RU2330947C1 - Methods of influx stimulation out of bed by means of reducing level of well fluid of new and repaired oil flowing wells with following maintaining of static level - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention refers to oil and gas industry, particularly to methods of influx stimulation of fluids out of a bed of producing oil, gas and gas condensate wells and can be used at development and stimulation of influx. This method provides reduction of bottom hole pressure and stimulation of bed fluid influx as well as upgraded efficiency of maintaining of constant gas effect onto a payout bed. The essence of the invention is as follows: the method consists in creating depression onto a bottom hole zone of the bed in a bored and cased well with the column of oil well tubing; the said depression is created by means of reduction of the level of well fluid with a gaseous medium, pumped into the annular space of the column of oil well tubing. As a working gas, neutral gas is pumped into the annular space of the column of oil well tubing of the well, the said annular space is filled with fluid. Neutral gas produces effect onto filling fluid of the annular space of the well under pressure of 150-600 kgm (kilogram-force)/cm² and with output of this gas supply of 10-1200m³/h with a following displacement of well fluid with neutral gas up to a bearing plate of lifting pipes and with reduction of gas fluid mixture density. Simultaneously the level of well fluid is raised up to a hole mouth and part of it is thrown off. At that priming pressure of neutral gas is reduced. Then, in the process of reducing well fluid level, pressure of working gas is steadily increased to the level of priming pressure, which is calculated on an analytic form. Maximum pressure of neutral gas is calculated with consideration of the depth of a kickoff valve installation. At that maximum priming pressure of neutral gas in a well exceeds working pressure of neutral gas pumping in the process of normal operation of well.

EFFECT: facilitates reducing of bottom hole pressure and stimulation of bed fluid influx at oil well development as well as increased efficiency of maintaining constant gas effect onto a payout bed.

3 cl, 1 ex

Description

The invention relates to the field of the oil and gas industry, and in particular to methods of stimulating the influx of formation fluid from the reservoir of new and repaired producing oil, gas and gas condensate wells, and can be used in the development and intensification of the flow of oil, gas and gas condensate wells by lowering the hydrostatic level of the fluid in the annulus the space of the tubing string and the subsequent maintenance of the level at a certain point.

There is a method of causing inflow from a formation by lowering the level of a borehole fluid, including creating a depression on the bottomhole formation zone in a drilled and cased well with a string of tubing in it by lowering the level of the borehole fluid by displacing it with a gaseous medium pumped into the annulus of the tubing string (see RF patent No. 2095560, IPC ЕВВ 43/27, 1997).

However, the known method of causing inflow from the reservoir has the following disadvantages:

- a slight increase in the productivity of the influx of reservoir fluid,

- has a sufficiently high bottomhole pressure,

- lack of effectiveness in maintaining a constant gas impact on the reservoir during the further operation of the well.

The objective of the invention is to provide a method of intensifying the influx from the reservoir by lowering the level of the borehole fluid of new and repaired oil fountain wells, followed by maintaining a static level.

The technical result is to reduce bottomhole pressure and intensify the influx of formation fluid, as well as increase the efficiency of maintaining a constant gas impact on the reservoir.

The technical result in the implementation of the invention is achieved by the fact that the proposed method of stimulating the inflow from the reservoir by lowering the level of the borehole fluid of new and repaired oil flowing wells with subsequent maintenance of a static level, including creating a depression on the bottom-hole formation zone in a drilled and cased well with a tubing string in her by lowering the level of the well fluid by displacing it with a gaseous medium pumped into the annulus of the pump-compressor column weed pipes, while as a working gas, neutral gas is pumped into the annular space of the tubing string of the well, the neutral fluid under the pressure of 150-600 kgf / cm ² and productivity will be applied to the filling fluid of the annulus of the tubing string of the well. the supply of neutral gas of 100-1200 m ³ / hour, followed by the displacement of the borehole fluid with neutral gas in the gas supply line to the shoe of the lifting pipes and lowering the density of gas-liquid the mixture with a simultaneous increase in the level of the well fluid to the mouth and the release of a part thereof, while the starting pressure of the neutral gas is reduced, then in the process of decreasing the level of the well fluid in the supply line of the neutral gas to the shoe of the lifting pipes and increasing the level of the gas-liquid mixture in the lifting pipes to the mouth monotonously increase working gas pressure to the value of the starting pressure, while the starting pressure of the neutral gas is previously calculated by the formula:

where h is the immersion depth of the pipes under the static level, m;

