RU2571321C1 - Method of determination of dynamic level in annulus of water cut gas well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: calculation device of the information and measuring system of the water cut gas well receives the signals from the pressure and temperature transmitters at the wellhead annulus output and at well bottomhole at input of the centrifugal pump, gas flowrate, gas and liquid densities. At that the liquid dynamic level is determined as per the iteration algorithm of successive approximation of the bottomhole pressure $$P_{\text{bottomhole}}^{calc}$$

from wellhead till its equality to the measured bottomhole pressure P_bottomhole as per hydraulic dynamic formulas.

EFFECT: method of determination of the liquid dynamic level in annulus of the water cut gas well based on the designed information and measuring system by means of measurement of the product parameters at the bottomhole and wellhead.

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Description

The invention relates to the gas industry and can be used to determine the dynamic fluid level in the annulus between the production string and tubing, waterlogged gas wells during the pumping of formation fluid by submersible electric centrifugal pumps (ESP).

Monitoring the level of various liquids is one of the most common tasks in various technological processes. This is the reason for a wide variety of level control methods based on ultrasonic, radar and other methods.

The closest to the achieved result is a method for determining the liquid level in an oil well with an ESP acoustic level gauge (echo sounder), which generates a pulsed acoustic signal at the wellhead in the annulus, receives an acoustic echo reflected from the liquid, converts it into an electrical signal and determines the acoustic transit time the signal from the wellhead to the fluid level (RF Patent No. 2447280, IPC Е21В 47/047, G01F 23/296. Method for determining the level of fluid in an oil well, publ. 10.04.2 012 g.). The described method is adopted as a prototype of the invention.

However, this method has drawbacks, since the accuracy of determining the level of a liquid from an echo sounder is mainly due to the accuracy of fixing the speed of sound in a well, depending on the design of the echo sounder and the physicochemical properties of the liquid, gases, and foam in the well (pressure, temperature, composition , concentration, etc.). Also, the large curvilinearity of the borehole, the eccentric location of the tubing due to the location of the ESP supply cable in the annulus, have a distorting effect on the measurement results with an echo sounder. Separate production of products from flooded gas wells through the use of ESPs involves pumping liquid through a tubing and producing gas through the annulus, which leads to the formation of foam on the surface of the liquid in the annulus of the well and disruption of the echo sounder, since the upper point of the foam column is fixed, Assuming that this is the liquid level, the actual liquid level is below the foam and remains unmeasured.

The technical result of the present invention is to provide a method for determining the dynamic fluid level in the annular space of a waterlogged gas well based on the developed information-measuring system by measuring production parameters at the bottom and well head.

от устья скважины до его равенства измеренному значению забойного давления по зависимостиIn the proposed method for determining the dynamic fluid level in the annular space of a waterlogged gas well using an information-measuring system, including receiving signals from sensors: pressure and temperature at the outlet of the annular space of the wellhead and at the bottom of the well at the entrance to the centrifugal pump, gas flow, the densities of gas and liquid, determine the dynamic level of the fluid N _din according to the iterative algorithm of successive approximations of the bottomhole pressure $$P_{s\mathrm{but}b}^{R\mathrm{but}\mathrm{from}h}$$

from the wellhead to its equality to the measured value of the bottomhole pressure according to

- расчетное значение забойного давления в МПа;Where $$P_{s\mathrm{but}b}^{R\mathrm{but}\mathrm{from}h}$$

- the estimated value of the bottomhole pressure in MPa;

ρ _W - the density of the liquid in kg / m ³ ;

H _Zab - the bottom hole depth at the entrance to the centrifugal pump in m;

H _din - the calculated value of the dynamic fluid level in the annulus of the well in m, to a first approximation, equal to the value of the depth H _zab ;

P _din - the calculated value of the pressure in MPa corresponding to the dynamic level of the liquid, determined on the basis of the hydrodynamic formula G. Adamova (Guide to well research / A.I. Gritsenko [et al.]. - M .: Nauka, 1995. - 523 p.)

where P _y is the measured pressure at the outlet of the annulus of the wellhead in MPa;

λ _g - coefficient of hydraulic resistance of the gas;

_Wed T - average between the measured temperature T products on the mouth and _at the bottom of the well in _Zab T K;

Z _cf - coefficient of supercompressibility of the gas mixture;

Q _g - the measured value of the gas flow in thousand m ³ / day;

d _e is the equivalent diameter of the annulus in mm;

S _article , S _din - parameters calculated by the expressions:

- относительная по воздуху плотность газа, которая вычисляется на основе значения плотности газа ρ_г в кг/м³;Where $$\overline{{\rho }_g}$$

- relative air density of the gas, which is calculated on the basis of the gas density ρ _g in kg / m ³ ;

L is the length of the tubing from the wellhead to a depth of H _dyne in m.

