RU2551038C2 - Method of tightness testing of injection well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, namely to method of tightness testing of the cased injection well. Methods includes: determination of actual pressure difference on the packer ΔC_{p_a}=P_wh1-P_fr-C_wh2+C_fr2-P_err1-P_err2, where P_wh1 and P_wh2 are measured wellhed pressure on injection to top and bottom reservoirs, respectively, C_fr1 and P_fr2 are pressure losses for friction during water movement via short and long strings. respectively, P_err1 and P_err2 are absolute errors of measurements by technical pressure gauge in short and long strings, respectively, atm. At that criterion of the tightness estimation is the pre-specified critical pressure difference ΔC_{d_cr}. System tightness is estimated by comparison of the actual pressure difference on packer ΔC_{p_a} and pre-specified critical pressure difference at |ΔC_{p_a}|>|ΔC_{d_cr}| the system is tight. Method of the tightness testing of the injection well contains stages at which: pressure change is registered in well blocked by the packer, by wellhead pressure measuring at input to tubing string in top and bottom reservoirs, respectively. Data analysis is performed, and tightness is determined. At that preliminary current water flowrate via pipeline is measured Q. Tightness is estimated if the following condition is met: $$\frac{\Delta C_{w\_c}}{\Delta C_{w\_a}}\ge {\left(\frac{Q_c}{Q_a}\right)}^2,$$

where ΔC_{w_c} and Q_c are measured current wellhead pressure difference and current water flowrate, respectively; ΔP_{w_a} and Q_a are actual measured current wellhead pressure difference and current water flowrate, respectively. If the condition is met the well is tight.

EFFECT: decreased number of tightness tests in wells operated under process of simultaneous-separate injection.

16 cl, 2 tbl, 2 dwg

Description

The invention relates to the oil and gas industry and may find application in monitoring the tightness of cased injection wells equipped with a tubing string and a packer.

A known method of testing the tightness of the production casing of an injection well (RF patent No. 2225506, IPC ЕВВ 47/00, published March 10, 2004), which includes lowering the packer into the well on a cable-rope that is brought into use by an electric motor, shutting off the wellbore packer, creating pressure above the packer by injecting fluid into the well, recording pressure changes simultaneously above and below the packer using pressure gauges, according to the conformity or inconsistency of the changes in the indicators of which indicate leakage and a packer or production string, and raising the packer to a surface, characterized in that the packer is lowered to a predetermined depth through the tubing space of the tubing and when the production string is tight, only the packer is raised to the surface, and if the production string is leaking, the pump compressor pipes.

A known method of monitoring the tightness of the production casing of the injection well (RF patent No. 2214508, IPC ЕВВ 47/00, ЕВВ 17/00, publ. 10/20/2003), including changing the operating mode of the well and fixing the change in pressure at the wellhead, while changing the operating mode wells, the flow rate of the working fluid is reduced to 70-50% of the initial one, and the pressure change is fixed in the time interval from the moment the well operating mode changes, during which the maximum rate of pressure drop is observed until it stabilizes, after which it is determined yayut pressure drop coefficient K1 from the relation curve: Κ1 = ΔΡ1 / Δt1, where ΔΡ1 - pressure change in the time interval Δt1 from the time change of the well operation, during which there is the maximum rate of pressure drop to its stabilization, MPa; Δt1 is the time during which a change in pressure was recorded, min; and similarly determine the coefficient K2 of the pressure drop curve with a frequency of at least once a year, while the production casing is not tight if K2> K1, provided that after determining K1 in this well there has been no work to increase the permeability of the formation, characterized in that the flow rate of the working fluid is reduced to 30-49% and 71-80% of the original.

