RU2266395C1 - Borehole fluid oscillation excitation method - Google Patents

Abstract

FIELD: mining industry, particularly to develop and rework production wells to stimulate borehole fluid inflow.

SUBSTANCE: method involves inserting weight connected to resilient suspension means into pipe string filled with fluid; exciting borehole fluid oscillations due to axial weight movement. The weight serves as a piston and comprises valves to permit fluid flow in both directions. The valve may be opened under predetermined pressure upon differential pressure draw-down on well bottom zone when weight moves upward and differential pressure increase when weight moves downward during pumping unit operation. Above differential pressure change actions is combined with natural weight vibration.

EFFECT: provision of vibratory and wave well bottom zone treatment within wide frequency range.

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Description

The invention relates to mining and can be used to develop and restore the production rate of production wells, in particular for the intensification of inflows of reservoir fluids.

There is a known method of operating a well (Ashchepkov Yu.S. Berezin G.V. Ashchepkov M.Yu. channels. With a decrease in flow rate periodically with a frequency of 1-2 times per month, they block the flow line of the well at the wellhead and produce 30-40 thousand strokes of the plunger to increase the flow rate of the well.

However, to transfer the swings of the pump plunger, it is necessary to close the flow line and stop production.

A known method and device for wave action on the reservoir (Vagin VP, patent No. 2196888, CL. E 21 B 43/25), when using which during the operation of the rocking machine during the upward stroke of the plunger, the liquid is compressed. The liquid is discharged into the column, as a result of which a shock wave is formed, which penetrates into the reservoir and forms pressure waves in it. Hydraulic fractures form by compressing the fluid in the elevator to the appropriate pressure.

However, the method is used in a wave fund well located at a considerable distance from the production well.

There is a known method of operating a well (Ashchepkov Yu.S., Berezin G.V., Ashchepkov M.Yu. Patent No. 2136851, Cl. E 21 B 43/00), which provides enhanced oil recovery due to dilatation-wave action on the formation. A pipe string with a shank of variable cross section in depth is lowered into the sump of the well. Periodically, with a decrease in flow rate, the flow line is closed, the swings of the pump-pump plunger are transmitted to the shank, which periodically compacts and softens the rock.

However, to transfer the swings of the pump plunger, it is necessary to block the flow line and stop production, in addition, a significant part of the pump energy is spent on deformation of the skeleton of the reservoir.

A known method and device for exciting transverse vibrations of a pipe string in a well (Ivannikov V.I., Ivannikov I.V., Patent No. 2157446, Cl. E 21 B 28/00), taken as a prototype, in which it is placed in a pipe string with fluid drummer on a flexible suspension and excite its periodic oscillations due to its axial movement.

However, for processing the well, it is necessary to stop it, launch special equipment and use a winch.

The objective of the invention is the implementation of the microwave processing of the bottom-hole zone of the well, equipped with a pump-rocker in a wide frequency range.

The problem is solved by the fact that, using a method of exciting fluid vibrations in a well, including placing in a pipe string filled with fluid, an elastic suspension load and exciting the well fluid vibration due to axial movement of the load, the load is a piston and contains valves capable of passing fluid in both directions and open at a given pressure when creating a depression on the bottom-hole zone of the well when moving the load up, or repression, when moving the load down, when the rocking machine is operating, while skie depression-repressionnye exposure, followed by the implosion effect and shock-wave action, combined with the natural oscillations of the load.

This method allows you to initiate combinations of vibrational and implosive effects transmitted through the borehole fluid into the borehole zone of the reservoir due to the axial movement of the load on the elastic suspension. Complex vibrations affect both the formation fluid and the formation skeleton.

An example of a device for implementing the proposed method is illustrated in the drawing, in which: 1 - well; 2 - rod pump-rocking; 3 - cargo: 4 - valves, 5 - well perforation.

The method is implemented as follows. A string of rods 2 is lowered into the well 1, in the lower part of which, above the perforation zone 3, a load 4 is placed. The load 4 contains valves 5 that can pass fluid in both directions and open at a given pressure.

During the operation of the pump-pump, the rod performs vertical reciprocating movements, moving the load in the cavity of the well. The load, being a piston, creates fluctuations in the borehole fluid with a rod speed of about 0.1 Hz.

Moving the load up creates depression in the perforation zone and increased pressure over the load. When the pressure drop between the sections of the well cavity separated by the load increases, the valves 5 open to a predetermined level, an implosion effect occurs, accompanied by water hammer and shock-wave action on the well perforation zone.

Moving the load down creates repression in the perforation zone. When the pressure drop between the sections of the cavity of the well shared by the load increases to a predetermined level, valves 5 open, water hammer and shock-wave impact on the perforation zone of the well occur.

The rod, having a significant length, is an elastic link, therefore, with vertical reciprocating movements of a load having a significant mass, oscillations occur, determined by the mass of the load and the length of the elastic link. The natural frequency of oscillation is equal to:

where E is Young's modulus (for steel E≈2.1 · 10 ¹¹ Pa);

A - cross-sectional area of the rod;

m is the reduced mass of the cargo, consisting of the masses of the cargo and part of the rod);

L is the length of the rod.

Vibrational impact on the bottom-hole zone is carried out by the interaction of low-frequency pump oscillations transmitted to the load through the rod, fluctuations in the mass of the load hanging on the elastic link, and the implosive shock-wave effect. The microwave action in the frequency range of about 0.1-10 Hz is produced on the formation fluid, on the deposits on the walls of the pore channels and on the skeleton of the formation.

The treatment of the bottom-hole zone can be carried out during the overhaul of the well, as well as in the process of oil production when the rocking pump and plunger and cargo are installed at the rod at different depths.

The relatively small mass of the load compared with the mass of the sucker rod does not adversely affect the operation of the suspension, balancer and gearbox of the sucker rod pump.

The application of the method does not require the use of sophisticated equipment, prolonged shutdown of the well. The fluid may contain chemicals for more efficient cleaning. The method can be applied in conjunction with other types of bottom-hole treatment: acid, thermal, acoustic, etc.

Claims (1)

A method of exciting fluid vibrations in a well, including placing in a string of pipes filled with fluid, a load on an elastic suspension and excitation of vibration of the well fluid due to axial movement of the load, characterized in that the load is a piston and contains valves that can pass fluid in both directions and open at a given pressure when creating a depression on the bottomhole zone of a well when moving the load up or repressing when moving the load down, when the rocking machine is operating, with periodic depressions Onno-repressionnye exposure, followed by the implosion effect and shock-wave action, combined with the natural oscillations of the load.