Method for oil extraction and device for controlling pit-face thermal and pressure parameters during oil extraction

FIELD: oil extractive industry.

SUBSTANCE: method includes lowering a tail piece into well with temperature, electric conductivity and pressure sensors placed on tail piece along its length. Pressure sensors are used in amount no less than three and placed at fixed distances from each other. After that, continuously during whole duration of well operation between maintenance procedures, temperature, conductivity of well fluid, absolute value of face pressure and difference of pressures along depth of well in area of productive bed are recorded. Different combinations of pairs of pressure sensors are used for determining special and average values of well fluid density. When absolute pit-face pressure is lower then saturation pressure for well fluid by gas and/or when average values of density deviate from well fluid preset limits and/or when its conductivity deviates from preset limits, adjustment of well operation mode is performed.

EFFECT: higher efficiency, higher safety.

2 cl

 

The present invention relates to the oil industry and can be used for oil extraction is preferably inclined, deviated or horizontal wells.

Famous oil extraction method and device for its implementation, in accordance with which the control bottomhole pressure by calculation according to the data obtained at the wellhead, maintaining the bottomhole pressure in the process of production at the prescribed level using the device in the form of a pressure regulator, placed also at the wellhead [1].

A disadvantage of the known solutions is dependent on environmental conditions at the wellhead and the unreliability of the control parameters of the well, leading to low performance.

Famous oil extraction method and device for monitoring well parameters, according to which taking the oil with a pump and control downhole pressure with a manometer, which is put together with a column for lifting oil [2].

The disadvantage of this method is insufficient information on the physical parameters of the produced fluid at different points of the wellbore at various depths in the process of oil production and, therefore, unreliable information and the low efficiency of production.

The known method of extraction is Efti, including the descent into the well pipe string to lift oil, equipped with a shank at the bottom of the column, the installation of the shank against the oil reservoir, tying the wellhead and operation of wells with the rise of oil at the wellhead when the control casing, wellhead and downhole well pressure and the regulation of the mode of operation of the well [3].

A device for the production of oil, including a string of pipe for lifting oil from the shank in the lower part of the column, tying the wellhead and pressure sensors [3].

A disadvantage of the known solutions in terms of both the method and devices is their low efficiency, due to the lack of controlled parameters as at one point of the well and the borehole at the depth, unreliability of the measured parameters and the difficulty for this reason, maintaining optimum production conditions.

The technical result of the invention is to increase the efficiency of the method and operatively receiving the optimal amount of reliable information on the borehole fluid with a minimum expenditure of time and used process equipment in the well during the overhaul period of the wells, and receive information without lifting devices and equipment at the surface regardless of the configuration with the oxen of these wells to ensure the safety of personnel.

Required technical result is achieved by the fact that the oil extraction method includes the descent into the well liner placed on it in its length sensors temperature, conductivity and pressure, at least the latter of which is used in an amount of not less than three and placed at fixed distances from each other, and then continuously throughout the overhaul life of the well fix it the temperature, the conductivity of the borehole fluid, the absolute value of the bottomhole pressure and the pressure difference on the well depth in the zone of the reservoir using different combinations of the combinations of pairs of pressure sensors to determine the private and the average density of the downhole fluid and, at the absolute bottom-hole pressure below the saturation pressure of the downhole fluid passing gas and/or the deviation of the average density of the downhole fluid and/or electrical conductivity of the established limits, the control mode of the well.

