Method for cleaning face-adjacent bed area

FIELD: oil and gas extractive industry.

SUBSTANCE: method includes forming of gas pillow by forcing gas into inter-tubular space. Further pushing liquid is forced therein with forcing away of liquid from inter-tubular space along tubing column into tank or store, pressure is dropped from inter-tubular space down to atmospheric and hydro-impact is used to effect well face by rotating liquid flow from tubing column. Pillow is formed by plant for forcing pushing liquid and gases. As gas, mixture of air and exhaust gases is used in relation no greater than 2:3. pillow pressure provides for prevention of gas from getting into tubing column. Volume of pushing liquid is determined from formula: Vpl=0.785.(d

21
-d22
).(HT-Hgp-Hi-t).10-6, where d1 - inner diameter of casing column, mm; d2 - outer diameter of tubing pipes, mm; HT - depth of lowering tubing column in well, m; Hgp - height of gas pillow in inter-tubular space, m; Hgp=K·Pgp; K - hydrostatic coefficient of resistance to pushing of liquid and gas (K=100 m/MPa), m/MPa; Pgp - end pressure of gas pillow, MPa; Hi-t - inter-tubular space height.

EFFECT: higher safety, higher efficiency.

3 cl, 2 dwg, 2 ex, 1 tbl

 

The invention relates to the oil industry and can be used to restore the productivity of producing wells and injection wells, and well development after drilling.

A known method of purification of bottom-hole formation zone (PPP) by creating a depression in the bottom zone of the injection of air into the annular space between the production column and tubing and the subsequent suppression of air aqueous solution of surface-active substances (surfactants) to isolate the annulus using pokerwise element (A.S. No. 426029 the USSR, E 21 B 43/22, 1972).

The disadvantage of this method is the low quality of cleaning and the implementation complexity associated with ensuring the tightness of the annulus patrolsim element, which significantly reduces its effectiveness.

Also known purification method bottom-hole formation zone by creating a depression by forcing air into the tube space and the subsequent suppression of his fluid, the vacuum pressure in the annular space (Allahverdiyev R.A. the stimulation by cyclic voltammetry, pulse effects on the bottomhole formation zone. Petroleum engineering and oil transportation. No. 3. - 1985. - p.10-12).

The disadvantage of this method is the low efficiency of cleaning PZ is, related to the fact that when a rapid discharge pressure in the annular space there has been a rapid evolution of gas from the oil reservoir, which leads to clogging of the pores of the rocks of the PPP.

The closest in technical essence is a way of development of oil wells, including injection of air into the space between tubing and casing, blowing his fluid and the pressure in the annular space, and a pressure relief carried out smoothly with the speed of 2-2,5 MPa/h, and at the end of the reset process produce hydraulic shock on the bottom hole rotating the falling stream of fluid from the tubing fluid, and reservoir presents labiekartosanai rocks (patent No. 1682540 EN, E 21 B 43/25, 1993).

The disadvantage of this method is that during injection of air into the space between tubing (tubing and casing when the presence of the hydrocarbon environment increases explosion and fire hazard.

In addition, in the process of cleaning the well there is a sharp pressure drop in the tubing and the PPP and the emission of air and fluid from the tubing, resulting in a possible emergency situation. An additional disadvantage of this method is the absence of a preliminary stage of purification of the PPP.

The present invention is directed n is the solution of the problem, consisting in the elimination of the danger of an accident and increase the success of the treatment wells.

The technical result, which is realized with the use of this invention is the enhancement of fire and explosion safety and effectiveness of the cleaning layer zones.

This technical result in the implementation of the present invention is achieved by a method of purification of bottom-hole formation zone, including the creation of a facility for pumping and squeezing liquids and gases of the gas cushion pressure of the gas in the annulus, the subsequent pumping and squeezing the liquid from the displacement of fluid from the annulus through the column tubing (tubing) into the container or the barn, the discharge pressure from the annulus to atmospheric and the impact of the hydraulic impact on the bottom hole of the rotating flow of fluid from the tubing at the end of the process vent, as a gas, a mixture of air and exhaust gases in a ratio of not more than 2:3 the formation of a gas cushion pressure, ensuring the avoidance of exposure to gas in the tubing, and the amount of squeezing of the liquid is determined by the formula:

Vmud=0,785· (d

2
1
-d
2
2
)· (Htubing-Hth-HCC)· 10-6,

where d1- inner diameter of the casing, mm;

d2- outer diameter tubing (tubing), mm;

Htubing- depth of descent of the tubing into the well, m;

Hth- the height of the gas cushion in the annular space, m;

Hth=To· Pth,

K - hydrostatic coefficient counter punching liquid and gas (K=100 m/MPa), m/MPa;

Pth- the final pressure of the gas cushion, MPa;

HCC- the height of the annular space required for the critical stock when pushing gas liquid (HCC50 m).

