RU2825368C1 - Filter unit for chute tank - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, in particular to treatment of process fluids during well repair. Chute tank includes three interconnected sections. Two filters are connected in parallel to the outlet section by means of inlet branch pipes. Outlet pipes of the filters are connected by a T-piece equipped with a valve at the free end. Inlet section is made with the possibility of supplying process liquid to it through the intake line and the damper, which provide for damping of flow rate and preliminary coarse cleaning. Each section is equipped with drain hatches with pressure plugs for removal of solid sludge. Level gauge is installed in the output section. Each of the filters consists of a cylindrical housing, which is plugged from below, and a cover fixed on the upper end of the cylindrical housing by means of a bolt joint. Cover is rigidly connected in the centre with the outlet branch pipe; inside the cylindrical housing there is a concentrically placed filtering screen of a cylindrical shape, which is screwed on the lower end of the cover and communicates with the outlet branch pipe. Above the filters the corresponding outlet branch pipes are connected to the T-joint. In the filter cover there is a hole in which a discharge branch pipe with a check valve passing from top to bottom is installed. Discharge branch pipe hydraulically connects the outlet branch pipe of the filter with the annular space of the cylindrical housing of the filter at the inlet of the filter screen. Cylindrical housing plugged from below is equipped with a drain valve. Pressure gauge is screwed into the T-joint.

EFFECT: improved quality of filtration of fluid spent in the well, excluding occurrence of emergencies in the well during subsequent technological operations, preventing negative environmental consequences as a result of repair works.

1 cl, 3 dwg

Description

The invention relates to the oil and gas industry, namely to devices for cleaning process fluid during well flushing from drilled rock (sludge), contamination during underground and major well repairs.

A sectional trough tank for well repair is known (patent for utility model RU No. 84443, IPC E 21 B 21/06, published 10.07.2009), consisting of sections communicating with each other through cutouts in the wall, equipped with drain cocks, the sectional trough tank consists of three sets of partitions installed at different heights and forming a labyrinth with the possibility of vertical liquid lifting, while the last section is equipped with two nets and a perforated pipe with a device for connecting to a mobile steam unit.

Disadvantages of the device:

- firstly, the low quality of filtration of the waste well fluid in the trough tank system, which during the well repair process leads to rapid overflow of the trough system tank and a spill of contaminated fluid (waste process fluid, drilled cement rock, etc.) may form on the well site. Calculations for cleaning the process fluid with a trough tank showed that at a flow rate of 10 l/s, contaminants of 1 mm or less in size pass freely through the cleaning system of the trough tank and are pumped back into the well;

- secondly, the probability of occurrence of emergency situations in the well during subsequent technological operations increases due to poor-quality (dirty) flushing, since pumping of poorly purified process fluid (with sand impurities of 1 mm or less) leads to the deposition of this sand in the well on the packer or other well equipment located in the well, which with a high probability can lead to the seizure of the packer or other well equipment located in the well;

- thirdly, negative environmental consequences caused by the spillage of contaminated process fluid and other harmful substances onto the soil;

- fourthly, poor working conditions for service personnel, since the personnel have to work in conditions of contaminated liquid spills on the well site.

A trough tank system SEZH 3-19 is known (patent for utility model RU No. 77333, IPC E 21 B 21/06, published on 20.10.2008), which is a tank in the form of sections communicating with each other through cutouts in the wall, with a hinged grid located above the inlet section, and drain hatches with a threaded plug, while the tank consists of three sections communicating with each other, behind the walls of which reflectors are installed with the possibility of converting turbulent fluid movement into laminar, while the supply of process fluid to the inlet section is carried out through a receiving line and a damper with preliminary damping of the flow velocity and rough cleaning, and for collecting and removing light fraction petroleum products, a compartment with a drain line is provided, and each section is equipped with drain hatches with clamping plugs for removing solid sludge, and for determining the volume A level gauge is provided for the selected process liquid, installed in the last output section.

Disadvantages of the device:

- firstly, the low quality of filtration of the waste well fluid in the trough tank system, which during the well repair process leads to rapid overflow of the trough system tank and a spill of contaminated fluid (waste process fluid, drilled cement rock, etc.) may form on the well site. Calculations for cleaning the process fluid with a trough tank showed that at a flow rate of 10 l/s, contaminants of 1 mm or less in size pass freely through the cleaning system of the trough tank and are pumped back into the well;

- secondly, the probability of occurrence of emergency situations in the well during subsequent technological operations increases due to poor-quality (dirty) flushing, since pumping of poorly purified process fluid (with sand impurities of 1 mm or less) leads to the deposition of this sand in the well on the packer or other well equipment located in the well, which with a high probability can lead to the seizure of the packer or other well equipment located in the well;

- thirdly, negative environmental consequences caused by the spillage of contaminated process fluid and other harmful substances onto the soil;

- fourthly, poor working conditions for service personnel, since the personnel have to work in conditions of contaminated liquid spills on the well site.

