RU2485302C1 - Stimulation method of formation fluid influx from well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: stimulation method of formation fluid influx from a well involves lowering to the well of a tubing string, reduction of counter pressure on a productive formation due to replacement of a fluid column in the well with liquid-gas mixture (LGM) at observance of the required value of depression on the productive formation. Prior to lowering to the well of the tubing string, the latter is equipped in an upward direction with a remote subsurface pressure gauge installed in a plugged container, a filter and a packer. The tubing string is lowered to the well so that the filter can be arranged opposite the formation bottom. The packer is put 5-10 m above the formation roof. Treatment of the bottom-hole zone of the formation is performed by pumping via the tubing string of a hydrocarbon solvent and by its forcing into the formation with process liquid. Process exposure for reaction is performed. At that, during process exposure for 1.5-2 hours, there unpacked is the packer, and in 3-4 cycles in every 0.5 hour, process liquid in the volume of 0.5-0.8 m³ is pumped in turn to the tubing string and to the inter-string space of the well. The packer is put again upon completion of process exposure. Into inner space of the tubing string there lowered is a string of flexible tubes (FT) so that its lower end is on the liquid level in the well. After that, the space on the wellhead is sealed between the tubing string and the string of flexible tubes. Then, with stops in every 200-300 m there lowered is a string of flexible tubes into the tubing string until lower end of the string of flexible tubes reaches the filter. Replacement of well fluid with LGM is performed in inner space of the tubing string during stops and during lowering process of FT in equal LGM volumes.

EFFECT: increasing efficiency and quality of simulation of formation fluid influx from productive formation, reducing LGM pumping volumes and intensity of LGM absorption with the productive formation.

3 dwg

Description

The invention relates to the oil industry and can be used in the development of production wells.

A known method of well development by creating a depression on the formation (patent RU No. 2272897, IPC E21B 43/18; 43/27, publ. 03/27/2006, in bull. No. 9), including replacing the fluid filling the well with a solution of surface-active (surfactant), followed by aerating by feeding it into the well as blowing agent ammonium carbonate, wherein prior to feeding the bottom zone of gas-forming substance is subjected to an acid treatment with an acid prodavkoy into the formation, as blowing agents, additional reagents are used aqueous solutions of sodium nitrate NaNO ₂ hydrochloric acid HCl, aqueous solutions of reagents blowing agents is injected in portions of 0.5-2.0 m ³ in the following sequence: ammonium carbonate, hydrochloric acid, sodium nitrite, each subsequent solution has a density greater than the previous amount of injected reagent is 0.3-1.0 well volume, but not less than 1.1 of the internal volume of the pressure column and is determined by the useful volume of the well, and the surfactant solution additionally contains hollow glass microspheres.

The disadvantage of this method is that the aeration of the surfactant solution occurs directly in the well by supplying gas-forming substances to the bottomhole zone of the well, while the sequence of chemical reactions and the temperature regime can change, which can lead to a change in the physical and chemical properties of the replacement fluid, including and decomposition of carbonated liquid into gas and water, which generally reduces the quality of well development.

Also known is a method of inducing formation fluid inflow from a well (N. A. Sidorov. Drilling and operation of oil and gas wells. - M .: Nedra, 1982, pp. 270-271), which includes reducing pressure on the producing formation by supplying it with the surface of the gas or gas-liquid mixture and replacing the column of liquid in the well with a gas-liquid mixture, while the gas is supplied by a compressor.

The disadvantages of this method are:

- firstly, the need for a compressor - a source of high-pressure neutral explosive gas;

- secondly, the compressor cannot push the entire column of fluid in the well, so you have to master it in stages, which delays the process of causing the flow of formation fluid from the well.

