SU1296714A1 - Method of controlling operation of gas-lift well - Google Patents

Abstract

The invention relates to the field of the oil and gas industry and is intended for the gas-lift well operation method (C) to establish and maintain an optimal gas-lift process mode. The purpose of the invention is to increase the flow rate of C in liquid with continuous gas lift. Install the maximum depression on the reservoir and regulate the flow rate of the working gas. The minimum pressure value of the gas-liquid production C is determined in the interval from the bottom C to the point of entry of the working gas and the flow rate of the working gas corresponding to the pressure found is maintained. The pressure increment at any fixed point in the elevator interval from the bottom to the gas injection point is used for control purposes. The procedure for finding the optimal flow rate of the working gas, at which the minimum pressure, a (P, means the maximum depressions on the formation and flow rates of the well, can be single-step with yawing around the optimum or multi-step, based on direct or indirect measurements. to with about

Description

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The invention relates to a gas-lift method of operating a well, establishing and maintaining an optimal gas-lift process mode by controlling the flow rate of the working gas and can be used in the oil and gas industry.

The purpose of the invention is to increase the production rate of the well in liquid with continuous gas lift.

The transition of a gas lift from one steady state to another due to a change in the flow rate of the working gas can be divided into three steps, which differ in the speed of the process.

The first stage: a relatively fast flow in the high-pressure gas line from the flow regulating valve to the gas injection point (TVG), which begins immediately after changing the flow area of the valve from changing the flow rate after the valve and ends by changing the flow rate of the working gas at the level of the gas generator. The time constant of a stage is determined by the mode of gas flow by its physical parameters, the design of the gas channel to a gas turbine and is on the order of several tens of minutes.

The second stage: a transient process in a system involving a gas-liquid lift, when a change in pressure at the level of tug results in a change in the nature of the flow of the gas-liquid mixture in the lift, including annulus, due to a variation in the flow rate of the gas component of the flow. After this stage is completed, a new pressure distribution is established in the tubing string, which is determined by the new gas flow rate from the TAG to the estuary. The time constant is determined by the velocity velocity of the pressure wave in the gas-liquid flow and the flow rate also has an order of several dozens of minutes. .

The third stage: changing the mode in the system with the participation of the productive formation, when the new pressure distribution established after the previous phase is transmitted to the formation, the annulus and causes a change in the fluid flow. The time constant is determined by the piezoelectricity of the formation in

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well and is in the order of several hours.

The operation of the gas-lift well is controlled by the proposed method based on the prediction of the transition process in the third stage, according to the state that occurs in the system after the end of the first two.

For this, as the most informative and low-noise parameter, the pressure value of the mixture of the lift is used at any fixed point from the bottom to TVG inclusive.

The interaction between the second and third stages of the gas-lift transitional process when changing the flow rate of the working gas is carried out through a new pressure distribution in the column, which is unstable, as the formation reaction follows the flow rate of fluid and, consequently, all other parameters.

Let us assume that the new distribution, the lazy pressure of the second stage, is such that it entails an increase in the flow rate of the liquid in the third stage. This is only possible due to a decrease in the bottomhole pressure at the end of the second stage. In the area from the bottom to the TVG at this moment, the flow rate of the liquid phase has not changed, the gas flow rate has also practically not changed due to the first fact, the relative pressure increment in the column is small and, therefore, the effect of degassing can be neglected. The hydraulic losses in the interval from the bottom to the TVG at the beginning and end of the second stage are equal, which means that at the considered time, the pressure in the studied lift interval is characterized by a new distribution, such that its value is arbitrary at any fixed fixed point in this interval took place before changing the flow rate of the working gas.

Similarly, the case of reducing fluid production is considered.

Thus, a certain limited time interval after the implementation of the increment of the flow rate of the working gas carries information about the trend in the dynamics of the well fluid. Pressure increment in

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any fixed point of the lift interval from the bottom to a THB, defined as the difference between the pressure at that point before and after the change in the flow rate of the working gas, the latter measurement should be made at a time interval corresponding to the end of the second stage of the transient process control, it allows to make an assessment of the feasibility of the realized gas flow in terms of the dynamics of fluid production by a well.

The search for the optimal gas flow, based on tracking the dynamics of the technological parameters of fluids during their flow in the tail section of the tubing string, depending on the flow rate of the working gas, can be one-step with a yaw about the optimum (flow variation - determination of pressure increment, etc.) or multi-step (several flow points - pressure dependence on flow - minimum pressure and optimum flow - realization of optimum, based on direct measurements of pressure dynamics, or indirectly of the metering unit of the working gas flow rate in combination with wellhead pressure measurements in the annular space.

In practical use before

In the well method, the following results were obtained on the well.

The measurements were carried out under isothermal conditions, when the temperature of the working gas was 341 K, the flow rate changed from 13 to 70 thousand standard meters per day. It was experimentally established for the well that the maximum time of the transition process in the gas line and gas-liquid lift when measuring the flow rate of the working gas is 186 s.

The pressure in TVG (P) was determined by the indications of a pressure transducer installed on the high-pressure gas line up to the orifice of a diaphragm flow meter, taking into account the pressure drop across the diaphragm, the working gas line from the diaphragm to the wellhead and the pressure difference between the wellhead and the THG when gas moves through the annular space between pipes 21/2 and 4 to a depth of 2100 m. Working gas is introduced

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under the edge of the tubing string, the atmospheric pressure was equal to 1.019 kgf / cm.

An approximation of the pressure value at the level of the TVG from the flow rate of the working gas in the indicated interval of its change in the form

PP 60,530-0,02339 V +

+ 0.000309977, (V) kgf / cm2),

and

where Vj, is the working gas consumption, reduced to normal conditions, thousand nm / day.

If the required tuning accuracy is 10% (the optimal value of the flow rate of the working gas is determined from the indicated equation under the condition dPp / dV О, which gives (v) - 37.7286 thousand norms, m per dayJ, at this flow rate the pressure P is minimal, then , maximal depressions on the reservoir and well production rate, then the fixed value of the flow step:

d-i

 100

37.7286 3.77286 thousand, normal meters per day.

At the point (V /) 37.7286 thousand normal meters per day Pf 60.08876 kg / cm with Vo (Vo) ± d 37.7286 ± ± 3.7229 thousand standard, m per day Rp 60.09317 kg / cm, whence it follows that the functional step is H

 0.00416 kg / cm. I

On measuring instrument

Sapphire 22 DI model 2161 was set to a range of 25 kg / cm with a zero offset to a point of 50 kg / cm.

Since the main source of error of the Sapphire type converter is temperature drift, and the measurement cycle is of the order of several minutes, with a significant thermal inertia of the control object, the pressure threshold of 0.004 kg / cm against the background of 60 kg / cm is detected quite confidently.

Claims (1)

Invention Formula A method of controlling the operation of a gas-lift well by establishing a maximum depression on the formation and controlling the flow rate of the working gas, characterized in that, in order to increase the flow rate of the well 512967146 liquid at a continuous well to the point of entry of the working gas-lift, determine the minimum gas and maintain the flow rate of the working value of the gas-liquid gas pressure, which corresponds to the found well output in the interval from injection.