RU2383726C1 - Facility for producing heat effect onto formation with heavy oil or bitumen - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil industry and is intended for producing heat effect on bottomhole zone and formation with heavy oil or bitumen, including preventing or heating paraffin-hydrate sediments. The facility consists of well electro-heater with current distributor arranged on flow column -FC. Above a well electro-engine but below dynamic level of production in the well the FC is equipped with a packer pressure tight dividing string-casing annulue of the well. Also inlet channels are made below the packer and above the electric heater in the FC; while above the channels in FC there is installed an inserted deep-well pump. Notably, from below the column is blanked-off. Outside and above the packer the FC is equipped with additional electric heaters connected to the current distributor; the electric heaters are arranged at distance sufficient for maintaining products of the well in a heated and fluid state. Additionally, the electric heaters are enveloped from outside with cases, internal cavities of which communicate with internal space of FC above and below the electric heater.

EFFECT: lowered heat losses, intensified heating of oil formation and maintaining oil heated condition while lifting from formation to wellhead.

2 dwg

Description

The invention relates to the oil industry and is intended for thermal effects on the bottomhole zone and the formation with heavy oils or bitumen, including for the prevention or heating of paraffin-hydrated deposits.

A well-known electric heater (copyright certificate SU No. 1627671, IPC 7 ЕВВ 36/04, Е21В 43/24, publ. 02.15.1991), containing a current lead with a tubular body mounted under it with a long heating element arranged in a spiral on its surface, however, the heating element is placed along the length of the housing unevenly with an increase in the pitch of the spiral from the end of the housing towards the current lead.

Also known is an induction borehole electric heater (patent RU No. 2198284, IPC 7 ЕВВ 36/04, ЕВВ 43/24, published in Bull. No. 4 of 02/10/2003), including a housing that is simultaneously a magnetic core, a heating element in the form an induction coil wound on the outer surface of the housing, a contact node with a current-supply cable, and the housing, which is also a magnetic core, is a tubing equipped with metal rings with cuts through which the wires of the windings of the induction cat ears, while the induction coil is made of two layers and has three windings of wires with heat-resistant insulation.

The disadvantages of both analogues are:

- firstly, a structurally complex device, in addition, most induction-type heaters with high electrical resistance of the heating element generate a large amount of heat per unit length and therefore are short-lived and not sufficiently reliable;

- secondly, they are not effective enough for heat treatment of thick formations, for example, carbonate, as well as for melting or preventing paraffin-hydrate plugs of great length; large-length asphalt-resinous, afaltosoloparaffin deposits in the tubing and on the sucker rods;

- thirdly, the devices are also not applicable for heating and reducing the viscosity of well products at the reception of deep pumps.

The closest in technical essence and the achieved result is a downhole electric heater (patent RU No. 2198284, IPC 7 ЕВВ 36/04, ЕВВ 37/00 publ. In Bulletin No. 9 of 03/27/2005), containing a current lead with a tubular a casing with a long-length heating element placed on its surface in the form of a cable with the possibility of supplying it with a voltage supply from a source through a current supply, characterized in that it is grounded to the tubular casing and a cable with low electrical resistance, installed in a ferromagnetic tube along the tubular body with the possibility of forming a closed loop and feeding from a source of supplying alternating voltage, while a cable with low electrical resistance is installed in the ferromagnetic tube along the tubular body along its perimeter in the form of a multi-pass sequence of parallel long-length heating elements, the ferromagnetic tube is made divided into sections, the number of which is determined by calculation depending on the intensity of the operational columns and overall dimensions, and the method of its application, including the descent of a borehole electric heater on a string of tubing into the interval of an oil reservoir, followed by heating and production of heated products from the well.

The disadvantages of this device are:

- firstly, large heat losses, since the heating of the well’s products occurs only in the interval of placement of the downhole electric heater and the main part of the heat generated by the electric heater is taken along with the products that are extracted from the well, and a small area coverage (practically this section is limited by geometric dimensions electric heater), on which the product is heated;

- secondly, the heating power of one electric heater is not enough to lift heated products (for example, heavy oil or bitumen) along the tubing string from the formation to the wellhead, as heavy oil will cool down as it moves along the tubing string.

The objective of the invention is to provide a device that allows to reduce heat loss and direct a significant part of the heat to warm up the oil reservoir by increasing the coverage of the heated section of the well and installing additional electric heaters to keep the heavy oil warmed up as it moves along the tubing string from the formation to the wellhead.

The problem is solved by a device for thermal exposure of a formation with heavy oils or bitumen, including a borehole electric heater with a current lead, located on a string of tubing.

What is new is that the tubing string is higher than the borehole electric motor, but below the dynamic level of production in the well, equipped with a packer hermetically separating the annulus of the well, while input channels are made below the packer and above the electric heater in the tubing string, and an insertion channel is installed above the channels in the tubing string a downhole pump, the column being plugged from below, while the tubing string outside the packer is equipped with additional additional electric heaters connected to the conductor, which are installed at a distance internal to maintain well production in a heated and flowable state, wherein the heaters are covered outside the casing, the inner cavity of which communicates with the interior of the tubing string above and below the electric heater.

The figure 1 shows the proposed device for thermal effects on the reservoir with heavy oils or bitumen at the time of selection of heated products.

The figure 2 shows the proposed device for thermal exposure of the formation with heavy oils or bitumen at the time of injection of heated products.

A device for thermal treatment of a formation with heavy oils or bitumen includes 2 downhole electric heaters 3 and additional electric heaters 3 '... 3 ⁿ lowered into a well 1 on a tubing string (tubing), connected by a conductor 4 placed on the tubing string ( Tubing) 2. Packer 5, installed in the tubing string 2 above the electric heater 3, located in the interval of the formation 6, is planted in the well 1 below the dynamic level of production in the well 1.