The closest in technical essence is the method of causing the flow of formation fluid from the well (patent RU No. 2263206, IPC E21B 43/25, publ. 10/27/2005, bull. No. 30), which includes reducing the pressure on the reservoir by replacing the liquid column in the well gas-oil mixture by supplying the mixture with a booster unit with the selection of the components of the mixture from a working well or from the collector of production, while the required ratio of the components of the mixture to achieve a given value of pressure reduction on the reservoir provide selection composition yayuschih mixture through the separator, the outputs of which are communicated to the collector of product collection.

The disadvantages of this method are:

- firstly, the low efficiency of the inflow from the well formation caused by the unstable state of the gas-oil (gas-liquid) mixture, while it is possible for the gas-liquid mixture or its components to be absorbed by the productive layer in the process of replacing the liquid in the well with a gas-liquid mixture and, as a result, a decrease in the natural permeability (reservoir properties) of the reservoir;

- secondly, it is almost impossible to choose the required ratio of the components of the gas-liquid mixture to achieve a given depression on the reservoir;

- thirdly, the low quality of the inflow call, due to the rapid decrease in the flow rate or the failure to achieve the specified flow rate of the well when calling the flow of formation fluid from the well;

- fourthly, the replacement of the liquid column must be carried out in the volume of the entire well, and this requires a large volume of an aqueous solution of a surfactant, which entails additional costs for the preparation of a gas-liquid mixture, its injection into the well, all this increases the duration of the technological process for causing the flow of formation fluid from wells.

The technical objectives of the invention are to increase the efficiency and quality of the flow of formation fluid from a well, reduce the injection volume of a gas-liquid mixture to replace a column of fluid in a well, and reduce the rate of absorption of a gas-liquid mixture by a productive formation while controlling the bottomhole pressure during the process of inducing formation fluid flow from a well.

The stated technical problem is solved by the method of inducing formation fluid inflow from the well, including lowering tubing tubing string into the well, reducing back pressure on the producing formation by replacing the column of liquid in the well with a gas-liquid mixture while observing the required depression value on the producing formation.

New is that the tubing string before lowering into the well from bottom to top is equipped with a remote depth gauge installed in the plugged container, a filter, a packer, the tubing string is lowered into the well so that the filter is located opposite the bottom of the formation, the packer is planted for 5-10 m above the top of the formation, the bottom-hole zone of the formation is treated by pumping a hydrocarbon solvent through the tubing string and pumping it into the formation with process fluid, carry out a technological exposure to the reaction, during which During 1.5-2 hours, the packer is unpacked and, after 3-4 hours every 0.5 hours, the technological fluid is pumped into the pipe string and the annulus of the well in a volume of 0.5-0.8 m ³ , at the end of the technological the shutter again sets the packer, the GT flexible pipe string is lowered into the interior of the tubing string so that its lower end is at the level of the fluid in the well, after which the space between the tubing string and the tubing string is sealed at the mouth, then they are allowed to stop every 200-300 m GT column in tubing to those x until the lower end of the GT column reaches the filter, at the same time, the well fluid is replaced with a gas-liquid mixture in the inner space of the tubing during shutdowns during the lowering of the GT with equal volumes of the gas-liquid mixture, after which the flow of the formation fluid is called up by supplying the gas-liquid mixture into the inner space GT with a gradual decrease in the density of the injected gas-liquid mixture until the desired depression on the formation is reached, controlled by the readings of the remote depth gauge, at the end SRI call process from the well inflow recovered HT column from the interior of the tubing string, is lowered into the well and start production equipment in the wellbore operation.

Figure 1 and 2 shows a diagram of the processing of the bottomhole formation zone by a chemical method.

Figure 3 shows a diagram of a call inflow of reservoir fluid from the well.

The proposed method is as follows.

