RU2387816C1 - Method of cluster water injection into fill-in wells - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to oil production and can be used in development of oil accumulations and operation of formation pressure maintenance system. Substance claim: proposed method comprises regulation of injection volume with due allowance for threshold value at certain injection volume per certain period of time to inject preset volume during said period of time. In compliance with this invention, in cyclic water injection into fill-in wells, threshold water injection volume for every well is selected, smaller than preset injection volume for certain time interval but making main injection volume of up to 95% of preset volume. This volume reached, injection is effected in smaller volumes increasing volume to preset one and, thereafter, pump-up conditions are selected with injection pressure and rate regulation. Further, main and pump-up conditions are alternated, distributed among different wells and carried out simultaneously by the same pumps.

EFFECT: reduced clogging of fill-in well formations, injection capacity decrease rate, as well as longer life and lower probability of fractures at high-pressure water ducts.

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Description

The proposal relates to the oil industry and may find application in the development of oil deposits and the operation of the reservoir pressure maintenance system.

There is a method of cluster injection of water into injection wells (see the manual "Operation of reservoir pressure maintenance systems in the development of oil fields", ed. Zeygman Yu.V., Ufa: Publishing House UGNTU, 2007, p.181-183), which water is fed through low-pressure pipelines to a cluster pump station, and then through high-pressure pipelines to injection wells to maintain reservoir pressure. This method of cluster water injection into injection wells is accepted by us as an analog.

There is a method of cluster injection of water into injection wells (see RF patent No. 2186954, 7 E21B 43/20. Publ. BI No. 22 of 08/10/2002), by which water is supplied through a low pressure pipe to a cluster pump station, and then - through high pressure pipelines to injection wells to maintain reservoir pressure. This method of cluster water injection into injection wells was adopted by us as the closest analogue.

For the closest analogue, the term “threshold value” for a certain period of time corresponds to (equal to) a given injection volume. In this case, the injection wells are shut off (closed) completely.

Known methods of cluster injection of water into injection wells during operation of the reservoir pressure maintenance system in a cyclic mode, providing for alternating switching on and off of injection wells (the well is “open” or the well is “closed”), have the following disadvantages:

a) when shutting off injection wells:

- there is a mudding of the layers of injection wells, composed of sandstones, and also, due to sedimentation of solid suspended particles from downhole equipment in the bottom-hole zone of injection wells, which requires work to clean it;

- in addition, during the winter period, high pressure water conduits and the mouth of injection wells freeze, which requires their insulation.

b) when you turn on injection wells:

- the shock dose of solid suspended particles is transported from the high pressure pipelines to the bottom-hole zone of the injection wells, which also requires cleaning;

- there are hydraulic shocks in high pressure water pipes, which leads to a decrease in the service life of water pipes.

The technical task of the invention is to reduce the mudding of injection wells, to reduce the rate of fall of injectivity of injection wells, to prevent freezing of high pressure water conduits and the mouth of injection wells in winter, to increase the service life and to reduce the likelihood of gusts in high pressure water conduits, due to the continuous controlled injection of water into injection wells and, as a result, lower material costs for the construction, maintenance and repair of water injection systems s, and ultimately, an increase in current production and oil recovery.

The technical problem is solved by the method of cluster injection of water into injection wells, including adjusting the injection volume taking into account the threshold value at a certain injection volume for a certain period of time for injection of a given injection volume for this period.

What is new is that in the cyclic mode of water injection into injection wells, a threshold value of the injection volume for each well is selected that is less than the injection volume set for it for a certain period of time, but constitutes the main injection volume up to 95% of the specified volume, after which it is reached within the remaining time of a certain period, the injection is carried out with a smaller volume until the specified volume is reached — they switch to the pumping mode with regulation of pressure and injection speed, hereinafter the main mode and p the swap hedgehog is alternated, distributed over various wells and carried out simultaneously by one pump.

Figure 1 presents the technological scheme of the system for maintaining reservoir pressure for implementing the method of cluster injection of water into injection wells.

Figure 2 presents the leader A adjustable hydraulic resistance, consisting of (options): a) from an adjustable valve; b) from an adjustable gate valve and an additional adjustable valve; c) from an adjustable gate valve and two additional calibrated valves.

Figure 3 presents graphs of water injection into injection wells by the pump pump.