The technical results of the invention are the development of a design for a filtering unit for a trough tank, which allows improving the quality of filtration of the liquid processed in the well and eliminating the likelihood of emergency situations in the well during subsequent technological operations, as well as preventing negative environmental consequences as a result of repair work in the well and improving the working conditions of the maintenance personnel of the repair teams. And also expanding the arsenal of means related to filtering units of the trough tank.

The technical results are achieved by a filtering unit for a trough tank, which is a tank consisting of three sections communicating with each other, wherein the process liquid is fed into the input section through a receiving line and a damper with preliminary damping of the flow rate and rough cleaning, and each section is equipped with drain hatches with clamping plugs for removing solid sludge, and a level gauge installed in the output section is provided to determine the volume of the process liquid being withdrawn.

What is new is that the trough tank is additionally equipped with a filter unit, wherein the filter unit consists of two filters, connected in parallel to the outlet section of the trough tank by means of inlet pipes, the outlet pipes of the filters are connected by a tee equipped with a valve at the free end, wherein each of the filters consists of a cylindrical body, sealed at the bottom and a cover fixed to the upper end of the cylindrical body by a bolted connection, wherein the cover is rigidly connected in the center to the outlet pipe, a cylindrical filter mesh sealed at the bottom is concentrically placed inside the cylindrical body, wherein the cylindrical filter mesh sealed at the bottom is screwed onto the lower end of the cover and communicates with the outlet pipe, wherein from above the filters the corresponding outlet pipes are connected to the tee, wherein an opening is made in the filter cover into which a discharge pipe with a check valve passing from top to bottom is installed, wherein the discharge pipe hydraulically connects the filter outlet pipe with the annular space of the cylindrical filter body at the entrance to the filter mesh, and the cylindrical body, plugged at the bottom, is equipped with a drain valve, while a pressure gauge is screwed into the tee, monitoring the pressure in the filter outlet pipes.

Fig. 1 shows a side view of the device.

Fig. 2 shows a top view of the device.

Fig. 3 shows the filter installation in an enlarged form (View I).

The filtering unit for the trough tank is a tank 1 (see Fig. 1-3), consisting of three sections 2' (Fig. 2), 2", 2"' (Fig. 1-3), communicating with each other. In this case, the process liquid is fed into the input section 2' through the receiving line and the damper (shown conditionally in Fig. 1) with preliminary damping of the flow velocity and rough cleaning.

Each section 2', 2", 2"', is equipped with drain hatches (not shown in Fig. 1-3) with pressure plugs for removing solid sludge.

To determine the volume of the process liquid being withdrawn, a level gauge (not shown in Fig. 1-3) is provided, installed in the output section 2".

The trough tank 1 is equipped with a filter unit 3 (see Figs. 1 and 2). The filter unit 3 consists of two filters 4 and 5, connected in parallel to the outlet section 2"' of the trough tank 1 by means of inlet pipes 6 (Figs. 1-3) and 7 (Figs. 1-2), respectively.

The outlet pipes 8 (Fig. 1-3) and 9 (Fig. 1-2) of filters 4 and 5, respectively, are connected by a tee 10 equipped with a valve 11 at the free end.

Fig. 3 shows view I of the filtering installation 3, including filters 4 and 5, in an enlarged form.

Each of the filters 4 and 5 consists of a cylindrical body 12 (see Fig. 3), sealed at the bottom, and a cover 13, fixed to the upper end of the cylindrical body 12 by a bolted connection 14, for example 4 bolts and 4 nuts (shown conditionally in Fig. 3).

The cover 13 is rigidly connected in the center to the outlet pipe 8 (9). Inside the cylindrical body 12, a filter mesh 15 of cylindrical shape, sealed at the bottom, is concentrically placed. For example, the filter mesh 15 of cylindrical shape, sealed at the bottom, has a filtering capacity of 50 µm and higher.

The filter mesh 15 of cylindrical shape, plugged at the bottom, is screwed onto the lower end of the cover 13 and communicates with the outlet pipe 8 (9). From above the filters 4 and 5, the corresponding outlet pipes 8 (9) are connected to the tee 10.

In the cover 14 of filters 4 and 5, an opening 16 is made (Fig. 3), into which a discharge pipe 17 with a check valve 18, passing from top to bottom, is installed.