It is known that during well operation, there is a decrease in the flow of formation fluid to the bottom of the producing well due to a deterioration in the permeability of the bottom-hole formation zone (BHP), and therefore there is a need to restore the flow of formation fluid to the bottom of the producing well. To do this, stop the production well 1 (see Fig. 1), remove production equipment, for example, a pipe string with an electric centrifugal pump (not shown in Figs. 1 and 2). Before lowering the tubing string 2, a remote depth gauge 3 is installed sequentially from the bottom up to its bottom end in a plugged container (not shown in FIG. 1), and then a filter 4 (see FIG. 1) and a packer 5. The pump string is lowered into the well 1 -compressor pipes (tubing) 2 with the above arrangement so that packer 5 is 5-10 m above the top of formation 6. Packer 5 is planted in well 1, i.e. the annular space 5 ′ of the well 1 is sealed, while the filter 4 should be located opposite the sole (not shown in FIGS. 1, 2, 3) of the formation 6 (see FIG. 1).

As a packer 5, any known pass-through packer can be used, for example, manufactured by the Packer research and production company (Oktyabrsky, Republic of Bashkortostan), with a mechanical axial installation of the corresponding standard size of the PRO-YamO brand. Using a packer allows you to cut off the annular space 5 ′ of well 1 and reduce the volume of foam injection to replace the liquid column and, as a result, reduce the duration of the process to cause the flow of formation fluid from the well.

Then, the bottom-hole zone 7 is treated (see FIGS. 1 and 2) of the formation 6, for example, with a hydrocarbon solvent to remove paraffin-resinous deposits.

To do this, at the wellhead 1 (see FIG. 2), the injection line 8 of the pump unit 9 (for example, CA-320) is connected with the inner space 10 of the tubing string 2. Next, using the pump unit 9, the pumping unit is pumped through the inner space 10 of the tubing string 2 into the tubing string 2 of the hydrocarbon solvent and pumping it through the filter 4 into the bottomhole zone 7 of the formation 6 using a process fluid, for example waste water, with a density of 1100 kg / m ³ with the creation of a "bath" of hydrocarbon solvent in the well 1 opposite to the formation 6 so that carbohydrate level native solvent in the well was above the roof (1, 2, 3, not shown) layer 6 (see FIG. 2), such as 5-10 m.

Carry out a technological exposure to the reaction for 1.5-2 hours, during which the packer 5 is unpacked and, when the packer 5 is unpacked, in 3-4 cycles every 0.5 hours, alternately into the pipe string 2 and into the annular space 5 ′ of the well 1, they are pumped technological fluid, for example waste water, with a density of 1100 kg / m ³ , in a volume of 0.5-0.8 m ³ . Thus, rinse is performed in the bottom-hole zone 7 of the formation 6, which leads to leaching of the paraffin-resinous deposits dissolved by the hydrocarbon solvent from the bottom-hole zone 7 of the formation 6 into the wellbore 1.

At the end of the technological exposure, the packer 5 is again planted in the well 1.

Then dismantle the discharge line 8 and the pump unit 9.

Then, the ground equipment is strapped as shown in Fig. 3, for this, the inner space 10 of the tubing string 2 is connected to the trough 11 at the wellhead 1 by means of an annular valve 12 and a flow line 13, while the readings of the remote depth gauge 3 correspond to the reservoir pressure .

At the end of the technological endurance (reaction time, for example, 12 hours), a string of flexible pipes (HT) 14, for example, 38 mm in diameter, placed on a drum (1, 2 and 3 is not shown) is lowered into the inner space 10 of the tubing string 2; coiled tubing installation 15 (see figure 3).

The use of GT 14 prevents the absorption of a gas-liquid mixture by the reservoir, as a result of which the preservation of its natural permeability (reservoir properties) of the reservoir is achieved.

GT column 14, i.e. the lower end 14 ′ is lowered to the liquid level (static level) in the tubing string 2. The static level depends on the bottomhole pressure of the wells, is individual for each well, determined by geophysical studies (leveling) and provided in advance before the implementation of the proposed method for planning process parameters . Those. a string of flexible pipes GT 14 is lowered into the inner space of the tubing string 2 so that its lower end 14 ′ is at the liquid level in the well 1, for example, in the range of 850 m.

