The method of pulse and ion-plasma treatment of oil reservoir

 

(57) Abstract:

The invention relates to the oil and gas industry, in particular to methods for increasing oil recovery. The method of ion-plasma exposure to the oil reservoir at the level of the perforation hole. Pass a constant electric current voltage 90-300 In density of 0.1 to 1 A/cm2through injected into the borehole salt water density of at least 1.12 g/cm3. Reservoir periodically every 25-30 min exercise pulsed electrical discharges in the form of 3-5 consecutive pulse discharge generated in the discharge chamber of the ion-plasma generator of the electrode is the anode and electrode-cathode to provide repression-depression mode. The duration of each discharge up to 100 μs. Energy greater than 100 joules. The duty cycle is not more than 5. Impulse responses carried out without interruption of ion-plasma process for continuous flushing of the well mineralized water. After pulse exposure to open annulus and by pumping saline water from the bottom-hole zone of the well to remove the products of decomposition and melting. Intensified production

The invention relates to the oil and gas industry and can be used for intensification of oil production, mining and hard to recover residual oil, as well as at the development of deposits with high viscosity oil.

The invention is directed to an enhanced oil recovery wells due to the decomposition of the produced water, residual oil, bitumen, mineral clots and due to depression-group proved hard to govern mode of action of the shock wave.

There is a method of developing oil fields on and. C. the USSR 1694872, IPC E 21 In 43/24, publ. 30.11.91 g, in which the impact on the oil reservoir is carried out by passing an electric current through electrodes placed in the bottom waters under the oil-bearing formation.

This method is not efficient enough and has limited technological capabilities of the application.

There is also known a method for electrochemical processing of oil and gas wells, including the process of passing a constant electric current through layered multicomponent mixture of wells using casing well as the cathode and installed in its area of perforation electrode as anode (RF patent 2087692, IPC and expensive operation.

The closest to the invention is a method of influence on the oil reservoir (RF patent 2163662, IPC E 21 In 43/24, publ. 24.02.01), including the transmission of direct current voltage inlet 150 up to 450, the density of 0.1-10 A/cm2through mineralized water is continuously pumped from the wellhead to provide electrolytic chemical and ion-plasma processes. While the casing of the well is used as a cathode and as an anode mounted in the perforation electrode.

The disadvantage of this method is that it does not provide removal of the products of decomposition and melting of the bottom-hole zone of the well, resulting in not achieved a sufficient radius of impact on the oil reservoir and its effectiveness.

The proposed invention is directed to the intensification of oil production due to the additional impact on the bottomhole formation zone pulse and electrical discharges, providing removal and the removal of her materials clogging, softened and dissolved clots various compounds.

This object is achieved by a method of ion-flaming exposure to the oil reservoir at the level of the perforation of the well is at the electrode is the anode and electrode-cathode through injected into the well mineralized water to provide modes of chemical and ion-plasma processes, which unlike the prototype uses the electrode is the anode and electrode-cathode, made in the form of the discharge chamber plasma ion generator to provide every 25-30 minutes mode of chemical and ion-plasma processes, switching to pulse electrical discharges in the form of successive 3-5 pulsed discharges with a duration of each pulse discharge to 100 μs, more energy 100 j and a duty cycle of no more than 5 formed in the discharge plasma ion generator for receiving repression-depression mode effects, the process of passing a constant electric current of lead at its voltage 90-600 In use salt water density of at least 1.12 g/cm3and after pulse exposure to open annulus and by pumping saline water from the bottom-hole zone of the well to remove the products of decomposition and melting.

Know the use of mud pulse impact on the productive formations (RF patent 2128285, IPC E 21 In 43/25, publ. 27.03.99 g), which is realized by means of an electrode of a spark gap is set in the pulse chamber.

It is also known electrolaser E 21 In 43/25, publ. 27.02.96 year).

These methods are used for the repair and insulation works well when productive layers isolated by creating an impervious rims around the wellbore, which after completion of the work should be removed from the well. With this purpose, the influence of discharge pulses. These methods do not provide a decomposition and melting of sediments in the bottom zone around the wellbore.

The proposed new set of essential features allows you to get a new effect to be produced by electric discharge impact, carried out periodically during ion-plasma process occurring continuously injected into the well mineralized water. This effect is represion-depression mode stimulation and removal from it softened and dissolved clots various compounds, resulting in rascality bottom-hole formation zone and reveal the smallest pores of the reservoir, put into operation previously untouched areas of the layer are removed from the bottom zone materials clogging, improving the flow of oil increases oil recovery.