где ΔP1 - изменение давления в промежутке времени от начала максимального темпа падения до его стабилизации, МПа; Δt1 - время, в течение которого фиксировалось изменение давления, мин, и аналогично определяют коэффициент K2 кривой падения давления частотой не менее чем один раз в год, при этом, если K2≈K1, то эксплуатационная колонна герметична, и она не герметична, если K2>K1, при условии, что после определения K1 в этой скважине не проводились работы по увеличению проницаемости пласта.A known method of monitoring the tightness of the production casing of an injection well (RF patent No. 2165016, IPC ЕВВ 47/00, publ. 04/10/2001), including changing the mode of operation of the well and fixing the change in pressure at the wellhead, characterized in that the change in the mode of operation of the well is carried out under cover valves at the wellhead with a decrease in the flow rate of the working fluid by 30-50% of the initial one, and the pressure change is fixed in the time interval from the moment of changing the well operating mode, during which max the actual rate of pressure drop, until it stabilizes, after which the coefficient of pressure drop is determined from the ratio $$K_{\mathrm{one}}=\frac{\Delta P_{\mathrm{one}}}{\Delta t_{\mathrm{one}}},$$

where ΔP1 is the change in pressure in the time interval from the beginning of the maximum rate of fall to its stabilization, MPa; Δt1 is the time during which the change in pressure was recorded, min, and similarly determine the coefficient K2 of the pressure drop curve with a frequency of at least once a year, while if K2≈K1, the production casing is tight and not tight if K2 > K1, provided that after determining K1 in this well, no work was done to increase the permeability of the formation.

A known method of monitoring the tightness of an injection well (RF patent No. 2246613. IPC ЕВВ 47/00, published on 02.20.2005), which is closest in technical essence and adopted as a prototype, includes shutting down a well, recording pressure changes in the annulus blocked by a packer, and the borehole space and determining the tightness of the annular space, characterized in that when registering changes in pressure in the borehole, pressure is measured at the mouth at the inlet of the tubing string, The pressure is measured by comparing the pressures before and after stopping the well at the rate of pressure drop at the wellhead and in the annulus after stopping the working well and comparing the pressures before and after starting the well for injection by the rate of increase in pressure at the wellhead and in the annulus after starting the well under injection, while determining the tightness of the annular space for the criterion for assessing the tightness of the annular space take the estimated value of the flow rate of the fluid entering or leaving m annulus of the well.

The task of the invention is the ability to accurately detect the presence or absence of tightness at the mouth of the injection well.

The technical result achieved by using the claimed invention is to reduce the number of studies on the tightness of the "tubing-packer" system in wells operated by technology ORZ (simultaneous and separate injection).

The invention reduces the risk of failure of the ground equipment of wells under fresh water injection due to freezing during research in the winter.

The technical result is achieved by the fact that in a method for monitoring the tightness of an injection well, which includes the steps of: recording a change in pressure in the well space blocked by the packer by measuring pressure at the mouth at the inlet of the tubing string in the upper and lower layers accordingly, they analyze the data obtained and determine the tightness, new is that the analysis of the data is carried out as follows: determine the actual pressure drop across the packer $$\Delta P_{P\_f}\text{A.}:$$

ΔΡ _{p_f} = P _y1 -P _mp1 -Ρ _y2 + Ρ _mp2 -P _pog1 -P _pog2 ,

where P _y1 and P _y2 - measured wellhead injection pressure into the upper and lower reservoirs, respectively, atm,

P _Tr1 and P _Tr2 - pressure loss due to friction during the movement of water along short and long columns, respectively, atm,

P _pogr1 and P _pogr2 - the values of the absolute measurement error with a technical manometer, atm,

at the same time, a predetermined critical value of pressure drop is taken as a criterion for assessing tightness $$\Delta P_{P\_\mathrm{to}R},$$

и заранее заданную критическую величину перепада давления, при $$\left|\Delta P_{п\_ф}\right|\le \left|\Delta P_{п\_кр}\right|$$

- скважина герметична.tightness is judged by comparing the actual pressure drop across the packer $$\Delta P_{P\_f}$$

and a predetermined critical pressure drop, at $$\left|\Delta P_{P\_f}\right|\le \left|\Delta P_{P\_\mathrm{to}R}\right|$$

- the well is tight.

Preset critical pressure drop $$\Delta P_{P\_\mathrm{to}R}=\mathrm{twenty}\mathrm{but}tm.$$

равен перепаду давления на штуцере, установленном на одной из линий нагнетания, если штуцеры установлены на обеих линиях - то разнице перепадов давления на штуцерах.Packer differential pressure $$\Delta P_{P\_f}$$

equal to the pressure drop across the nozzle installed on one of the discharge lines, if the nozzles are installed on both lines, then the difference in pressure drops across the nozzles.

The change in pressure drop is proportional to the square of the change in fluid flow through it.

