RU2531496C1 - Oil production method - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes rising of oil well fluid through a flow column under impact aimed to change physical properties of the fluid. According to the invention impact on oil well fluid is made by electrode heating in a closed working chamber by means of electric power delivery from the ground surface via a multicore electric cable to the electrodes placed inside the working chamber. In result thermal expansion of the oil well fluid and its flowing to the flow column is ensured via a flow channel with low cross section in regard to its length. At that in order to implement filling of the working chamber and electrode heating of the oil well fluid with its further expansion the unit is equipped with a suction valve to ensure delivery of the oil well fluid to the working chamber, with a pressure valve to ensure flowing of the fluid part from the working chamber to the flow column and batch transportation of the fluid to the ground surface and with a shift force valve with ability of its closure upon complete filling of the working chamber with the fluid and its opening upon heating of the oil well fluid up to the preset value.

EFFECT: improving production efficiency due to temperature impact on the produced oil well fluid.

2 cl, 1 dwg

Description

Proposed for consideration the invention relates to the oil industry, in particular to technologies for oil and water.

In a method of oil production that is widely used in the oil industry using a deep plunger pump, portion-wise pumping of products from a well into lift pipes is carried out by alternating vertical movement of the plunger in the pump chamber and regular opening and closing of the suction and discharge valves (Operation of deep pump wells. Enikeev V. .R. And others - M .: Nedra, 1971). To organize the movement of the plunger, a power unit and overcoming friction forces are necessary, therefore, the efficiency of such pump units remains at a relatively low level.

In many oil-producing regions of the country, the gas-lift method of oil production is widely used (Belov I.S. Theory and practice of periodic gas-lift. - M .: Nedra, 1975), based on a decrease in the density of oil in the pipe string due to the forced injection of gas into the pipe string through a system of gas lift valves. The disadvantage of this method of oil production is its significant capital intensity and energy intensity. In addition, significant volumes of gas prepared for injection are required.

The invention is known in which the production of borehole fluid is carried out by reducing the density of the borehole product in the tubing string by electrolysis of the water contained in the borehole fluid (RF Patent for the invention No. 2132454. Method for oil production. - Publish. June 27, 1999). The in-line electrolysis according to the invention is carried out without supplying electric current due to the creation of a chemical current source in the column of elevator pipes, for example, by installing magnesium bushings, inside the elevator pipes. Unfortunately, the electrostatic field created between such a sleeve and the surface of the elevator pipe actually turns out to be so small that this field is not able to cause hydrolysis with abundant release of gas bubbles from hydrogen and oxygen molecules, followed by a decrease in the density of the liquid.

There is also an electrode method for heating a liquid, which consists in placing the liquid between the electrodes and heating it with electric current flowing through the liquid from one electrode to another. The heating process occurs by the flow of electric current through a liquid, due to the resistance of which heating occurs. To avoid electrolysis, only alternating current is used for electrode heating. Electrode heating is considered direct heating - here the liquid serves as a medium in which electrical energy is converted into heat (http://electricalschool.info, School for an electrician: electrical engineering and electronics. Articles, tips, useful information).

The technical task of the claimed invention is the creation of such a method of producing well fluid in which batch pumping of well products through the working chamber from the suction valve to the discharge valve and then into the tubing string would be carried out on a known physical phenomenon without mechanical impact on these portions of the well fluid. According to the invention, a positive result should be obtained, consisting in the absence of a plunger or other mechanical element in the scheme for the method of oil production for batch transfer of well fluid together with their negative side - the presence of friction force.

The problem is solved in that the proposed method of oil production is carried out by electrode heating of the wellbore fluid through an installation comprising a housing, suction, pressure valves, forced-action valve, temperature sensor, lift channel, a working chamber in which electrodes are pre-installed. A compulsory valve (for example, with an electromagnetic principle of operation) is located in the upper part of the working chamber, which in turn is connected to the column of elevator pipes by a lifting channel with a small cross section relative to its length. The temperature sensor and the forced-action valve are connected to the control station of the installation on the ground to organize optimal and safe operation of the installation (for example, to exclude heating of the well fluid in the working chamber above the critical temperature). In the working chamber of the installation, electrode heating of the liquid is carried out, as a result of which the liquid in the space closed at the time of heating (the working chamber) expands and flows into the lifting channel of the installation and further into the lift pipes.