The invention is illustrated in the drawing, which shows a diagram of the determination of the dynamic fluid level in the annular space of a flooded gas well with an information-measuring system for controlled pumping of formation fluid.

от устья скважины до его равенства давлению P_заб по приведенным выше формулам.The method is as follows, the computing device 8 of the information-measuring system of a water-cut gas well receives signals from sensors at the wellhead: P _y , T _y , Q _g , ρ _g — pressure, temperature, flow rate, and gas density, respectively, from manometer 1, thermometer 2 , a flow meter 3 and a device for sampling gas 4 installed at the outlet of the annulus, ρ _W is the density of the liquid from the device for sampling the liquid 5, located at the outlet of the tubing, and from the sensors at the bottom of the well: P _zab , T _zab - pressure and t the production temperature at the bottom of the well from the pressure gauge 6 and thermometer 7 and determines H _din - the dynamic fluid level according to an iterative algorithm of successive approximations of the bottomhole pressure value $$P_{s\mathrm{but}b}^{R\mathrm{but}\mathrm{from}h}$$

from the wellhead to its equal pressure P _zab according to the above formulas.

Based on the foregoing, with the measured values of the parameters of the vertical well production (bottom hole depth H _zab equal to 1621 m, tubing length L is 1621 m, tubing outer diameter is 73 mm, production casing inner diameter is 161.8 mm, equivalent annulus diameter d _e is equal to 137.8 mm): the pressure at the exit of the annulus of the wellhead Р _у is 5.91 MPa, the production temperature at the wellhead Т _у is 281.1 K, the gas flow rate Q _g is 63 thousand m ³ / day, the density of the gas ρ _g is 0.73 kg / m ³ , the density of the liquid ρ _g is 1170 , 00 kg / m ³ , pressure at the bottom of the well P _zub equal to 8.23 MPa, temperature of production at the bottom of the well T _zb equal to 300.8 K, as a result of iterative calculations according to the formulas proposed above, the values of the parameters were determined: coefficient of supercompressibility of the gas mixture Z _cp equal to 0.814, the coefficient of hydraulic resistance of the gas λ _g is equal to 0.0182, the average temperature T _cf is equal to 290.9 K, the pressure corresponding to the dynamic level of the liquid, P _dyne is 6.61 MPa, and the dynamic level of the liquid H _dyne is 1486.4 m The error of pressure gauges is ± 0.1%, of thermometers ± 0.25%, flow meter 0.3%.

The specified method for determining the dynamic liquid level in the annulus of a waterlogged gas well can be applied to gas condensate fields that are at a late stage of development.

Such a task is especially relevant for wells stopped due to flooding, but having the potential to produce products using an electric centrifugal pump for pumping formation fluid. The use of this method is undergoing trial operation at OOO Gazprom dobycha Orenburg at the Orenburg oil and gas condensate field.

Claims (1)

A method for determining the dynamic liquid level in the annular space of a waterlogged gas well using an information-measuring system, which includes receiving signals from sensors: pressure and temperature at the outlet of the annular space of the wellhead and at the bottom of the borehole at the entrance to the centrifugal pump, gas flow, gas densities and fluid, characterized in that the dynamic fluid level H _dyn is determined by an iterative algorithm of successive approximations of the bottomhole pressure $$P_{s\mathrm{but}b}^{R\mathrm{but}\mathrm{from}h}$$

from the wellhead to its equality to the measured value of the bottomhole pressure P _zab according to

Where $$P_{s\mathrm{but}b}^{R\mathrm{but}\mathrm{from}h}$$

- estimated value of bottomhole pressure, MPa;
ρ _W - the density of the liquid, kg / m ³ ;
H _zab - the bottom hole depth at the entrance to the centrifugal pump, m;
H _din - the calculated value of the dynamic fluid level in the annulus of the well, m, in the first approximation is equal to the value of the depth H _zab ;
P _din - the calculated value of the pressure in MPa corresponding to the dynamic level of the liquid, determined on the basis of the hydrodynamic formula G. Adamova

where P _y is the measured pressure at the outlet of the annulus of the wellhead, MPa;
λ _g - coefficient of hydraulic resistance of the gas;
T _cf - the average between the measured production temperatures at the mouth of T _y and the bottom T of the _{bottom of the} well, K;
Z _cf - coefficient of supercompressibility of the gas mixture;
Q _g - the measured value of the gas flow, thousand m ³ / day;
d _e - the equivalent diameter of the annulus, mm;
S _article , S _din - parameters calculated by the expressions:

Where $$\overline{{\rho }_g}$$

- relative air density of the gas, which is calculated on the basis of the gas density ρ _g , kg / m ³ ;
L is the length of the tubing from the wellhead to a depth of H _din , m

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