The values of the absolute errors P _pog1 and P _{pog2 of} the measurement results determine:

P _pogr1 VPI = ₁ * RT ₁ / 100th - manometer, which is measured in a pressure discharge line,

P _pogr2 VPI = ₂ * CT _2/100 - gauge, which pressure is measured in another discharge line,

where VPI ₁ , VPI ₂ - the upper limits of measurement; CT ₁ , CT ₂ - accuracy classes.

The technical result is also achieved by the fact that in a method for monitoring the tightness of an injection well, comprising the steps of: recording a change in pressure in the well space blocked by the packer by measuring pressure at the mouth at the inlet to the tubing string in the upper and lower layers, respectively, analyze the data and determine the tightness, new is that the pre-current is measured for water conduit water flow Q _m, of tightness is judged if the following condition tions:

и Q_т - соответственно замеренные текущий устьевой перепад давления и текущий расход воды по водоводу, $$\Delta P_{у\_n}$$

и Q_n - соответственно фактический перепад давления и общий расход воды по водоводу, если условие выполняется, скважина герметична.Where $$\Delta P_{\mathrm{at}\_t}$$

and Q _t - respectively measured current wellhead pressure drop and current water flow through the water conduit, $$\Delta P_{\mathrm{at}\_n}$$

and Q _n - respectively, the actual pressure drop and the total water flow through the water pipe, if the condition is met, the well is tight.

The pressure at the wellhead is measured once a month when measuring the injectivity of the well.

Analysis of the information obtained is carried out periodically at least once a month.

на входе в колонну насосно-компрессорных труб (НКТ) в верхнем и нижнем пластах соответственно, проводят анализ полученных данных и определяют герметичность, новым является то, что анализ полученных данных проводят следующим образом:The technical result is also achieved by the fact that in a method for monitoring the tightness of an injection well, which includes the steps of: recording a change in pressure in the well space covered by the packer by measuring the pressure drop across the wellhead $$\Delta P_{\mathrm{at}\_f}$$

at the entrance to the string of tubing in the upper and lower layers, respectively, analyze the data and determine the tightness, new is that the analysis of the data is carried out as follows:

determine the estimated pressure drop across the mouth $$\Delta P_{\mathrm{at}\_R}:$$

ΔΡ _{y_p} = P _y1 -Ρ _y2 = ΔP _p - (Ρ _hydr1 -Ρ _mp1 ) + (Ρ _hydr2 -Ρ _mp2 ) + P _pog1 + P _pog2 ,

ΔΡ _y1 = P ₁ -Ρ _hydr1 + Ρ _mp1

ΔΡ _y2 = P ₂ -Ρ _hydr2 + Ρ _mp2

where P ₁ , P ₂ - pressure at points above the packer and under the packer, respectively, atm;

P _hydr1 and P _hydr2 - hydrostatic pressure of the liquid column in the short tubing string and long, respectively, atm,

P _Tr1 and P _Tr2 - pressure loss due to friction during the movement of water along short and long columns, respectively, atm,

ΔΡ _p - the pressure drop across the packer, atm,

и фактическую (замеренную) $$\Delta P_{у\_ф},$$

при $$\left|\Delta P_{у\_ф}\right|\ge \left|\Delta P_{у\_р}\right|$$

- система герметична. При закачке в разделенные пласты воды с одного водовода (одинаковой плотности) перепад давления на устье принимает вид:tightness is judged by comparing the estimated value of the pressure drop across the mouth $$\Delta P_{\mathrm{at}\_R}$$

and actual (measured) $$\Delta P_{\mathrm{at}\_f},$$

at $$\left|\Delta P_{\mathrm{at}\_f}\right|\ge \left|\Delta P_{\mathrm{at}\_R}\right|$$

- the system is tight. When water is pumped into separated layers from one conduit (of the same density), the pressure drop across the mouth takes the form:

ΔΡ _y = P _y1 -Ρ _y2 = ΔP _n + Ρ _mp1 -Ρ _mp2 + P _pog1 + P _pog2 ,

where P _y1 and P _y2 - measured wellhead injection pressure into the upper and lower reservoirs, respectively, atm,

ΔP _p - the pressure drop across the packer, atm,

P _TP1 and P _TP2 - pressure loss due to friction during the movement of water along short and long columns, respectively, atm,

P _pog1 and Ρ _pog2 - the absolute error of measurements with a technical manometer for short and long columns, respectively, atm.

