RU2261147C2 - Method and device for separation of suspensions by classes of particles - Google Patents

Abstract

FIELD: regeneration of drilling muds and flushing fluids; concentration of minerals; separation of various suspensions and emulsions; purification of waste water and circulating water.

SUBSTANCE: proposed method includes delivery of suspension at pressure differential to device of separation of suspensions by means of sieving classification on filtering surface under flooded conditions at oscillation of suspension, discharge of filtrate, precipitation and discharge of solid phase sediment. Suspension in form of horizontal flow is first passed through labyrinth of oscillating plates and then is directed for sieving classification performed in pulse-wave mode of pumping the suspension through sieve due to reflected waves. Proposed method is performed by means of device having closed reservoir with stack of precipitation plates, sieve, branch pipe for delivery of suspension inside reservoir, suspension oscillation source, screw feeder for discharge of sediment and gas and filtrate discharge branch pipes. Precipitation plates are rigidly secured to housing by two fins and are hermetically fastened with housing and cover of reservoir; they are coupled together on opposite sides in form of combs, thus forming labyrinth in plan for passage of suspension; they have different sizes: minimum size at inlet and maximum size at outlet; plate of maximum size is used as reflecting shield. Sieve is placed in perforated rigid cassette and oscillation source is brought in contact with flexible wall of reservoir.

EFFECT: enhanced efficiency of separation, clay and sludge suspensions in particular which are used as drilling muds.

8 cl, 4 dwg

Description

Technical field

The invention relates to the field of drilling fluid regeneration and can be used in mineral processing, separation of various kinds of suspensions and emulsions.

State of the art

There is a method of classifying fibrous materials in a liquid medium [1], which includes feeding the initial suspension stream into a zone of its separation into coarse and fine fractions when moving along one surface of a vertical perforated septum under the action of low-frequency vibrations directed perpendicular to its surface and outputting the obtained fractions in opposite side.

The specified method is accepted by us as an analog.

Its common disadvantages include the following:

1) the separation of the suspensions into fractions is carried out in a vertical downward flow, disadvantageous for the separation of clay-slurry suspensions,

2) for technological reasons, this method is not suitable for cleaning drilling fluids with an internal thixotropic structure.

A device for cleaning drilling fluids (vertical slurry sump) [2]. It is a container containing inside the partition (overlapping plates) and a conical bottom with a valve for the release of sludge. Drilling fluid (clay suspension) is pumped through the inlet to the lower part of the tank and exits through the upper part of the tank. This device is the closest analogue to the claimed.

The disadvantages of the known device:

1) due to thixotropy, the drilling fluid moves upstream and therefore is not completely freed from sludge;

2) to ensure the movement of the drilling fluid requires a residually powerful pump;

3) when unloading sludge from the conical part of the tank, part of the solution is lost, because the precipitate is slightly condensed.

A known method of separating suspensions into classes of particles, including feeding the suspension under a differential pressure into a device for separating suspensions by a screen classification method on a filter surface in flooded conditions with suspension fluctuations, filtrate withdrawal, precipitation and precipitation of a solid phase [3]. It differs in that the suspension is supplied by a flow moving from top to bottom, the suspension is separated on two filter surfaces, while low-frequency oscillations are excited in-phase from two sides, perpendicular to the peripheral layers of the suspension flow, and after separation of the suspension on the filter surfaces, the sands are subjected to scrubbing in an expanding chamber gravitational deposition.

This method, as the closest to the claimed, adopted by us as a prototype.

The disadvantages of the prototype include the following:

1) the separation of the suspension into classes of particles on filtered surfaces is carried out in a vertical downward flow, which does not favor the separation of clay-slurry suspensions;

2) for the drive of pistons performing in-phase reciprocating movements, a rather complicated mechanism is required;

3) with a large flow rate of the suspension, part of it does not have time to filter on sieves;

4) precipitation plates located in the tank at the outlet of the suspension flow do not fulfill their role.

A device for separating suspensions according to particle classes, comprising a closed container with a set of precipitation plates, a sieve, a suspension supply pipe inside the container, a suspension oscillation source, a screw with a drive for removing sediment, a filtrate outlet pipe [3], which is closest to the proposed invention on the basis of the characteristics and purpose, and adopted in the prototype.

