RU2451158C1 - Device for heat treatment of bottomhole zone - electric steam generator - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: device for heat treatment of bottomhole zone includes electric steam generator being zero electrode, which is filled with water, isolated central current lead placed inside the housing and connected to phase electrodes installed on it one above the other. At that, each phase electrode is made in the form of multiple-thread screw with blade attack angle of 20°-40°. At that, condensate collectors in the form of steel rings are located on inner surface of the housing.

EFFECT: improvement of well heat treatment efficiency.

4 dwg

Description

The invention relates to mining and can be used for heat treatment of a productive formation with highly viscous oil, restoration of hydraulic connection between a formation and a well, increase in oil recovery from highly viscous oil and production rates, as well as the resumption of unprofitable wells for oil, natural gas, fresh, mineral and thermal waters.

Known induction heater (patent RU No. 2010954, publ. 04/15/1994), having a hollow body, a concentric casing, forming an annular cavity with the housing with the placement of induction coils in it. However, the heater is not intended for thermal effects on the reservoir and is used to prevent the buildup of asphalt-resin-paraffin deposits on the walls of the compressor pipe.

Known downhole heat generator (copyright certificate SU No. 381736, publ. 01.01.1973), including a coaxial arrangement of electrodes to which a direct current is connected. However, the downhole heat generator does not allow to transfer large capacities for thermal impact on the bottom-hole zone of the reservoir.

A device is known for heat treatment of the bottom-hole zone of a well (patent RU No. 2368760, publ. September 27, 2009), including a sealed heater body, which is a zero electrode, partially filled with water, a central current lead located inside the body and connected to a phase electrode. The phase electrode is made in the form of a thin-walled pipe located inside the tubular insulator of the housing. The disadvantage of this device is the inability to separate the steam obtained for heat treatment of the well.

A well-known heater for an oil well (patent RU No. 2249672, published April 10, 2005), comprising a current source, an output cable, as well as a heating cable. The conductive conductors of the heating cable at one end are interconnected, and the other ends are connected to the current source through the output cable. The output cable passes through the wellhead into the well along the riser pipe and is electrically connected to the heating cable located in the well. The disadvantage of this heater is the fact that it does not allow thermohydrodynamic effects of steam on the reservoir.

Known electric heating device for heat treatment of the bottom-hole zone of the well (patent RU No. 2169830, publ. 06/27/2001), taken by us as a prototype, including a heater casing, power cable, disk electrodes mounted on a current lead placed along the axis of the casing. Electrode disks are perforated and assembled in alternating pairs, where the upper electrode disks are connected to the housing and the lower ones are mounted on the current lead; moreover, heat-resistant insulators are placed in the inter-disk intervals of the current lead and the housing, and the heater case is filled with conductive fluid to the level of the uppermost electrode. This design allows to reduce heat loss and increase the power of electric heating devices. The disadvantage of this device is the low intensity of convection due to the increased hydraulic resistance created by the electrodes, as well as reduced dryness of the vapor due to the absence of its separation inside the device, which reduces the efficiency of its use for heat treatment of the well.

The technical result is to increase the degree of dryness of the steam at the outlet of the steam generator.

The technical result is achieved by the fact that in the device for heat treatment of the bottom-hole zone of the well, including an electric steam generator, which is a zero electrode, filled with water, a central insulated current lead, placed inside the housing and connected to the phase electrodes mounted on it in height one above the other, each phase electrode is made in the form of a multi-start screw with an angle of attack of the blades of 20-40 °, and on the inner surface of the casing there are fenders in the form of steel rings.

The implementation of the phase electrode in the form of a multi-screw with an angle of attack of the blades of 20-40 ° allows you to create a circulation movement in the upward flow of the steam-water mixture relative to the axis of the electric steam generator.

The presence of fenders condensate traps on the inner surface of the electric steam generator allows you to catch liquid droplets from the steam stream, which generally leads to the separation (separation) of the steam-water mixture along the cross section of the electric steam generator.

