial channel, and in another case, the supply of washing liquid occurs through the annular cavity into the filter element.

A distinctive feature is the connection of the filtering and guide pipes in a telescopic manner with their fixing to each other by means of a shear pin. A different number of bypass holes in the filter and guide tubes provides a guaranteed flow area for passing the flushing fluid to the hydraulic motor.

At the free end of the filter pipe, a contact is established for transmitting vibration from the housing on it, which allows for more dense packing of the sludge and its separation from the filter holes.

The disadvantages of the design of the filter include:

- the implementation of the telescopic connection of the filter pipe with the guide pipe makes it possible to continue the drilling process after filling the internal cavity with slurry, by opening an additional hydraulic channel. But this leads to a direct supply of untreated drilling fluid into the cavity of the hydraulic motor or drill bit, which can lead to premature wear.

Sealing the separated sludge in the accumulation cavity only by transmitting vibration from the drill pipe string to the filter housing is ineffective.

It should also be noted that not only sludge particles whose dimensions exceed the cross section of the perforation holes on the filter pipe are delayed, but also smaller ones that form arched structures on the perforation holes that impede further filtration of the drilling fluid. As practice shows, to destroy these structures only by the chaotic vibration of the hollow body is not always effective.

The known design of the mud filter (see RF patent No. 2429342, IPC ЕВВ 43/08, published on September 20, 2011), adopted by the authors and the patent holder for the prototype.

The invention is intended for cleaning drilling fluid, when drilling wells using downhole hydraulic motors, with installation in the layout of the bottom of the drill string.

The filter includes a hollow body with threads at the ends, a filter module installed in the hollow body, equipped with a filter tube and a tubular cone, which form a cavity for receiving mechanical impurities. The filter tube is equipped with slotted slots, fastened with a cowl, input and output sleeves, with annular grooves for the sealing rings. The input sleeve is made with a centering belt directed to the tubular casing. The output sleeve is also provided with a centering belt directed towards the tubular casing. The filter pipe is connected to the output sleeve by means of a thread, which is equipped with an exhaust hook.

Filter operation.

The drilling fluid through the drill string enters the annular cavity, from where through the slotted slots flow into the inner cavity of the filter pipe and then into the receiving chamber of the hydraulic motor.

Large fractions of sludge are trapped on the outside of the filter pipe and accumulate in the annular cavity above the output sleeve. When filling it with sludge, the process of supplying drilling fluid through the filter to the hydraulic motor decreases sharply. This makes it necessary to stop the drilling process and raise the drill string to the surface in order to replace the filter and the drilling tool.

The disadvantages of the design include: rather difficult to manufacture and assemble the structure, since the presence of a tubular body narrows the bore of the annular chamber, makes the construction more expensive.

The presence of only the output sleeve, with its support on the protrusion in the hollow body, fully preserves the operability of the structure.

The presence of an input sleeve in the construction increases the hydraulic resistance to the flow of the drilling fluid and can adversely affect the filtration process due to the accumulation of sludge on it, for example, from fibrous material.

From the practice of operating filters with slit or round perforations, it is known that arches are formed on the holes from particles that are smaller than the holes on the filter pipe. This design does not provide any effect on the flow of the drilling fluid, so that these arched structures disrupt or prevent their formation.

The technical result that can be obtained by implementing the invention:

- the ability to prevent clogging of the perforation holes with sludge due to the destruction of the arch structures by the swirling flow of the drilling fluid;

- reducing the speed of the direct flow of the drilling fluid in the axial channel of the filter, by installing a divider and reducing the dynamic effect of the jet on the bottom;

- the ability to eliminate the stagnant zone above the bottom by making perforations in it;

- elimination of the speed of the filtered mud flow behind the perforated pipe, by its structural design in the form of a truncated cone;

- the ability to control the filling of the axial channel of the perforated pipe under the divider, by marking the pressure jump at the wellhead;

- the ability to prevent the ingress of structural elements of the filter, when it is destroyed by fixing the bottom of the cable with a support ledge.