Disclosure of invention

The objective of the invention is to increase the efficiency of separation of suspensions, in particular clay-slurry suspensions used as drilling fluids.

The technical result is to simplify, reduce the cost and reduce the energy consumption of the process of cleaning drilling fluids from drill cuttings.

The technical result is achieved by the fact that in a method comprising supplying a suspension under a differential pressure to a device for separating suspensions by a screen classification method on a filter surface in flooded conditions with a fluctuation of the suspension, the filtrate is withdrawn, the precipitate and the solid precipitate are withdrawn, according to the invention, the suspension is first passed into horizontal flow through a maze of plates of various sizes, arranged perpendicular to the direction of flow, which force to oscillate, and then sent to a sieve The first classification is carried out in the pulse-wave mode of pumping a suspension through a sieve due to reflected waves. The precipitate is separated from the sieve by direct waves from the source of oscillation of the suspension. The amplitude, frequency and vibration acceleration of the source of oscillation of the suspension is regulated depending on the transparency of the sieve and the performance of pumping the suspension.

The technical result is achieved in that in a device for separating suspensions into classes of particles, containing a closed container with a set of precipitation plates, a sieve, a pipe for supplying the suspension inside the container, a source of oscillation of the suspension, a screw with a drive for outputting sediment; a filtrate outlet pipe, characterized in that it is equipped with a gas outlet pipe, while the precipitation plates with two ribs are rigidly and hermetically fastened to the body and the tank lid, and are interconnected from opposite sides in the form of combs, forming a labyrinth for the suspension flow, and made different sizes - the minimum at the entrance and the maximum at the exit of the suspension, and the plate of maximum size serves as a reflective screen, the sieve is placed in a perforated rigid cassette, and the vibration source is in contact with about the wall of the tank, made flexible.

Vibro-settling capacity has mobility in the direction of transmission of vibrations to it.

The walls of the tank are made rigid except for one end wall, through which the suspension vibrations are transmitted inside the tank. The device is equipped with additional screens enclosed in perforated rigid cassettes and installed between the flexible wall of the tank and the reflective screen. The lower part of the tank has a tapering bottom, equipped at the bottom with a sediment divider and a screw for unloading the sediment of a solid phase.

The set of features that characterize the invention includes all the essential features, each of which is necessary, and all together are sufficient to achieve a technical result.

An embodiment of the invention

The invention is illustrated by drawings, in which Fig. 1 shows a General view of the device from the side in section, in Fig. 2 shows a top view with the cover removed, in Fig. 3 - an end view in section in a cc, in Fig. 4 shows the wave difference pressure on the sieve.

The method is carried out in a device including a container (1) with a cover (2), which is hermetically connected to the container body. Capacity (1) is made in the form of a strong and rigid parallelepiped construction with one flexible end wall (3), connected to the bottom with a conical bottom (4), in which there is a conical draft divider (5), rigidly connected to the end walls of the bottom (4) at the ends ) The bottom (4) is connected to the pipe (6), inside which there is a screw (7) for unloading the solid phase sediment on one side equipped with a drive (8), and on the other hand, with a shut-off slide gate valve (9). At the end of the tank (1) with a flexible wall (3) the oscillation emitter (10) is in contact, the latter can have a drive combined with a screw drive (7).

Inside the container (1) are located: one or more screens (11) enclosed in rigid perforated cassettes (12) and a set of precipitation plates (13). Precipitation plates (13) have a stepwise decreasing height: minimum at the inlet of the suspension and maximum at the outlet. The precipitation plate of maximum size (14) serves as a reflective plate. The deposition plates (13) are rigidly and hermetically connected by two ribs to the walls of the container (1) and the lid (2) and are joined together in plan view in the form of combs, forming a labyrinth for the suspension flow, as shown in Fig. 2. The clay-slurry suspension is fed into the tank (1) by gravity through the pipe (15) under the influence of the height difference between the wellhead and the tank level (1), which is at least 2 m. The filtrate is released through the drain pipe (16) located on one level with inlet.

In the cover (2) there is a pipe (17) for the gas outlet, raised to the height of the wellhead.

An example of the practical implementation of the proposed method

Drilling fluid (clay-slurry suspension) is fed into the vibratory sedimentation tank by gravity through the filler pipe (15) and flows after cleaning and classification through the filler pipe (16). The suspension flow is regulated by a system of precipitation plates and occurs as a snake in the labyrinth channel. The distance between the settling plates is approximately 0.1 m to cause the suspension to spread over the area of the plates.

