RU2278964C1 - Method for production well bottom zone treatment by outflow - Google Patents

Abstract

FIELD: oil production industry, particularly enhanced recovery methods for obtaining hydrocarbons.

SUBSTANCE: method involves selecting well characterized by reduced intake capacity for following well treatment so that total outflow time is to be not more than 5 hours; bringing the selected well into operation for not less than 10 days along with liquid injection via the well; providing maximal conditional passage of well fittings; stopping liquid injection in well; discharging liquid from well to reach necessary calculated liquid volume at maximal flow rate; injecting liquid through the well at flow rate equal to 3 initial well intake capacity values up to pressure stabilization; injecting liquid in well at increased flow rate equal to 4 initial well intake capacity values; performing flow rate increase in several stages under stabilized injection pressure, wherein each flow rate increase step is equal to initial well intake capacity value, up to full control valve opening; discharging liquid from well at maximal flow rate so that discharged liquid volume is equal to calculated one; repeating liquid injection and discharge operations 3 times, wherein the last liquid discharge operation is carried out at maximal flow rate and in amount equal to the volume of the first liquid discharge.

EFFECT: increased well cleaning efficiency.

1 ex

Description

The invention relates to the oil industry and may find application in cleaning the bottom-hole zone of an injection well.

A known method of repairing an injection well, including the accumulation of fluid in the bottomhole zone and its spout to the surface (RF Patent No. 2079637, class E 21 B 43/00, publ. 1997.05.20).

The known method is not effective enough due to the uncontrolled parameters of fluid accumulation and spout.

The closest to the proposed invention in technical essence is a method of cleaning the bottom-hole zone of a well by pulse drainage, which includes treating wells in 15-45 cycles, each of which produces 6-30 depressive-repressive drainage pulses that create when the overpressure in the well exceeds reservoir, by pumping fluid into the annulus. At first, the well is opened with a ground breaker and the fluid is poured through tubing into a surface collection tank. When the spout reaches its maximum speed, the well is closed abruptly and a damped standing wave is created, which reaches the sump of the well in 2-2.5 s and returns to the wellhead, while doing pulsed impacts on the bottom-hole formation zone. The oscillations are monitored by the wellhead pressure gauge and interrupted during the beginning of the wave return to the wellhead, increasing the depressive removal of contaminants from the bottom-hole zone by the in-phase spout of the liquid and through tubing to the groove tank. The spout is produced for 2-4 s and then a standing wave is again formed and is repeated until the overpressure in the well decreases. The fluid is injected at a constant rate to control the time it takes to reach a specific overpressure in the well. If time increases, then processing continues, if it does not increase, then stop (RF Patent No. 2159326, CL E 21 B 43/25, publ. 2000.11.20 - prototype).

The known method allows you to control the injection parameters of the fluid and the spout, however, it is not effective enough due to the small amount of liquid poured from the well and the shortness of the spout.

The proposed invention solves the problem of increasing the efficiency of cleaning the bottom-hole zone of the injection well.

The problem is solved in that in the method for processing the bottom-hole zone of the injection well by spout, including pumping liquid into the bottom-hole zone to increase pressure and pouring the liquid from the well, according to the invention, a well is selected in advance, at which the injectivity decreased during operation for processing from the condition of the total time of the spout no more than 5 hours, before treatment, the well is operated for at least 10 days. with fluid injection through the well, provide the maximum conditional passage of the piping of the well, stop fluid injection through the well, pouring fluid from the well to the required calculated fluid volume at maximum flow rate, fluid injection through the well is carried out at a flow rate of not more than 3 times the originally measured injectivity wells before pressure stabilization, after pressure stabilization, fluid is pumped through the well with an increase in flow rate to a value of not more than 4-fold of the initially measured value of the well injectivity, a further increase in the flow rate is carried out in stages with stabilization of the injection pressure with a step equal to the initially measured value of the well injectivity until the control valve is fully open, the fluid is poured out of the well at the maximum flow rate in the volume equal to the calculated one, the pumping is repeated and the fluid is not spilled less than 3 times, the last outflow of fluid from the well is performed at a maximum flow rate in the volume of the first outflow.

SUMMARY OF THE INVENTION

During the operation of the injection well, accumulating elements occur in the near-wellbore zone, which reduce its permeability and, as a result, reduce the productivity of the well. Traditionally used methods for processing the bottom-hole zone can increase the productivity of the well, however, their effectiveness is low. The proposed method solves the problem of increasing the efficiency of cleaning the bottom-hole zone of the injection well. The problem is solved by the following set of operations.

When cleaning the bottom-hole zone of the injection well with a spout, select a well in which the injectivity decreased during operation to process from the condition of the total spout time of not more than 5 hours.

When selecting wells, the condition must be met:

In the formula (1) t _izl - the total time of the outflow of fluid from the well (hour);

k _CR - injectivity coefficient of the injection well, m ³ / day · MPa · 10;

R _zab , r _PL - bottomhole and reservoir pressure on the injection well, MPa · 10;

V is the total volume of liquid poured from the well, m ³ , determined by the formula:

In the formula (2) V ₁ , V ₂ - the estimated volume of the poured liquid, m ³ .

In the formula (3) D _tubing - the inner diameter of the tubing string, m;

L _tubing - the length of the tubing string, m;

D _ek - the inner diameter of the production casing, m;

L _x is the distance from the shoe of the tubing string to the bottom of the lower perforated formation, m;

N _PL - perforated thickness of the reservoir, m;

R is the radius of the perforated formation spout, m;

m - formation porosity, fractions of units

As a result of hydrodynamic studies (from the pressure drop curve), the filtration parameters of the reservoir and well (hydraulic conductivity, permeability, piezoconductivity), flow rates (injectivity), wellhead, reservoir and bottomhole pressures, productivity coefficients (injectivity), and reduced radius are determined. The required volume V _{1 of the} first spout is calculated, which consists of the volumes: the internal cavity of the tubing string from the mouth to the shoe, the volume of the production string from the bottom of the perforated formation to the shoe of the tubing string, the volume of the perforated formation.