The values of the absolute errors Ρ _pog1 and P _{pog2 of} the measurement results are _determined :

_Pogr1 ΒΠI P = ₁ * ΚΤ _1/100 - manometer, which is measured in a pressure discharge line,

P _pogr2 VPI = ₂ * CT _2/100 - gauge, which pressure is measured in another discharge line,

where VPI ₁ , VPI ₂ - the upper limits of measurement; CT ₁ , CT ₂ accuracy classes.

The pressure at the wellhead is measured once a month when measuring the injectivity of the well.

Analysis of the information obtained is carried out periodically at least once a month.

The invention is illustrated by drawings.

In FIG. 1 shows a layout diagram of underground equipment for ARI.

In FIG. Figure 2 shows a graph of the system's leak test.

The essence of the invention is to control the difference in bottom-hole pressures (differential pressure on the packer) and accept the condition that, while providing a certain differential pressure (critical value), the system is tight. A sharp drop in the drop below the critical is a signal of a loss of system tightness.

The pressure drop across the packer can be determined as follows:

ΔΡ _p = (P _y1 + Ρ _hydr1 -Ρ _mp1 ) - (P _y2 + Ρ _hydr2 -Ρ _mp2 ) -P _pog1 -P _pog2 , (1)

where ΔΡ _p is the pressure drop across the packer, atm;

Ρ _у1 and Р _у2 - measured wellhead injection pressure, respectively, in the upper layer and lower, atm;

P _hydr1 and P _hydr2 are the hydrostatic pressure of the liquid column, respectively, in the short tubing string and long, atm,

where ρ is the density of the injected water, kg / m ³ ;

g is the acceleration of gravity equal to 9.81 m / s ² ;

h - packer installation depth (middle of the packer), m;

P _Tr1 and P _Tr2 pressure loss due to friction during the movement of water, respectively, along a short column and a long, atm;

P _pogr1 and P _pogr2 - values of the absolute measurement error with a technical pressure gauge, atm.

The pressure drop across the mouth (3) is determined by setting the pressure drop across the packer (ΔΡ _p ):

ΔΡ _y = P _y1 -Ρ _y2 = ΔP _p - (Ρ _hydr1 -Ρ _mp1 ) + (Ρ _hydr2 -Ρ _mp2 ) + P _bur1 + P _bur2 , (3)

ΔΡ _y1 = P ₁ -Ρ _hydr1 + Ρ _mp1

ΔΡ _y2 = P ₂ -Ρ _hydr2 + Ρ _mp2

where P ₁ is the pressure at a point above the packer, P ₂ is the pressure at a point below the packer.

This dependence is graphically presented on the layout of underground equipment for ARI (Fig. 1).

- система герметична (ΔΡ_{у_ф} - фактический (замеренный) перепад давления на устье, $$\Delta P_{у\_р}$$

- расчетный).Comparing the calculated value of the pressure drop across the mouth and the actual (measured), we can judge the tightness of the system "DK NKT-packer-EC": $$\left|\Delta P_{\mathrm{at}\_f}\right|\le \left|\Delta P_{\mathrm{at}\_R}\right|$$

- the system is tight (ΔΡ _{у_ф} - the actual (measured) pressure drop at the mouth, $$\Delta P_{\mathrm{at}\_R}$$

- estimated).

When water is pumped into separated layers from one conduit (of the same density), the pressure drop across the mouth takes the form:

ΔΡ _y = P _y1 -Ρ _y2 = ΔP _n + Ρ _mp1 -Ρ _mp2 + P _pog1 + P _pog2 (4)

Upon reaching the pressure drop across the packer ΔΡ _p = 20 atm, one can judge about the tightness of the system “DK NKT-packer-EK”.

P _{Tr are} determined by the corresponding formulas of hydrodynamics. Table 1 presents the values of P _Tr per 1000 m of pipes when injecting fresh water (density 1.00 g / cm ³ ) for various injections.

The magnitude of the frictional pressure loss is directly proportional to the density of the liquid, therefore, to recalculate P _Tr for another injected agent, it is sufficient to multiply the value from Table 1 by its density (in g / cm ³ ).