The circuit contains a high pressure pump 1 of a cluster pump station 2, a flow line 3 of a cluster pump station 2, a comb unit 4 (see FIG. 1) with adjustable hydraulic resistance 5, consisting of an adjustable valve 6 (see FIG. 2, option a), with adjustable hydraulic resistance 5, consisting of an adjustable valve 6 and an additional calibrated adjustable valve 7 (see Fig. 2, option b), with adjustable hydraulic resistance 5, consisting of an adjustable valve 6 and two additional calibrated adjustable valves 8, 9 (see Fig. .2, option c), and flow meters 10, 11, 12, water conduits 13, 14, 15, check valves 16, 17, 18, injection wells 19, 20, 21 (see figure 1). Options b and c (see figure 2) allow you to more accurately control the volume of injection, as they are equipped with calibrated adjustable valves 7 (see figure 2, option b), 8 and 9 (see figure 2, option c), which are calibrated (verified) for a certain pre-calculated volume. With option a (see figure 2), coarse adjustment of the injection volume is possible by covering the adjustable gate valve 6, which is permissible for very large injection volumes (for example, with injection volumes exceeding 200 m ³ per day). In the presence of one calibrated adjustable valve 7 (see Fig. 2, option b), a stepwise fine adjustment of volume is possible (adjustable valve 6 and calibrated adjustable valve 7 are open or adjustable valve 6 is closed, and calibrated adjustable valve 7 is open) and is used in wells 19 , 20 or 21 (see figure 1) with injection volumes, for example, 100-200 m ³ per day. Moreover, if there is more than one calibrated adjustable valve 8 (see Fig. 2, option c) and 9, more precise step-by-step volume control is possible (with open or closed adjustable valve 6: calibrated adjustable valves 8 and 9 are open, calibrated adjustable valve 8 or open calibrated adjustable valve 9) for wells 19, 20 or 21 (see figure 1), which do not allow excessive injection volume (for example, with injection volumes of 50-99 m per day). The number of additional calibrated adjustable valves can be more than two (not shown in FIG. 2), but in very rare cases requiring very precise adjustment of injection volumes for complicated wells 19, 20 or 21 (see FIG. 1), with small volumes injection (for example, with injection volumes less than 50 m ³ per day).

The scheme works as follows (see figure 1, figure 2). The proposed method of cluster injection of water into injection wells involves continuous injection of water by a high pressure pump 1 of a cluster pump station 2 through a flow line 3 of a cluster pump station 2, a comb unit 4 (see FIG. 1) with adjustable hydraulic resistance 5 (see FIG. 2, options a, b, c) and flow meters 10, 11, 12, water conduits 13, 14, 15, check valves 16, 17, 18 into the injection wells 19, 20, 21 (see figure 1) and is carried out using alternating two modes: main mode and swap mode. In the main mode, up to 95% of the specified injection volume is provided for a certain period of time; in the pumping mode, in the remaining time of a certain period, the injection is performed with a lower volume until the specified injection volume is reached. In this case, the main mode and the swapping mode for different wells are distributed in time and carried out simultaneously by one pump, due to this, the performance of the high pressure pump 1 of the cluster pump station 2 remains unchanged.

Adjustable hydraulic resistance 5 (see figure 2, options a, b, c) are selected for each injection well individually. By adjusting the value of the hydraulic resistance 5 (see Fig. 2, options a, b, c), the pressure and speed of water injection into injection wells 19, 20, 21 are regulated. The reservoir pressure maintenance system for implementing the method of cluster injection of water into injection wells is connected to the system telemechanics.

An example of a specific implementation.

An average of 5 to 30 injection wells are connected to a cluster pumping station. Consider an example of a specific implementation when 12 injection wells are connected to a cluster pumping station (see FIG. 3). In accordance with the task of injection for a certain period of time - one day (24 hours) into injection wells 19, 20 or 21 (see figure 1), etc., indicated on the schedule of water injection into injection wells by a pump of KNS (see Fig. 3): A, B, C, D, E, F, G, H, I, J, K, L, it is necessary to pump 1680 m ^{3 of} water with a central pump 63-1400. The daily injection of 1680 m ^{3 of} water is distributed among injection wells as follows: well A 170 m ³ / day, well B 165 m ³ / day, well C 155 m ³ / day, well D 150 m ³ / day, well E 145 m ³ / day, well F 140 m ³ / day, well G 135 m ³ / day, well H 130 m ³ / day, well I 130 m ³ / day, well J 125 m ³ / day, well K 120 m ³ / day , well L 115 m ³ / day (see figure 3).