The discharge branch pipe 17 hydraulically connects the outlet branches 8 (9) with the annular space 19 of the cylindrical body 12 of the filter 4 (5).

The cylindrical body 12, sealed at the bottom, is equipped with a drain valve 20. A pressure gauge 21 (Fig. 1, 2) is screwed into the tee 10, monitoring the liquid pressure in the outlet pipes 8 (9) of the filters 4 (5).

Since one of the objectives of the invention is to improve the filtration quality of the liquid processed in the well, this requires effective removal of the volume of liquid filtered in filters 4 (5) from the device.

Therefore, it is necessary to fulfill the condition, verified in laboratory conditions:

s ₁ = k × (0.75 ×(π × (d ₁ ) ² /4)) s ₂ = k × (π × (d ₂ ) ² /4)) = S = (π × (D) ² /4)

s ₁ = 2 × (0.75 × (π × (d ₁ ) ² /4)) s ₂ = 2 × (π × (d ₂ ) ² /4) = S = (π × (D) ² /4)

s ₁ = 1.5 ×(π × (d ₁ ) ² /4) s ₂ = 2 × (π × (d ₂ ) ² /4) = S = (π × (D) ² /4)

or transforming the expression: d ₁ = 0.75×√(s ₂ /π) (1),

where s ₁ is the total cross-sectional area of inlet pipes 6 and 7, m;

k = 2 – number of inlet (outlet) pipes;

…….d ₁ – diameter of the passage opening of inlet pipes 6 and 7, m;

s ₂ – total cross-sectional area of outlet pipes 8 and 9, m;

d ₂ – diameter of the passage opening of outlet pipes 8 and 9, m;

D – tee diameter 10, m;

S – cross-sectional area of tee 10, m.

Let's take d ₁ = 0.05 m.

Then: s ₁ = 1.5 × (π× (d ₁ ) ² /4) = 1.5×(3.14× (0.05 m) ² /4) = 0.00294 m ²

Substituting into formula (1) we obtain:

d ₂ = k×2√s ₁ /π = 2×2 √0.00294 ^m2 /3.14 = 0.069 m.

s ₂ = 2 × (π× (d ₂ ) ² /4) = 2 × (3.14 × (0.069 m) ² /4) = 0.007474 ^{m 2}

D = 4√s ₂ /π = 4√0.007474m ² /π =0.11 m

Thus:

d ₂ = 0.069 m = 69 mm, and D = 0.11 m = 110 mm,

which ensures the efficient removal of the volume of liquid filtered in filters 4 (5) from the device and, as a result, improves the quality of filtration of the liquid used in the well.

The device works as follows.

First, trough tank 1 with filter unit 3 is installed as shown in Figure 1, 2, 3. For ease of use, trough tank 1 with filter unit 3 can be mounted on one frame. Then, trough tank 1 with filter unit 3 is connected to a well (not shown in Figures 1 and 2) via a pump unit, for example, brand CA-320. Inlet section 2' of trough tank 1 is connected to the well. Valve 11 on tee 10 is opened (see Figure 1, 2). The direction of movement of process liquid during cleaning in sections 2', 2", 2"' of trough tank 1 and filter unit 3 is shown by arrows.

The pump unit ensures the circulation of process fluid during flushing, for example when drilling out cement plugs, in a circle: trough tank with a filter unit - pump unit - well - trough tank with a filter unit.

The process fluid processed in the well enters the input section 2' of the trough tank 1 through the receiving line and the damper with preliminary damping of the flow velocity and rough cleaning. Then, in the trough tank 1, the process fluid processed moves through the upper and lower cutouts (shown by dotted lines in Fig. 2) along sections 2' - 2" - 2"', in which a vertical rise of the fluid in section 2' and natural precipitation of the sludge with the overflow of the fluid through the upper cutouts into section 2" and subsequent vertical descent of the fluid into section 2" occurs. The liquid then flows through the lower cutouts into section 2", where the liquid again rises vertically and the sludge naturally settles. Thus, in sections 2', 2", 2"' of the trough tank 1, preliminary cleaning of the process liquid used in the well is ensured during its circulation during the process of drilling out the cement plug by flushing the well.