The value of the absolute error of the measurement results with a technical pressure gauge is determined by:

P _burr = VPI ∗ CT / 100, (5)

where VPI is the upper limit of measurements; CT - accuracy class.

For pressure gauges with a measuring range from 0 to 250 atm and an accuracy class of 1.5, most commonly used in PPD workshops, P _bur = 3.75 atm.

The pressure drop ΔР _у is equal to the pressure drop across the nozzle installed on one of the discharge lines (if the nozzles are installed on both lines then the difference in pressure drops across the nozzles). The pressure drop across the nozzle depends on the fluid flow through it, and the change in pressure drop is proportional to the square of the flow rate change. Accordingly, with a decrease in water flow through the water conduit (when changing the operation mode of the pumping station, regulation of injection through water conduits, etc.), ΔР _у may decrease to a value lower than the calculated one. Therefore, with a decrease in the wellhead pressure drop, it is necessary to check whether this is a consequence of a decrease in water flow through the water conduit. Under the following condition, the system “DK NKT-packer-EK” can be considered leakproof:

и Q_т - соответственно замеренные текущий устьевой перепад давления и текущий расход воды по водоводу;Where $$\Delta P_{\mathrm{at}\_t}$$

and Q _t - respectively measured current wellhead pressure drop and current water flow through the water conduit;

и Q_n - соответственно фактический перепад давления и общий расход воды по водоводу в одном из предыдущих исследований, при котором фактический перепад давления был выше расчетного, а также при условии, что операции по установке или снятию штуцеров после этого не производились. $$\Delta P_{\mathrm{at}\_n}$$

and Q _n - respectively, the actual pressure drop and the total water flow through the water pipe in one of the previous studies, in which the actual pressure drop was higher than the calculated one, and also provided that the installation or removal of the fittings were not performed after that.

The procedure for monitoring the tightness of the system "DC NKT-packer-EC".

If there is no effect of injection on reacting producing wells, a study of the DK NKT-Packer-EK system on leak tightness according to the method of NGDU AN is mandatory. In the absence of nozzles on both injection lines, it is possible to use the claimed method only after installing on one of the nozzle lines and putting the well into steady state injection mode.

To conduct the study it is necessary:

1. Measure injectivity and injection pressure after the fitting on each discharge line. Measurement should be carried out simultaneously on both lines (or sequentially with a break of no more than 10 minutes) with the operating station.

1.1. Working pressure at the mouth of injection wells is measured once a month when measuring injectivity of the well.

1.2. When equipping wells with telemechanized flow and pressure sensors, control is carried out according to the information received from them. The maximum frequency of analysis of the information received is once a month.

2. Calculate the right side of equation 3 or 4 (for the injection of different agents into the separated formations - formula 3, for the injection of one agent - 4), using table. one.

3. Compare the calculation result according to p. 2 with the measurement result according to p. 1, analyze the results of previous studies and use the map (table 2) to determine the state of the system and / or the need for additional studies.

The implementation of the invention

Example 1

Well No. 1

Initial data

DK tubing: D = 48 mm, L = 1676 m, Q = 39 m ³ / day, P _y = 62 atm, a fitting d = 3 mm is installed on the line; injection agent - wastewater (ρ = 1.09 g / cm ³ ). QC tubing: D = 48 mm, L = l655 m, Q = 24 m ³ / day, P _y = 94 atm, a fitting is not installed on the line; the injection agent is wastewater (ρ = 1.09 g / cm ³ ). When measuring Р _у , a technical pressure gauge of accuracy class 1.5 was used with a measurement limit from 0 to 160 atm.

Payment

We calculate $$\Delta P_{P\_f}$$

ΔΡ _p = 20 atm

P _bur1 = Ρ _bur2 = 160 × 1.5 / 100 = 2.40 atm (formula 5)

P _Tr1 = 0.88 (Table 1, select the value corresponding to the nearest higher flow rate) × 1.68 (L tubing in km) × 1.09 (water density) = 1.61 atm

P _mp2 = 0.88 × 1.66 × 1.09 = 1.59 atm

(31,21>20,00)Result

(31.21> 20.00)

According to the map (table. 2), this condition is sufficient to recognize the system as airtight.