Before treatment, the well is operated for at least 10 days. with fluid injection through the well. At the same time, the bottomhole zone is saturated with liquid. Provide the maximum conditional pass of the piping of the well. To do this, dismantle the connecting devices and check valves, reducing the conditional passage of the piping of the well. Stop operation and stop pumping fluid through the well. The first liquid is poured into the required calculated volume V ₁ from the well into the water carrier at maximum flow rate. The flow rate is regulated by opening the control valve. After the spout, fluid is injected through the well at a flow rate of not more than 3 times the originally measured value of the well injectivity until the pressure stabilizes. After stabilization of the pressure, the fluid is pumped through the well with an increase in flow rate to a value of not more than 4 times the initially measured value of the well injectivity until the pressure stabilizes. After that, the fluid is pumped through the well with an increase in flow rate at each stage until stabilization of the injection pressure in increments equal to the initially measured value of the injectivity of the well to the maximum flow rate (until the control valve opens completely). After stabilization of the injection pressure at the last stage, the fluid is poured out of the well at the maximum flow rate in a volume equal to the calculated V ₂ . Repeat the injection and pouring of the liquid at least 3 times. The last outflow of fluid from the well is performed at a maximum flow rate in the volume of the first outflow V ₁ .

Concrete example

Spend treatment of the bottom-hole zone of the injection well. Determine the suitability of the injection well for this treatment. When selecting wells, the condition must be met:

In the formula (1) t _rad - the total time of the outflow of fluid from the well should be no more than 5 hours.

The characteristics of the well and bottom hole are as follows:

k _CR - injectivity coefficient of the injection well, equal to 1.31 m ³ / day · MPa · 10;

P _zab - bottomhole pressure at the injection well, equal to 262 · MPa · 10;

P _PL - reservoir pressure at the injection well, equal to 207 · MPa · 10;

D _tubing - the inner diameter of the tubing string is equal to 0.062 m;

l _tubing - the length of the tubing string is equal to 1785 m;

d _ek - the inner diameter of the production casing is 0.128 m;

L _x - the distance from the shoe of the string of tubing to the bottom of the lower perforated layer is 21.4 m;

N _PL - perforated thickness of the reservoir, equal to 2 m;

R is the radius of the perforated formation spout, equal to 0.5 m;

m - the porosity of the reservoir is equal to 0.21 (fractions of units).

In the formula (2) V ₁ , V ₂ - the estimated volume of the poured liquid, m ³ .

V is the total volume of liquid poured from the well, m ³ , determined by the formula:

The total time of liquid outflow from the well is less than 5 hours. Therefore, the well is suitable for processing in this way.

The initial injection rate of the injection well was 63 m ³ / day. The current injection rate of the injection well was 13 m ³ / day. The task is to increase the injectivity of the injection well to the initial level. The problem is solved as follows.

Before treatment, the well is operated for 10 days. with the injection through the well of liquid - water as a working agent in the development of an oil reservoir. Provide the maximum conditional pass of the piping of the well. To do this, dismantle the connecting devices and check valves, reducing the conditional passage of the piping of the well. Stop pumping fluid through the well. The first outflow of fluid from the well is carried out to the required calculated fluid volume V _{1 of} 5.99 m ³ at a maximum flow rate of 72 m ³ / day. Water is pumped through the well at a flow rate of not more than 3 times the originally measured value of the well injectivity 25 m ³ / day until the pressure stabilizes. After pressure stabilization, fluid is pumped through the well with an increase in flow rate to a value of not more than 4 times the originally measured value of the well injectivity 38 m ³ / day. A further increase in flow rate is carried out in two stages with stabilization of the injection pressure in increments equal to the initially measured value of the injectivity of the well 13 m ³ / day, until the control valve opens in the second stage. Spill the fluid from the well at a maximum flow rate of 72 m ³ / day in a volume equal to the estimated V ₂ = 0.33 m ³ . Repeat the above injection and pouring liquid 3 times. The last outflow of fluid from the well is performed at a maximum flow rate in the volume of the first outflow V ₁ = 5.99 m ³ .

As a result of processing, the injectivity of the injection well was increased to 50 m ³ / day., While using known methods it is possible to achieve half the effect of the achieved.

The application of the proposed method will improve the efficiency of cleaning the bottom-hole zone of the injection well.

Claims (1)

A method of treating the bottom-hole zone of an injection well by spout, including pumping liquid into the bottom-hole zone to increase pressure and pouring liquid from the well, characterized in that it pre-selects a well at which injectivity has decreased during operation, for processing from the condition of a total outflow time of not more than 5 h, before treatment, the well is operated for at least 10 days. with the injection of fluid into the well, provide the maximum conditional passage of the piping of the well, for which dismantling devices and check valves are disassembled in it, the fluid is stopped into the well, the fluid is poured out of it, the fluid is pumped into the well at a flow rate of not more than 3 times the originally measured values of injectivity of the well until pressure stabilization, after which fluid is injected into the well with an increase in flow rate to a value of not more than 4 times the initially measured value of the injectivity well, a further increase in flow rate is carried out in stages with stabilization of the injection pressure with a step equal to the initially measured value of the injectivity of the well until the valve is fully opened, the fluid is poured out of the well, the fluid is injected and spilled at least 3 times, and the last fluid spout is performed in volume of the first spout.