The technical result is achieved in that the drill string filter consists of a hollow body, with a narrowing of the axial channel, a filter module, in the form of a perforated pipe, with an inlet sub, equipped with a gripper and a support ring on the outside. A spiral is installed in the axial channel of the input sub. A divider in the form of a rod is installed in the body of the perforated pipe perpendicular to its axis and has a cross-section in the shape of a triangle facing the apex to the inlet sub. At the lower end of the perforated pipe, made in the form of a truncated cone, a bottom with perforation holes along the axis and a radial hole is installed. The support ring is provided with an opening in which a cable is fixed with its upper end, the lower end of which is missed and secured in a radial hole in the bottom.

The drill string filter is shown in the figure, where: in fig. 1 is a sectional general view of the filter structure; in section AA, a cross-sectional view of the structure at the location of the divider is shown. View B - view from below.

The drill string filter consists of a perforated pipe 1, with a sub 2. On the lower end of the perforated pipe 1, a bottom 3 is installed, equipped with a number of perforations 4. A radial hole 5 is made in the body of the bottom 3.

On the outside of the sub 2, a support ring 6 is installed and fixed by welding, in which a hole 7 is made, with a cable 8 placed in it, the opposite end of which is passed through a radial hole 5 in the bottom 3, with fixation from movement in it.

In the middle part of the perforated pipe 1, a through radial hole 9 is made, into which a flow divider 10 in the form of a rod 8 is passed. Two bevels are made on the outside of the rod 10 (see section AA, the apex of the triangle of which faces the mud flow).

In the axial channel 11 of the sub 2, a spiral 12 is installed and fixed, above the place of placement of which a gripper 13 is installed and fixed by welding, to ensure removal of the device from the installation site.

The perforated pipe 1 is made in the form of a truncated cone, the smaller base of which is turned towards the drilling tool (hydraulic motor).

The support ring 6 is based on the narrowing 14 in the hollow body.

Filter operation.

The complete assembly of the filter is mounted by the support ring 6 to constrict 14 in the axial channel of the hollow body 15. When the drilling fluid is supplied under pressure, its flow passes into the axial channel 11 of the sub 2 and interacts with the spiral body 12, which leads to rotation of the flow, with averaging of the velocity value over the entire cross section of the axial channel of the perforated pipe 1. When the flow moves down the axial channel of the perforated pipe 1, the flow is distributed over the perforations, with the output of the filtered drilling fluid in the rings th gap between the perforated pipe body 1 and the hollow body 15. In this case, by making the perforated tube 1 is tapered, is an increase in the cross section of the annular gap, which stabilizes the flow rate of the filtered drilling fluid.

The mud flow is also supplied to the flow divider 10, with partial damping of its speed.

Behind the divider 10, the mud stream is reconnected, with its continued filtration through the perforations in the body of the perforated pipe 1 and perforations 4 in the body of the bottom 3, which eliminates the formation of stagnant zones. Sludge from the mud flow settles on the bottom 3, and over time, it accumulates in the axial channel of the perforated pipe 1, with their perforation holes overlapping under the divider 10. Due to the twisting of the flow, the arch structures on the perforation holes of the perforated pipe 1 are constantly destroyed. which increases the reliability of the device. Overlapping part of the perforation holes above the sludge divider 10 serves as a signal in the form of a pressure increase, which indicates the need for work to lift the equipment to the surface.

The practice of operating filters of a similar design shows that there are cases when, as a result of abrasive action, the lower part of the perforated pipe 1 is destroyed, which can lead to its detachment and movement to the drilling tool, with negative consequences.

To exclude this event, the device is equipped with a cable 8, connecting the bottom 3 with the support ring 6.

In case of destruction of the bottom 3 in the lower part of the perforated pipe 1, its elements remain in the axial channel of the hollow body 15, holding the cable 8 and do not fall into the drilling tool.

Claims (1)

A drill string filter equipped with a hydraulic motor, consisting of a hollow body with a narrowing of the axial channel of the filter module in the form of a perforated pipe, with an inlet sub, a gripper, a support ring, characterized in that the filter is equipped with a spiral in the axial channel of the sub and a divider in the form of a rod installed in a perforated pipe perpendicular to the flow, having a cross section in the shape of a triangle facing the apex to the inlet sub, the perforated pipe is made in the form of a truncated cone, facing with a smaller base to the hydraulic motor, equipped with a bottom with perforations along the axis and one radial hole, the support ring is rigidly connected to the body of the upper inlet sub and provided with a hole in which the upper end of the cable is fixed, the opposite end of which is placed in the radial hole of the bottom.

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