Example 2

Well No. 2

Initial data

DK tubing: D = 48 mm, L = 1676 m, Q = 29 m ³ / day, P _y = 69 atm, a fitting d = 3 mm is installed on the line; injection agent - wastewater (ρ = 1.09 g / cm ³ ). QC tubing: D = 48 mm, L = 1655 m, Q = 20 m ³ / day, P _y = 90 atm, a fitting is not installed on the line; injection agent - wastewater (ρ = 1.09 g / cm ³ ).

When measuring R _y , a technical pressure gauge of accuracy class 1.5 was used, with a measurement limit of 0 to 160 atm.

Payment

By formula 4 (since the same agent) we calculate ΔΡ _{у_р}

ΔΡ _p = 20 atm

P _burnt1 = P _burnt2 = 160 × 1.5 / 100 = 2.40 atm (formula 5)

P _Tr1 = 0.88 (Table 1) × 1.68 (L tubing in km) × 1.09 (water density) = 1.61 atm

P _tr2 = 0.17 × 1.66 × 1.09 = 0.31 atm

(13,00<26,10)Result

(13.00 <26.10)

In this case (Table 2), it is necessary to analyze the results of studies for the previous 6 months and verify the fulfillment of the conditions of formula 6. The result of the study is presented in the example of SLE. No. 1.

$$\frac{\Delta P_{y\_t}}{\Delta P_{y\_P}}=\frac{90-69}{94-62}=0.66$$

$${\left(\frac{Q_t}{Q_P}\right)}^2={\left(\frac{\mathrm{29th}+\mathrm{twenty}}{39+24}\right)}^2=0.60$$

According to the map (table. 2) the system is tight.

Example 2

Well No. 3

The initial data are the same as for well No. 2. At the same time, none of the previous 6 months received data that satisfy the condition of formula 6.

Result

It is not possible to ascertain the tightness of the system. It is necessary to conduct a study with other values of Q and P _y (for example, after replacing the nozzle with a smaller diameter).

In the process of operating wells using ARI technology, it is necessary to examine the system for leaks at least once every six months. The aim of the study is to determine the presence of a hydrodynamic connection between the injection zones. The study is carried out at the steady state of the well. This study is carried out by connecting simultaneously to each line of electronic pressure gauges (for recording readings), with an alternate stop and start of injection on each line and monitoring the effect of one line on the pressure in another (Fig. 2). In FIG. 2 it can be seen that the pressure difference between the layers is 2 atm, when the injection into the reservoir 1 was stopped, there were no changes in the reservoir 2, an increase in pressure in the reservoir 2 occurred due to pressure redistribution in the water conduit. When starting injection into the reservoir, there is no change in injection pressure across the reservoir 2. According to this graph, we can say that the system is leaking.

The duration of the study is from 1 to 5 hours. In winter, at low temperatures, during the study, when injection is stopped into one of the reservoirs, the wellhead gauges freeze and the wellhead harness freezes, which leads to failure of the well harness and additional costs for heating and restoration of the well harness. In order to reduce the cost of researching the system, as well as the possibility of research in the winter, improve the research methodology. In ORZ wells, the main equipment requirement is to ensure the tightness of the system with a pressure differential between the layers, that is, if there is a pressure difference, it can be considered that the system is tight. The improvement lies in the fact that it is possible to determine the tightness of the system without conducting a long study with electronic pressure gauges, as well as without the risk of freezing the well at low temperatures. The injectivity and injection pressure are measured monthly for each well. As a rule, pressure gauges with a measurement limit of 0-250 atm with an accuracy class of 1.5 are used. Those. the maximum error of the manometer is 3.75 atm (the difference in the readings of the two manometers in the absence of a pressure difference can be 7.5 atm). It is necessary to take into account the pressure loss during the movement of water in the tubing (from 1 to 12, depending on the injectivity of the formation, a calculation is required for each well). It is also necessary to take the minimum pressure drop across the packer, at which the system is considered airtight. It is proposed to take 20 atm as this value. As a result, with a pressure difference at the mouth equal to the sum of these three values, the system is considered airtight. Wells on which this differential pressure is maintained during operation may not be further explored. In winter, for wells where this difference in operation is not achieved, it is possible to change the operating mode for several days using fittings, and if it is achieved, then the system will be considered leakproof. Also, this method allows you to quickly detect the tightness of the system, while reducing the pressure drop between the reservoirs. When reducing the pressure drop below the minimum permissible pressure value (20 atm) at the mouth, it is necessary to conduct a leak test.

