RU2355879C1 - Procedure of treatment of well bottomhole zone - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention refers to mining and can be implemented for development and recovery of producing wells yield reduced because of bottomhole mudding with asphaltic-resinous-paraffin formations and mechanical impurities. The object of the invention is generating periodic pulses of pressure in the bottomhole zone of a reservoir with regulated amplitude and frequency characteristics for each alternating stage of well treatment. The essence of the invention is as follows: the procedure consists in pumping fluid into the cavity of the well, in creating depressive drop of pressure between the bottomhole zone and the cavity of the well by means of generating periodic pulses of pressure in the bottomhole zone in form of a shock wave moving along the cavity of the well; the shock wave is formed, when the cavity of the well at the well head is periodically opened to let well fluid under pressure drain and then it is shut off with valves. One of the valves is a drain valve. It communicates the well cavity with a drainage capacity. The second valve is a fluid filling valve. It facilitates connection with a fluid source under pressure. The fluid drain valve performs opening and shutting off the well cavity at the well head for draining well fluid under pressure. Periodically pressure in the well is raised connecting the well head with the fluid source under pressure by means of opening the fluid filling valve. According to the invention at the stage of removing mechanical and hydrocarbon formations there is performed quick drain valve opening and comparatively slow shutting off to create depression, facilitating implosion extraction of mud out of botomhole thickness, and to create repression preventing mud reverse moving. At the stage of working agent supply into an interval of perforation there is performed drain fluid opening and quick shutting off for creating repressive pulses of pressure facilitating expansion of fractures when working agent penetrates them. At the stage of removing working agent and products of chemical reaction from the bottomhole zone again there is performed drain valve quick opening and slow shutting off for implosion extraction of residual mud out of bottomhole zone thickness. Also frequency of pulses at mud removal is chosen providing resonant swinging of well fluid column and maximum value of depression amplitude, and during fractures expanding - also providing working agent moving in fractures to flush off rock of the bottomhole zone from hydrocarbon film.

EFFECT: new procedure of well bottomhole zone treatment.

Description

The present invention relates to mining and can be used to develop and restore the production rate of production wells, decreased as a result of mudding of the bottomhole zone with asphalt-resin-paraffin formations and solids.

There is a method of development and cleaning of the bottomhole zone of wells by pulse drainage (Nosov P.I., Senochkin P.D., Nurislamov N.B. et al. Patent No. 2159326, class Е21В 43/25), in which the formation of a pressure drop between the bottom-hole zone of the formation and the cavity of the well is made by pre-pumping fluid into the well, creating periodic pressure pulses in the bottom-hole zone of the formation in the form of a damped standing wave moving along the cavity of the well, and bleeding off the pressure when moving the fluid through the well from the bottom-hole ons of the formation to the day surface with a sharp opening of the well cavity.

However, the method does not allow to create, if necessary, depressive or repressive water hammer in the bottomhole zone of the well.

A known method of processing the bottom-hole zone of the injection well (Ibragimov N.G., Zakirov A.F., Nikitin V.N., Ozheredov E.V. Patent No. 2258134, class E21B 43/18), in which a bath is organized in the perforation interval a working agent by selling it in a pulsed drainage mode with technological exposure.

However, the method does not allow the creation of hydraulic waves for various stages of the treatment of the bottom-hole zone with an adjustable speed and frequency of pressure change.

A known method of processing the bottom-hole zone of the wellbore (Gubar V.A., Gubar D.V. Patent No. 2262591, class E21B 43/18), comprising hydraulically cleaning the perforation zone of the productive formation, injecting a chemical reagent into the bottom-hole zone, flushing the well and subsequent high-energy gas-pulse impact on the bottom-hole zone of the wellbore with a pressure at the front of the shock wave equal to or greater than the rock pressure in the treatment zone.

However, the method does not allow the creation of hydraulic waves for various stages of the treatment of the bottom-hole zone with an adjustable speed and frequency of pressure change.

A known method and device for the development and cleaning of the bottom-hole zone of wells by pulse drainage (Guryanov A.I., Fassakhov R.Kh., Fayzullin I.K. et al. Patent No. 2272902, class Е21В 43/25), in which the pressure is released at the movement of fluid from the bottomhole zone to the surface to create periodic pressure pulses in the bottomhole formation zone. Depression differential pressure between the bottomhole formation zone and the cavity of the tubing and the formation of periodic pulses are created by pumping fluid into the borehole space at a predetermined pressure. Bleeding to a predetermined pressure is carried out when the control valve is opened through the annulus.

