EA024517B1 - Well strainer - Google Patents

Abstract

The invention relates to the mining industry, in particular, to the gas-and-oil producing industry, and can be used to prevent ingress of sand from the bottom-hole zone to the well. The set task is solved by provision of a well strainer comprising a body with covered perforations mounted on the casing string, and a protective housing, the perforation covers and the protective housing being made of a material destructed under action of chemicals, wherein inner and outer filtering elements are mounted concentrically on the body, the named elements being made of wire wound around support bars and being fixed by inner and outer rings, the annular space between the filtering elements being filled with gravel and restricted by a washer fixed by a spring-loaded ring, the protective housing being mounted on the outer filtering element. The outer filtering element may be mounted on an outside perforated tube. The inner and outer filtering elements are made of wire with a rhombic cross-section.

Description

The invention relates to the mining industry, and more specifically to the oil and gas industry, and can be used to prevent the entry of sand from the bottomhole zone into the well.

Known downhole filter, consisting of two concentrically arranged perforated nozzles, a mechanical packer, a magnet, two bushings, one of which is spring loaded [1].

The disadvantage of the filter is the need for additional operations for well development (perforation, unpacking, etc.), which significantly increases the cost and length of the development process.

A well-known filter containing a casing installed on the casing with holes blocked by plugs in the form of a glass filled with a viscoplastic substance and protruding from the bottom into the body [2].

The disadvantage of the downhole filter is the flow of sand into the well due to the destruction of the skeleton of the reservoir under the action of a large pressure gradient and the rate of filtration fluid flow.

Closest to the invention is a downhole filter containing a casing mounted on a casing with closed holes and a casing, the overlap of the holes and the casing are made of material that is destroyed by chemical exposure [3].

However, due to the lack of an additional filter layer during operation, sanding of the well occurs.

The objective of the invention is to prevent the destruction of the production casing and cement stone, as well as limiting the flow of sand into the well.

The task is achieved by the fact that in the well filter containing a casing installed on the casing with closed holes and a protective casing, the overlap of the holes and the protective casing of which is made of material that is destroyed by chemical exposure, the inner and outer filter elements made of the wire wound on the support rods and fixed by the inner and outer rings, while the annular space between the filter elements is filled with gravel and limited by a washer, fixed by a spring ring, while the protective casing is mounted on an external filter element.

An external filter element can be mounted on an external perforated pipe.

The inner and outer filter elements of the downhole filter are made of rhombic wire.

The proposed downhole filter (Fig. 1) consists of a perforated casing - housing (1), internal (2) and external (3) filter elements, upper (4) and lower (5) adapters, internal (6) and external (7 ) rings, plugs (8), gravel packing (9), protective cover (10). The inner (2) and outer (3) filter elements are made of corrosion-resistant rhombic wire by winding on the support rods. A large number of support rods increases the strength characteristics of the filter in both axial and radial directions. The wire and support rods are connected by resistance welding at each intersection. The use of resistance welding provides a strong and reliable connection of the wire with the support rods, as well as a constant value of the inter-turn gap during operation of the filter. The size of the slit of the external filter element is determined based on the particle size of the formation sand, and the size of the slit of the internal filter element is the size of the particles of gravel packing. Specially prepared gravel is introduced into the annular space between the internal and external filtering elements, forming a gravel layer with a certain thickness in order to protect the sand formation from flow into the well. The optimum thickness of the gravel pack should be at least 20 mm. Uniformly located holes in the area of the filtering part of the perforated casing-casing (1) are offset by 30 ° relative to each other and during installation are blocked by plugs (8) of chemically active metal.

The filter is assembled in the following sequence: the holes of the corresponding perforated casing pipe-casing (1), having connecting threads at the ends, are first damped by plugs (8) from material destroyed by chemical attack. Then, the inner filter element (2) is put on the perforated casing-casing (1). In the area of the holes at a certain distance from the edge of the perforated casing pipe (1), the inner filter element (2) is fixed by clamping on both sides with inner rings (6), which are then welded to the pipe. The perforated casing pipe-casing (1) together with the internal filtering element (2) is screwed into the lower adapter (5), on which the stop (11) is then mounted and welded to it. Having put on an emphasis (11) the external filtering element (3) the latter is welded to it. The cavity between the inner (2) and outer (3) filtering elements is filled with gravel packing (9) and blocked by a washer (12), which is fixed by a spring ring (13). By screwing the upper adapter (4) onto the perforated casing pipe (1) and putting on the outer ring (7) the latter, pressing it against the external filtering element (3), weld to the upper adapter (4). Then, a protective cover (10) is put on the external filter element (3) from a thin sheet of active metal, which protects the surface of the filter when it is installed in the well. The protective cover (10) sits with one end on the stop (11) and is clamped with a nut (14), which is fixed on the upper

- 1 024517 adapter (4) with screws (15). When descending into the well, the filter is centered by the outer diameters of the lower adapter (5) and the nut (14).