JV is at the level of the perforations of the casing-chamber plasma ion generator, inside which there is a discharge chamber formed between dischargers: electrode-the anode and housing-cathode. The negative phase of the ground source of constant current through the casing of the well is connected to the generator housing, zero - phase cable with electrode-anode discharge chamber of the generator. Pump-compressor pipe into the borehole salt water density of at least of 1.12 mg/cm3and through the ion-plasma chamber of the generator pass a constant electric current voltage 90-300, the density of 0.1-10 A/cm2. Under the influence of the electric current inside the wells occur chemical and ion-plasma processes which result in the casing pipe, which is the cathode, and a hydrogen and is formed alkali, reducing the surface tension of the oil film and dissolution of various deposits in the critical zone of the oil reservoir. At the anode of the ion-plasma chamber of the generator is formed Protasova shell conducive to spontaneous ignition of the plasma, resulting in intense heating of the mixture in the reaction zone. Under these conditions, around the anode is formed of active oxygen and creates acidic seniu tubes of residual oil, and in the acidic environment dissolves mineral clots various compounds (caso3, MgCl2, Na2SO4and others ). Active oxygen plays a special role, oxidizing the hydrocarbon oil reservoir to carbon dioxide; gases (O2, CO2) contribute to the further destruction of the tubes in the bottom-hole zone and in the oil reservoir due to the local increase of the pressure. In the presence of sulfur compounds in the composition of the oil reservoir of active oxygen oxidizes them to oxides of sulfur, which contributes to a partial reduction of sulfur in oil.

The effect is amplified by the increasing pressure in the reaction zone of the generator, which promotes the migration of alkaline and acidic environments from the zone of ion-plasma exposure to the depth and horizontal directions of the reservoir.

After 25-30 minutes of work in the mode of ion-plasma processes alternator with ground power supply switch mode pulse operation and the discharge chamber of the generator between its electrodes are formed of electrical discharges in the form of continuously following each other 3-5 pulses of each pulse of 100 μs, more energy 100 j and a duty cycle of up to 5. In the pulsed discharges prozharyatsya and into the oil reservoir. The shock wave pressure promotes the transfer from the perforations into the formation of products of ion-plasma processes, and on reaching the reservoir boundary line is reflected and returns to the casing pipe with removal of the products of decomposition and melting. The number and characteristics of the pulses are selected based on the capacity of the reservoir, reservoir pressure, radius of influence, etc. After pulse exposure opens the valve annulus and by pumping saline water from the bottom-hole zone of the well is removed decomposition and melting.

After pumping annulus close the mouth valve and the described cycle is repeated at least 2-3 times.

As a result of this combined effect of addition the temperature of the ion-plasma, electrochemical processes in the critical zone of the oil reservoir, is provided repression-depression mode, which is accompanied by change and redistribution of pressure between the reservoir and the bottom of the borehole, which in turn contributes to rasilimali bottom-hole formation zone and the flow of oil to the bottom of the borehole.

An example of a specific implementation.

On the 5th year of field development well production rate decreased to 3 tons/day.

Were treatment of bottom-hole zone of the well under the proposed method. Within 4 hours using ion-plasma generator impacted bottom-hole formation zone cycles: 30 min in the mode of ion-plasma process, 5 pulses of the electric discharge duration of each 100 μs, duty cycle 5. The exposure was carried out at a voltage of 240 V, density 0.25 a/cm2.

As a result of this combined effect of the flow rate increased to 16.5 tonnes.

Thus, the proposed invention allows to intensify oil production due to the combined effect on the bottomhole formation zone, including ion-plasma process and a pulsed electrical discharges.

The method of ion-plasma treatment of oil reservoir at the level of the perforation of the well, including the process of passing a constant electric current of voltage 150-300 and density of 0.1-10 A/cm2between electrode is the anode and electrode-cathode through injected into a well mineralizovannoj anode and electrode-cathode, made in the form of the discharge chamber plasma ion generator to provide every 25-30 min mode chemical and ion-plasma processes, switching to pulse electrical discharges in the form of successive 3-5 pulsed discharges with a duration of each pulse discharge to 100 μs, more energy 100 j and a duty cycle of no more than 5 formed in the discharge plasma ion generator for receiving repression-depression mode exposure, the process of passing a constant electric current of lead at its voltage 90-600 V, use salt water density of at least 1.12 g/cm3and after pulse exposure to open annulus and by pumping saline water from the bottom-hole zone of the well to remove the products of decomposition and melting.

 

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