However, periodic pressure pulses have a small amplitude (1.5-2 MPa) and a duration (of the order of 200 sec), which excludes sharp pressure drops in the bottom-hole zone and resonant buildup of the liquid column, contributing to the separation of adsorption deposits from the walls of the pore channels.

A known method of reagent-pulse impact on the well and the reservoir and the installation for its implementation (Kononenko P.I., Boguslaev V.A., Kvitchuk K.K. et al. Patent No. 2275495, class Е21В 37/06), in wherein the active liquid medium containing a mixture of aliphatic and aromatic hydrocarbon solvents is squeezed into the formation, held for 12-24 hours and removed from the bottom-hole zone with wave unloading of the well by a pulse-wave depressive effect, then the pulse-wise interval treatment of the bottom-hole is carried out th process fluid zone flat fan jet formation on the level, after which the process liquid is removed from the reservoir zone.

However, the active liquid medium is crushed into the reservoir at a constant speed, which does not allow it to penetrate into small cracks; when holding in the thickness of the reservoir, the active liquid medium is in a stationary state, which does not contribute to its active reaction with reservoir elements.

A known method of processing the borehole zone of the formation (Shipulin A.V. Patent No. 2266404, class ЕВВ 43/25), taken as a prototype, which includes the creation of periodic pressure pulses in the borehole zone of the formation in the form of a shock wave moving along the cavity of the well, which is generated during periodic opening well cavities at the wellhead using valves, one of which connects the well cavity to a drain tank, the second to a source of pressurized fluid.

However, the method does not allow the creation of hydraulic waves for various stages of the treatment of the bottom-hole zone with an adjustable speed and frequency of pressure change.

The objective of the invention is to create periodic pressure pulses in the bottomhole formation zone with adjustable amplitude and frequency characteristics for each of the alternating stages of the well treatment.

The problem is solved in that, using a method for processing the bottom-hole zone of a well, including pumping a liquid into the cavity of the well, forming a depressive differential pressure between the bottom-hole zone and the cavity of the well by creating periodic pressure pulses in the bottom-hole zone in the form of a shock wave moving along the cavity of the well, which is generated during periodic opening the well cavity at the mouth for leakage of well fluid under pressure and closing it using valves, one of which is a valve To drain the fluid connects the well cavity with a drain tank, the second valve topping up the fluid with a source of pressurized fluid, opening and closing the well cavity at the wellhead for the outflowing pressurized fluid is carried out by a fluid drain valve, periodically increase the pressure in the well by connecting wellhead with a source of fluid under pressure by opening the valve topping up the fluid in the injection well at the stage of removing mechanical and of hydrogen deposits form the quick opening and relatively slow closing of the drain valve from the condition of creating a depression that provides implosive extraction of colmatants from the thickness of the bottomhole zone, and repression that counteracts the movement of colmatants in the opposite direction, at the stage of delivery of the working agent to the perforation interval, open and quickly close the drain valve from the condition of creating repression pressure pulses that contribute to the expansion of cracks at the time of penetration into them of the agent, and at the stage of removing the working agent and their chemical reaction products from the bottomhole zone, again, quickly open and slowly close the drain valve for implosive extraction of residual muds from the thickness of the bottomhole zone, while the pulse frequency when removing the muds is selected from the condition of resonant buildup of the borehole column fluid and obtaining the maximum value of the amplitude of the depression, and with the expansion of cracks - from the condition of ensuring the movement of the working agent in these cracks with the washing of the rock pr bottomhole zone of a hydrocarbon film.

This method allows the well to be treated using, if necessary, a significant in amplitude and short in time depressive pulse of hydraulic pressure and a relatively small in amplitude and longer pulse of repression, or a long depression pulse and a short and powerful pulse of repression, as well as change the frequency of their alternation .

The method is implemented as follows. At the wellhead, valves are installed, the first of which connects the tubing cavity to the drainage tank, the second - the annular space with a source of fluid under pressure, for example, a fluid line designed for injection into injection wells or the CA-320 unit. The fluid is pumped into the annulus to a technologically permissible pressure.

At the moment of opening the drain valve, the well fluid begins to pour into the drain tank, the pressure of the fluid at the wellhead drops sharply to atmospheric pressure, a rarefaction wave forms, which moves from the wellhead to the bottom of the well and forms a depression impulse in the bottomhole zone. When the fluid drain valve is closed and the moving fluid flow is interrupted, a high pressure region is formed at the wellhead, which moves from the wellhead to the bottom of the well and generates a repression pulse in the bottomhole zone. Periodic opening and closing of the drain valve leads to the regular passage of pressure waves and rarefaction along the tubing cavity.

