RU2405933C1 - Method for survey of gas and gas-condensate wells - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: at each mode from the moment of start-up and end of mode, curves of wellhead and well pressures and temperatures are recorded. Liquid and solid phases separated in separator are sent into tight reservoir for collection of liquid and solid phases, and via pipeline are sent to separated gas - in to gas debit metre. Then gas-liquid mixture is transported along pipeline into flow line or torch. From the moment wellhead pressure and temperatures stabilise at wellhead, pipeline of liquid and solid phases is closed at separator and gas debit metre. Time of liquid and solid phases accumulation start is registered in reservoir of liquid and solid phases accumulation. Debit of separated gas is measured. Mode is terminated, time of mode termination is recorded. Volumes of accumulated liquid and solid phases per mode are measured.

EFFECT: increased efficiency of gas hydrodynamical research in prediction of water invasion processes due to more accurate definition of values of specific content of liquid and solid phases in gas flow.

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Description

The invention relates to the field of the oil and gas industry and can be used when conducting gas-hydrodynamic studies of wells.

A known method of gas-dynamic research of gas and gas condensate wells, where the separation of products, measuring the flow rate of gas and the carried out liquid and solid phases and sampling is carried out at the wellhead [1]. The technological disadvantage of this method is that until the measured gas-dynamic parameters are stabilized, the gas-liquid stream is sent to the flare line or to the loop, and from the moment the measured parameters are stabilized, the gas-liquid stream is transferred to the separator, as a result of which the gas-dynamic mode of the studied well, pressure, temperature and, accordingly, gas flow rate in the process of accumulation of liquid and solid phases change, which does not allow high-quality and representative gas and gas condensate studies. The technical drawback is the significant metal consumption of the separation equipment, the need for paved roads for transportation of equipment. The economic disadvantage of this method is the significant labor costs during transportation and installation of the separator, as well as the capacity for collecting liquid and solid phases. All this leads to a limitation of the application of the method or the general impossibility of its implementation in wells located in remote areas of the Far North.

Also known, adopted as a prototype, is a method for gas-dynamic research of gas and gas condensate wells, including separation of well production, measurement of gas production and volume of solid and liquid phases carried out, measurement of wellhead pressures and temperatures at the wellhead at several established modes, carried out until all measured parameters are stabilized [2]. The known method has the following disadvantages. From the moment of starting up to the stabilization of the measured gas-dynamic parameters, the flow rate of the gas-liquid mixture and, accordingly, the specific content of liquid and solid phases in the gas stream of the well change. The gas production rate at the time of the start-up of the well is maximum, and the specific content of liquid and solid phases in the gas stream is minimal, or there is no such moment. After the time required for the removal of the liquid phase from the bottom of the well, an "avalanche discharge" of liquid is observed at the wellhead. At this moment, the specific liquid content is maximum, and the gas flow rate is minimal. Further, the fluid flow rate decreases and stabilizes, while the gas flow rate, on the contrary, increases. The removal of mechanical impurities (solid phases) is recorded later, and their dependence is of a similar nature. Stabilization of gas flow occurs after stabilization of the removal of liquid and solid phases, pressures and temperatures at the wellhead. These processes are associated with partial cleansing of the bottom of the well in the investigated mode. These negative factors affect the measured volumes of liquid and solid phases and, accordingly, the determination of the specific content of liquid and solid phases in the gas stream during gas and gas condensate studies. In addition, with a significant content of liquid and solid phases in the gas stream, as well as due to an "avalanche discharge", overflow of the collection capacity of liquid and solid phases occurs. Overflow occurs faster than the stabilization of the measured gas-dynamic parameters. The mode is violated and the well is stopped. For this reason, to conduct research on gas and gas condensate wells with a significant content of liquid and solid phases in the modes that ensure their removal from the bottom of the well, using the known method is not possible.

The task to be solved by the proposed method is to increase the efficiency of gasdynamic studies in predicting watering processes, the accumulation of solids at the bottom of wells of the production fund, as well as issuing timely conclusions and recommendations for the overhaul of wells.