The downhole filter, depending on the capacity of the reservoir, can consist of several links that are connected together using connecting threads at the ends of the adapters (4, 5), couplings and nozzles.

In FIG. 2 shows a downhole filter, the distinguishing feature of which is that the external filter element is mounted on the surface of the perforated pipe (a weighted drill pipe with a machined inner diameter). This downhole filter (Fig. 2) consists of an internal perforated casing (1), an internal (2) and an external (3) filter element, an external perforated pipe (4), an upper (5) and a lower (6) adapter, inner (7) and outer (8) rings, plugs (9), gravel packing (10), protective casing (11). The inner (2) and outer (3) filter elements are also made of a profile wire of a rhombic section, by winding on support rods. The start of assembly of the second variant of the downhole filter is carried out in the same sequence as the first. First, the holes of the corresponding inner perforated casing pipe-body (1), having connecting threads at the ends, are damped by plugs (9) from material destroyed by chemical attack. Then, the inner filter element (2) is put on the inner perforated casing pipe (1). In the area of the holes at a certain distance from the edge of the perforated casing (1), the inner filter element (2) is fixed, clamped on both sides by the inner rings (7), which are then welded to the pipe. Then, the inner perforated casing pipe-casing (1) together with the internal filtering element (2) is screwed into the lower adapter (6), onto which the external perforated pipe (4) is then screwed. An external filter element (3) is put on the external perforated pipe (4) and clamped on both sides by outer rings (8), which are then welded to the external pipe (4) in the area of the holes at a certain distance from the edge. The cavity between the inner (2) and outer (3) filtering elements is filled with gravel packing (10) and blocked by a washer (12), which is fixed by a spring ring (13). Then, a protective casing (11) is put on the external filter element (3) from a thin sheet of active metal, which protects the surface of the filter when it is installed in the well. The protective casing (11) abuts against the lower adapter (6) with one end and is clamped with a nut (14), which is fixed on the external perforated pipe (4) with screws (15). Next, an upper adapter (5) is screwed onto the inner perforated casing (1), on the outer surface of which an external perforated pipe (4) is mounted at the same time, which is welded to it. When descending into the well, the filter is centered by the outer diameters of the lower (6) and upper (5) adapters.

This well filter, depending on the capacity of the reservoir, can also consist of several links that are connected together using connecting threads at the ends of the adapters (5, 6), couplings and nozzles.

The manufactured filter, assembled depending on the length of the productive object, is lowered into the well on the casing and installed against the production object. Depending on the height of the cement lift behind the string, the calculated volume of cement mortar is pumped into the casing and left to harden the cement.

After the cement has hardened, hydrochloric acid of the calculated volume is pumped into the tubing, deflated to the lower holes on the filter housing, then the pipes are raised above the acid level. After injection, hydrochloric acid, reacting with plugs (8), dissolves them. At the same time, the acid passing through the inner filter element (2), the gravel layer filtering the barrier (9) and the external filter element (3) reacts with the protective casing (10) of the active metal.

Thus, a permeable barrier is created against the productive object, which prevents the destruction of the production string and cement stone, as well as the restriction of the flow of sand into the well.

During well operation, formation fluid with sand and mechanical impurities, being filtered through an external filter element (3), a gravel layer barrier (9), an internal filter element (2) and passing through holes on the filter housing (1), enters the well and tubing rises to the day surface (Fig. 1).

The downhole filter is part of the casing string; installation and installation are combined with the casing runoff, which does not require additional hoisting operations and, therefore, the use of additional hoisting mechanisms and downhole equipment is excluded.

The use of the device allows to simplify the technology of opening the formation, since sighting operations with the help of perforators and the call of the geophysical lot to conduct these operations are excluded, and this, in turn, eliminates the danger of destruction of the cement ring in the annulus, as well as the restriction of sand, which ultimately will lead to an increase in the overhaul period of wells, a reduction in current and capital work, and an increase in the flow rate of wells.

- 2,024,517

Information sources

1. USSR author's certificate No. 874990, ЕВВ 43/08, 1981.

2. USSR author's certificate No. 1091619, CL Е21В 43/08, 1996.

3. USSR author's certificate No. 1055860, CL E21B 43/08; EB21 3/08, 1981.

Claims (3)

CLAIM 1. A downhole filter comprising a casing installed on the casing with closed openings and a protective casing, the capping of the openings and the protective casing of which is made of material that is destroyed by chemical attack, characterized in that the inner and outer filter elements made of wire are concentrically mounted on the casing wound on support rods and fixed by inner and outer rings, while the annular space between the filter elements is filled with gravel and limited by a washer, fixed by a spring ring, and a protective casing is mounted on an external filter element. 2. The downhole filter according to claim 1, characterized in that the external filter element is mounted on an external perforated pipe. 3. The downhole filter according to claims 1, 2, characterized in that the internal and external filtering elements are made of rhombic cross-section wire.