RU2256780C2 - Well filter - Google Patents

Abstract

FIELD: oil industry, particularly means to prevent sand appearance in well and sand ingress into acting well pump.

SUBSTANCE: well filter comprises tubular filtering means including metal body with perforated part and two fastening members for filtering means securing inside casing pipe. Fastening members are made as rubber sealing collars closing perforated zone of the casing pipe from both sides thereof in axial direction and opening flow of fluid obtained from well to the filter. Body consists of two parts releasable along diameter. The parts may be securely pressed to casing pipe and include above sealing collars. Body part area located under the sealing collar has plasticity exceeding that of above perforated part, which is formed of metal with increased hardness. Filter provides free passage of special equipment through filter cross-section for simultaneous or alternate development of upper or lower production beds.

EFFECT: simplified structure, increased reliability of filter installation and operation.

1 dwg

Description

The invention relates to the oil industry, in particular to methods for controlling sand occurrences in wells.

Known devices for preventing sand from entering a pump operating in a well, which are installed at the pump inlet in the form of filters or separators, the operation of which is based on the action of gravitational forces or inertia in all methods of oil production, is the implementation of a set of measures aimed at preventing the ingress of sand from the reservoir to the trunk.

The most effective method of dealing with sand occurrences during well operation is the installation of special filters at the bottom.

The main types of bottomhole structures are given in the book Ashrafyan M.O. and others. Improving the design of the bottom of the wells. M .: Subsoil. -1987, are determined depending on the strength of the formation rocks, the conditions of their occurrence.

Downhole tubular downhole filters can have various types of designs.

The wire - welding filter is structurally performed in the form of a pipe segment with regular perforation and a large number of longitudinal support rods, on which a steel alloy wire profiled in the form of a trapezoid is wound (see A. Pirverdyan, Protection of the well pump from gas and sand. M .: Nedra. -1986. And Catalog of OJSC NPO Rosneft-Permneft DOAO Machine-Building Plant Neftetermmash, “Sand-Filter from Profiled Wire FPT1-146 / 168). A known type of filter can be installed on the shoe of the tubing in the interval of perforation of the wellbore.

The disadvantage, as shown by operating experience, is that wire-welded filters are short-lived, quickly deteriorate due to abrasion and chemical influences on the main filter element - the wire.

Another type of tubular well filter is based on porous titanium filter elements (see NTS Oilfield Business, No. 10, 1981, pp. 35-39).

The disadvantage is that the filter eliminates the drawbacks of the previous one, but carries others - accumulation of clay particles in its pores, gradual siltation and termination of hydraulic conductivity.

The most reliable gravity filters, the use of which, as shown by foreign and domestic experience (see Ashrafyan M.O. et al. Improving the design of bottom faces of wells. M .: Nedra, 1987.), in 85-90% of cases gives positive results. During the construction of the well after opening the reservoir, a pre-perforated blind column with slit sizes slightly larger than the size of the gravel particles is lowered into the wellbore. Then, gravel packing with a particle size from 0.15 to 1.4 mm and then fixing it with reagents or resins is washed onto the column using various liquids - carriers with high viscosity.

The creation of a gravel or gravel-sand filter does not provide a full guarantee against the removal of sand from the bottomhole zone of the reservoir, since over time the gravel in the filter sags and compacts, opening the perforated wall of the countersunk column, open cavities can reach 29% of the original height in height filter.

To solve the problems with settling of the filtering gravel pack behind a previously hidden column, special permeable grouting materials are created for attaching weakly cemented reservoirs and form a filtering zone at the bottom of the well.

In terms of technical equipment, the simplest and most reliable design of a well filter is a filter device that is lowered into the wellbore of a production well (see NTS “Oilfield Business”, No. 10, 1981, pp. 35-39). The source contains sand filters with various types of filter elements that are installed in the wellbore on the shoe of the tubing and without rigid connection with the support on the bottom of the well and the packer, including the well filter, consisting of a tubular filter device comprising a metal casing with perforated section, and fixing the specified device in the casing of the elements.

