RU2232260C2 - Process of fluid lifting from well - Google Patents

Abstract

FIELD: oil production, extraction of oil carrying great amount of sand in stratal fluid and large curvature of well.

SUBSTANCE: process includes expulsion of fluid from cylinder of well pump by means of plunger making reciprocating motions in cylinder under action of energy of power plant put on wellhead. In correspondence with invention plunger is made of heavy fluid in which capacity zinc bromide-calcium bromide are used. Suction valve of well pump is linked to shank fitted with packer. This packer separates well fluid from heavy fluid. Translational motions of plunger are carried out by means of light fluid periodically injected by power pump into tubular annulus Backward motion of plunger is carried out thanks to difference in densities of heavy and light fluid and pressure at intake of well pump.

EFFECT: enhanced functional reliability of well pump under conditions of recovery of sand and other mechanical impurities, prolonged overhaul period, automatic pumping-out of fluid from well.

3 cl, 1 dwg

Description

The invention relates to the oil industry and can be used for oil production with a high content of sand in the reservoir fluid and a large curvature of the wells.

A known method of lifting fluid from a well, including displacing it from the cylinder of a deep pump using a plunger that performs reciprocating movements in the cylinder under the influence of the energy of the rocking machine through the rod string / N. Sidorov. Drilling and exploitation of oil and gas wells. M .: Nedra, 1982. - p.303-305 /.

The disadvantage of this method is the influence of mechanical impurities in the borehole fluid on the overhaul period, frequent breaks of the rods and the effect of the curvature of the well during its implementation.

A known method of lifting fluid from a well, including displacing it from the cylinder of a deep pump using a plunger that performs reciprocating movements in the cylinder using a hydraulic actuator under the influence of the energy of the power pump / Molchanov G.V. and others. Machinery and equipment for oil and gas production. - M .: Nedra, 1984. - p. 227-229 /.

The disadvantage of this method is the significant influence of mechanical impurities / sand / in the well fluid on the overhaul period of the deep pump as a result of mechanical impurities between the cylinder and the plunger.

A known method of lifting fluid from a well, comprising displacing fluid from a cylinder of a deep pump using a plunger that performs reciprocating movements in the cylinder under the influence of energy from a power pump installed at the wellhead. Moreover, the length of the cylinder is limited / L. Chicherov. and other Hydro-rod installations in the oil industry. M .: VNIIOENG. - 1985, p.1-3 /.

The disadvantage of this method, adopted by us as a prototype, is also the significant influence of solids / sand and salts / in the well fluid on the overhaul period of the downhole pump, because the plunger and cylinder wear and jam.

The objective of the present invention is to increase the reliability of the downhole pump in the conditions of removal of sand and other mechanical impurities, increasing the overhaul period.

EFFECT: reduced wear of a cylinder of a downhole pump under conditions of a high content of mechanical impurities in the well fluid.

The specified technical result is achieved by the fact that the rise of fluid from the well is also carried out by displacing it from the cylinder of the deep pump using a plunger that performs reciprocating movements in the cylinder, under the influence of the energy of the power pump installed on the wellhead, but new and different from the prototype the fact that the plunger is made of heavy fluid, and the translational movement of the plunger is carried out using a light fluid periodically pumped by a power pump into the annulus This is due to the difference in the return movement of the plunger due to the difference between the densities of the heavy and light liquids and the pressure at the intake of the deep pump, which depends on the depth of the pump descent, while the cylinder length is not limited.

As a heavy liquid, a solution of zinc bromide - calcium bromide is used. It is known that a solution of zinc bromide - calcium bromide is used for pumping oil and gas wells, for the second opening of productive formations, for washing gravel filters and for overhaul of wells.

The solution of the highest density / up to 2300 kg / m / differs in the absence of a solid phase. Appearance - a transparent, non-volatile liquid with a slight yellowish tint. The content of the main components: zinc bromide 54.0-58.0%, calcium bromide 19.0-22.0%. The crystallization temperature is at least -7 ° C. Solutions of zinc bromide - calcium bromide are stable over time, non-flammable, non-explosive. / Composite - directory. Equipment, materials and services for the oil and gas industry. T.1. - M., 1999 /.

The plunger is made of heavy fluid (solution), which prevents it from jamming in the cylinder, since sand from the borehole fluid cannot get between the cylinder and the plunger and does not require special treatment of the inner surface of the cylinder. As a light fluid, a borehole (formation) fluid or light oil is used. As a light fluid, as calculation shows, it is possible to use well fluid with a density of 900 kg / m ³ or light oil with a density of 850-860 kg / m ³ .

The ratio of the densities of the heavy and light liquids withstand recommended: ρ _tzh / ρ _LV> / = 2.0. At lower values of this ratio, it is necessary to reduce the depth of the pump, which makes its operation less efficient.

The frequency of oil production equipment operation cycles is set automatically in full accordance with the production capabilities of the well, i.e. based on the conditions for ensuring the intensity of fluid flow from the reservoir into the well.

As a power pump, you can use a piston, centrifugal or plunger pump.

The drawing shows a diagram of the implementation of the method of lifting fluid from the well.