The pressure and rarefaction waves, moving along the well cavity from the wellhead to the bottom and back, create shocks, including in the bottomhole zone, and contribute to the separation of adsorption deposits from the walls of the pore channels and cracks, destruction of the formation skeleton. The periodic alternation of pulses of low and high pressure contributes to the loosening and chipping of low-permeability fragments of the reservoir.

Impulses of depression contribute to the extraction of colmatants from pores and fractures of the formation, their output into the cavity of the well. Impulses of repression contribute to the short-term expansion of cracks, which then close to their original state.

The amplitude and duration of the depression pulse depends on the steepness of the front of the rarefaction wave, and therefore on the acceleration of the fluid flow when opening the drain valve. The amplitude and duration of the repression pulse depends on the steepness of the front of the pressure wave, therefore, on the rate of interruption of the fluid flow when the drain valve is closed. The parameters of the pressure pulses are determined taking into account the features of the geological structure of the reservoir, as well as the allowable pressure determined by the state of the pipe string.

Well fluid may contain chemicals for more productive processing. The method can be applied in conjunction with other types of bottom-hole treatment: acidic, thermal, vibrational, acoustic, etc.

The sequence of specific application of the method is illustrated by the example of treatment of the bottom-hole zone of an injection well, the injectivity of which is reduced as a result of the injection of waste water containing solid and hydrocarbon inclusions.

1. Carry out the cleaning of the bottom-hole zone from mechanical and hydrocarbon deposits, for which periodically open and close the drain valve, which leads to the regular passage of pressure waves and rarefaction through the tubing cavity. Carrying out quick opening and relatively slow closing of the drain valve, they create a short and powerful depressive pressure drop and smooth repressive pressure, which contributes to implosive extraction of colmatants from the reservoir and counteracting their movement in the opposite direction. Colmatants are discharged into the well cavity for further removal by spouting or flushing. The frequency of the pressure pulses is selected according to the conditions of the resonant buildup of the borehole fluid column in order to obtain the maximum value of the amplitude of the pressure depression pulse.

2. A working agent (acid solution, distillate or other solvents) is delivered to the perforation interval by circulation. Then, the discharge valve is opened and quickly closed, which creates powerful repressive pressure pulses that contribute to the short-term expansion of the formation cracks and the penetration of the working agent into them. The frequency of the pressure pulses is chosen for reasons of maximum crack opening, as well as ensuring the movement of fluid in order to wash the formation rock from the hydrocarbon film and ensure its chemical reaction with the working agent. Fluid buildup in the bottom-hole zone, as necessary, is alternated with technological excerpts.

3. Carry out the removal of the working agent and chemical reaction products from the bottom-hole zone, for which they quickly open and slowly close the drain valve, create a depressurized pressure drop for the purpose of implosive extraction of residual colmatants from the formation thickness, withdrawing them into the well cavity for further removal by spout or washing . The frequency of the pressure pulses corresponds to the conditions of the maximum amplitude of the pressure depression pulse.

4. Determine the injectivity of the well and translate it into working condition.

Claims (1)

A method of processing a bottom hole of a well, including pumping a liquid into the cavity of a well, forming a pressure drop between the bottom and the well cavity by creating periodic pressure pulses in the bottom in the form of a shock wave moving along the well cavity, which occurs when the hole is periodically opened at the wellhead for leakage well fluid under pressure, and closing it using valves, one of which is a fluid drain valve that connects the strips b wells with a drain tank, the second is a fluid top-up valve with a source of pressurized fluid, opening and closing the well cavity at the wellhead for the flow of pressurized wellbore is carried out by a fluid drain valve, periodically increase the pressure in the well by connecting the wellhead with a source of liquid under pressure by opening a valve topping up the liquid, characterized in that in the injection well at the stage of removing mechanical and hydrocarbon from the bottomhole zone x deposits carry out quick opening and relatively slow closing of the drain valve from the condition of creating a depression that provides implosive extraction of colmatants from the thickness of the bottomhole zone, and repression that counteracts the movement of the mud in the opposite direction, at the stage of delivery of the working agent to the perforation interval, open and quickly close the drain valve from the condition of creating repression pressure pulses that contribute to the expansion of cracks during the penetration of the working agent into them, at the stage of removal of the working agent and their chemical reaction products from the bottom-hole zone - again, the quick opening and slow closing of the drain valve for implosive extraction of residual muds from the thickness of the bottom-hole zone, while the pulse frequency when removing the muds is selected from the condition of resonant buildup of the well column and obtaining the maximum values of the amplitude of the depression, and with the expansion of cracks - from the condition of ensuring the movement of the working agent in these cracks with washing out the rock bottom hole they are from a hydrocarbon film.