Analysis of the filters shows that the most effective design is to install a filter with a packer, it is envisaged that the gravel pack behind this filter will be formed naturally by filtering and accumulating sand particles with a predetermined size.

All of the above and considered designs of filters launched to the bottom of the production well directly in the reservoir, cannot be used if it is necessary to simultaneously or repeatedly operate several reservoirs with one wellbore. These filters are designed in such a way that sand removed from the formation and retained by the filter accumulates below the productive zone closed by the filter, in addition, passage through the filter cross section to lower or overlying productive layers is impossible.

The purpose of the invention is to simplify the design and increase the reliability of the installation and operation of the tubular filter in the perforated zone of the casing by providing a free passage through the internal section of the filter along its axis for simultaneous or sequential operation of lower or overlying reservoirs.

This goal is achieved by the fact that in the downhole filter, consisting of a tubular filtering device, including a metal housing with a perforated section, and fixing the device in the casing string, both locking elements are made in the form of rubber sealing cuffs overlapping on both sides along the axis of the casing string its perforation, which allows access to the filter extracted from the reservoir, the body has two parts that are distributed in diameter and rigidly pressed against the casing with the specified mange s, by which the body portion is more ductile than said perforated portion made of a hard-metal, while ensuring free passage through special equipment through the interior of the filter section for the alternate or simultaneous operation or below- overlying reservoirs.

The drawing shows a tubular sand filter installed in the casing.

The filter is installed in the casing with the help of special technical means used to install metal adhesives for overhaul of the casing.

In the casing 1, a tubular filter casing 2 is installed with a first rubber cuff 3, a closing cuff 8, cutting off the perforation 4 in the casing, behind which there is an accumulated gravel pack 5. Filter perforation 6 is made in the filter casing.

The filter is as follows.

When installing both parts of the metal filter housing 2 with rubber cuffs 3, 8 are alternately distributed in diameter and rigidly pressed against the casing 1. The metal filter housing has a regular through-hole perforation 6 made by a laser beam over the entire area, while all holes have the same the same size, calculated according to the mid-frequency sizes of mechanical particles carried out from the reservoir. To increase the abrasive and corrosion resistance of the filter, the perforated section 6 can be made of metal of increased hardness and connected to a more plastic section of the body under the rubber cuffs 3 by plasma or laser welding.

This design of the downhole sand filter allows you to carry out operational work in the wellbore, passing through an open internal section to the lower - or overlying layers. In this case, the operating state of the filter does not change, and it can continue to perform a function. Between the tubular filter housing 2 and the casing 1 in a cavity bounded on both sides by rubber cuffs 3 and 8, gravel packing is naturally formed due to the accumulation of large sand particles having the highest percentage in the mechanical phase carried out from the reservoir. At the same time, the removal of sand into the wellbore and its accumulation in the bottomhole zone and in the sump of the well are prevented. Since gravel packing is formed naturally, it is constantly in a dense state without caverns and subsidence. In case of siltation of the gravel zone or deposition of paraffin-resinous substances, the filtering zone can be treated with backwashing with special liquids. The rubber sealing cuffs 3 and 8 make it possible to seal zone 7 to the filter from the wellbore cavity, vertically bounded by casing 1, without the use of expensive packer devices, which simplifies fixing and increases the reliability of the filter kit.

The use of the present invention will allow simultaneously or alternately exploiting lower- or overlying productive formations.

Claims (1)

A downhole filter, consisting of a tubular filtering device including a metal housing with a perforated section, and fixing elements in the casing string, characterized in that both locking elements are made in the form of rubber sealing cuffs overlapping the perforation zone on both sides along the axis of the casing string, opening access to the fluid extracted from the reservoir, the housing has two parts that are distributed in diameter and rigidly pressed against the casing with the specified cuffs under which The housing casing is more plastic than the specified perforated section made of metal of increased hardness, while ensuring through-pass free passage of special equipment through the internal section of the filter for simultaneous or sequential operation of lower or overlying reservoirs.