Next, the process liquid purified in the trough tank 1 enters the corresponding filters 4 and 5 of the filter unit 3 through the inlet pipes 6 and 7. Then the process liquid enters the annular spaces 19 of the cylindrical bodies 12 of the filters 4 and 5, respectively. From there, the process liquid rises upward through the filter mesh 13 and enters the outlet pipes 8 (9). The filter mesh 13 filters out dirt, sludge, debris, etc., having a size of more than 50 μm to the bottom of the plugged cylindrical body 12 of the filters 4 (5). The finer sludge that has passed through the filter mesh into the outlet pipes 8 (9) through the discharge pipe 17 with the check valve 18, passing from top to bottom, settles down through the annular space 19 to the bottom of the plugged cylindrical body 12 of the filters 4 and 5. As the cylindrical body 12 of the filters 4 (5) is filled with filtered sludge, the valve 20 is opened and the sludge filtered on the filter mesh 13 is disposed of. The pressure of the liquid in the outlet pipes 8 (9) of the filters 4 (5) is controlled by the pressure gauge 21. Then the process liquid with particle sizes less than 50 µm, filtered from sludge and contaminants in the filter unit 3, enters the tee 10 and, with the valve 11 open, enters the intake of the pumping unit, for example, the CA-320, with the help of which the liquid is pumped, for example, along a column of pipes into a well, from where it rises through the annular space to the wellhead and again enters the inlet section 2' of the trough tank 1. Thus, one cycle of circulation and purification of the waste liquid in the trough system of the tank occurs.

Pressure gauge 21 shows the working pressure in filter unit 3 during its operation. For example, the working pressure is 0.3-0.5 MPa. Exceeding the working pressure, above the designated interval, indicates clogging of filters 4 and 5 and signals the need to replace filter mesh 13. Replacement of filter mesh 13 of filters 4 and 5 is performed with the pump unit stopped.

After completion of repair work on the well, before transportation, each section 2', 2", 2"' of the tank 1 is emptied through drain pipes. To remove solid sludge (which has settled naturally during overflows from section to section), drain hatches (not shown in Figs. 1-3) are opened at the bottom of each section 2', 2", 2"' and discharged through threaded plugs into a special tank, which is subsequently disposed of.

Due to the fact that the outlet section of the trough tank is equipped with a filtering unit consisting of two filters, connected in parallel with the outlet section of the trough tank using inlet pipes, additional filtration of the waste liquid from contaminants with a fineness of 50 microns and higher is performed, thereby improving the quality of cleaning of the process liquid pumped back into the well.

It has been established experimentally that particles of sand, sludge, etc. 50 µm in size do not cause emergency situations in the well. Therefore, the probability of emergency situations in the well is excluded, since the filter unit filters out liquid with sand impurities of 1 mm or less. This eliminates the sedimentation of sand in the well on the packer or other well equipment located in the well, which in turn eliminates the seizure of the packer or other well equipment in the well.

Thanks to the presence of a filter unit in the design of the trough tank, negative environmental consequences caused by the overflow of contaminated liquid and other harmful substances onto the soil are eliminated.

The working conditions of the maintenance personnel are improved, as spillage of contaminated liquid on the well site is excluded. The use of a trough tank with a filter unit allows preventing damage to the natural environment from waste pollution and improving the working conditions of the maintenance personnel of repair teams.

The filter installation for the trough tank allows:

- improve the quality of filtration of the liquid processed in the well;

- eliminate the possibility of emergency situations occurring in the well during subsequent technological operations;

- eliminate environmental consequences caused by the spillage of oil-containing raw materials, acids and other harmful substances onto the soil;

- improve working conditions for service personnel.

Claims (1)

A filtering unit for a trough tank consisting of three sections communicating with each other, in which the inlet section is designed with the possibility of feeding process fluid into it through a receiving line and a damper, ensuring the damping of the flow rate and preliminary rough cleaning, each section is equipped with drain hatches with clamping plugs for removing solid sludge, and a level gauge installed in the outlet section is provided for determining the volume of the process fluid being collected, characterized in that it is equipped with two filters, tied in parallel with the outlet section of the trough tank by means of inlet pipes, the outlet pipes of the filters are connected by a tee equipped with a valve at the free end, wherein each of the filters consists of a cylindrical body, plugged at the bottom, and a cover fixed on the upper end of the cylindrical body with a bolted connection, wherein the cover is rigidly connected in the center to the outlet pipe, a filter mesh plugged at the bottom is concentrically placed inside the cylindrical body cylindrical in shape, wherein the filter mesh of cylindrical shape, plugged at the bottom, is screwed onto the lower end of the cover and communicates with the outlet branch pipe, wherein the corresponding outlet branches are connected to a tee on top of the filters, wherein an opening is made in the filter cover, into which a discharge branch pipe with a check valve passing from top to bottom is installed, wherein the discharge branch pipe hydraulically connects the outlet branch pipe of the filter with the annular space of the cylindrical body of the filter at the entrance to the filter mesh, and the cylindrical body, plugged at the bottom, is equipped with a drain valve, wherein a pressure gauge is screwed into the tee, monitoring the pressure in the outlet branches of the filters.