SU1717807A1 - Liquid lever inrlicator in well equipped with well plunger pump - Google Patents

Description

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The invention relates to the field of oil production, in particular, devices for determining the level of a liquid, mainly in low-production oil wells equipped with submersible plunger pumps.

The aim of the invention is to increase the reliability of operation and improve the accuracy of determining the level of fluid in the well.

Fig. 1 shows a level indicator of a fluid in a well equipped with a submersible plunger pump, the level of the fluid above the receiving part of the pump, a cross section; figure 2 - the same, the liquid level below the receiving part of the pump.

Liquid level indicator in a well equipped with a deep plunger

the pump comprises a housing 1 with inlets 2 formed on the side surface of the housing 1 of the indicator. Outside, the indicator housing 1 is enclosed by an annular damper 3, which is installed opposite the inlet openings 2. The damper 3 is attached by means of a pull 4 to the float 5. Which is also mounted outside the indicator housing 1 with its ability to move along with the damper 3 along the indicator housing 1. The float 5 is made hollow in the form of a torus.

The housing 1 and the flap 3 of the liquid level indicator can be made in the form of an expanding cone to more reliably block the inlets 2. The indicator housing 1 is connected to the housing b of a submersible plunger pump, for example. using adapter 7. At the same time, VJ 00

About vj

A borehole space 8 through the inlets 2 in the indicator housing 1, the inner cavity 9 of the indicator, the suction valve 10 of the submersible pump is connected to the injection cavity 11 of the submersible pump. The volume of the discharge cavity 11 is determined by the stroke of the pump plunger 12,

A buoyant force directed upward acts on the submerged floatB, tu 4 and the flap 3, the buoyancy force Pb for the float 5, the pull 4 and the flap 3 are determined by the expression

FB (Vi + V2 + V3) p g,

where Vi is the volume of liquid displaced by the float, m3;

V2 — volume of the displaced by a throat fluid, m3;

UZ- volume of the fluid displaced by the valve, m3;

p is the density of the liquid, kg / m;

q is the acceleration of free fall,. ..

Due to the fact that the weight of the float 5, the weight 4 and the damper 3 is less than the buoyancy force Pb, the float 5 with thrust 4 and the damper 3, completely immersed in the liquid, are suspended in it.

The level indicator works as follows.

The submersible plunger pump and the liquid level indicator on the pump-compressor pipes 13 are lowered into the well under the dynamic fluid level. During normal pump flow, when the level of fluid in the annulus 8 of the well is significantly higher than the intake of a submersible pump, the indicator float 5 pops up and carries the valve 3 with it. At the same time, the inlets 2 in the indicator housing 1 are open to allow the produced fluid to pass (figure 1). As the plunger 12 of the submersible pump moves upward, the suction valve 10 opens, the fluid out. annulus 8 enters the injection cavity 11 of the submersible pump. As the plunger 12 moves downward, the pumped liquid is forced out of the injection cavity 11 through the discharge valve 14 and is brought to the surface through the tubing string 13 at the next upward stroke of the plunger 12.

When the level of fluid in the annulus 8 of the well drops to the receiving part of the pump and below, the weight of the float 5, tons of 4 and valve 3 will be greater than the buoyancy force RB. The valve 3 goes down and overlaps the inlets 2 of the level indicator (Fig. 2). Thus, the internal cavity 9 of the indicator and the injection cavity 11 of the submersible pump will be separated from the annulus 8 of the well. When the fluid level exceeds

the receiving part of the pump. and with the suction valve open, the load on the polished rod of the deep-pumping installation is equal to the weight of the pump rods in the liquid, the weight of the liquid column in the pump-compressor

pipes and frictional force when the plunger moves upwards relative to the pump cylinder. With the suction valve closed and the discharge valve open, the load on the polished rod is equal to the weight of the pumping

rods in the fluid minus the friction force when the plunger moves down relative to the pump cylinder. The process of receiving loads and unloading loads is recorded, for example, by a torque sensor. Moreover, the dependence of the load on the polished rod on the stroke of the plunger, perceived by the sensor, during normal pump flow has the form of an incorrect parallelogram, two opposite sides of which are shifted by the amount of weight of the liquid column.

When the fluid level in the well is lower at the pump inlet, with the inlets 2 closed, the load on

the polished rod will be equal to the weight of the pump rods minus the pressure on the vacuum in the discharge cavity 11 and the force of friction at the output of the plunger 12 down relative to the pump cylinder. When the pump plunger travels upwards with the intake of a deep pump injected, the load on the polished rod will be equal to the weight of the liquid column in the tubing, the weight of the pump rods in the liquid plus additional

the force determined by the magnitude of the vacuum in the discharge cavity 11 of the submersible pump and the internal cavity 9 of the indicator liquid level.

Since the produced fluid is

gas-containing (density of oil in reservoir conditions is 0.640 g / cm3; density in surface conditions is 0.810 g / cm3; oil gas saturation in field conditions is 325 m / t; volume coefficient

1,720; oil saturation pressure of gas 182 kgf / cm2), then Boyle-Mariott’s law

Pi Vi P2 V2, where Pi is the pressure of the gas-liquid mixture in

pump cylinder at the lower position of the plunger;

Vi is the volume of the injection cavity of the submersible pump under the plunger at its lower position;

V2 is the volume of the injection cavity of the deep pump with the upper position of the plunger of the deep pump:

P2 is the pressure of the gas-liquid mixture in the discharge cavity of the submersible pump when the plunger of the submersible pump is in the upper position.

Consequently, the pressure in the injection cavity 11 of the submersible pump and in the internal cavity 9 of the indicator, upon the fact that there are no leaks, is equal to Pi Vi

P2

V2

The additional force caused by the vacuum in the discharge cavity 11 of the submersible pump is equal to

with Р1 (V2-Vi) Рдоп--S V2

Thus, the appearance of an additional load in the cycle of the downhole pump installation, depending on the magnitude of the vacuum in the discharge cavity, will make it possible to judge reliably the level

no fluid relative to the intake pump. Moreover, the dependence of the load on the stroke of the polished rod, having the shape of a narrow slot, indicates a decrease in the level of the liquid below the pump intake.

The level of the load sensing line and the level of the load shedding in the resulting loop (i.e., in the resulting plot of load versus polished rod stroke), due to the additional force produced by the vacuum in the discharge cavity 11, makes it possible to unambiguously determine the fluid level relative to receiving part of the pump.

The signal on the level of the fluid in relation to the receiving part of the pump from the output of the load cell is transmitted to the control room to make a decision on the well operation. When the fluid level falls below the inlet part of the submersible pump, the motor of the downhole pump unit is disconnected from the network for the time of accumulation of fluid in the well.

1

Editor A. Motyl

Tehred M. Morgenthal

Order 862Tirage- Subscription

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow. Zh-35, Raushska nab., 4/5

Production and Publishing Combine Patent, Uzhgorod, Gagarin st., 101

2

Proofreader M. Demchik

Claims (2)

(54X57) 1. LIQUID LEVEL INDICATOR IN A WELL EQUIPPED WITH A DEPTH PUMP PUMP, comprising a housing with inlet openings 2, mi and a float, characterized in that. in order to increase the reliability of operation and improve the accuracy of determining the liquid level, it is equipped with an adapter and an annular valve with a draft, and the float is made in the form of a hollow torus, and the float and annular valve cover the indicator housing and are interconnected by a rod, while the valve is located with the possibility of overlapping the inlet openings of the indicator housing, and the latter is rigidly connected through an adapter to the pump housing. 2. The indicator according to claim 1, with the fact that the indicator housing and the annular damper are made in the form of expanding cones.