To achieve the named technical result in the proposed method of gas-hydrodynamic research of gas and gas condensate wells, including the separation of well production, measuring gas flow rate and the volume of solid and liquid phases carried out, measuring wellhead pressures and temperatures at the wellhead in several steady-state modes, carried out until all measured parameters are stabilized characterized in that in each mode from the moment of starting to stopping the mode, stabilization curves of wellhead pressures and well temperatures are recorded the liquids separated in the separator, the liquid and solid phases are sent to a sealed container for collecting liquid and solid phases, and through the pipeline they are taken to a separated gas to a gas flow meter, and then the gas-liquid mixture is piped to the loop or to the flare device, and from the moment the wellhead is stabilized pressure and temperature at the wellhead on the separator and on the gas flow meter close the pipeline for the removal of liquid and solid phases, record the start time of the accumulation of liquid and solid phases in the tank for collecting liquid and solid h, they measure the flow rate of the separated gas, stop the mode, note the time the mode stops, measure the volumes of accumulated liquid and solid phases for the mode, change the mode.

Distinctive features of the proposed method is that the accumulation of the separated volumes of liquid and solid phases (liquids, mechanical impurities) and the measurement of the separated volume of gas is carried out from the moment of stabilization of the measured gas-hydrodynamic parameters of the well until the regime is stopped, which increases the accuracy and reliability of gas-hydrodynamic studies. And before stabilization of the measured parameters, gas, liquid and solid phases - gas-liquid mixture, are fed to the gas flow meter, which does not violate the parameters of the gas-dynamic mode.

The proposed method is illustrated by drawings: 1-4. Figure 1 shows the essence of the method. After starting well 1 in the test mode (the well mode is set using a diaphragm of a given diameter), the gas-liquid mixture flows through line 2 to the separator 3, where liquid and solid phases are separated from the gas, which are sent through pipeline 7 to a sealed container to collect gas liquid and solid phases 9 and, further, through pipeline 10 through valve 8 to pipeline 4. In pipeline 4, the liquid and solid phase are mixed with purified gas coming from separator 3 and sent to a gas flow meter 5. From a deby meter That 5 gas-liquid mixture through pipeline 6 is sent to the loop, and then to the gas treatment unit for transporting gas, or to the flare device for combustion. After stabilization of pressure, temperature and gas flow rate at the wellhead, on the separator and on the gas flow meter, valve 8 is closed. The time of the beginning of the accumulation of liquid and solid phases in the tank for collecting liquid and solid phases is noted 9. Continue to record the pressures and temperatures at the wellhead 1, on the separator 3 and on the gas flow meter 5. Using the measured parameters on the gas flow meter 5 determine the well flow on mode. After fixing the stable wellhead pressures and temperatures and determining the flow rate, the regime is stopped - the valve in the well is closed, which shuts off the gas-liquid flow entering the separator. In the separator 3 and in the tank for collecting liquid and solid phases 9 release pressure. Measure the volume of liquid and solid phases. Next, change the aperture to change the mode. They start the well in the next mode.

The flow rate determination procedure is described in chapters IV.7 and VI.3.1 “Instructions for the comprehensive study of gas and gas condensate reservoirs and wells” [1].

The production rate of the well during operation of the well in a loop using differential flow meters is calculated by the formula:

where Q _g is the measured gas flow rate in the mode, thousand n m ³ / day; the coefficients α, ε, k _t , k ₁ , d included in the formula are determined in accordance with the procedure described in Chapter VI.3.1., parameters p ₁ , Н, Т, are measured, ρ _rel is taken from the gas composition; z - gas compressibility coefficient is calculated in accordance with the method described in chapter III “Instructions for the comprehensive study of gas and gas condensate reservoirs and wells” [1]. To more accurately determine the flow rate of a gas well, it is necessary to use the "Rules for measuring the flow of liquids, gases and vapors with standard diaphragms and nozzles" [2].

The well production rate during well operation on a flare device using a critical flow diaphragm meter (DICT) is calculated by the formula:

where Q _g is the measured gas flow rate in the mode, thousand n m ³ / day; C _dict - coefficient determined by the method [1] and depending on the diameter of the diaphragm; R _dict - the absolute pressure on the DICT, measured from the moment of stabilization of the wellhead and bottomhole parameters, ata; Δ _hell - correction factor to account for changes in the adiabatic index of real gas; ρ _rel - the relative density of the gas through the air; T _dict is the absolute temperature of the gas in front of the diaphragm, measured from the moment of wellhead and bottomhole parameters stabilization at the well, K; Z is the gas compressibility coefficient [1]. If the gas flow rate is measured by another device or device, then the flow rate is determined according to the operating instructions of the device or device.

