RU2566544C1 - Method for formation treatment with combustible and oxidising composition - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method includes running in tubing to the well, injecting combustible and oxidising composition (COC) to the tubing, running in ignition source at a cable to the tubing to COC interval, delivering control signal to the cable and igniting COC. At the wellhead bottom part of the tubing is equipped with a combustion chamber and burned faced outside, and to the upper end of the burner a thermocouple is fixed with an extension cord. At the wellhead the upper end of the extension cord is fixed to a device measuring temperature. Thereafter source of ignition, which is an electric flame igniter, is run in into tubing-casing annulus up to openings in the burner. Then from the wellhead permanent injection of COC is started to the tubing by means of a pump. At that COC of the following composition is used in wt %: ammonium nitrate - 65.8%; 2% aqueous solution of polyacrylamide - 28.2%; potassium bichromate - 1%; ethylene glycol - 5%. When COC reaches openings of the burner the electric flame igniter is actuated by delivery of control signal to the cable, COC is ignited. The cable with electric flame igniter is removed from the tubing, burning temperature is controlled in the interval of formation treatment by the device measuring temperature. When burning temperature is increased within the interval of treated formation above the permitted value COC delivery to the tubing is reduced, and when burning temperature is decreased within the interval of treated formation below the permitted value COC delivery to the tubing is increased.

EFFECT: increased reliability and quality of formation treatment.

2 dwg

Description

The invention relates to the oil industry and can be used for treating a formation with highly viscous oil with heated gas generated during the combustion of a liquid fuel-oxidizing composition (GOS).

A known method of processing the bottom-hole formation zone with a liquid combustible-oxidizing composition (patent RU No. 2459946, IPC ЕВВ 43/263, published in Bulletin No. 24 dated 08/27/2012), comprising placing the GOS in the well, installing the GOS combustion initiator by lowering it is in a sealed container, while the GOS is placed in the well by delivering it with the chasing container on the cable and pouring the GOS as a single mass into the bottom to the bottom level of the processing interval, the combustion initiator is delivered in a sealed container by a cable to the gra the interface between the GOS and the well fluid, and a small-gas, slow burning and high-temperature solid composition, for example, based on iron-aluminum termite, is used as a combustion initiator in a sealed container, then the combustion initiator is directly triggered from an electric power source supplied through a cable cable from the wellhead, with the possibility of layer-by-layer combustion of GOS.

The disadvantages of the method:

- firstly, the low reliability of the implementation of the method, due to the failure of the bailer container on the cable to the bottom of the well and, as a result, the inability to pour the GOS from the bailer to the bottom of the well;

- secondly, the low quality of the treatment of a highly viscous oil formation, due to pouring a limited amount of GOS on the bottom of the well to the bottom of the processing interval with its subsequent ignition, so the time during which the estimated amount of GOS is burned may not be enough to warm the formation;

- thirdly, the low efficiency of the combustion of GOS, which is used as a liquid composition, consisting, wt. % of ammonium nitrate - 60.4; glycerol - 10 and water - 29.6 with a density of 1390 kg / m ³ due to its low formation enthalpy, i.e. heat release to the mass of combustible product, as well as low flammability and incomplete combustion of GOS;

- fourthly, the uncontrolled process of GOS combustion, leading to the creation of an explosive situation in the well and due to the lack of control of the GOS combustion temperature in the interval of the formation treatment.

The closest in technical essence and the achieved result is a method of treating a formation with a liquid combustible-oxidizing composition (patent RU No. 2092682, IPC ЕВВ 43/263, published in bulletin No. 28 of 10/10/1997), containing placement of GOS in the well, installing a heat source in it for igniting the GOS by lowering it into the well, supplying a control signal to turn on the heat energy source and igniting the GOS by generating heat in the heat energy source, and the GOS is placed in the well by lowering the pump compressor pipes (tubing), injecting the estimated amount of GOS into the deflated tubing, pushing the GOS to the processing zone and then raising the tubing from the GOS location, and the heat source is installed at a depth of 10-50 m from the upper GOS boundary, while the source thermal energy use a source with energy release (E, MJ), the minimum value of which is determined from the expression Ε = k · (T _p -T _o ), where k is approximately 0.1-0.125 MJ / K; T _p - the temperature of the beginning of the intensive decomposition of the most heat-resistant component GOS, K; T _o - initial GOS temperature in the ignition zone, K; moreover, when the GOS is located in the well for a long time before the ignition is ignited, a separation fluid is used, and its density should not be higher than the GOS density and not lower than the density of the well fluid, and when the treatment zone is far from the bottom of the well, a restriction screen is installed at the lower boundary of the GOS placement. The tubing is lowered to pump the GOS to the restriction screen. To prevent water hammer on wellhead equipment, part of the well fluid is removed from the well before igniting the GOS, and a powder charge from ballistite or mixed solid fuel weighing at least 7 kg is used as a source of thermal energy.