In addition:

in the hole down deep pump, and the shank down to pump deep, with sensors placed on the shank along its length and above receiving the downhole pump;

private value density of the produced fluid (ρ, g/cm3) is determined by the ratio of:

where ΔP is the pressure difference along the depth of the borehole between the pressure sensors in the selected combinations combinations of pairs of sensors, g/cm3;

g is the acceleration of gravity (g = 9,8 ), cm/sec2;

ΔNabs- the vertical distance between the pressure sensors in the selected combinations combinations of pairs of sensors, cm;

the water content of the downhole fluid (Vin, %) advanced control ratio:

where ΔP is the pressure difference between the pressure sensors in the selected combination combination of pairs of sensors, MPa;

g is the acceleration of gravity (g = 9,8 ), cm/sec2;

ΔH is the vertical distance between the pressure sensors in the selected combinations combinations of pairs of sensors, cm;

α - the angle of the wellbore in the area between the pressure sensors in the selected combinations combinations of pairs of sensors, deg;

ρnthat ρinthat ρfis the density, respectively, of oil, water, borehole fluid, g/cm3;

V - volume of water;

measurement data encode digital information, which is remembered and stored in the electronic memory unit and, as appropriate, transmit to the surface via the cable communication line for processing and visualization.

Required technical result is achieved by the fact that the device for control C the flow temperature and pressure parameters of the fluid in the extraction of oil includes the string of pipe to lift oil, the shank of the pipe or cable, or rope length up to the roof of the reservoir, temperature sensors, conductivity and pressure placed on the shank, all sensors have a cable line connection to the surface, and the pressure sensors in the amount of not less than three placed at fixed distances from each other, are made with the possibility of continuous measurement of time, temperature, electric conductivity of borehole fluid, the absolute value of the pressure and pressure drop along the length of the shank in the zone of the reservoir between the pairs of pressure sensors at various combinations of these pairs;

the device has a submersible pump that is hydraulically connected with the column pipe, and the shank is rigidly connected with the lower part of the downhole pump, the sensors are placed on the shank and above receiving the downhole pump column pipe for lifting oil;

the device is equipped with a single-wire cable line to the surface;

the device is equipped with an electronic memory unit for storing the measured parameters in the form of digital information and an interface for transmitting information to the surface for visualization and processing.

The essence of the invention.

Information about the wells is only reliable when it is obtained in real conditions of operation of the oil reservoir in the process of extraction of oil is, i.e. at a specific downhole pressure, temperature and composition of the downhole fluid is continuous in time. The availability of this information allows you to make the right and timely decision on the regulation of specific wells, a field in General, to evaluate, for example, the state developed Deposit for any period of time for all wells and to prepare a complete history of the development of deposits. Thus obtained downhole information does not require recalculation taking into account complex transients, as required by the information received at the wellhead. It is noted that the instrumentation is reduced essentially to the minimum number of types of sensors - pressure sensors, temperature and conductivity of the borehole fluid. On the basis of the data of the pressure sensors determine the density of the medium flowing from the reservoir, for example, to the pump intake. To obtain the density parameter measuring the pressure at two spaced apart points well (on a pair of sensors placed on the shank and on the pressure difference, measured in the data points in the wellbore, the density of the downhole fluid. While the hydraulic resistance between the measuring points of pressure should be minimal. On this being is not the sensors are placed on the outer surface of the shank or lift pipes, where fluid flow is virtually absent, or carry out short-term shutdown of the pump. The actual shank are made of tubes of small diameter, for example, tubing, 1.5 to 2 inches, or cable, for example, logging armored, or rope diameter 3-36 mm Method of calculating the density of the downhole fluid at a pressure difference in the liquid column, measured at two different points along the borehole depth eliminates the necessity of such hazardous to personnel techniques, such as gamma radiation or method of delayed neutrons. To improve the reliability of measuring the density of the medium in the well involve the use of pressure sensors in the amount of not less than three. However, these sensors are dispersed along the length of the shank on a strictly fixed and verified with the required accuracy distances from each other. The pressure difference along the length of the shank calculated using different combinations of the combinations of pairs of pressure sensors installed in different points. For example, if the pressure sensors set at three points of the wellbore, namely the bottom - at the bottom of the shank above the roof of the reservoir, the average of them is below the pump intake, and the top - 50-150 m above the pump intake, the pressure difference is determined when the following combinations of pairs of sensors:

lower - middle;

n the life - top;

middle - top.