Determination of the amount of squeezing of the liquid is necessary in order to avoid gas in the tubing when cleaning the PPP.

The ratio of air and exhaust gases choose no more than 2:3, by volume, in order to eliminate the ignition of the gas by injecting the mixture into the annular space.

To discharge a mixture of air and exhaust gases in the annulus perform the acid treatment of the PPP. The peculiarity of the acid treatment is that to reduce the speed of response when hydrochloric acid processing bottom-hole formation zone of injection and production wells in Sol the strong acid type surfactants neprinol VVD, repellent TRS. This allows you to align in time the process of chemical exposure and depression purification of the PPP and to eliminate the secondary pollution of the PPP.

The essence of the invention lies in the fact that, as a mixture of air and exhaust gases in the gas cushion annulus using fire - proof mixture in terms of hydrocarbon environment. For this purpose, the mixture of air and exhaust gases of the internal combustion engine is the main element of the installation of the discharge annulus. The ratio of the volumes of air and exhaust gases is taken not more than 2:3, provides the oxygen content in the gas mixture is not more than 8.4% and fire - and explosion protection (Levin A. M. the Principles of rational flaring. Leningrad: Nedra, 1977. - p.30-33).

In addition, decreases the risk of an accident by taking into account the allowable amount of squeezing of the liquid, depending on the parameters of the downhole equipment and the gas cushion.

Figure 1 shows the scheme of implementation of the method; figure 2 is a variant of the block diagram of the device for explosion-proof gas.

Scheme implementation (figure 1 and figure 2) includes a casing 1, pump-compressor pipe 2, the connecting pipe 3, the valve 4-9, pipelines 10-12, installation for pumping a mixture of air and exhaust gases and water 13 connected through pipes 11, 12 and 3, zadig and 5, 6 and 7 with the annular space 14. The installation exit 13 is connected through the cooler 15 of the exhaust gases, the gas flow meter 16 with the inlet of the ejector 17, the second input of which is connected through the valve 18 and the air flow meter 19 with atmospheric air. The output of the ejector 17 is connected with the input set 13, the second input of which is connected through a water meter 20 with a capacity of 21 for water. As installed to discharge a mixture of air and exhaust gases and water 13 in the annular space 14 can be used pumping-ejector, compressor, gas booster installation, for example, self-propelled installation type UNG 8/15, which provide the required parameters of gas-liquid mixture under pressure and performance.

The connecting pipe 3 provided with a pressure gauge 22. Casing 1 is connected with the PPP and the reservoir 23 through the perforations 24. Rotator stream 25 provides rotation of falling on tubing fluid flow for additional purification of slaughter.

The method is implemented as follows. To discharge a mixture of air and exhaust gases in the annular space 14 perform the acid treatment (acid treatment scheme not shown). The peculiarity of the acid treatment is that to reduce the speed of response when means of hydrochloric acid processing bottom-hole formation zone of injection and production is their wells in the acid type surfactants neprinol VVD, (0,4-1,0%), repellent TRS-1 (0,1-0,5%), while the hydrochloric acid concentration to 12.0-of 24.0 wt.% - for 98.5-99.5%pure. This allows you to align in time the process of chemical exposure and depression purification of the PPP and to eliminate the secondary pollution of the PPP.

After acid treatment of the PPP installation 13 in the annular space 14 create a gas cushion of a mixture of air and exhaust gas pressure of 8-10 MPa. The mixture of air and exhaust gases get when turning on the internal combustion engine (not shown) installation 13, the exhaust gases thus pass through the cooler 15, the flow meter 16 and the ejector 17, the latter creates a vacuum causing air to flow through the flow meter 19. Knowing the flow of exhaust gases and the desired ratio of air and gases, with valve 18 specify the allowable air flow. When the ratio of costs of air and gas mixture 2:3 and less than the oxygen content in the mixture does not exceed 8.4% and the mixture is safe for the conditions of ignition of hydrocarbon environment. During injection of a mixture of gases valves 6, 7 and 9 are open, and valves 4, 5 and 8 are closed. Superseded by a mixture of air and exhaust fluid from the annulus 14 through the tubing through the valve 9 serves in the capacity or the barn (not shown). After raising the pressure of the mixture of air and exhaust gases in the annular space 14 to required the second value (for example, up to 10 MPa) valve 6 is closed, and the installation of 13 translated after the opening of the valve 5 at the pump mode, i.e. the injection of fluid into the annulus. The amount of squeezing liquid Vmuddetermined by the proposed formula. So, when Rth=10 MPa, NCC=50 m, d1=130 mm and d2=73 mm, Vmud=8.6 m3. While the valves 4, 6 and 8 are closed, and 5 and 9 are open. The same amount of liquid (namely 8.6 m3) is displaced from the tubing.

