RU2346147C1 - Operating method of wells and gas collection system during compressor period of developing gas and gas condensate fields - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to gas industry. The effect of the invention is improvement of operating efficiency of marginal wells. Method is realised due to the fact that gas production on the field is stopped for a short period of time by switching booster compression station over to the idle mode. Then, that station is switched over to normal operating mode, and produced gas is supplied to gas main pipeline. Thus, fluid plug being the result of stopped gas production on the field is removed from connecting pipelines at low pipeline route sections. At that, fluid level is simultaneously lowered in bottom holes of the wells due to increasing gas flow velocities.

EFFECT: improving capacity of watering out wells and their connection pipelines, tails and headers due to removing fluid phase from well shafts and pipelines.

2 dwg, 1 ex

Description

The invention relates to the gas industry and can be used in the development, gas production at gas and gas condensate fields in the compressor period of their development when connecting a booster compressor station (BCS) and operation of gas wells.

The prior art method of operating gas wells, including blowing wells and connecting pipelines (loops, collectors) to the torch. The purge is carried out with the aim of removing the accumulated liquid, reducing the hydraulic resistance of the gas collection system and thereby ensuring stable operation of the field for a certain period of time (V. Muravyov, Operation of oil and gas wells. M .: Nedra, 1973, pp. 275-279 )

The disadvantage of this method is that the purging of wells and loops is carried out into the atmosphere through a torch. In practice, this method of preventing the above technological complications is quite often used, while a significant amount of gas is irretrievably lost. It should be noted that in the final period of field development, such purges have to be carried out more and more often.

A known method of removing fluid from gas wells and loops, including gas production and periodic removal of fluid from the bottom of the well produced gas. The liquid from the bottom of the well is removed by blowing loops through a gas ejector, and each well is periodically connected to the mixing chamber of the ejector, at the entrance of which a high-pressure gas with DCS is supplied. The mixed stream is directed to the inlet of the booster compressor station, and the purge period of each well is determined by stabilizing the temperature in it (RU 2017941, 08/15/1994).

The purpose of this method is to increase the efficiency of low-production wells, however, losses do not overlap when using this method, which leads to a decrease in the overall productivity of the gas field and not to make up for production losses in the subsequent time.

The closest analogue of the claimed invention is a method of periodic removal of fluid from wells. During well operation, fluid accumulates in the fountain column and the control unit gives a command to the controlled shut-off device to partially or completely shut off the gas flow from the fountain column in order to accumulate gas for lifting liquid from the bottom. After executing the command on the shut-off device, the pressure drop increases, the value of which is controlled. Upon reaching the threshold, the shut-off device opens, the gas velocity in the fountain column increases and the gas accumulated in the annulus removes fluid from the well to the surface (SU 354119, 10/09/1972).

During the period of declining production and at the final stage of field development, a decrease in reservoir pressure leads to an increase in the moisture content of the gas, while the gas velocity and mass flow rate decrease over time to critical values at which the gas flow is not able to carry the accumulated liquid in the pipelines. In this case, a gradual accumulation of the liquid phase occurs in the connecting pipelines and at the bottom of the wells. This leads to an increase in the hydraulic resistance of the gas collection system as a whole, to a decrease in pressure at the wellheads and to the possibility of their "self-pressing".

The problem to which the proposed invention is directed, is to create such a method of periodic removal of fluid from wells and connecting pipelines, which would eliminate the above disadvantages.

The technical result achieved by the implementation of this invention is to increase the efficiency of wells and gas collection systems in the compressor period of field operation due to the organization of periodic removal (removal) of the liquid phase from the bottom of the wells, connecting pipelines, loops and reservoirs while reducing labor and operating costs as well as improving safety and economy.

The specified technical result is achieved in a method for periodically removing liquid from wells and pipelines, in which the gas production in the field is briefly stopped by switching the booster compressor station to idle, then turning it into normal operation and supplying produced gas to the main gas pipeline and thereby removing formed during the period of stopping the fishing of the liquid plug in the connecting pipelines in the lower sections of the route and at the same time a decrease liquid level at the bottom of gas wells by increasing the speed of gas flows.

The invention is illustrated by drawings, where figure 1 shows a functional diagram of the installation of production and preparation for transport; figure 2 is a graph of the results of using the invention per day.

Gas from the wells through the loops enters the inlet separator 1 or the dust collector, is compressed to the BCS 2, and is cooled in the gas air coolers 3. After it is sent for drying to the absorber 4, it passes through the filter for trapping diethylene glycol 5, it is measured by the measuring diaphragm in the gas metering unit 6 and enters the interfield collector (IPC).

The installation comprises pressure gauges 7-13, inter-jet valve 14, operating 15 and buffer 16 valves, input electric actuator valve 17, measuring diaphragm of the loop input 18, valve 19 with a diameter of 400 mm, discharge valve 20 with a diameter of 300 mm, check valve 21 and outlet valve 22 .