When this measurement is carried out continuously in discrete time. Measurement accuracy with increasing number of measurements from the three sensors pressure increase 1.7 times.

To determine the effect of the dynamic mode oil flow parameters (pressure) define mutually perpendicular cross-sections of the flow of oil along the stream and perpendicular to the flow) downhole devices containing sensors for measuring pressure and temperature, where the contact sensors of the downhole fluid is carried out in two planes at right angles. Deviations of the density and conductivity of the downhole fluid from the established intervals of its values, in particular, on average, at different points in the well bore witness about his or flooding, or degassing. These data, obtained in the process of oil extraction, are very valuable because they allow when continuously incoming information to ensure optimum performance of the well and the adjacent and nearby wells to maintain reservoir pressure. This helps to ensure optimal development of oil deposits in General. In flooding of oil to an acceptable rate in single wells stop the wells and establish the nature of the incoming water into the reservoir. P the following that are holding events to disable vodopodayuschih horizons. If the water in the oil is water carried out during the development of deposits flooding, transferred, for example, a cyclic mode of development of deposits, when the number of wells temporarily stop the redistribution of flows in the reservoir.

When the downhole well pressure below the saturation pressure of oil associated gas is the degassing of oil and the formation of rims free gas, which prevents normal operation of the well pump. In this case, change the mode of operation of the well and increase the bottomhole pressure to a pressure above the saturation pressure.

When bezmasenoj (fountain) operation is sometimes advantageous to operate well in the regime of phase separation of oil and gas. In any case, the optimal mode of operation of the well or the development of deposits can be made only on the basis of the continuously incoming information from downhole (productive formation wells.

The method is as follows.

Carry out the descent into the well pipe string to lift oil. Before descending column equip the pump with a shank attached to its lower part. In the process of lowering the tubing to lift oil to it fixed wireline, which consistently connect Autonomous devices with sensors rigidly attached to the tube and the shank. Tie the mouth of the wells is determined. After that they operate well with the rise of oil at the wellhead. Simultaneously engaged by the cable communication line control casing, wellhead, downhole well pressure and control temperature and density and the conductivity of the borehole fluid. Additionally you can control the flow and content of the downhole fluid by another method, for example, according to the pressure measurements. Measurement data encode digital information, which is remembered and stored in the electronic memory unit and, if necessary, the line read from the devices and transmit to the surface.

All these parameters are controlled continuously in time and the depth of the productive formation throughout the overhaul life of the well (20-600 day). To control the above parameters devices equipped with sensors, mounted on the shaft and lifting the pipe not less than three and dispersed in depth in the wellbore on a strictly fixed distances from each other. Calculate the pressure difference between the section of the wellbore using different combinations of the combinations of pairs of pressure sensors and determine the density of the downhole fluid in the wellbore. Fix also the absolute value of the bottomhole pressure, temperature and conductivity skvazhina what about the fluid. At the absolute bottom-hole pressure below the saturation pressure of the downhole fluid passing gas and/or the deviation of the average density of the downhole fluid and/or electrical conductivity from the established limits of the control mode of the well.

The device for implementing the method is, essentially, a device for controlling bottomhole temperature of the well parameters and composition of the downhole fluid in the process of oil extraction. Due to the simplicity of the device it doesn't require graphics support.

The device includes a string of pipe for lifting oil. It has a submersible pump with a shank. It is rigidly connected with the lower part of the pump and is made of pipe or cable, or rope. On the shank and above the pump intake, i.e. pipes for lifting oil placed offline digital devices with sensors for measuring temperature, pressure and conductivity of the borehole fluid. Each device cable line is connected to the surface. At least the pressure sensors installed in an amount of not less than three on the outer surface of the pipe to lift oil and the shank. They are dispersed on the precise distances. In principle, other sensors can be installed in not less than three. The sensors provide the ability to measure, in a discrete R is the bench and in real time throughout the overhaul life of the well, temperature, pressure and conductivity of the downhole fluid at the points of their installation in the borehole. Each device with a sensor is a solid state nonvolatile memory for storing the registered sensors in digital form and interface for transmission via the cable communication line to the surface for processing and visualization through, for example, a computer.