The implementation scheme includes a deep pump 1, including a cylinder 2 with an open bottom, a plunger 3 made of heavy fluid, and a valve assembly 4 mounted between the cylinder 2 and the tubing string / tubing / 5. The valve assembly 4 contains a discharge valve 6 and a suction valve 7. A suction valve 7 is connected to a “liner” 8 provided with a packer 9, which separates the well fluid from the heavy fluid in the casing 10. The annular space 11 is connected to the output of the surface power pump 12, the input of which is connected to a tank 13 equipped with a level sensor 14. To control the operation of the power pump 12, the circuit is equipped with an automation unit 15 and a valve 16.

The annular space is understood to mean the space between the outer wall of the tubing and the inner wall of the casing.

The rise of fluid from the well is as follows.

After descent into the well on the tubing 5 of the downhole pump 1 with the valve assembly 4, the “liner” 8 is packaged by the packer 9 and the calculated volume of heavy fluid is pumped into / annular space 11, the level of which is set higher than the lower open end of the cylinder 2 of the downhole pump 1. For the translational movement of the plunger from the heavy fluid 3 in the cylinder 2 upward and pushing the well fluid therein by the power pump 12 additionally feeds light fluid from the reservoir 13 into the annular space 11. The valve 16 and the suction yuschy valve 7 closes and the discharge valve 6 opens. The liquid level in the tank 13 decreases and, when the minimum value is reached, the level sensor 14 sends a signal to the automation unit 15 to turn off the engine of the power pump 12 and at the same time open the valve 16. The pressure in the annular space 11 also decreases and part of the liquid from the annular space through the open the valve 16 is pushed into the tank 13 under the influence of a pressure equal to the sum of the pressures: at the intake of the downhole pump 1 / valve assembly 4 /, the pressure of the wellbore fluid column from the valve assembly to the level of the heavy fluid spine in the cylinder 2 deepwell pump 1 and a heavy fluid column pressure in the cylinder 2. In the reverse movement of the plunger 3 closes the discharge valve 6, the suction valve 7 is opened and wellbore fluid enters the cylinder. At the end of the stroke of the plunger from the heavy liquid 3 downward, the level of light liquid in the tank 13 reaches its maximum value and the level sensor 14 gives a signal to turn on the engine of the power pump 12 and close the valve 16. After this, the cycle repeats.

The method of lifting fluid from a well is described by the following mathematical expression.

The equation of equality of pressure at the end of the stroke of the plunger up is:

R _y + ρ _compress · g · N _ku + ρ _tf · g · h ₃ = P _n + ρ _false · g / N _ku + h ₃ /,

where P _y - pressure at the wellhead, MPa;

ρ _compress - the density of the borehole fluid, kg / m;

g is the acceleration of gravity, m / s;

N _ku - the distance from the mouth to the valve assembly 4, m;

ρ _tj is the density of the heavy liquid, kg / m;

h ₃ - the height of the heavy fluid in the cylinder, m;

P _n - the pressure of a light liquid on the surface developed by the pump 12, MPa;

ρ _LV - the density of a light liquid, kg / m ³ .

The equation of equal pressure at the end of the plunger down stroke is:

P _ol + ρ _compress · g · h ₁ + ρ _tf · g · h ₂ = ρ _false · g · / N _ku + h ₁ + h ₂ /,

where R _CR - pressure at the intake of the deep pump, MPa;

h ₁ - decrease in the height of heavy fluid in the cylinder or plunger stroke, m;

h ₂ - the height difference of the heavy fluid in the cylinder and annular space, m

With the initial data: P _y = 1.5 MPa, ρ _cr = 900 kg / m ³ , N _k = 1900 m, ρ _tf = 2300 kg / m ³ , h ₃ = 500 m, ρ _LV = 900 kg / m ³ , h ₁ = 50 m, h ₂ = 400 m and a well depth of 2500 m, we obtain P _n = 8.4 MPa, and P _ol = 11.3 MPa.

The above calculation shows the possibility of implementing the proposed method for certain values of the parameters of the deep and surface pumps.

Thus, the above information shows that when using the claimed invention, the following conditions are met.

The method of lifting fluid from wells is intended for use in the oil industry.

For the claimed method of lifting fluid from wells, as described in an independent claim, the possibility of its implementation using the described means and methods is confirmed.

An advantage of the invention is that the wear of the cylinder of the submersible pump and the risk of jamming it under conditions of a high content of mechanical impurities in the well fluid are reduced. In addition, automatic determination of pumping fluid from the well (the number of strokes of the reciprocating hydraulic plunger per unit time at a constant stroke length) is provided in exact accordance with the production capabilities of the well - with the rate of fluid flow from the formation into the well.

Claims (3)

1. The method of lifting fluid from the well, including displacing it from the cylinder of the deep pump using a plunger that performs reciprocating motion in the cylinder under the influence of the energy of the power pump installed on the wellhead, characterized in that the plunger is made of heavy fluid, the quality of which use zinc bromide - calcium bromide, the suction valve of the downhole pump is connected to a liner equipped with a packer that separates the well fluid from the heavy fluid in the casing, while translational movement of the plunger is performed using the light liquid pump power are periodically injected into annular space and the return movement of the plunger is effected by the difference in density the heavy and light liquids and intake pressure submerged pump. 2. The method according to claim 1, characterized in that the formation fluid or light oil is used as the light fluid. 3. The method according to claim 1, characterized in that the frequency of the cycles of oil production equipment is set automatically in full accordance with the production capabilities of the well.