Note that the temperature sensor should be located in the upper part of the cavity of the working chamber for objective monitoring of the temperature characteristics of the well fluid.

We give the necessary calculations to assess the degree of expansion of the borehole fluid in the working chamber with an increase in its temperature by a certain amount. To simplify the calculation, since the borehole fluid contains oil, we will calculate the degree of expansion of oil in the working chamber when it is heated. In oil production directories, it is noted that in the ADPM oil dewaxing unit, oil for heating downhole equipment (a column of lift pipes in its upper part) is heated to 150 ° C (L. Kaplan, Oil and associated gas production operator. - Ufa, 2005 . - 553 s). This temperature is below the critical temperature of the oil heating in the installation, which is determined by the temperature characteristic of the structural elements of the installation. It is known that most composite materials (for example, F-4 fluoroplastic), which can be part of the installation, can be heated to 200 ° C. Let the temperature of the oil in the working chamber of the well installation for the conditions of the Ural-Volga oil and gas province be 30 ° C, then it can be heated in the working chamber proposed for consideration by 120 ° C, that is, up to 150 ° C. The coefficient of thermal expansion of oil is 9.2 · 10 ^-4 K ^-1 . The degree of expansion of oil during its heating in percentage terms will be found by the formula:

(1) $$P=\mathrm{one\; hundred}\%\cdot \Delta V/V=\mathrm{one\; hundred}\%\cdot \Delta k\cdot \Delta T$$

(one)

where: ΔV is the increment in oil volume due to thermal expansion;

V is the initial volume of oil in the working chamber of the installation;

k is the coefficient of thermal expansion of oil;

ΔТ is the increase in oil temperature after its heating.

So, the degree of expansion P = 100% · 9.2-10 ^-4 K ^-1 · (423-303) K = 11.04%.

Calculations show that when oil is heated by at least 120 ° C, approximately 11% of its initial volume can be transferred from the working chamber of the installation above to the column of elevator pipes.

A diagram of the method of oil production is shown in the drawing, in which 1 is the installation case, 2 is the working chamber, 3 is the suction valve, 4 is the pressure valve, 5 is the forced action valve, 6 is the electrodes, 7 is the lifting channel, 9 is the temperature sensor 10 - multi-channel submersible cable for power supply and feedback information, 11 - installation control station, 8 - column of elevator pipes. It should be noted that valves 3 and 4 are single-acting valves and easily open under a small pressure drop, while in their design they can be poppet type or a valve pair: ball-seat, by analogy with plunger deep-well pump valves.

Equipment for implementing this method of oil production is mounted and operated as follows.

1. The installation descends on a column of elevator pipes 8 (tubing) to a predetermined depth below the level of the fluid well. During the descent, valve 5 is opened forcibly, and valves 3 and 4 open themselves under the resulting pressure drop.

2. At a given depth, the working chamber 2 of the installation is in a filled state — well fluid with a nominal temperature of 30 ° C. Valves 3 and 4 are closed by gravity of the locking element (ball or poppet valve) on the valve seat. The valve 5 is closed from the control station forcibly after the installation is completely filled with liquid (the time is calculated experimentally and depends on the volume of the working chamber), provided that the current has not yet been supplied to the electrodes.

3. An electric current is supplied to the electrodes 6 along the power part of the multicore cable 10, as a result of which there is a process of electrode heating of the well fluid - the temperature rises to the value set at the control station (SU) - conditional 150 ° C. Due to the thermal expansion of the borehole fluid, the pressure in the chamber 2 rises, as a result of which the pressure valve 4 opens, and the heated borehole fluid flows into the lift pipe string 8 through the lift channel 7. According to the calculations, when heating oil at 120 ° C from the working chamber 2, approximately 11% the volume of oil will flow into the column of elevator pipes through the lifting channel of the installation. It should be noted that the lifting channel 7 plays an important role in the operating principle of the installation. This channel has a small cross section with respect to its length, and this excludes the movement of heated uphole fluid up and downhole fluid from the column of elevator pipes in the opposite flows. The heated borehole fluid from the working chamber 2 will move upward along the lifting channel 7 piston-like until the temperature in the working chamber 2 reaches the value set in the control system (in our example, it is 150 ° C).