ρ is the density of the liquid, t / m ³ ;

g is the acceleration of gravity, m / s ² ;

D is the inner diameter of the production casing, mm;

d is the inner diameter of the lifting pipes, mm, the distance from the wellhead to the installation location of the first valve is calculated by the formula:

where L is the distance from the wellhead to the installation location of the first valve, m,

h article - the distance from the wellhead to the static level, m,

P max - the maximum pressure of a neutral gas, MPa,

ρ is the density of the liquid, t / m ³ ,

the maximum neutral gas pressure is calculated taking into account the installation depth of the start valve according to the formula:

where P max - the maximum pressure of the neutral gas, MPa,

ρ is the density of the liquid, t / m ³ ,

g - acceleration of gravity, m / s ² ,

D is the inner diameter of the production string, mm,

d is the inner diameter of the lifting pipes, mm,

L is the distance from the wellhead to the installation location of the first valve, m,

h article - the distance from the wellhead to the static level, m,

in this case, the highest starting pressure of neutral gas in the well exceeds the working pressure of the injection of neutral gas in the normal operation of the well. In this case, nitrogen, helium or argon is used as a neutral gas well pumped into the annular space of the tubing string of the pumped tubing filled with liquid. At the same time, oil is additionally pumped onto a “pillow” of neutral gas pre-pumped into the well until the neutral gas reaches the pump shoe and “slip”, and the oil column pressure is calculated by the formula:

Rzh = 0,1 · ρ · N,

where ρ is the density of the liquid, t / m ³ ,

H is the height of the oil column.

Among the essential features characterizing the method of stimulating the inflow from the reservoir by lowering the level of the borehole fluid of new and repaired oil fountain wells with subsequent maintenance of a static level, the following are distinguishing:

- injection as a working gas into the annular space of the tubing of a neutral gas well filled with liquid,

- the impact on the filling fluid of the annulus of the tubing string of the well with neutral gas at a pressure of 150-600 kgf / cm ² and a neutral gas feed rate of 100-1200 m ³ / h,

- displacement of the borehole fluid with neutral gas in the gas supply line to the shoe of the lifting pipes and lowering the density of the gas-liquid mixture with a simultaneous increase to the mouth of the borehole fluid level and the release of its part, while the starting pressure of the neutral gas is reduced,

- in the process of reducing the level of the borehole fluid in the neutral gas supply line to the shoe of the lifting pipes and increasing the level of the gas-liquid mixture in the lifting pipes to the mouth, a monotonic increase in the neutral gas pressure to the starting pressure value,

- preliminary calculation of the starting pressure of neutral gas according to the formula:

where h is the immersion depth of the pipes under the static level, m,

ρ is the density of the liquid, t / m ³ ,

g - acceleration of gravity, m / s ² ,

D is the inner diameter of the production string, mm

d is the inner diameter of the lifting pipes, mm, is the calculation of the distance from the wellhead to the installation location of the first valve according to the formula:

where L is the distance from the wellhead to the installation location of the first valve, m,

h article - the distance from the wellhead to the static level, m,

P max - the maximum pressure of a neutral gas, MPa,

ρ is the density of the liquid, t / m ³ ,

- calculation of the maximum pressure of the neutral gas, taking into account the installation depth of the start valve according to the formula:

where P max - the maximum pressure of the neutral gas, MPa,

ρ is the density of the liquid, t / m ³ ,

g - acceleration of gravity, m / s ² ,

D is the inner diameter of the production string, mm,

d is the inner diameter of the lifting pipes, mm,

L is the distance from the wellhead to the installation location of the first valve, m,

h article - the distance from the wellhead to the static level, m,

the highest starting pressure of neutral gas in the well exceeds the working pressure of the injection of neutral gas in the normal operation of the well,

- the use of nitrogen, helium or argon as injected into the liquid-filled annulus of the tubing string of a neutral gas well,

- an additional injection of oil onto a “pillow” of neutral gas previously pumped into the well until the neutral gas reaches the shoe of the tubing and obtains “slip”, the oil column pressure being calculated by the formula:

Rzh = 0,1 · ρ · N,

where ρ is the density of the liquid, t / m ³ ,

H is the height of the oil column.

The method is as follows.

