RU2279538C1 - Well bottom zone treatment method - Google Patents

Abstract

FIELD: oil industry, particularly to stimulate or resume oil and gas well operation by performing thermal-chemical treating and cleaning of well bottom zone to remove deposits, namely asphalt-tar and paraffin deposits.

SUBSTANCE: method involves lowering flow string in well interval to be treated via casing pipe; supplying heat-generating substances; creating increased pressure; treating bottomhole formation zone; performing technological time delay and applying depression action to heated zone to be treated. Lower part of flow string is provided with uncontrollable plug valve, which is pinned to flow string and defines sealed cavity along with flow string interior. As flow string is lowered in well hydrogen peroxide is supplied in flow string. Then hydrogen peroxide-neutral acetate buffer solution is fed and the buffer solution is isolated from hydrogen peroxide with uncontrollable plug valve. 5% manganese solution and water are supplied in well. Acetate buffer solution has density exceeding that of manganese solution. Manganese solution density exceeds water density. After flow string lowering in well backpressure is created in well interval to be treated by filling space between casing pipe and flow string with water. Then pressure is increased in flow string. Once pressure jumps water is supplied via flow string in well interval to be treated. After technological time delay execution bottomhole formation zone is subjected to depression action by flushing thereof with aerated acetate buffer solution.

EFFECT: increased efficiency of well bottom zone treatment.

1 dwg

Description

The invention relates to the oil industry and can be used to activate or renew oil and gas wells by thermochemical treatment and cleaning of the borehole space from various deposits, especially asphalt resin and paraffin.

A known method of heat treatment of the bottom-hole zone of a well using hydrogen peroxide (Beiles J. X. A new method of heat treatment of the bottom-hole zone of a well using hydrogen peroxide, "Oil and Gas Technologies", No. 5-6, 1998). The method involves the injection into the formation of hydrogen peroxide in the amount of approximately 1564 liters per meter of power of the produced formation, technological exposure for the decomposition of 40% hydrogen peroxide for about 25 days and the subsequent commissioning of the well. Also in the method, options for using 30% and 50% concentrations of hydrogen peroxide are considered. The disadvantage of this method is the long period of technological exposure and shutdown of the oil well, as well as low cleaning efficiency of the bottom hole zone of the well.

A known method of processing the bottom-hole zone of the well and a device for its implementation, adopted as a prototype (RF patent No. 2219333, E 21 B 43/25, 12/20/2003). The method is carried out using a device containing a sealed container, the upper part of which is closed by an uncontrolled valve. The container is connected to a fence having side slots. The intake is connected to the top with a depression chamber containing a controlled valve. Carry out the delivery in the processed interval of the well on the logging cable of a thermogas generator located in an airtight container. Inside the container are a fuel substance in the form of calcium carbide and a vessel with water containing a depressurization unit. From the ground control panel along the core of the wireline cable, an electric wire is supplied with a pulse to the depressurization unit of the vessel with water. Water interacts with calcium carbide, generating heat and hydrogen. There is pressure inside the container and the uncontrolled plug valve opens. Through the slots of the intake, the heated mixture will fall into the well. The bottomhole formation zone is treated with hot reaction products. After the reaction is completed, the technological pause is maintained for the full use of the generated heat. Create a depressive effect on the heated treated area. A current pulse is supplied from the ground control panel to the controlled valve, depressurizing the depression chamber.

The disadvantage of this method is the low cleaning efficiency of the bottomhole zone of the well.

The technical result of the method is to increase the efficiency of cleaning the bottom-hole zone of the well.

The technical result is achieved by the fact that in the method of processing the bottom-hole zone of the well, including the descent into the treated interval of the well through the casing of the tubing and heat-generating substance, creating pressure, processing the bottom-hole zone of the formation, technological exposure of the well and the depressive effect on the heated treated zone, according to of the invention, an uncontrolled valve plug, which forms a pump with the interior, is fixed on studs at the lower end of the tubing but the compressor pipe is a sealed container, and as they descend into the tubing, hydrogen peroxide is poured, then an acetate buffer neutral to hydrogen peroxide is supplied, which is separated from it by a second uncontrolled valve plug, then a 5% manganese solution and water are fed moreover, the density of the acetate buffer is taken to be higher than the density of the manganese solution, and the density of the manganese solution is chosen to be higher than the density of water, after the descent of the tubing in the processed interval of the well create back pressure e filling the gap between the tubing and casing with water, then create pressure in the tubing, after which, through the tubing, water is pumped into the treated interval of the well, and after technological soaking, the back pressure is removed and the depression is applied to the bottom-hole formation zone by rinsing with aerated acetate buffer.

The application of the proposed method in comparison with the prototype improves the efficiency of cleaning the bottom-hole zone of the well.

The method of processing the bottom-hole zone of the well is illustrated in the drawing, where:

1 - tubing;

2 - casing;

3 - uncontrolled valve plug, fixed with studs on the lower end of the tubing 1;

4 - the processed interval of the well;

5 - downhole filter;

6 - hydrogen peroxide (fuel substance);

7 - the second uncontrolled valve plug;

8 - buffer liquid - acetate buffer;

9 - catalyst - 5% manganese solution;

10 - water;

11 - emergency valve;

12 - control valve;

13 - pressure gauge;

14 - pump;

15 - reservoir.