4. When the temperature of the borehole fluid in the working chamber 2 of the set value is reached, a command is sent from the control system to stop the operation of the electrodes 6 and simultaneously force the valve 5 to open. Thanks to the force of Archimedes, the heated borehole fluid through the open valve 5 will flow into the annulus of the borehole, and the borehole will take its place liquid through the suction valve 3, which opened under the appeared differential pressure.

5. As soon as the complete replacement of the borehole fluid in the working chamber occurs, the temperature in the chamber 2 by the sensor 9 will again equalize in value with the initial values of the borehole fluid temperature - 30 ° C. In this case, a corresponding signal will be received from the sensor 9 to the control station 11, and the forced action valve 5 will be closed. This position is the initial one, and it is given at the end of the second paragraph of this description of the operation of the installation.

6. The next cycle of the installation will be the same as the steps described in paragraphs 3-5.

The proposed method of oil production is preferable for lifting high-viscosity and heavy oil with a minimum gas content and, as a result, a small value of the gas saturation pressure along the column of elevator pipes. Such characteristics of the produced oil will ensure its entry into the working chamber through the suction valve 3 without degassing and the appearance of free gas. The principle of operation of the installation is based on the fact that an incompressible liquid (oil, water) will be in the working chamber, the pressure of which, when heated, will exceed the pressure above the discharge valve 4 due to its temperature expansion. The resulting pressure drop will ensure the opening of the pressure valve 4 and the flow of part of the well fluid from the chamber 2 into the column of elevator pipes, i.e., portioned transport of the well fluid (oil, water) to the earth's surface will be carried out.

According to the invention, the temperature effect on the wellbore fluid, in particular on highly viscous oils, provides not only the rise of the wellbore fluid to the surface, but also has an additional positive effect - it reduces the viscosity of the oil and prevents deposits of heavy oil elements - asphalt-resin-paraffin compounds on the surface of the working bodies of the installation and the lift pipe string. .

Temperature sensor 9 is required for:

- heating the borehole fluid from the borehole temperature to the maximum allowable (for example, from 30 ° C to 150 ° C);

- determining the moment of filling the installation chamber 2 with a fresh portion of the borehole fluid, that is, changing the hot borehole fluid with a liquid with a lower temperature, this determines the position of the sensor in the upper part of the cavity of the working chamber 2.

In our opinion, the presented invention has the following elements of novelty and significant differences from previously known methods of oil production:

1. Batch pumping of borehole oil and water is carried out without mechanical moving parts based on controlled electrode heating of the liquid and expansion of the liquid in the working chamber of the installation.

2. To eliminate the oncoming overflow of the well fluid from the column of elevator pipes into the working chamber, the movement of the heated well fluid upward is organized along the lifting channel with a small cross section relative to its length.

3. A temperature sensor is installed in the upper part of the cavity of the working chamber due to the fact that the maximum heating of the well fluid occurs in this zone due to the universality of the manifestation of the Archimedes law in many physical phenomena, in particular, convective motion of a heated fluid. When changing heated borehole fluid to borehole fluid vertically, it is also important to fix the end of this process using a temperature sensor located in the maximum upper cavity of the working chamber.

Claims (2)

1. A method of oil production, including the process of raising well fluid along a string of elevator pipes as a result of exposure to it in order to change its physical properties, characterized in that the effect on the well fluid is carried out by electrode heating in a closed working chamber of the installation by supplying electric current with the surface of the earth through a multicore electric cable to the electrodes located inside the working chamber, as a result of which provide thermal expansion of the well fluid and its flow installation of elevator pipes into the column through the lifting channel with a small cross-section relative to its length, while for the process of filling the working chamber of the installation and the process of electrode heating of the borehole fluid, followed by its expansion, the installation is equipped with a suction valve to ensure the flow of borehole fluid into the working chamber, pressure valve to ensure the flow of part of the well fluid from the working chamber into the tubing string and to provide portioned transport of the well the surface of the liquid and valve forced action having the possibility of closing after the complete filling of the working chamber and downhole fluid opening after heating the wellbore fluid to a set value. 2. The method according to claim 1, characterized in that the installation includes a temperature sensor located in the upper part of the cavity of the working chamber of the installation, for objective monitoring of the temperature characteristics of the borehole fluid in the working chamber of the installation.

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