Additional electric heaters 3 '... 3 ^{n are} installed at a distance sufficient to maintain the production (heavy oil) of well 1 in a heated and fluid state. In the tubing string 2, a plug-in deep pump 7 is installed above the packer 5, consisting of a plunger 8 and a cylindrical casing 9. The tubing string 2 is muffled by a plug 10 from the bottom, and the tubing string 2 is equipped with input channels 11 below the packer 5, which allows the heat generated by the electric heater 3 to be accumulated. at a distance S, that is, in the section of the tubing string 2 from the plug 10 to the input channels 11, a stagnant zone is formed by the well production heated by the electric heater 3.

Additional electric heaters 3 '... 3 ^{n are} covered externally by casings 12, the inner cavity of which is connected with the interior of the tubing string 2 above and below the additional electric heaters 3' ... 3 ⁿ .

The packer 5 hermetically separates the annular spaces 13 and 14 of the well 1 among themselves.

A device for thermal exposure of a formation with heavy oils or bitumen works as follows.

The assembled device, as shown in figure 1, is put into operation (turn on the electric heater 3 and additional electric heaters 3 '... 3 ⁿ , and also start the plug-in deep pump 7), while the electric heater 3 simultaneously transfers heat to the heavy oil in the interval of formation 6 on the inner wall of the tubing string 2.

As a result, heavy oil is heated inside the tubing string 2 from the plug 10 to the radial holes 11 in section S, so the heat transfer area of the electric heater 3 increases several times, i.e., a stagnant zone of heated products forms inside the tubing string 2 in section S.

The heat from the walls of the tubing string 2 in section S is aimed at heating the well products in the annulus 14, and this allows you to expand the coverage of the heated section to a distance S in comparison with the prototype, where heavy oil is heated only within the electric heater, and also save as much as possible warm products (heavy oil) both during production from well 1 and when injected into formation 6, since products heated up in the annulus 14 enter the formation 6.

At the same time, the plunger 8 of the plug-in deep pump 7, through the rod string 15 and the drive (not shown in FIGS. 1 and 2), makes reciprocating movements with respect to the cylindrical plunger 9, supplying the tubing string 2 heated by the electric heater 3 from the annulus 14 of the well 1 moreover, the heated heavy oil enters the intake of the plug-in deep pump 7 from the annular space 14 through the inlet channels 11, since the lower end of the tubing string 2 is plugged with a plug 10.

In the tubing string 2, as the heavy oil rises, it is heated from the reservoir to the wellhead 1 due to additional electric heaters 3 '... 3 ⁿ , which helps prevent its solidification and produce heated heavy oil at the wellhead, and the number of additional electric heaters 3' ... 3 ⁿ , installed in the tubing string, determined by calculation based on the maintenance of heavy oil or bitumen in a fluid state when it is raised along the tubing string 2 from the formation 6 to the wellhead 1, depending on the electron power revatelya.

In addition, in the process of lifting heavy oil along the tubing string 2, it passes through the internal space of additional electric heaters 3 '... 3 ⁿ along the tubing string 2 above and below these electric heaters, and under the casing 12, which is made on each of the additional electric heaters 3' 3 ... ^n, which provides an additional warming of heavy oil by passing it additional electric heaters 3 '... 3 ⁿ and fuller use of the heat generated by electric heaters 3' ... 3 ^n, is to heat the heavy oil, therefore, menshayutsya not productive heat loss and, consequently, there is an economy of material resources spent on electricity.

Before the injection of the heated product into the formation 6, the plunger 8 is lifted (see FIG. 2) from the cylindrical body 9 of the plug-in deep pump 7. Then, from the wellhead 1, the heated product (heavy oil) extracted from the well 1 is pumped through the tubing string 2 through the inlet channels 11, since the bottom of the tubing string 2 is plugged with a plug 10 back into the reservoir 6.

After the heated products are pumped into the formation 6 (see FIG. 1), the plunger 8 is installed back into the cylindrical body 9 and the drive of the deep pump 7 is put into operation and heavy oil is again extracted from the tubing string 2 from the well 1. After that, the device’s cycle of work is repeated .

The proposed device for thermal action on a formation with heavy oils or bitumen allows to reduce heat loss and direct a significant part of the heat to warm up the oil reservoir due to the fact that the tubing string is drowned from below, and the electric heater simultaneously transfers the heat to the internal tubing string walls, and this allows you to accumulate heat on the tubing string section from the plug to the packer, thereby significantly increasing the coverage of the heated section of the well. In addition, the proposed device due to the installation of additional electric heaters in the tubing string allows maintaining heavy oil or bitumen in a heated and flowing state during its lifting along the tubing string from the formation to the wellhead, and the presence of casings with which additional electric heaters are equipped allows additional heating of heavy oil or bitumen in the range of additional electric heaters during the lifting of heavy oil or bitumen.

Claims (1)

A device for thermal impact on a formation with heavy oils or bitumen, including a borehole electric heater with a conductive pipe, located on the tubing string — tubing, characterized in that the tubing string is higher than the borehole electric motor, but below the dynamic level of production in the well, is equipped with a packer that hermetically separates the annulus of the well, while below the packer and above the electric heater in the tubing string, input channels are made, and above the channels in the tubing string there is an inserted deep pump moreover, the column from the bottom is plugged, while the tubing string outside the packer is equipped with additional electric heaters connected to the conductor, which are installed at a distance sufficient to maintain the well production in a heated and flowing state, while the electric heaters are enclosed on the outside by shells whose inner cavity is in communication with the internal space tubing columns above and below the electric heater.

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