The volume of gas released during the study of wells in the mode is calculated by the formula:

where V _g is the volume of gas discharged from the moment of stabilization of the measured parameters to the stop of the regime during the study of the well, m ³ ; Q _g - the measured gas flow rate in the mode, thousand n m ³ / day; t _dir.stab - measurement time from the moment of stabilization of the measured parameters until the mode stops during well exploration, minutes.

The specific content of the liquid (liquid phase) when examining a well in the mode is calculated by the formula:

where W _w - Specific liquid content (liquid phase) at the time when the well study cm ³ / m ^3; V _W - the volume of the measured liquid (liquid phase) in the mode during the study of the well for a time t _dir.stab , cm ³ ; V _g - the volume of gas released from the moment of stabilization of the measured parameters to stop the mode during the study of the well, m ³ .

The specific content of mechanical impurities (solid phases) when examining a well in a mode is calculated by the formula:

where W _m.pr - specific content of mechanical impurities (solid phases) in the regime during the study of the well, cm ³ / m ³ ; V _m.spr - the volume of measured mechanical impurities (solid phases) in the mode during the study of the well for a time t _dir.stab , cm ³ ; V _g - the volume of gas released from the moment of stabilization of the measured parameters to stop the mode during the study of the well, m ³ .

The volumes of liquid and solid phases (V _W and V _m.spr ) are measured with laboratory calibrated dishes. For metering volumes V _w and V _m.pr vent pressure in the separator tank and collecting liquid and solid phases and in part drained fluid and mechanical impurities tared into laboratory dishes. Withstand the liquid and solid phase until the sediment and precipitation of mechanical impurities, then the liquid is separated and measured. The solid phase separated from the liquid is collected separately and the volume is measured with more accurate laboratory calibrated dishes.

The proposed method is carried out using the collector "Nadym-1", designed for gas-hydrodynamic studies of wells, which is commercially available from the plant NPO "Tyumengaztekhnologiya" [3].

Figure 2 shows a diagram of the implementation of the method using the collector "Nadym-1" 3 (separator), which is carried out using valves 8, 12 and tubes for the removal of liquid and solid phases 10 from the containers for collecting liquid and solid phases 9 of the collector "Nadym- 1 "3 (figure 2) in the gas flow meter of the well 5 - diaphragm meter of critical gas flow (DICT) as follows. From the moment of the start-up of the well to the stabilization of the gas-hydrodynamic parameters at the wellhead, valves 8 at the reservoirs for collecting liquid and solid phases 9 of the Nadym-1 collector 3 and at DIKT 5 are fully open, and valves 12 at the pipes for removing liquid and solid phases 10 are closed (Fig. .2). Due to the difference in the pressure of the incoming gas-liquid mixture flow into the Nadym-1 collector 3 and the gas pressure in DICT 5, the separated liquid and solid phases from the liquid and solid phase collection tanks 9 of the Nadym-1 collector 3 through the exhaust pipes 10 together with part of the flow gas enter DICT 5, where they are mixed into a gas-liquid stream. After stabilization of the measured gas-dynamic parameters of the well (Fig. 3), the arrow t _d.stab marks the beginning of the regime, valves 8 are closed, and valves 12 are opened to drain the remaining liquid and solid phases in the exhaust pipes 10. Time is noted and the accumulation of volumes starts from this moment. volumes of liquid and solid phases in containers for collecting liquid and solid phases 9 of the Nadym-1 collector 3. After stopping the mode and bleeding off the pressure from the Nadym-1 collector 3, the volumes of liquid and solid phases are measured. For this, the valves 12 are opened and the liquid and solid phases are poured in parts into laboratory calibrated dishes. Next, change the aperture on the DICT to change the mode. They start the well in the next mode.

The well production rate and the volume of gas released are calculated according to the measured parameters in accordance with the methods of the “Instructions for the comprehensive study of gas and gas condensate reservoirs and wells” set forth in chapters III and IV [1]. The specific content of liquid and solid phases in the investigated mode is calculated.

