RU2330954C1 - Method of treatment of well bottomhole zone with low bed pressure - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to mining and can be used for development and rejuvenation of producing wells yield, reduced as a result of mudding of a bottomhole zone with asphalt-tar-paraffin formations and mechanical additives. The method of treatment of a bottomhole of a well with a low bed pressure includes formation of a depressive pressure drop between the bottomhole zone and a reservoir of the well. Fluid is pumped into the well reservoir up to a process acceptable pressure. A shock wave, traveling in the well reservoir, creates recurrent pressure impulses in the bottomhole zone; the said wave occurs with alternate opening of the well reservoir at the mouth of the well for well fluid under pressure flowing out, and with its closing by means of valves. One of these - the fluid discharge valve - connects the well reservoir with a discharge reservoir; the second - the fluid refill valve - connects the well reservoir with the fluid source under pressure. The discharge reservoir is connected with a pump compressor pipe through the fluid discharge valve. The fluid source under pressure is connected with the annular space via the fluid refill valve. Pumping of fluid into the well up to a process acceptable level is performed through the annular space within time intervals between operations for creating the shock wave transfer in the well reservoir. The technical result is avoiding of mudding sediments penetration into the bed at rising of well pressure, required for creating the shock wave traveling in the well reservoir.

EFFECT: efficient method of treatment of a well bottomhole zone with low bed pressure by means of avoiding of mudding sediments penetration into the bed at rise of well pressure.

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.

A known method of processing the borehole zone of the formation and a device for its implementation (Agliullin M.N., Kurpanov A.S., Rakhmatullin R.Kh., Abdullin M.M. Patent No. 2123591, class E21B 43/25), which produce simultaneous physical and pulsed depression and repression to stabilize the current values of hydraulic conductivity.

However, to implement the method requires the use of a string of tubing, tubing, equipment and cable using a winch, etc.

A known method of cleaning a well from deposits during its operation (Veliev F.G., Kurbanov R.A.-I., Aliev E.N. Patent No. 1700207, class E21B 37/00), in which waves are periodically generated at the wellhead negative pressure, for which they block the valves on the flow line and maintain it in the closed state, then open.

However, the maximum pressure change from water hammer when opening the flow line is 1.5 MPa for a fraction of a second, which is not enough for the formation of a powerful wave, in addition, it is necessary to use a tubing string and a pump with its power supply.

There is a method of developing and cleaning the bottom-hole zone of wells by pulsed 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 borehole zone of the formation and the cavity of the well is carried out by pre-pumping fluid into the well, creating periodic pressure pulses in the borehole zone of the reservoir 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 well the other zone of the formation to the day surface with a sharp opening of the well cavity.

However, the method is applied only during well overhaul using tripping and flushing the well through the annulus in the absence of a packer.

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 formed during periodic opening the well cavity at the wellhead using valves, one of which connects the well cavity to the drain tank, the second to the pressure source of fluid.

However, at low reservoir pressure in the near-well zone of the well, the amplitude of the shock wave is small, which reduces the productivity of the method. The increase in pressure in the well by opening the topping valve with the suspension of the formation of a shock wave for a long time leads to the flow of fluid into the formation and drifts into it of mud pollution.

The objective of the invention is to prevent the penetration of sedimentation deposits into the reservoir with increasing well pressure necessary for the formation of a shock wave moving along the cavity of the well.

The problem is solved in that, using the method of processing the borehole zone with low reservoir pressure, including pumping fluid into the cavity of the well to the technologically permissible pressure, the formation of a depressive differential pressure between the bottomhole zone and the cavity of the well by creating periodic pressure pulses in the bottomhole zone in the form of moving along the cavity a well of the shock wave generated by periodically opening the well cavity at the wellhead for the outflow of well fluid under pressure, and closing it using valves, one of which - a fluid drain valve connects the well cavity to a drain tank, the second - a fluid fill valve - with a source of liquid under pressure, connect a drain tank to the tubing through a fluid drain valve, connect through a fluid fill valve a source of liquid under pressure with an annulus, pumping a liquid into the well to a technologically permissible pressure is carried out through the annulus for periods of time between operations of the formation of a shock wave moving along the well cavity.

This method allows you to increase the pressure in the well directly in the process of formation of the shock wave and thereby provide a significant pressure drop in the bottomhole zone during its processing, as well as to limit the flow of injected fluid into the reservoir.

The method is implemented as follows. At the wellhead, which is completely filled with fluid, two fluid flow breakers are installed, the first is a fluid drain valve for connecting the tubing to the drain tank, and the second is a fluid filling valve for connecting the annulus to the pressure source. Both gates are equipped with timers and open according to a given algorithm.

When you open the valve topping up the fluid pressure in the well increases sharply. Upon reaching a borehole pressure sufficient for the formation of a shock wave and technologically acceptable for the integrity of the casing, close the topping valve and open the drain valve. The borehole fluid pours out with increasing speed, a rarefaction wave is formed in its cavity, propagating from the mouth to the bottomhole zone. When closing the drain valve, the flow stops abruptly with the formation of water hammer and the propagation of a pressure wave from the mouth to the bottomhole zone.

The shock waves of rarefaction and pressure are reflected from the sump and returned to the wellhead. A standing wave in a well cavity is formed by the addition of rarefaction and pressure waves. Opening and closing the drain valve is carried out in such a way that the amplitudes of rarefaction and pressure waves are summed in the bottomhole zone of the well, which contributes to the formation of a standing wave with a significant pressure drop and the creation of hydraulic shocks, including in the bottomhole zone, where adsorption deposits are separated from the pore walls channels and cracks and fracture of the skeleton of the reservoir.

Downhole pressure is increased by opening the topping valve for a short period of time immediately before the operation of generating another wave by opening and closing the drain valve. The rate of fluid injection into the well is much higher than the rate of its filtration through the borehole zone of the formation. Resin-tar-paraffin deposits, torn off from the walls of pore channels and cracks due to water hammer, are carried out of the well into the drain tank when the drain valve is opened; their penetration into the formation during the short-term pressure increase operation is insignificant.

The process is carried out until the required degree of bottom-hole treatment is achieved.

The described method can be used without stopping the well for overhaul, as well as in the process of overhaul, replacing it with a swab operation.

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.

Claims (1)

A method of processing a near-wellbore zone with low reservoir pressure, including pumping a fluid into a well cavity to a technologically permissible pressure, forming a depressurized pressure differential between the bottom-hole zone and the well cavity by creating periodic pressure pulses in the bottom-hole zone in the form of a shock wave moving along the well cavity, which is generated during periodic opening the well cavity at the mouth for leakage of well fluid under pressure and closing it using veins mud, one of which is a fluid drain valve connects the well cavity with a drain tank, the second is a fluid topping valve with a source of liquid under pressure, characterized in that through the fluid drain valve a drain tank is connected to the tubing through a topping valve liquids connect the source of liquid under pressure with the annulus, pumping the liquid into the well to the technologically permissible pressure is carried out through the annulus for periods of time Meni between operations on a moving forming cavity shock wave wells.