Next, at the wellhead 1, the GT string 14 is connected to the injection line 17 of the booster unit 18 through the discharge valve 16, for example, a gas booster system of the UNG 8/15 brand is used. The space between the columns (not shown in Figs. 1, 2 and 3) is sealed at the mouth of the tubing 2 (see Fig. 3) and GT 14.

At the wellhead 1, a gas-liquid mixture is prepared, which is an aqueous solution with a surfactant, which is used as a foaming agent.

The required volume of an aqueous surfactant solution for inducing the formation fluid inflow from the well is calculated based on the multiplicity of the gas-liquid mixture, which is 3.5-5 in the process of invoking the formation fluid inflow from the well, as well as from the required volume of the gas-liquid mixture V _g , consisting of two volumes the inner space of 10 tubing 2, namely:

where V is the volume of the inner space 10 of the tubing string 2;

V _g - the required volume of the gas-liquid mixture.

For example, when the height of the liquid column from the reservoir to the mouth is H = 1800 m and the diameter of the tubing string 2 is d = 73 × 5.5 mm, the volume of the inner space 10 of the tubing string 2 is determined by the formula:

where V is the inner space of the tubing string, m ³ ;

N is the height of the liquid column from the mouth to the bottom, m, for example, N = 1800 m;

d _in - the inner diameter of the tubing string, m

The inner diameter of the tubing string is determined by:

where d _n is the outer diameter of the tubing string, m;

δ - column wall thickness, m

For a tubing string with an outer diameter of 73 mm = 0.073 m with a wall thickness of 5.5 mm = 0.0055 m, the inner diameter is determined by substituting in the formula (3):

d _in = 0.073 m - (2 · 0.0055) m = 0.062 m.

When the multiplicity of the gas-liquid mixture is 4, the volume of the aqueous surfactant solution is determined by the formula:

where V _in - the volume of an aqueous solution of a surfactant, m ³ ;

V _g - the required volume of the gas-liquid mixture, m ³ .

Then substituting the formula (2): V = (3,14 · ( 0,062) ^2/4) * 1800m = 5.43 m ^3, and substituting into formula (1) the desired amount of liquid mixture: V _g = 2 · V = 2 · 5.43 m ³ = 10.86 m ³ .

Substituting values into the formula (4), we obtain: V = _a 2 · V _r / 4 = 10.86 m 2 · ^3/4 = 5.43 m ^3, the volume take aqueous surfactant solution equal to 5.5 m ^3.

To increase the stability of the gas-liquid mixture, a stabilizer is added to the aqueous surfactant solution - a 1% solution of CMC-700 with the addition of 2% KCl. CMC-700 is a sodium salt of cellulose ether and glycolic acid - a polymer from MI Drilling Fluids (USA). Practical experiments have shown that the stability of the foam with the addition of a stabilizer increases 5-9 times. In fresh water ρ = 1000 kg / m ³ , a stabilizer is added with constant stirring (it is desirable to heat the water to 40-45 ° C), the process of complete dissolution takes 2.0-2.5 hours; 2% KCl in dry form is added to the prepared stabilizer solution with stirring, and after complete dissolution, the calculated volume of the required surfactant is added, mixed for 20-30 minutes.

As surfactants used, for example, sulfanol (according to TU 6-01-862-73) in a volume concentration of 0.1-0.3% of the volume of fresh water or other surfactants, for example, OP-7, OP-10 (according to TU 8433-81) in a volume concentration of 0.3-0.6% of the volume of fresh water.