Before start-up, the well is filled with liquid (degassed oil, killing fluid or water), the level of which corresponds to the reservoir pressure. Liquid is displaced by selling with working gas, while neutral gas is pumped into the annular space of the well tubing string filled with water, neutral gas is applied to the annular space of the well tubing string with neutral gas at a pressure of 150-600 kgf / cm ² and output feed neutral gas 100-1200 ^m3 / h, followed by displacement of the wellbore fluid with inert gas in the gas supply line to the shoe lifting tubes lowering the density of gas-liquid mixture while increasing the mouth of the borehole fluid level and the ejection part.

In this case, nitrogen, helium or argon is used as a neutral gas well pumped into the annular space of the tubing string of the pumped tubing filled with liquid.

Starting pressure of neutral gas is preliminarily calculated by the formula:

where h is the immersion depth of the pipes under the static level, m,

ρ is the density of the liquid, t / m ³ ,

g - acceleration of gravity, m / s ² ,

D is the inner diameter of the production string, mm,

d is the inner diameter of the lifting pipes, mm

The highest starting pressure of neutral gas in the well exceeds the working pressure of the neutral gas injection during the normal operation of the well.

The starting pressure of the neutral gas is reduced and then the pressure of the neutral gas is monotonically increased to the value of the starting pressure in the process of lowering the level of the borehole fluid in the neutral gas supply line to the shoe of the lifting pipes and increasing the level of the gas-liquid mixture in the lifting pipes to the mouth.

The distance from the wellhead to the installation location of the first valve is calculated by the formula:

where L is the distance from the wellhead to the installation location of the first valve, m,

h article - the distance from the wellhead to the static level, m,

P max - the maximum pressure of a neutral gas, MPa,

ρ is the density of the liquid, t / m ³ .

The maximum neutral gas pressure is calculated taking into account the installation depth of the start valve according to the formula:

where P max - the maximum pressure of the neutral gas, MPa,

ρ is the density of the liquid, t / m ³ ,

g - acceleration of gravity, m / s ² ,

D is the inner diameter of the production string, mm,

d is the inner diameter of the lifting pipes, mm,

L is the distance from the wellhead to the installation location of the first valve, m,

h article - the distance from the wellhead to the static level, m

If the calculated starting pressure exceeds the pressure of the operating column, then to prevent the column from rupturing the “pillow” of neutral gas previously pumped into the well, oil is additionally pumped into the well until the neutral gas reaches the shoe of the tubing and obtain “trapping”, moreover, the pressure oil column calculated by the formula:

Rzh = 0,1 · ρ · N,

where ρ is the density of the liquid, t / m ³ ,

H is the height of the oil column.

Experimental studies and the practice of operating the proposed method of stimulating the inflow from the reservoir by lowering the level of the borehole fluid of new and repaired oil fountain wells with subsequent maintenance of the static level showed its high efficiency. Using all the essential features of the proposed method, the bottomhole pressure was reduced, the influx of formation fluid was significantly intensified, and the efficiency of maintaining a constant gas impact on the reservoir was achieved.

The implementation of the proposed method of stimulating the inflow from the reservoir by lowering the level of the borehole fluid of new and repaired oil fountain wells with subsequent maintenance of a static level is illustrated by the following examples of implementation

Example 1. Work was carried out to intensify production of a well with a column diameter of 146 mm, taking into account the static level of the borehole fluid, reservoir pressure, bottomhole pressure, oil density, water cut, reservoir type, porosity and permeability, initial and present flow rate, depth of the current bottom and pressure of pressure production casing.

A gasification installation, for example, AGU-2M, was mounted and grounded at the well, tied to the annulus of the well using shut-off and gas relief valves, safety and non-return valves, pressure gauges and connecting fittings. Then, the neutral gas injection line was pressed at one and a half times the working pressure. Nitrogen was used as the working gas. We checked the operation of the gasification system with a test switch.

Taking into account all the technological characteristics of this well, the starting pressure, the distance from the wellhead to the installation site of the first valve, and the maximum nitrogen pressure, taking into account the installation depth of the starting valve, were previously calculated according to the method proposed in the method.

By injecting nitrogen into the annulus of the well under a pressure of 600 kgf / cm ² and a productivity of 100 m ³ / h, a depression was created on the bottom hole zone of the formation in a drilled and cased well with a tubing string in it.

Achieved a decrease in the level of the well fluid by displacing it with a gaseous medium and lowering the density of the gas-liquid mixture with a simultaneous increase to the mouth of the level of the well fluid and the ejection of part of it. Got a "prohvat" - exit from the tubing of a gas bubble. Reduced starting pressure of nitrogen. Then, in the process of lowering the level of the borehole fluid in the nitrogen supply line to the shoe of the lifting pipes and increasing the level of the gas-liquid mixture in the lifting pipes, the nitrogen pressure monotonically increased to the starting pressure value to the mouth.

