RU2388904C2 - Arrangement of well strainers for decreasing flooding of oil wells - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: arrangement of well strainers for decreasing flooding of oil wells includes well strainers installed in lower part of pipe string in the area of productive formation. Strainers consist of perforated tubes and filtering elements. A flow string passes inside pipe string with strainers, and in lower part of which there installed is a bore-hole pump to the location area of which the area of perforation holes throughout the length of the well decreases and then increases. At that, there can be no perforation in location area of bore-hole pump. At that, all perforated tubes of strainers have marking for proper installation.

EFFECT: decreasing flooding of wells, prolonging the time of their operation, increasing oil production volumes, and decreasing its production cost.

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Description

The invention relates to the oil and gas industry and can be used in oil production to reduce watering wells and extend their life.

Known well filter, which is a steel pipe with holes on which a profiled wire is wound (Gavrilko V.M. Filters for boreholes, M., "Nedra", 1985, p.7 ... 9). The main disadvantage of this design is the change in the inter-turn gaps when installing the filter in the well, the lack of protection of the filter mesh from mechanical influences during transportation and installation of the filter, which negatively affects the degree of filtration.

Known for the inventor's certificate for invention No. 941548, a downhole filter consisting of a supporting tubular perforated frame and a fibrous filter coating made in the form of separate plates of wire nonwoven material, rigidly lapped by welding and soldering on the filter tubular frame against perforation holes. The main disadvantage of this design is the presence of welded zones, which over time activates the processes of metal corrosion. The snug fit of the filter element to the perforated pipe significantly reduces the filtration zone, which is limited by the area of the holes in the pipe. There is no protection of the filter element from mechanical influences during transportation and installation of the filter.

A known filter design according to the patent of the Russian Federation No. 516644, consisting of a supporting frame made of a perforated pipe, and a filter coating of wire nonwoven material, the filter coating is made in the form of a tubular element and is mounted on the supporting frame in the grooves of the support rings fixed by the sub. Between the filter coating and the supporting frame there is a drainage layer made in the form of a spiral of wire wound on a supporting frame. This spiral forming the drainage layer may be made of spring wire. The tubular filter element is made of wire non-woven material obtained by pressing wire (metal rubber). Metal rubber was developed at the Samara State Aerospace University (formerly Kuibyshev Aviation Institute) and was used primarily for engine mount dampers. The downhole filter is protected by a casing with holes.

A disadvantage of the known filter design is the rapid clogging of the filter element with mechanical impurities. The protective casing with holes (radial gaps) does not perform the function of protecting the filter element from clogging of mechanical particles by large particles, performing the function of protecting the filter from mechanical damage during transportation and installation. In addition, the protective casing with radial clearances creates increased resistance when the fluid passes through the protective casing, which reduces the rate of fluid flow to the filter element and, accordingly, reduces the throughput of the downhole filter.

Known downhole well filters according to US patent No. 4771829. These filters contain a perforated pipe and wire wound in a spiral with a gap between the turns of the spiral. The wire is wound on longitudinal elements (stringers).

Disadvantages: large tolerance on the width of the gap between the rows of wire (up to 40%), which leads to the fact that the filter passes particles 40% larger than declared. In addition, if during transportation of the filter or its descent there is a local increase in the gap between the rows of wire several times, respectively, larger abrasive particles come into contact with the produced product inside the filter, which causes wear on the ground equipment: pump and valves.

Known column well filters according to the patent of the Russian Federation 222692. This column contains sequentially installed between themselves well filters. The disadvantage is the flow of the extracted product in the annulus. This disadvantage is eliminated in the filter arrangement according to the patent of the Russian Federation No. 2260679. The column of downhole filters contains several downhole filters, screwed together and having the same design and elastic connecting rings mounted on them.

A known method and device for reducing watering of oil wells according to the patent of the Russian Federation No. 2268999. The device contains a casing string separator. The disadvantages of the device are the large dimensions of the device, the complexity of maintenance.

A known method and device for reducing watering of oil wells according to the patent of the Russian Federation for invention No. 2241733, prototype. The device contains a casing string dehydration in the form of containers with hydrophobic elements.

Disadvantages: large diametrical dimensions of the device, its fast clogging with solid particles and high cost.

The objective of the invention is to reduce the watering of wells, extending their life, as well as increasing the volume of oil production and reducing its cost.

The solution to these problems has been achieved in a method of reducing oil well watering, including oil production using well filters made of perforated pipes on which filter elements are installed, thereby reducing the effect of rarefaction generated by the pump on the formation, which prevents local rise of formation water in the installation area pump.

The solution of these problems was achieved in the layout of well filters to reduce watering of oil wells, containing well filters consisting of perforated pipes and filter elements, in that the area of perforation holes per unit side surface of each pipe is variable. The area of the holes of the perforated pipes per unit surface increases to its lower part. The area of the holes per unit surface along the length of the perforated pipes increases to its upper part. The area of the holes of the perforated pipes per surface unit along the length of the well first decreases, and then increases. The area of the holes of the perforated pipes along the length of the pipe string varies due to changes in the diameter of the holes of the perforation. The area of the holes of the perforated pipes along the length of the column is changed by changing the number of perforation holes per linear meter of the perforated pipe. The area of the holes of the perforated pipes along the length of the column is changed by changing the pitch of the holes. All perforated filter tubes are marked for proper installation.