Figure 3 presents a graph of changes in gas-hydrodynamic parameters in the test mode when conducting well studies using the Nadym-1 reservoir. Figure 3 noted:

t _dir - the time of measurement of liquid and solid phases in the investigated mode from the moment of start to stop by a known method;

t _dir.stab - time for measuring liquid and solid phases in the test mode from the moment of stabilization of the measured parameters to the stop mode when exploring the well according to the proposed method;

1 - pressure on the annulus;

2 - pressure on the well buffer;

3 - pressure on the diaphragm meter of critical gas flow (DICT);

4 - gas flow rate in the test mode;

5 - gas temperature at the DICT;

6 - specific content of liquid (liquid phase) in the gas stream;

7 - specific content of mechanical impurities (solid phase) in the gas stream.

From figure 3 it is seen that the measurement of volumes of liquid and solid phases begin to be carried out after stabilization of the measured gas-dynamic parameters at the wellhead, thereby eliminating the influence of negative factors of "avalanche discharge" of liquid and solid phases in the process of cleaning the well in the test mode (figure 3 , dependencies 6 and 7).

4 shows the dependence of the maximum values of the specific content of the fluid (W _w) of the gas flow rate (Q _d), which may be measured when carrying out research on a known gas-hydrodynamic (1) and proposed (2) method. As can be seen from figure 4, the inventive method (dependence 2) makes it possible to conduct gas-hydrodynamic studies without increasing the volume of the reservoirs for collecting liquid and solid phases of the Nadym-1 collector, with values of the specific liquid content in the gas stream, from 4 to 10 times large than when conducting research according to the known method (dependence 1). This is due to the fact that after stabilization of the measured gas-dynamic parameters, it is possible to reduce the time for the accumulation of liquid and solid phases (figure 3).

The proposed method can be applied to almost any separation device. The method allows to increase the efficiency of work on predicting the processes of watering wells, issuing conclusions and timely recommendations for the overhaul of wells in order to maintain and increase gas production by increasing the quantity and quality of the studied wells.

According to the proposed method, in September 2005, gas-hydrodynamic studies of 8 watered gas wells at the Medvezhye field were carried out. Data were obtained on the basis of which timely recommendations were issued on the establishment of optimal technological operating conditions and on the overhaul of wells. It should be specially noted that conducting research without the application of the proposed method would not have been possible at all, since the specific liquid content at gas rates of 171.65 n. thousand m ³ / day reached 139.8 cm ³ / m ³ . Thanks to the proposed method, wells with long stabilization modes of the measured parameters that could not be investigated due to overfilling of the tanks for collecting liquid and solid phases were investigated. In addition, the data obtained showed that the informativeness and reliability of gas-hydrodynamic studies of wells significantly increased. By eliminating the influence of negative factors of “avalanche discharge” of liquid and solid phases during the well cleaning process, the pressure, temperature, gas flow rate, and the volume of liquid and solid phases that are necessary to establish the technological mode of well operation were more reliably measured. Based on the obtained data, the proposed method was recommended for implementation during gas-hydrodynamic studies at the fields of Gazprom dobycha Nadym LLC.

Information sources

1. Instruction for a comprehensive study of gas and gas condensate reservoirs and wells, ed. G.A.Zotova, Z.S. Aliyev. M., "Nedra", 1980, p.116-118.

2. RF patent No. 2070289, publ. 12/10/96

3. "Guide to the study of wells" Gritsenko A.I., Aliev Z.S., Ermilov O.M., Remizov VV, Zotov G.A. from the "Science", Moscow, 1994, pp. 499-503.

Claims (1)

A method of researching gas and gas condensate wells, including the separation of well production, measuring gas production and the volume of solid and liquid phases carried out, measuring wellhead pressures and temperatures at the wellhead in several established modes, carried out until all measured parameters are stabilized, characterized in that in each mode from the moment of starting up to stopping the regime, stabilization curves for wellhead pressures and well temperatures are recorded, the liquid and solid phases separated in the separator are sent to a sealed collection vessel liquid and solid phases are led through the pipeline to the separated gas - to the gas flow meter, and then the gas-liquid mixture is sent through the pipeline to the loop or to the flare device, and from the moment of wellhead pressure and temperature stabilization at the wellhead, on the separator and on the gas flow meter close the pipeline for the removal of liquid and solid phases, record the start time of the accumulation of liquid and solid phases in the tank for collecting liquid and solid phases, measure the flow rate of the separated gas, stop the mode, note the stop time new modes, measure the volume of accumulated liquid and solid phases per mode, change the mode.

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