The vibrations from the vibration source are directed perpendicular to the position of the precipitation plates and are transmitted through the container body. This causes the precipitation plates to oscillate. If the frequency of the forced oscillations and the natural frequency of the oscillations of one of the precipitation plates coincide, the latter will enter the resonant mode and thus enhance the mechanical vibrations of the other plates.

Passing between the vibrating settling plates, the clay suspension will liquefy and be freed from sand, as well as degassed.

After the flow leaves due to the last settling plate (it is also reflective), the suspension tangentially enters the filter screen (a sieve enclosed in a rigid perforated cassette). The filtering process here occurs under the influence of pressure wave pulses created by a vibration source (10) through a flexible wall of a precipitation tank (1). The pressure wave passes through a sieve (11) and is reflected from the plane of the reflective plate (14). The reflected pressure wave carries out the pumping of the suspension through the sieve, leaving non-passing particles of the solid phase in the form of a precipitate on the sieve, and the next direct wave separates the sediment from the sieve. As a result, a curtain of sludge particles is formed in front of the sieve, which, as the latter accumulates, falls down into the storage part of the sedimentation tank and from there together with the sands is removed by the screw (7) in the form of a condensed and dehydrated mass.

The wave pattern in the filter compartment is formed in accordance with its size and the frequency of the forced vibrations of the flexible wall of the sedimentation tank.

The wave differential pressure on the sieve is shown in Fig.4.

Depending on what transparency (mesh size) the sieve has, it is necessary to form a pressure drop in the reflected wave in order to provide the necessary suspension filtration rate. The latter should correspond to or be higher than the performance of pumps operating on the well. In turn, the pressure drop in the wave depends on its amplitude, which is determined by the vibration acceleration of the source of oscillation and the reflection coefficient of the wave, as well as the conditions for combining the phases of direct and reflected waves. These conditions ensure the formation of standing waves, a characteristic feature of which is the doubling of the wave amplitude, and therefore the quadrupling of the pressure drop across the sieve.

In calculations of the wave field of the suspension oscillation source, among other things, one should take into account the natural frequency of the filter compartment and its parts to allow the use or exclusion of the resonance mode.

The mobility of the entire apparatus in the direction of transmission of vibrations is achieved by the fact that it is supported by wheels, which in turn are supported by rails.

The movement of the apparatus with the frequency of natural vibrations enhances the overall dynamics and expands the spectrum of forced vibrations of the system of precipitation plates, and also contributes to the expulsion of sediment from the apparatus.

The advantage of a horizontal slurry flow versus a vertical flow for sand deposition.

Gravitational planting of sands from clay suspensions (which are the most commonly used types of drilling fluids) requires a certain time for sedimentation of particles from the stream, the absence of mixing of the stream and dilution of the current solution in order to completely exclude the formation of the clay phase and get the stream spreading in the form of a flat stream.

These conditions are most fully satisfied in apparatuses with a horizontal flow of a suspension carrying cuttings in the form of sands of various fractions.

In the deposition chamber, sand is disembarked. Drilling fluid, zigzagging through the labyrinth of the vibrating plates, is freed from sand, i.e. large particles up to 0.1 mm. Vibrations transmitted to the plates sharply reduce the structural viscosity of the suspension and thereby accelerate the deposition of sand. The labyrinth created by the plates lengthens the path of movement of the suspension and thereby creates a reserve of time for the deposition of sand.

A set of precipitation plates of various sizes allows one to obtain a wide resonance spectrum: at a certain frequency of excited vibrations, one of the plates will enter the resonance mode and thereby enhance the effect of sand deposition.

In flooded conditions, the suspension is filtered through a sieve due to two force factors: stationary pressure drop across the sieve and wave pressure drop. The stationary pressure drop (in our case it is 0.2 atm) determines the direction of the suspension flow in the apparatus and a certain filtration rate through the sieve, which decays as the precipitate settles on the sieve. The wave pressure drop across the sieve can reach large values if the wave pattern in the given volume is correctly organized from the wave emitter to the reflecting plate, between which the sieve is located.