The proposed technical solutions (method and device) have novelty, inventive step and industrial applicability. Novelty and inventive step are confirmed by patent research. Industrial applicability is due to the fact that for the application of the invention does not require new materials and technologies not previously mastered.

The invention is illustrated in the drawings (figure 1 ... 9), where

figure 1 shows a conventional diagram of oil production in a horizontal well,

figure 2 shows the design of the downhole filter,

figure 3 shows a diagram of the first embodiment of the layout of the downhole filters to reduce watering of a horizontal or directional well,

figure 4 shows a diagram of the change in the area of the holes of the perforation for the first version of the layout of the well filters to reduce water cut in the well,

5 is a diagram of a second embodiment of a well filter arrangement for reducing watering of a horizontal or directional well, for the case when the submersible pump is lowered below the filter connection to the pipe string,

figure 6 shows a diagram of the change in the area of the holes of the perforation for the second variant of the layout of well filters to reduce water cut in the well,

Fig.7 shows a conventional diagram of oil production in a vertical well,

on Fig shows a third embodiment of the layout of the downhole filters to reduce flooding of a vertical well,

figure 9 shows a diagram of the change in the area of perforation holes for the third layout option to reduce well watering.

The arrangement of downhole filters to reduce water cut in oil wells (Fig.1 ... 9) contains downhole filters 1 containing a perforated pipe 2, with holes "B" and filter elements 3, which are installed in the lower part of the pipe string 4 in the well 5, made in productive reservoir 6. Below the reservoir 6 may be an aquifer 7. The annular gap "B" is isolated above the reservoir 6 by the packer 8. Inside the pipe string 4 passes the tubing string 9, in the lower part of which there is a submersible pump with 10 in the preferred installation area of the submersible pump "G". During the operation of the submersible pump 10, a vacuum is created along the entire length of the pipe string 4, it has a maximum value in the “G” zone, which can cause local rise of formation water in the installation zone of the submersible pump 10, which, as a rule, occurs during normal operation of wells and illustrated in figure 1 and figure 7. In this case, the pipe string 4 begins to receive water from the aquifer 7. All of the downhole filters 1 are marked 11 (figure 2) for proper installation in a certain order.

For horizontal wells (figure 1, 3 and 5) and vertical (figure 7, 8), the closer to the submersible pump 10, the greater the vacuum. In the usual layout of the pipe string (Fig. 1 and Fig. 7), this contributes to the capture of water from the aquifer 7. To prevent this phenomenon, three configuration options are proposed.

The first option of the layout of the downhole filters (Fig. 3) is made with increasing the area of the holes F of the perforated pipes 2 per unit surface to the bottom of the pipe string 4 (Fig. 4), for example, by changing the diameter "d" for the round holes "B". Changing the area is also possible by changing the number of holes in the section or step "h". The same principle can be implemented for non-circular holes. The first option is applicable mainly for horizontal or shallow wells with an aquifer 7 located under the reservoir 6.

In the second embodiment of the arrangement (Fig. 5), the area of the perforation holes per unit lateral surface of the perforated pipes 2 (or 1 linear meter) first decreases to the location zone of the submersible pump "G", and then increases (Fig. 6). In the area of the submersible pump "G", perforation may be completely absent.

The third option is applicable for vertical wells (Fig. 8). The area of the orifice of the holes of the perforated pipes 2 per unit lateral surface of the perforated pipe 2 is increased to its upper part (Fig.9) to prevent or reduce the capture of produced water, as shown in Fig.7.

Perforated pipes 2 (figure 2) have a diameter D, holes with a diameter d are made in them with a step h.

For all three filter configurations, the holes in the perforated pipe 2 can be round and / or non-circular, and the area of the perforation holes per unit length of the perforated pipe can be changed, for example, in the following ways:

- by changing the area of the holes d,

- by changing the number of perforation holes,

- by changing the step "h" of their location.

Figure 4, 6 and 9 shows two options for changing the area of the perforation holes: discrete - pos.12 and smooth (proportional) - pos 13.

When assembling, well filters 1 are installed in the lower part of the pipe string 4 in the area of the productive formation 6, taking into account marking 11. During production, oil passes through openings “B” into the perforated pipes 2 and then is pumped by the pipe string 9 to the surface by a submersible pump 10 to wellhead equipment (wellhead equipment is not shown in FIGS. 1 ... 9). Water from an aquifer 7 is not sucked in all three versions of the device because the installation area of the submersible pump "G" is far from the water waist seam 7 or protected from the stimulation or lack of perforations low degree of perforation of the perforated pipe 2.

The application of the invention allowed

1. Reduce the percentage of water in the produced oil.

2. To provide optimization of the process of reducing water cut, both for vertical and horizontal wells.

3. Extend the life of the well.

4. Increase oil recovery.

5. Reduce the cost of oil production.

6. Reduce well construction costs.

7. To reduce the cost of the device due to the simple design and reduce the number of holes in the part of the well filters of one set.

8. Ensure continuous operation of the device without clogging.

Claims (1)

The arrangement of well filters to reduce water cut in oil wells, comprising well filters installed in the lower part of the pipe string in the area of the reservoir, consisting of perforated pipes and filter elements, characterized in that a pipe string passes through the pipe string with filters of the part of which a submersible pump is installed, to the location zone of which the area of perforation holes per unit side surface of perforated pipes along the length of the well decreases, and then elichivaetsya, wherein the submersible pump in the location area perforations may be omitted, and all perforated tube filters are marked for proper installation.

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