The heat treatment device is illustrated by drawings. The section of the downhole electric steam generator - EPG is shown in figure 1. The structural dimensions of one link of the EPG containing the phase electrode are shown in figure 2. The view of the body of the EPG along the section line AA and the view B of the body of the EPG from the side are shown in Fig.3.

In the drawing 1 - metal body of the EPG (zero electrode); 2 - heat-resistant insulating sheath; 3 - central current lead; 4 - zone of heating of the supply fluid; 5 - phase electrode (its blade); 6 - side wall of a fluoroplastic ceramic glass; 7 - conductive windows; 8 - downhole fluid; 9 - direction of convective flow of the working fluid; 10 - production casing; 11 - direction of steam; 12 - condensate trap; 13 - flowing condensate; 14 - steam zone; 15 - steam outlet channel; 16 - valve; 17 - column tubing; 18 - bushing.

The design of the device for heat treatment of the bottom-hole zone of wells located in the zone of the reservoir inside the production string 10 includes a downhole electric steam generator, which is mounted on the end of the tubing string 17. The electric steam generator consists of a metal casing 1 made in the form of a cylinder and being a zero electrode. The central current lead 3, having a heat-resistant insulating shell 2, is fixed in the upper part of the housing 1 through the bushing 18, on the inner surface of the housing 1 are located in the form of steel rings fenders 12. Inside the housing 1 on the current lead 3 at regular intervals separated by tubular heat-resistant insulators 2 , phase electrodes 5 are mounted one above the other in height, each phase electrode is made in the form of a multi-screw with an angle of attack of the blades of 20-40 °, used to twist the flow around the axis with the aim of radiation of the tangential component of velocity and steam separation. The interelectrode distance is determined by the power of the device, supply voltage, surface current density and resistivity of the conductive fluid. Each phase electrode is placed in a fluoroplastic ceramic glass having a side wall 6 and conductive windows 7. The upper part of the housing 1, free of phase electrodes and forming a vapor zone 14 of the electric heater, contains a steam outlet channel 15 with valve 16.

The heat treatment device operates as follows. After assembling the device and placing it in the area of the reservoir, through the central current lead 3, isolated by the packer, through the high-voltage power supply cable to the phase electrodes 5 (Fig. 1), made in the form of a multi-screw with a blade angle of 20-40 ° of the device, filled conductive liquid 4, a voltage of 3-6 kV, a frequency of 50 Hz is applied, after which from phase electrodes 5, through liquid 4 and conductive windows 7, the area of which S is equal to the surface area of phase electrodes 5, to the metal casing 1, which is zero e an electric current flows (the arrows in figure 2 show the direction of the current), causing intense heating of the liquid 4, boiling and formation of steam 11, which in the process of moving in the vertical direction acquires the tangential velocity component, which leads to the twisting of the steam-water mixture using phase electrodes 6 around the central axis of the electric steam generator, steam separation and its discharge through the steam outlet channels 15 with valve 16 into the zone 8 filled with the downhole fluid, with condensate 13 arising in the reservoir Tate condensation and separation of vapor deposited on the inner surface of the housing 1 elektroparogeneratory delayed kondensatosemnikami 12 and flows back into the boiling zone. Boiling and the formation of steam leads to heat exchange between the wall of the housing 1 of the proposed device and the downhole fluid 8, while feeding boiler fluid through the central current lead 3.

The device of thermal impact on the bottom-hole zone of wells is based on heating fluid in an isolated producing section of the well at the level of the producing formation with a specific power of 3-9 MW / m ³ .

Thus, the device for heat treatment of the bottom-hole zone of the well provides an increase in dryness of steam at the outlet of the electric steam generator.

Claims (1)

A device for heat treatment of the bottom-hole zone of the well, including an electric steam generator, which is a zero electrode, filled with water, a central insulated current lead, placed inside the housing and connected to one above the other phase electrodes mounted on it in height, characterized in that each phase electrode is made in the form of multi-lead a screw with an angle of attack of the blades of 20-40 °, and on the inner surface of the body are located fenders in the form of steel rings.

Images