Sources of information

1. EN 2018644 C1, 30.08.94.

2. EN 2077735 C1, 20.04.97.

3. EN 2165517 C1, 20.04.2001.

1. The oil extraction method, including the descent into the well liner placed on it in its length sensors temperature, conductivity and pressure, at least the latter of which is used in an amount of not less than three and placed at fixed distances from each other, and then continuously throughout the overhaul life of the well fix it the temperature, the conductivity of the borehole fluid, the absolute value of the bottomhole pressure and the pressure difference on the well depth in the zone of the reservoir using different combinations of the combinations of pairs of pressure sensors to determine the private and the average density of the downhole fluid and at the absolute bottom-hole pressure below the saturation pressure of the downhole fluid passing gas and/or the deviation of the average values of the density of wells is different fluid and/or electrical conductivity from the established limits of the control mode of the well.

2. The method according to p. 1, characterized in that hole down deep pump, and the shank down to pump deep, with sensors placed on the shank along its length and above receiving the downhole pump.

3. The method according to claim 1 or 2, characterized in that the private value density of the produced fluid (ρ, g/cm3) is determined by the value

where ΔP is the pressure difference along the depth of the borehole between the pressure sensors in the selected combinations combinations of pairs of sensors, g/cm3;

g is the acceleration of gravity (g = 9,8 ), cm/s2;

ΔNabs- the vertical distance between the pressure sensors in the selected combinations combinations of pairs of sensors, see

4. The method according to one of paragraphs. 1-3, characterized in that the water content of the downhole fluid (Vin, %) advanced control ratio

where ΔP is the pressure difference between the pressure sensors in the selected combinations combinations of pairs of sensors, MPa;

g is the acceleration of gravity (g = 9,8 ), cm/s2;

ΔH is the vertical distance between the pressure sensors in the selected combinations combinations of pairs of sensors, cm;

α - the angle of the wellbore in the area between the pressure sensors in the selected combination of the combination of the pairs of sensors, deg;

ρnthat ρinthat ρf~ density, respectively, of oil, water, borehole fluid, g/cm3,

V - volume of water.

5. The method according to one of paragraphs. 1-4, characterized in that the measurement data to encode digital information, which is remembered and stored in electronic memory block and, as necessary, transmitted to the surface via the cable communication line for processing and visualization.

6. Device for controlling downhole temperature and pressure parameters of the fluid in the extraction of oil, including a string of pipe for lifting the oil, the shank of the pipe, or cable, or rope length up to the roof of the reservoir, temperature sensors, conductivity and pressure placed on the shank, all sensors have a cable line connection to the surface, and the pressure sensors in the amount of not less than three placed at fixed distances from each other, are made with the possibility of continuous measurement of time, temperature, electric conductivity of borehole fluid, the absolute value of the pressure and pressure drop along the length of the shank in the zone of the reservoir between the pairs of sensors pressure at various combinations of these pairs.

7. The device according to p. 6, characterized in that it has a submersible pump that is hydraulically connected with the column pipe, and the shank is rigidly connected with the bottom h is STU deep pump, when the sensors are placed on the shank and above receiving the downhole pump column pipe for lifting oil.

8. The device according to claim 6 or 7, characterized in that it is provided with single-wire cable line to the surface.

9. Device according to one of paragraphs. 6-8, characterized in that it is equipped with an electronic memory unit for storing the measured parameters in the form of digital information and an interface for transmitting information to the surface for visualization and processing.



 

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25 cl, 1 tbl, 3 ex

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