When implementing the proposed method of cluster injection of water into injection wells in the first 12 hours (first half of the day), injection wells A, C, E, G, I, K operate in the main mode, which provides up to 95% of the specified volume of injection into these wells: well A 156 m ³ , well C 144 m ³ , well E 134.4 m ³ , well G 123.96 m ³ , well I 122.76 m ³ , well K 111 m ³ . Injection wells B, D, F, H, J, L operate in the pumping mode (see figure 3).

When implementing the proposed method of cluster injection of water into injection wells in the next 12 hours (second half of the day), injection wells A, C, E, G, I, K operate in the pumping mode. Injection wells B, D, F, H, J, L operate in the main mode, which provides up to 95% of the specified volume of injection into these wells: well B 156 m ³ , well D 141.6 m ³ , well F 132 m ³ , well N 122.4 m ³ , well J 117.6 m ³ , well L 107.52 m ³ (see FIG. 3).

By adjusting the hydraulic resistance 5 (see figure 2), regulate the pressure and speed of water injection into injection wells in the pumping mode. In the future, an alternation of modes occurs: the main mode and the swap mode.

When implementing the proposed method of cluster injection of water into injection wells, the continuity of water injection by the high pressure pump 1 (see Fig. 1) of the cluster pump station 2 is provided, while the performance of the high pressure pump 1 of the cluster pump station 2 remains unchanged and amounts to 70 m ³ / h or 1680 m ³ / day (see figure 1, figure 3).

The following are formulas with which you can determine the parameters when implementing the proposed method of cluster injection of water into injection wells.

where T is the period of time during which the specified volume of injection is provided, is taken equal to 24 hours;

T ₁ - the period of time after which the threshold value of the specified injection volume occurs and during which up to 95% of the specified injection volume is provided (main mode), hour;

T ₂ - the remaining period of time during which water is pumped to a predetermined injection volume (pumping mode), hour.

Preset download volume Q _ass :

Where

where Q ₁ is the injection volume over a period of time T ₁ , m ³ ;

Q ₂ - injection volume for the remaining time period T ₂ , m ³ ;

q _main - injection volume in the main mode, m ³ / h;

q _under - pumping volume in the swap mode (throughput of the regulated valve or tared valve), m ³ / hour.

Substituting formulas (3) and (4) into formula (2), we obtain:

Using formula (5), we can determine T ₁ and q _under :

The technical and economic efficiency of the proposed method of cluster injection of water into injection wells of a system for maintaining formation pressure of an oil field is achieved by continuously controlled injection of water into injection wells.

The use of this invention in the oil industry allows to reduce costs per unit (1 m ³ ) of pumped process water and, ultimately, reduce the cost of a unit of oil produced (1 t) due to:

- reduction of mudding of reservoirs of injection wells;

- reduce the rate of fall of the injectivity of injection wells;

- exclusion of the costs of warming high pressure pipelines and the mouth of injection wells in the winter;

- increase the service life and reduce the likelihood of gusts on high pressure pipelines;

- increasing current production and oil recovery by ensuring the system’s operability in the winter, reducing downtime associated with repair work on water pipelines and in the bottomhole formation zone, and reducing pollution of productive formations.

Thus, the use of this invention will reduce the mudding of the injection wells, reduce the rate of fall of the injectivity of the injection wells, eliminate freezing of the high pressure water conduits and the mouth of the injection wells in the winter, increase the service life and reduce the likelihood of gusts on the high pressure water conduits, due to the continuous controlled injection water into injection wells and, as a result, reduce material costs for the construction, maintenance and repair of water injection systems, and ultimately, increase current production and oil recovery.

Claims (1)

The method of cluster injection of water into injection wells, including adjusting the injection volume taking into account a threshold value for a certain injection volume for a certain period of time for injection for a given injection volume for this period, characterized in that during the cyclic mode of water injection into injection wells, a threshold value of the injection volume is selected for each well, less than the specified injection volume for a certain period of time, but making up the main injection volume - up to 95% of the specified volume, after reaching eniya which over the remaining period of time from an injection is carried out with a smaller volume to achieve a given volume - switching to pumping mode with pressure control and injection rate, hereinafter the basic mode and pumping mode alternate, distributed over the various wells and performed simultaneously among pumps.

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