The disadvantages of the method:

- firstly, low implementation reliability due to the fact that GOS is forced from the tubing to the bottom of the well; therefore, GOS can “escape” through the restriction screen or disturbance in the well, as well as GOS absorption at perforation intervals into the formation;

- secondly, the low quality of the treatment of the formation with high viscosity oil by heating, due to the injection and sale in the interval of the treated formation of the estimated (limited) amount of GOS, so the time during which the estimated amount of GOS is burned may not be enough and the formation will not heat up to temperature necessary to dilute highly viscous oil, for example, due to incomplete combustion of GOS. In addition, GOS combustion occurs below the intervals of perforation of the treated formation, which reduces the efficiency of heat penetration deep into the formation with high viscosity oil;

- thirdly, the uncontrolled process of ignition and combustion of GOS, the lack of control of the GOS combustion temperature in the interval of the formation treatment, as well as the uncontrolled operation of a heat energy source (powder charge from ballistite or mixed solid fuel weighing at least 7 kg) for a long time . All this can lead to the creation of a fire and explosive situation in the well;

- fourthly, it is necessary to prepare the well before processing the formation, namely, to establish a restriction screen in the form of an artificial bottom (packer plug, cement bridge) below the treated formation. This leads to a higher cost of implementing the method;

fifthly, the low efficiency of standard GOS used in the implementation of the method, due to their low formation enthalpy, i.e. heat release to the mass of combustible product, as well as low flammability and incomplete combustion of GOS.

The technical objectives of the invention are to create a reliable and high-quality method of treating a formation by heating with gases generated during the combustion of GOS with the possibility of controlling the combustion temperature in the interval of the treated formation, as well as the exclusion of the installation of a restriction screen below the treated formation with the possibility of using a more effective composition of GOS for processing the formation.

The stated technical problems are solved by the method of treating the formation with a combustible-oxidizing composition - GOS, including the descent of tubing pipes - tubing, injection into the tubing string of the GOS, launching the ignition source on the cable into the tubing string into the GOS interval, supplying a control signal to the cable and ignition GOS.

What is new is that at the wellhead, the bottom of the tubing string is equipped with a combustion chamber with a burner located outside, and a thermocouple with an extension wire is fixed to the upper end of the burner, at the wellhead the upper end of the extension wire is attached to a temperature measuring device, and then into the annulus of the well the ignition source — an electric igniter — is lowered to the burner holes on the cable, then from the wellhead with the help of a pump, the GOS is continuously pumped into the tubing string, and the GOS of the following composition weight. %:

- ammonium nitrate - 65.8%;

- 2% aqueous solution of polyacrylamide - 28.2%;

- potassium dichromate - 1%;

- ethylene glycol - 5%,

upon reaching the GOS, the burner openings activate the electric igniter by supplying a control signal to the cable, the GOS ignites, the cable with the electric igniter is removed from the tubing string, the combustion temperature is monitored during the formation processing interval by means of a temperature measuring device, with an increase in the combustion temperature in the interval of the treated formation above the permissible combustion temperature, the supply of GOS to the tubing is reduced, and with a decrease in the temperature of combustion in the interval of the processed about the reservoir below the permissible combustion temperature, the supply of GOS to the tubing string is increased.

In FIG. 1 and 2 schematically and sequentially depicts a method of treating a formation with a fuel-oxidative composition.

At the wellhead 1 (see FIG. 1), the bottom of the tubing string 2 is equipped with a combustion chamber 3 with an external burner 4.

As a tubing string 2, for example, a 73 mm tubing string in accordance with GOST 633-80 is used, and as a combustion chamber, a pipe segment with a diameter of 114 mm and a wall thickness of 7 mm in accordance with GOST 633-80 is used.