Then dump the fluid from the annulus 14 through the pipe 10 into the reservoir (not shown). Valve 7 regulates the speed at which the pressure drop in the range of 2-2 .5 MPa/hour, a pressure Change control pressure gauge 22. In this case, valve 4 is opened and the valves 5, 6, 8 and 9 are closed.

The spout of a mixture of air and exhaust gases is carried out gradually with the speed of the pressure drop in the range of 2-2 .5 MPa/h regulated by the valve 4. This provides a smooth increase of depression on the layer 23 and the pressure drop in the PPP. As air vent hole is filled with the products of pollution, waste chemical reactions and the PPP cleared the reservoir fluid.

After the vacuum annulus to atmospheric pressure produce additional drainage layer 23 and the cleaning of the face: open valve 9 and the liquid column in the tubing 2 falls to the bottom of SLE the new well. Impulse responses resulting from a drop of fluid from the tubing to the bottom, leads to the uncovering of old and formation of new microcracks, the destruction of deposits on the perforation holes 24 of the casing 1 without violating the technical condition of the well. The rotating stream carries away the sludge from the perforations.

Immediately after performing the last operation begin to repeat all operations, i.e. the completion of the second cycle. The cycles repeat 3-4 times. When oil it is directed into the reservoir by opening valve 8. Work stopped when the discharge pressure of the mixture of gases does not exceed 5 MPa.

Example 1. Determination of the amount of squeezing of the liquid.

Source data: depth of descent of the tubing into the borehole Htubing=1600 m, the liquid level in the annulus HW=0 m, the final pressure of the gas cushion Pth=10 MPa hydrostatic coefficient counter punching fluid K=100 m/MPa, the height of the annular space required for the critical stock HCC=50 m, inner diameter of the casing d1=130 mm, outer diameter tubing d2=73 mm height of the gas cushion is equal to Nth=100· 10=1000 meters the Amount of squeezing of the liquid is equal to

Vmud=0,785· (1302-732)· (1600-1000-50)· 10-6=5 m3

Volumes and squeezing of liquids and possible process parameters are shown in table 1.

Table 1

The results of calculations of the amount of squeezing of liquid for different wells
HtubingmPth, MPaHthmHWmVmudm3
1200880003,18
   400-
   600-
 10100001,36
   400-
   600-
160088000for 6.81
    4003,18
   6001,36
 10100005,0
   4001,36
   600-
20008800010,44
   400for 6.81
   6005,0
 10100008,63
   4005,0
    6003,18
Note: In all versions of the calculation of d1=130 mm, d2=73 mm

Example 2. When conducting means of hydrochloric acid treatment of wells in West Siberia, the success rate is, on average, 51%. The success rate of depression treatment in the same conditions, does not exceed 71%. When conducting experimental plots of the joint means of hydrochloric acid and depression treatment according to the claimed method, the success rate increases, on average, up to 80%.

Thus, the preliminary acid treatment, the use of explosive and nonflammable gas mixture under conditions of hydrocarbon environments, pumping into the annulus permissible fluid volume significantly (1.5-2.0 times) to increase the cleaning efficiency of the PPP, to increase by 10-20% success rate of treatments to reduce the risk of accident when implementing method.

1. The method of purification of bottom-hole formation zone, including the creation of a facility for pumping and squeezing liquids and gases of the gas cushion pressure of the gas in the annulus, the subsequent pumping and squeezing the liquid from the displacement of fluid from the annulus through the column tubing (tubing) into the container or a barn, a pressure relief of the annular what about the space to atmospheric and the impact of the hydraulic impact on the bottom hole of the rotating flow of fluid from the tubing at the end of the process pressure relief, characterized in that the gas is used as the mixture of air and exhaust gases in a ratio of not more than 2:3 with the formation of a gas cushion pressure, ensuring the avoidance of exposure to gas in the tubing, and the amount of squeezing of the liquid is determined by the formula

Vmud=0,785(d

2
1
-d
2
2
)(HTubing-Hth-NCC)·10-6,

where d1- inner diameter of the casing, mm;

d2- outer diameter tubing (tubing), mm;

HTubing- depth of descent of the tubing into the well, m;

Hth- the height of the gas cushion in the annular space, m;

Hth=CUth,

K - hydrostatic coefficient counter punching liquid and gas, K=100 m/MPa;

Pth- the final pressure of the gas cushion, MPa;

HCC- the height of the annular space required for the critical stock when pushing gas liquid (HCC≥50 m).

2. The method according to claim 1, characterized in that use exhaust installation for pumping and squeezing the liquid.

3. The method according to claim 1, otlichuy is the, as to discharge the mixture of air and exhaust gases in the annulus perform the acid treatment of bottom-hole formation zone.



 

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