Fill the tank 19 (see figure 3) of the booster unit 18 with an aqueous solution of a surfactant (see figure 3). As a gas that is safe under ignition conditions of a hydrocarbon medium, gas (for example, nitrogen) generated by the gas generator 20 of the booster unit 18 is used, as a result of the combustion of fuel (e.g. gasoline, diesel fuel) in compressed air, i.e. burnout of oxygen. Gas from the gas generator 20 is supplied to the booster (mixing) device 21, where the gas is continuously mixed with the process liquid in the form of an aqueous surfactant solution (with the formation of a gas-liquid mixture), while the aqueous surfactant solution is supplied with a constant flow rate, for example 3 l / s, by a pump 22 from the tank 19 of the booster unit 18.

Then, starting from the liquid level (850 m) in well 1, with stops, every 200-300 m, the GT 14 column is let into the tubing string 2 until the lower end 14 ′ of the GT 14 column reaches filter 4, while the gas-liquid mixture is injected in the inner space 10 tubing 2 in order to replace the borehole fluid produced only during stops during the launch of GT 14 equal volumes of gas-liquid mixture of the total volume V _g = 10.86 m ³ . For example, the replacement of the borehole fluid in the inner space 10 of the tubing string 2 with a gas-liquid mixture is performed in 4 intervals, i.e. in the intervals of 1050, 1300, 1550 and 1800 m, i.e. until reaching the lower end 14 ′ GT 14 of the filter 4 of the tubing string 2.

Thus, each of the slots 1050, 1300, 1550 and 1800 m is pumped by V _d = 10.86 m ^3/4 = 2.715 m ³ of the gas-liquid mixture and thus replace the wellbore fluid carried in the interior of space that the tubing 10 at the gas-liquid mixture 2 .

To do this, open the annular 12 and discharge 16 valves and through the discharge line 17 the booster unit 18 serves a gas-liquid mixture (of higher density and, accordingly, with a minimum degree of aeration of 5-10 m ³ / m ³ ) into the GT column 14. Through the GT 14 column, the gas-liquid mixture is pumped into the inner space 10 of the tubing string 2 to replace a well fluid having, for example, a density of 1100 kg / m ³ , with a gas-liquid mixture, for example, a density of 700 kg / m ³ . At a certain point, the displaced gas-liquid mixture in the well 1 reaches the wellhead 1 and from the inner space 10 of the tubing string 2 through the annular valve 12 and the discharge line 13 into the groove tank 11, the outflow of the well liquid displaced by the gas-liquid mixture begins.

Thus, in each of the above intervals, the fluid in the borehole is replaced in the inner space 10 of the tubing string 2 with a gas-liquid mixture until the lower end 14 ′ of the GT 14 string reaches filter 4 of the tubing string 2, while not exceeding the maximum allowable the pressure developed by the booster unit 18 (see figure 2), for example, 15 MPa. As the GT 14 column is lowered into the tubing string 2 and pumped into the gas-liquid mixture with equal volumes (2.715 m ³ each) through the GT 14 column into the inner space 10 of the tubing string 2, the liquid in it is replaced by a gas-liquid mixture of the above density in volume well 1 (V ₁ = 5.43 m ³ ), while tracking the readings of a remote depth gauge 3, the value of which is gradually decreasing. When the lower end 14 ′ of the GT 14 column reaches the filter 4 of the tubing string 2, the lowering of the GT 14 column is stopped.

Under such conditions, the minimum amount of gas-liquid mixture penetrates into the bottom-hole zone of formation 6, and the component composition of the gas-liquid mixture allows to reduce the intensity of its absorption by the productive formation or completely prevent absorption, thereby preserving the natural permeability (reservoir properties).