The possibility of applying this invention is a practical example. The well has been in operation since 2006 with an average pressure drop of 29 atm. An ongoing study of the tightness of the system confirmed the serviceability of the underground equipment and the lack of hydrodynamic communication between the layers.

In accordance with the established periodicity, wellhead pressure was measured, which showed equal wellhead pressure values for working formations. Further, a study was conducted that confirmed that there was a hydrodynamic connection between the working formations in this well. When injection is stopped in formation 1 (previously injection pressure was 80-90 atm, lower 50-60 atm), pressure on formation 2 decreases, which indicates the presence of fluid gaps in underground equipment as a result of loss of system tightness.

Thus, conducting research on wells operated by the ARI technology, with drops of more than 20 atm, it is possible to reduce the number of studies and conduct them with a decrease in the pressure drop between the reservoirs.

Claims (16)

1. A method for monitoring the tightness of an injection well, comprising the steps of:
register a change in pressure in the borehole space blocked by the packer by measuring the pressure at the mouth at the inlet to the tubing string in the upper and lower layers, respectively,
analyze the data and determine the tightness,
characterized in that the analysis of the data obtained is carried out as follows: determine the actual pressure drop across the packer
$$\Delta P_{P\_f}=P_{y\mathrm{one}}-P_{tR\mathrm{one}}-P_{y2}+R_{tR2}-P_{P\mathrm{about}gR\mathrm{one}}-P_{P\mathrm{about}gR2},$$

where P _y1 and P _y2 - measured wellhead injection pressure into the upper and lower reservoirs, respectively, atm,
P _Tr1 and P _Tr2 - pressure loss due to friction when water moves along short and long columns, respectively, atm,
P _pogr1 and P _pogr2 - values of the absolute measurement error with a technical manometer for short and long columns, respectively, atm,
at the same time, a predetermined critical value of pressure drop is taken as a criterion for assessing tightness $$\Delta P_{P\_\mathrm{to}R},$$

tightness is judged by comparing the actual pressure drop across the packer $$\Delta P_{P\_f}$$

and a predetermined critical pressure drop, at $$\left|\Delta P_{P\_f}\right|>\left|\Delta P_{P\_\mathrm{to}R}\right|$$

- the well is tight. 2. The method according to p. 1, characterized in that the predetermined critical value of the differential pressure $$\Delta P_{P\_\mathrm{to}R}=\mathrm{twenty}\mathrm{but}tm.$$

3. The method according to p. 1, characterized in that the pressure drop across the packer $$\Delta P_{P\_f}$$

equal to the pressure drop across the nozzle installed on one of the discharge lines, if the nozzles are installed on both lines, then the difference in pressure drops across the nozzles. 4. The method according to p. 3, characterized in that the change in pressure drop is proportional to the square of the change in fluid flow through it. 5. The method according to p. 1, characterized in that the values of the absolute errors Ρ _pog1 and P _pog2 measurement results determine:
_Pogr1 ΒΠI P = ₁ * ΚΤ _1/100 - manometer, which is measured in a pressure discharge line,
P _pogr2 VPI = ₂ * CT _2/100 - gauge, which pressure is measured in another discharge line,
where VPI ₁ , VPI ₂ - the upper limits of measurement; CT ₁ , CT ₂ - accuracy classes. 6. The method according to p. 1, characterized in that the pressure at the wellhead is measured once a month when measuring injectivity of the well. 7. The method according to p. 1, characterized in that the analysis of the information obtained is carried out periodically at least once a month. 8. A method for monitoring the tightness of an injection well, comprising the steps of:
register a change in pressure in the borehole space blocked by the packer by measuring the pressure at the mouth at the inlet to the tubing string in the upper and lower layers, respectively,
analyze the data and determine the tightness,
characterized in that the current flow rate of the water in the Q _t conduit is preliminarily measured;