The method of processing the bottom-hole zone of the well is as follows. Fasten on the lower end of the tubing 1 with studs (not shown conditionally in the drawing) uncontrolled valve plug 3. The valve plug 3 forms a sealed container with the interior of the tubing 1. A tubing 1 is lowered along a casing pipe 2 into a machining interval 4 of a well 1 with an uncontrollable valve plug 3 fixed on the lower end of the well. cleaning) bottom-hole zone of the well. Then install the second uncontrolled valve plug 7 and serves a buffer fluid 8 (acetate buffer), neutral to hydrogen peroxide. The density of the buffer fluid 8 (acetate buffer) is taken to be higher than the density of the catalyst 9 (5% manganese solution) to ensure their minimum mixing. After supplying the buffer liquid 6, the catalyst 9 (5% solution of manganese) is poured. The density of catalyst 9 (5% manganese solution) is taken to be higher than the density of water 10 supplied after it to ensure their minimum mixing. After the descent of the tubing 1 into the processed interval of the borehole 4, counter-pressure is created by filling the gap 10 between the tubing 1 and the casing 2 with water 10. Then, pressure is created on the internal capacity of the tubing 1 formed by the valve plug 3 using the pump 14. After the pressure surge caused by the cut of the studs of the uncontrolled valve plug 3 fixed by the pressure gauge 13, water 10 is pumped through the tubing 1 the processed interval of 4 wells in a volume taken based on the required depth of cleaning (treatment) of the processed interval of 4 wells. After technological exposure, the back pressure from the gap between the tubing 1 and the casing 2 is removed and a depressive effect is applied to the bottom-hole zone of the formation (well) by washing it with aerated drilling fluid (acetate buffer) collected on the surface into reservoir 15. As a buffer fluid 8 neutral to hydrogen peroxide, use an acetate buffer having the chemical formula of the type CH ₃ COOH + CH ₃ COONa (5% solution), which will increase the safety of the process and reduce the cost of oil production and. As a catalyst, a 5% manganese solution is used, which allows to increase the heat of decomposition of the solution in the oil reservoir. To prevent the occurrence of critical pressures during the implementation of technological operations of the method, an emergency valve 11 and a control valve 12 are installed.

Injecting in a given volume of hydrogen peroxide 6 directly through the tubing 1 can lead to premature decomposition of hydrogen peroxide 6 directly in the pipe 1, since it interacts with the well fluid containing hydrocarbons and produced water. In addition, hydrogen peroxide 6 is in direct contact with the walls of the tubing 1, and iron oxides are decomposition reaction catalysts. Therefore, it is proposed to place a predetermined volume of hydrogen peroxide in an airtight container formed by the interior of the tubing 1 and an uncontrolled valve plug 3 fixed to the studs on the lower end of the tubing 1 and sealing it, as well as a second uncontrolled valve plug 7, made, for example, from an elastic or brittle material. When installing a sealed container with a fuel substance in the treated interval 4 of the well, the annulus (between the casing 2 and the tubing 1 pipe) is filled with water 10 and the wellhead is shut off (sealed) to create hydrostatic counterpressure, ensuring effective penetration of hydrogen peroxide 6 into the bottomhole formation zone (wells). During the reaction during the decomposition of hydrogen peroxide 6, various decomposition products are released that contribute to an increase in the mobility of oil and significantly reduce its viscosity. During the reaction, the pressure at the wellhead rises. As it begins to fall at the wellhead, the annulus opens. To create a depressive effect on the bottom-hole zone of the formation and remove colmatants, molten paraffins, and also asphalt-tar deposits in the tubing 1, an aerated drilling fluid is supplied to create circulation and clean the bottom-hole zone of the formation, similar to the well development process. After that, the well is put into operation.

The application of the proposed method for processing the bottom-hole zone of the well provides the following advantages:

- improving the efficiency of cleaning the bottom-hole zone of the well;

- improving the efficiency of use of released energy;

- reduction in oil production costs.

Claims (1)

A method of treating a bottomhole zone of a well, including a descent into a wellbore interval along a casing of a tubing and a heat-generating substance, creating pressure, treating a bottomhole zone of a formation, holding a well and depressing a heated treatment zone, characterized in that it is fixed on studs on the lower end of the tubing is an uncontrolled plug valve that forms an airtight container with the interior of the tubing, p why, as they descend into the tubing, hydrogen peroxide is poured, then an acetate buffer neutral to hydrogen peroxide is supplied, which is separated from it by a second uncontrolled valve plug, then a 5% solution of manganese and water are supplied, while the density of the acetate buffer is taken the density of the manganese solution is higher, and the density of the manganese solution is chosen to be higher than the density of the water, after lowering the tubing in the processed interval of the well, counter-pressure is created by filling the gap between the pump pressor and the casing, and then pressurized in the tubing, after the jump which is at the tubing injecting water into the treated wellbore section, wherein after process extracts relieve backpressure and carried depression effects on bottomhole formation zone by washing aerated acetate buffer.