In the method of periodically removing liquid from wells and connecting pipelines, and / or loops, and / or reservoirs, gas production is temporarily stopped at the field by switching DCS 2 to idle speed (“unloading to the ring”), followed by its normal operation and supplying produced gas to the main gas pipeline. During the period of the field shutdown, fluid plugs are formed in the connecting pipelines in the lower sections of the route, and the liquid in the wellbores accumulates at the bottom, partially absorbed into the reservoir. Subsequent rather quick switching of DCS 2 to work in the gas pipeline leads to the removal (removal) of the liquid phase from the wells and connecting pipelines and, thereby, decreases the hydraulic resistance of the gas collection system. At the same time, the technological possibility of maintaining increased well production rates (and gas production productivity as a whole) is realized for approximately one hour, which further contributes to the removal of accumulated fluid in the "relief" pipelines. The effect of increasing the flow rates of the wells lasts more than a day.

Thus, there is an increase in gas production in the whole field, which lasts a certain time (more than a day), after which the short-term shutdown procedure can be repeated (the frequency of the process is determined empirically).

As for the duration of a short-term shutdown of the field, this value is also determined experimentally in order to ensure the maximum possible increase in gas production in the field as a whole under specific operating conditions, for example, for the Medvezhye field gas collection and treatment systems, the optimal field-stop time is 10 minutes.

When using this method, operating costs are reduced (there are no technological gas losses), additional gas production is ensured, and environmental requirements are observed (environmental damage caused by the technology of liquid removal by blowing wells and connecting pipelines into the atmosphere with gas flaring is eliminated).

An essential feature of the proposed method lies in the fact that the hydraulic efficiency of the wells and the gas collection system in the entire field is improved simultaneously, and not in individual wells and their connecting pipelines (loops). The method is carried out automatically from the operator panel. Thus, the complexity of the proposed method is significantly lower compared to previously known methods for removing liquid.

The method of removing liquid from wells and connecting pipelines (loops, collectors) is that an unloading valve 20 is opened, then a valve 19 and DCS 2 are opened, thereby being idled (“DCS 2 operation on the ring”). The optimal period of operation of the BCS 2 in the idle mode is established experimentally and is 10 minutes. The indicated time period is sufficient for the liquid phase to accumulate in the lower sections of the connecting pipelines (pipeline routes), and the liquid from the gas-liquid flow in the well to accumulate at the bottom. Subsequent switching of the BCS 2 to the normal mode is as follows. The crane 19 is completely closed, while the discharge valve 20 is closed gradually taking into account the permissible technological regime of the wells (all in total) in the gas field. The gas velocity increases sharply, which leads to the removal of fluid from the lower sections of the connecting pipelines (loops, reservoirs) and the bottom of the well during plug flow regime of the gas-liquid mixture.

Example. The Bear Field.

The initial data before starting the test of the proposed method: gas flow rate at the measuring diaphragm of the gas metering unit 6 (Fig. 2) - 172 thousand m ³ / hour, the pressure at the wellhead by gauges 7, 8 is 1.2 MPa, by gauges 9 and 10 - 1.1 MPa, gauge 11-1.85 MPa, gauges 12 and 13-1.75 MPa.

After 10 minutes of working on the “ring”, the pressure on gauges 7-12 was 1.41 MPa, on the pressure gauge 13 - 1.75 MPa. Pressure gauge 13 did not change pressure, which indicates that there is no significant change in flow rate in the whole field.

When starting DCS 2 into the track after closing the crane 19 (Fig.2), the closing of the unloading crane 20 was carried out for more than 1 hour, since the flow rate rose to the maximum allowable technological mode for the quarter, namely 210 thousand m ³ / hour. Figure 2 shows that the loss of production for 10 minutes, which amounted to about 28 thousand m ³ , significantly overlap in the first hour after the start of fishing in operation using the proposed method. The increase in production at constant operating parameters of the BCS and the technological equipment of the gas treatment plant amounted to 80 thousand m ³ in one day.

The claimed invention allows to increase the productivity of waterlogged wells and their connecting pipelines (loops, reservoirs) by removing the liquid phase from the wellbores and pipelines and to reduce operating costs, as well as provides additional gas production and meets environmental requirements (eliminates environmental damage caused by standard removal technology liquids by blowing wells and connecting pipelines into the atmosphere with gas flaring).

Removing the liquid phase is achieved by stopping gas production in the field for a short period of 10 minutes by switching the booster compressor station (BCS) to idle (“unloading to the ring”) and then turning it on to normal operation in the main gas pipeline. During the period of stopping gas production in the connecting pipelines, liquid plugs are formed in the lower sections of the route, and the liquid in the wellbores accumulates at the bottom, partially absorbed into the reservoir. The subsequent rather quick switching of the booster compressor station to work in the gas pipeline leads to the removal of the liquid phase from the wells and connecting pipelines and thereby reduces the hydraulic resistance of the gas collection system. At the same time, the effect of increasing gas production in the whole field is observed, which remains for some time, after which the procedure for short-term shutdown of the field is repeated (the frequency of the process is determined empirically and for gas wells of the Medvezhye field once a day).

Claims (1)

A method for periodically removing liquid from wells and pipelines, characterized in that the gas production is temporarily stopped at the field by switching the booster compressor station to idle, then turning it into normal operation and supplying the produced gas to the main gas pipeline and thereby carrying out for the period stopping the oil cork fishery in connecting pipelines at lower sections of the route and at the same time lowering the liquid level at the gas faces output wells by increasing gas flow rates.

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