The wave motion of the suspension, initiated by the emitter through the flexible wall of the apparatus’s capacity, provides not only a high pressure drop of the reflected waves on the sieve, but also prevents sludge from forming on the sieve due to direct waves, which reject solid particles that do not pass through the sieve.

For the selective separation of weighting agents from drilling fluids according to the proposed technology, the vibrating device must be equipped with a system of several screens and the question of removing the weighting agent sludge separately from the sludge should be structurally solved.

To separate the hydrocarbon emulsion, the sieves must be coated with a layer of hydrophobic material and the question of the removal of the hydrocarbon phase is structurally resolved.

Industrial utility

Currently, complex multi-stage equipment systems are used for cleaning and regenerating drilling fluids (clay slurries), including linear vibrating screens, hydrocyclone sand separators, hydrocyclone desilters and centrifuges equipped with centrifugal and screw pumps for feeding the suspension, as well as submersible mixers, degassers and other auxiliary mechanisms. These systems lend a lot of power to drive all the mechanisms into action, they need the coordinated work of all the elements of the system, they require appropriate maintenance personnel and have a high selling price.

The search for alternative technical solutions, one of which is the proposed invention, makes it possible to use the wave dynamics of the working fluid itself (drilling fluid) to filter it through thin sieves, as well as to precipitate a foreign solid phase due to vibration exposure to a thixotropic clay suspension.

Experience has shown that cassette sieves in flooded conditions have a resistance of more than 1000 hours, while vibrating sieves (vibrating screens) can withstand no more than 100 hours before a rush.

When the solid phase of the suspension is removed through hydrocyclone devices, up to 10% of the liquid phase containing chemicals is lost, which harms the ecological situation in the wells being drilled.

The proposed vibration control module eliminates the above negatives.

Sources of information

1. USSR copyright certificate No. 1417928 A1, cl. B 035/02, 1986.

2. Ivannikov V.I. “The experience of using the domestic system of fine cleaning of drilling mud during drilling of the Kola superdeep well.”, NTZ “Construction of oil and gas wells on land and at sea”, Moscow, VNIIOENG, No. 4, 2003, p.14-18.

3. RF patent 2114698, cl. B 03 B 5/14, published July 10, 1998.

Claims (8)

1. A method for separating suspensions into particle classes, including feeding the suspension under a differential pressure into a device for separating suspensions by a screen classification method on a filter surface in flooded conditions with suspension fluctuations, filtrate withdrawal, precipitation and precipitation of a solid phase, characterized in that the suspension is first passed in the form of a horizontal flow through a maze of plates of various sizes, arranged perpendicular to the direction of flow, which are forced to oscillate, and then sent to a sieve lassifikatsiyu carried out in pulsed wave mode, pumping slurry through a screen due to the reflected waves. 2. The method according to claim 1, characterized in that the separation of the precipitate from the sieve is carried out due to direct waves from the oscillation source of the suspension. 3. The method according to claim 1, characterized in that the amplitude, frequency and vibration acceleration of the source of oscillation of the suspension is regulated depending on the transparency of the sieve and the performance of pumping the suspension. 4. A device for separating suspensions into classes of particles, containing a closed container with a set of precipitation plates, a sieve, a suspension feed pipe into the container, a suspension oscillation source, a screw with a sediment discharge drive, a filtrate output pipe, characterized in that it is equipped with a gas outlet pipe, in this case, the precipitation plates with two ribs are rigidly and hermetically bonded to the body and the lid of the tank and are interconnected from opposite sides in the form of combs, forming in plan a labyrinth for the suspension flow, and p of various sizes - the minimum at the inlet and the maximum at the outlet of the suspension, the plate of maximum size serving as a reflective screen, the sieve is placed in a perforated rigid cassette, and the oscillation source is in contact with the wall of the container, made flexible. 5. The device according to claim 4, characterized in that the vibrational settling capacity has mobility in the direction of transmission of vibrations to it. 6. The device according to claim 4, characterized in that the walls of the tank are made rigid except for one end wall, through which the oscillation of the suspension is transmitted inside the tank. 7. The device according to claim 4, characterized in that the device is equipped with additional screens enclosed in perforated rigid cassettes and installed between the flexible wall of the container and the reflective screen. 8. The device according to claim 4, characterized in that the lower part of the tank has a tapering bottom, equipped with a sediment divider and a screw for discharging the solid phase sediment at the bottom.

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