Then cause the influx of formation fluid from the well by feeding a gas-liquid mixture into the inner space 10 of the tubing string 2, gradually reducing the density of the gas-liquid mixture by gradually increasing the degree of aeration from 5-10 m ³ / m ³ to 120-160 m ³ / m ³ . Those. increase the supply of gas produced by the gas generator 20 to the booster device 21 of the booster unit 18, at a constant flow rate of an aqueous surfactant solution, for example 3 l / s, supplied by the pump 22 from the tank 19 of the booster unit 18. In this case, the circulation of the gas-liquid mixture is continued by pumping the booster unit 18 through the discharge line 17, the GT string 14, the inner space 10 of the tubing string 2 and its output from there through the flow line 13 with the open valve 12, into the groove tank 11 until the desired depression is reached (pressure reduction reservoir 6) by increasing the degree of aeration and, accordingly, reducing the density of the gas-liquid mixture. Thus, the gas-liquid mixture is circulated until the volume of V _{g is used up} , while the changes in the readings of the deep remote pressure gauge 3 are monitored.

For example, the initial bottomhole pressure is 9 MPa, and the value of the required depression (pressure reduction) on the reservoir 10 is P = 4 MPa (the set value for pressure reduction is determined by the geological service of the oil and gas company individually for each well, depending on the strength of the cement ring behind the casing and other factors (see Bulatov A.I. Well development [Text]: reference, allowance / A.I. Bulatov, Yu.D. Kagmar, P.P. Makarenko: edited by R. Yaremiichuk - M .: Nedra-Business LLC, 1999. - 473 p.).

Then the readings of the remote depth gauge 3 should not be lower than 9 MPa - 4 MPa = 5 MPa. Thus, gradually increasing the degree of fluid aeration (by increasing the volume of gas supplied by the gas generator 22 of the booster unit 18), depending on the change in the reservoir pressure, we achieve an acceptable depression on the reservoir 6. The presence of inflow from the reservoir 6 is determined visually by the volumetric output of the reservoir fluid from the well into the trough 11 together with the gas-liquid mixture. If there is a sufficient amount of formation fluid inflow from the well (determined by the geological service of the oil and gas company individually for each well, depending on the previous production rate during the operation of the well), the formation fluid inflow is stopped.

GT 14 is lifted from the inner space 10 of the tubing string 2. The production equipment is lowered into the well 1 and put into operation.

The proposed method allows to increase the efficiency and quality of the flow of formation fluid from the reservoir, to reduce the injection volume of the gas-liquid mixture to replace the column of fluid in the well, and to reduce the rate of absorption of the gas-liquid mixture by the reservoir by controlling the change in bottomhole pressure during the flow of the reservoir fluid from the well .

Claims (1)

A method of inducing formation fluid inflow from a well, including lowering tubing tubing string into the well, reducing backpressure to the reservoir by replacing the liquid column in the borehole with a gas-liquid mixture while observing the required amount of depression by the reservoir, characterized in that the tubing string before lowering from the bottom up, they are equipped with a remote depth gauge installed in the plugged container, a filter, a packer, the tubing string is lowered into the well so that the filter is placed on Having ousted the bottom of the formation, the packer is planted 5-10 m above the roof of the formation, the bottom-hole zone of the formation is treated by pumping a hydrocarbon solvent through the tubing string and pumping it into the formation with process fluid, carry out technological exposure to the reaction, while during technological exposure for 1 , 5-2 h raspakerovyvayut packer and 3-4 cycle every 0.5 hours alternately in the pipe string and the borehole of annular space of the process liquid is injected in a volume of 0.5-0.8 m ^3, at the end of the process extracts a packer is planted, a column of flexible tubing GT is lowered into the interior of the tubing string so that its lower end is at the level of the fluid in the well, after which the space between the tubing string and tubing is sealed at the mouth, then the string is stopped every 200-300 m HT in the tubing until the lower end of the HT string reaches the filter, while replacing the wellbore fluid with a gas-liquid mixture in the inner space of the tubing during stops during the descent of the GT with equal volumes of gas-liquid mixture, p After that, the challenge is to start the influx of formation fluid by supplying a gas-liquid mixture into the internal space of the gas turbine with a gradual decrease in the density of the injected gas-liquid mixture until the desired depression is achieved on the formation, controlled by the readings of the remote depth gauge; , lower operational equipment into the well and start the well into operation.

Images