The length - L of the burner 4 is equal to the height - h of the treated formation 5 with highly viscous oil (hereinafter, formation 5).

As a burner, use any known device that allows you to burn a combustible oxidizing composition, for example, a burner for burning gas and fuel oil (patent RU No. 2403498, IPC F23D 17/00, published in bulletin No. 31 dated 10.11.2010) or a burner for burning gas and fuel oil (Khzmalyan D.M., Kagan Y.N. / Combustion theory and furnace devices. - M.: Energia, 1976. - P. 204.)

A thermocouple 6 (temperature sensor) with an extension wire 7 is fixed to the upper end of the burner 4.

Use any known thermocouple 6 having a temperature measurement range within the GOS combustion temperature, for example, use a tungsten-tungsten fusion thermocouple (TBP - Type A-1) according to GOST 50431-92 for long-term use with a temperature range of 0-2200 ° C. Extension wires are made of the same material as thermocouples 6.

Placing the burner 4 opposite the treated formation 5 and fulfilling the condition L = h allows heating 5 to be covered by heating throughout its height and to provide deeper penetration (radius of coverage) of heat deeper into the formation 5 through perforation holes 5 ′ and thereby improve the quality of processing the formation 5 by heating ( reduce the viscosity of high-viscosity oil to a value that ensures its selection from reservoir 5 by pumping equipment lowered into well 1.

The tubing string 2 is lowered into the well 1, while the extension wire 7 is fastened with clips (not shown in FIGS. 1 and 2) on the outer surface of the tubing string 2.

At the wellhead 1 (see FIG. 1), the thermocouple wire 6 is connected to a temperature measuring device 8.

Then, from the wellhead 1 into the annular space 9 of the well 1 to the openings 10 of the burner 4 on the cable 11, the ignition source is lowered - an electric ignitor 12.

At the wellhead 1 in the tank 13 GOS is prepared or delivered in finished form to the well 1, and then the GOS is poured into the tank 13 in the required quantity, for example, 2 m ³ .

To prepare GOS in the tank, add the following components, which are mixed in the tank, wt.%:

- ammonium nitrate - 65.8%

- 2% aqueous solution of polyacrylamide - 28.2%

- potassium dichromate - 1%

- ethylene glycol - 5%

To prepare 2 m ³ GOS it is necessary to use components in the following proportion, kg:

- ammonium nitrate - 1310.6 kg;

- 2% aqueous solution of polyacrylamide - 560.4 kg;

- potassium dichromate - 20 kg;

- ethylene glycol - 100 kg.

Ammonium nitrate is used as an oxidizing agent and is produced according to GOST 2-2013, and polyacrylamide is used as a stabilizing additive, and is also a thickener for GOS.

Potassium dichromate is used to increase flammability, reduce initial ignition and complete combustion of fuel and is produced in accordance with GOST 2652-78. Ethylene glycol is used as fuel and is produced according to GOST 19710-83.

From the wellhead 1, with the help of a pump 14, from the reservoir 13, GOS is pumped at a constant flow rate, for example, at a flow rate of 15 l / min, into the tubing string 1.

As the pump 14, any known pump is used, which supplies the GOS to the openings 10 of the burner 4 with a flow rate that allows maintaining the GOS in a given temperature range, for example, 900-800 ° C. For example, use the NSh-10 gear pump, creating a flow rate from 0 to 21 l / min.

Upon reaching GOS openings 10 of the burner 4, an electric igniter 12 is activated by supplying a control signal to the cable 11.

As a result of the supply of the control signal to the cable 11 in the electric igniter, a spark discharge occurs that ignites the GOS in the burner 4 of the combustion chamber 3 with the formation of an open flame in the holes 10 of the burner 4 opposite the interval of the treated formation 5.

The reliability of processing a formation with highly viscous oil is increased due to the fact that in the proposed method the liquid GOS does not fall on the bottom of the well, but burns in the burner 4 of the combustion chamber 3, therefore, “leaving” (loss) of the non-ignited GOS is eliminated.

The cable 11 is removed (see Figs. 1 and 2) with an electric igniter 12 from the tubing string 2.

In the process of burning GOS, the formation 5 is heated (see Fig. 2) in height and depth, and the combustion temperature in the processing interval of the formation 5 is controlled by means of a temperature measuring device 9.

