RU2638679C1 - Drill string filter - Google Patents

Abstract

FIELD: mining engineering.

SUBSTANCE: filter includes a perforated pipe with an adapter, a grip and a supporting ring installed at the tapering in the axial channel of a hollow body. The body of the upper adapter has bypass openings hydraulically connecting the axial channel of the drill string with the inner cavity of the perforated pipe. The grip is provided with a flow turbulizer located in the axial channel of the perforated pipe and made in the form of a rod, in the middle part of which there is a row of transverse cuts arranged in staggered order in height. A helical spiral cut is made at the lower end of the rod. The perforated pipe is made in the form of truncated cone and provided with a bottom with a row of drain holes and central hole in the form of a conoid nozzle.

EFFECT: improved efficiency and reliability of filtration.

1 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 year, pp. 182-186) installed on the suction or flow lines 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 over the body of the pipe.

The disadvantages of the design of the filter include low filtration efficiency with fast clogging of 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 / M .: Nedra, 1976, p. 5-8), which is a perforated pipe, the rows of perforations on which are staggered. 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 the settling of sludge in the 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 storage 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, but smaller ones that form arched structures on the perforations that impede further filtration of the drilling fluid, are retained. As practice shows, to destroy these structures only by the random vibration of a hollow body is not always effective.

A well-known design of the mud filter (see RF patent No. 2429342, IPC B21B 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 while drilling 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 pipe and a tubular cone, which form a cavity for receiving mechanical impurities. The filtering pipe is equipped with slotted slots, fastened with a cowl, the 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 it flows through the slotted slots 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 necessitates stopping the drilling process and raising the drill string to the surface to replace the filter and the drilling tool.

The disadvantages of the design include:

- a structure that is quite complicated in manufacturing and assembly, since the presence of a tubular body narrows the bore of the annular chamber and 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;

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

- maintaining the speed of the filtered mud flow behind the perforated pipe by constructing it in the form of a truncated cone;

- excitation of hydrodynamic pulses in the mud stream with the destruction of arched structures on the perforation holes of the filter pipe;

- the imposition of vibrations on the housing and the filter pipe contributes to a more dense packing of sediment in the annulus and in-tube space.

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 perforations, an adapter in the upper part, with a grip and a support ring. The capture is equipped with a flow turbulator in the form of a rod, in the middle part of which a series of transverse slots are made, arranged in a checkerboard pattern, below which a spiral spiral thread is made. The rod is placed in the inner cavity of the perforated pipe, which is made in the form of a truncated cone and provided with a bottom, with perforations and a hole in the center in the form of a conoidal nozzle.

The drill string filter is shown in the drawing in section and consists of a perforation pipe 1 with an upper sub 2 with a gripper 3. At the lower end of the perforation pipe 1 there is a bottom 4, equipped with a number of drainage holes 5, and an axial hole 6 in the form of a conoidal nozzle. On the outer side of the upper sub 2, a support ring 7 is installed and fixed by welding, which rests on the narrowing 8 in the hollow body 9. The inner cavity 10 of the perforated pipe 1 is hydraulically connected to the axial channel 11 of the drill string by a number of bypass holes 12 made in the body of the upper sub 2.

The capture 3 is equipped with a flow turbulator 13, made in the form of a rod 14 with a number of transverse slots 15 placed around the perimeter in a checkerboard pattern.

At the lower end of the rod 14, a helical spiral thread 16 is made for guiding and swirling the flow when it is fed into the inner cavity 10 of the perforated pipe 1. The structurally perforated pipe 1 is made in the form of a truncated cone directed by a smaller base towards the drilling tool, which increases the annular gap area along the length of the perforated pipe 1 and averages the flow rate of the drilling fluid.

Filter operation

The design of the filter assembly is installed by the support ring 7 on the narrowing 8 in the axial channel of the hollow body 9.

When the drilling fluid is supplied into the drill pipe under pressure, the flow through the bypass holes 12 in the body of the upper sub 2 is fed into the inner cavity 10 of the perforated pipe 1. Next, the flow flows through the perforations in the body of the perforated pipe 1 and the drain holes 5 and the axial hole 6 in the bottom 4 enters the annular gap between the wall of the hollow body 9 and the outer conical surface of the perforated pipe. At the same time, the speed of the filtered mud flow is averaged as it moves downward, that is, the flow velocity remains stable.

When the flow enters the internal cavity 10 of the perforated pipe 1, it is given a rotational movement when interacting with a spiral spiral thread 16 of the flow turbulator, which, due to the presence of transverse slots 15, carries out oscillatory actions with excitation of mechanical action on the flow and perforated pipe 1. Sludge particles, Settling in the area of perforations in the internal cavity 10, cannot create a stable arched structure, which prevents normal filtration of the drilling fluid.

At the same time, mechanical and hydrodynamic vibrations superimposed on the flow of the drilling fluid contribute to a denser packing of sludge in the inner cavity 10 of the perforated pipe 1.

Claims (1)

Drill string filter, comprising a hollow body with a constriction, a perforated pipe with perforations, an upper sub, with a grip and a support ring, characterized in that the grip is provided with a flow turbulator in the form of a rod, in the middle of which a series of transverse slots are placed staggered below which there is made a spiral spiral cut placed in the inner cavity of the perforated pipe, the perforated pipe made in the form of a truncated cone and provided with a bottom with perforation nnym holes and a hole in the form of a conoid nozzles in the center.

Images