Where $$\Delta P_{\mathrm{at}\_t}$$

and Q _t - respectively measured current wellhead pressure drop and current water flow through the water conduit;
$$\Delta P_{\mathrm{at}\_n}$$

and Q _n - respectively, the actual pressure drop and the total flow of water through the conduit,
if the condition is met, the well is tight. 9. The method according to p. 8, characterized in that the pressure at the wellhead is measured once a month when measuring injectivity of the well. 10. The method according to p. 8, characterized in that the analysis of the information obtained is carried out periodically at least once a month. 11. A method for monitoring the tightness of an injection well, comprising the steps of:
register the pressure change in the borehole space blocked by the packer by measuring the pressure drop at the wellhead $$\Delta P_{\mathrm{at}\_f}$$

at the entrance to the tubing string in the upper and lower layers, respectively,
analyze the data and determine the tightness,
characterized in that the analysis of the data obtained is carried out as follows: determine the estimated value of the pressure drop at the mouth $$\Delta P_{\mathrm{at}\_p}:$$

$$\Delta P_{\mathrm{at}\_p}=P_{y\mathrm{one}}-P_{y2}=\Delta P_P-(P_{g\mathrm{and}dR\mathrm{one}}-P_{tR\mathrm{one}})+(P_{g\mathrm{and}dR2}-P_{tR2})+P_{P\mathrm{about}gR\mathrm{one}}+P_{P\mathrm{about}gR2},$$

ΔΡ _y1 = P ₁ -Ρ _hydr1 + Ρ _mp1
ΔΡ _y2 = P ₂ -Ρ _hydr2 + Ρ _mp2
where P ₁ , P ₂ - pressure at points above the packer and under the packer, respectively, atm;
Ρ _hydr1 and P _hydr2 are the hydrostatic pressure of the liquid column in the short tubing string and long, atm _{_} , respectively
P _Tr1 and P _Tr2 - pressure loss due to friction during the movement of water along short and long columns, respectively, atm,
ΔΡ _p - the pressure drop across the packer, atm,
tightness is judged by comparing the estimated value of the pressure drop across the mouth $$\Delta P_{\mathrm{at}\_R}$$

and actual (measured) $$\Delta P_{\mathrm{at}\_f},$$

at $$\left|\Delta P_{y\_f}\right|\ge \left|\Delta P_{\mathrm{at}\_R}\right|$$

the system is tight. 12. The method according to p. 11, characterized in that they determine the pressure drop across the packer:
ΔΡ _n = (P _y1 + Ρ _hydr1 -Ρ _mp1 ) - (Ρ _y2 + Ρ _hydr2 -Ρ _mp2 ) -P _pog1 -P _pog2 ,
where ΔΡ _p is the pressure drop across the packer, atm;
P _y1 and P _y2 - measured wellhead injection pressure, respectively, in the upper layer and lower, atm;
P _hydr1 and P _hydr2 - hydrostatic pressure of a liquid column in a short tubing string and a long, respectively, atm,
P _Tr1 and P _Tr2 - pressure loss due to friction during the movement of water, respectively, along a short column and a long, atm;
P _pogr1 and P _pogr2 - values of the absolute measurement error with a technical pressure gauge, atm. 13. The method according to p. 11, characterized in that when the water is injected into the separated layers from one conduit (of the same density), the pressure drop across the mouth takes the form:
ΔΡ _y = P _y1 -Ρ _y2 = ΔP _n + Ρ _mp1 -Ρ _mp2 + P _pog1 + P _pog2
where P _y1 and P _y2 - measured wellhead injection pressure into the upper and lower reservoirs, respectively, atm,
ΔΡ _p - the pressure drop across the packer, atm,
Ρ _TP1 and P _TP2 - pressure loss on friction when the water moves along the short and long columns, respectively, atm,
P _pog1 and P _pog2 - the absolute error of measurements with a technical manometer for short and long columns, respectively, atm. 14. The method according to PP. 11-13, characterized in that they determine the values of the absolute errors P _bur1 and Ρ _bur2 measurement results:
P _pogr1 VPI = ₁ * ΚΤ _1/100 - manometer, which is measured in a pressure discharge line,
P _pogr2 VPI = ₂ * CT _2/100 - gauge, which pressure is measured in another discharge line,
where VPI ₁ , VPI ₂ - the upper limits of measurement; CT ₁ , CT ₂ - accuracy classes. 15. The method according to p. 11, characterized in that the pressure at the wellhead is measured once a month when measuring injectivity of the well. 16. The method according to p. 11, characterized in that the analysis of the information obtained is carried out periodically at least once a month.

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