Improves the quality of treatment of the formation 5 due to the constant injection of GOS with a given flow rate, and not a limited volume of GOS, as described in the prototype. As a result of this, heating (processing) of the formation occurs over its entire height, while eliminating the risk of incomplete combustion of GOS.

With an increase in the combustion temperature in the range of the processed 5 above the permissible combustion temperature, which is in the range as noted above 700-800 ° C, for example to 900 ° C, the GOS supply to the tubing is reduced from 15 l / min, as noted above, for example up to 10 l / min.

When the combustion temperature decreases in the range of the treated formation below the permissible combustion temperature, which is in the range as noted above 700-800 ° C, for example to 550 ° C, the GOS supply to the tubing is increased from 15 l / min, as noted above, for example, to 20 l / min

The presence of a thermocouple 6 installed on the upper end of the burner, which transmits a signal to a device that measures the temperature in the interval of treatment of the formation 5, allows full control of the GOS combustion process (success of ignition of the GOS in the burner, temperature mode), since the combustion temperature in the interval of the formation is controlled by a thermocouple .

The implementation of the method is continued until the viscosity of high-viscosity oil is reduced to a value ensuring its selection from reservoir 5 by pumping equipment. After that, the implementation of the method is stopped, a tubing string 2 with a combustion chamber 3 is removed from the well, pumping equipment, for example a screw pump, is lowered into the well 1 and liquefied high-viscosity oil is taken from the formation 5.

The use of an electric igniter as an ignition source eliminates the uncontrolled operation of a heat energy source (powder charge from ballistite or mixed solid fuel weighing at least 7 kg) for a long time, as described in the prototype, since the electric igniter is lowered into the well once for ignition GOS, after which it is removed from the well.

The proposed method eliminates the need for well preparation, namely the installation of a restriction screen in the form of artificial bottom (plug packer, cement bridge).

The GOS supplied through the tubing string burns down in the combustion chamber, generating heat, and is not forced to artificial bottomhole, as described in the prototype, which leads to a reduction in financial and material costs for the installation of the restriction screen and, as a result, cheaper implementation of the method.

Implementation of the proposed composition of GOS allows to increase the efficiency of its use due to its high enthalpy of formation (3112 kJ / kg), i.e. heat generation to the mass of combustible product, as well as high flammability (an electric ignition spark is enough to ignite the GOS in the burner) due to the addition of ethylene glycol and complete combustion of the GOS due to the addition of potassium dichromate to the GOS in the combustion chamber.

The proposed method allows

- to improve the reliability of the implementation of the method when processing a formation with high viscosity oil by heating;

- to improve the quality of the treatment of high-viscosity oil by heating;

- to control the entire process of the method implementation, from ignition of the mineral reserves to the cooling of the bottom-hole zone of the formation after the burning of the mineral deposits, which means to exclude the creation of a fire and explosion hazardous situation in the well;

- exclude the creation of a restrictive screen in the form of artificial slaughter (packer plugs, cement bridge);

- increase the effectiveness of the GOS.

Claims (1)

A method of treating a formation with a combustible-oxidizing composition (GOS), including lowering a string of tubing (tubing) into a well, injecting a GOS tubing into a string, lowering an ignition source on a cable to a tubing string into the GOS interval, supplying a control signal to the cable and igniting the GOS characterized in that at the wellhead the bottom of the tubing string is equipped with a combustion chamber with a burner located outside, and a thermocouple with an extension wire is fixed to the upper end of the burner, at the wellhead the upper end of the extension wire is attached to the device, measured yuschemu temperature, after which the annular space in the well to the burner orifices is lowered on a cable ignition source - an electric igniter, and then with the wellhead via pump starting to download constant CRP in the tubing, the CRP using the following composition. %:
ammonium nitrate - 65.8
2% aqueous solution of polyacrylamide - 28.2
potassium dichromate - 1%
ethylene glycol - 5%,
upon reaching the GOS, the burner openings activate the electric igniter by supplying a control signal to the cable, the GOS ignites, the cable with the electric igniter is removed from the tubing string, the combustion temperature is monitored during the formation processing interval by means of a temperature measuring device, with an increase in the combustion temperature in the interval of the treated formation above the permissible combustion temperature, the supply of GOS to the tubing is reduced, and with a decrease in the temperature of combustion in the interval of the processed about the reservoir below the permissible combustion temperature, the supply of GOS to the tubing string is increased.

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