Achieved intensification of the influx of reservoir fluid from the reservoir by 15-18%. At the same time, the efficiency of maintaining a constant gas impact on the productive formation of the well has been increased.

Example 2. Work was carried out on the development of a well with a diameter of 168 mm, taking into account the static level of the borehole fluid, reservoir pressure, bottomhole pressure, oil density, water cut, reservoir type, porosity and permeability, depth of the current bottom and pressure of the commissioning of the commissioned string.

A gasification installation, for example, AGU-2M, was mounted and grounded at the well, tied to the annulus of the well using shut-off and gas relief valves, safety and non-return valves, pressure gauges and connecting fittings. Then, the neutral gas injection line was pressed at one and a half times the working pressure. Argon was used as the working gas. We checked the operation of the gasification system with a test switch.

Taking into account all the technological characteristics of this well, the starting pressure, the distance from the wellhead to the installation site of the first valve, and the maximum argon pressure, taking into account the installation depth of the starting valve, were previously calculated according to the method proposed in the method.

By injecting argon into the annulus of the well under a pressure of 100 kgf / cm ² and a productivity of 1200 m ³ / h, a depression was created on the bottom-hole zone of the formation in a drilled and cased well with a string of tubing in it. Due to the fact that the calculated starting pressure exceeded the pressure of the crimping of the commissioned string, oil was pumped into the “pillow” of neutral gas that had previously been pumped into the well to prevent breakage of the string until the neutral gas reached the pump shoe and received “trapping”, moreover oil column pressure was calculated by the formula:

Rzh = 0,1 · ρ · N,

where ρ is the density of the liquid, t / m ³ ,

H is the height of the oil column.

Achieved a decrease in the level of the well fluid by displacing it with a gaseous medium and lowering the density of the gas-liquid mixture with a simultaneous increase to the mouth of the level of the well fluid and the ejection of part of it. Got a "prohvat" - exit from the tubing of a gas bubble. Reduced starting pressure of argon. Then, in the process of lowering the level of the borehole fluid in the argon supply line to the shoe of the lifting pipes and increasing the level of the gas-liquid mixture in the lifting pipes to the mouth, the argon pressure monotonously increased to the starting pressure.

We have reached the inflow of formation fluid from the developed reservoir in the calculated volume while effectively maintaining a constant gas effect on the productive formation of the well.

Claims (3)

1. A method of intensifying the inflow from the formation by lowering the level of the borehole fluid of new and repaired oil fountain wells with subsequent maintenance of a static level, including creating a depression on the bottom-hole zone of the formation in a drilled and cased well with a string of tubing in it by lowering the level of the borehole fluid by displacing it gas medium injected into the annulus of the tubing string, characterized in that as a working gas in a liquid-filled the annulus of the tubing string of the well is pumped with neutral gas, the annular space of the tubing of the tubing string of the well is injected with neutral gas at a pressure of 150-600 kgf / cm ² and a flow rate of neutral gas of 100-1200 m ³ / h followed by displacing the wellbore fluid with neutral gas in the gas supply line to the shoe of the lifting pipes and lowering the density of the gas-liquid mixture while increasing the wellbore fluid level to the mouth; and by ejecting a part of it, while the starting pressure of the neutral gas is reduced, then, in the process of lowering the level of the borehole fluid in the neutral gas supply line to the shoe of the lifting pipes and increasing the level of the gas-liquid mixture in the lifting pipes to the mouth, the neutral gas pressure monotonously increases to the starting pressure, while starting pressure of neutral gas (RP) is preliminarily calculated by the formula

where h is the immersion depth of the pipes under the static level, m; ρ is the density of the liquid, t / m ³ ; g is the acceleration of gravity, m / s ² ; D is the inner diameter of the production casing, mm; d is the inner diameter of the lifting pipes, mm, the distance from the wellhead to the installation location of the first valve is calculated by the formula

where L is the distance from the wellhead to the installation location of the first valve, m; h article - the distance from the wellhead to the static level, m; P max - the maximum pressure of a neutral gas, MPa; the maximum neutral gas pressure is calculated taking into account the installation depth of the start valve according to the formula

in this case, the highest starting pressure of neutral gas in the well exceeds the working pressure of the injection of neutral gas in the normal operation of the well. 2. The method according to claim 1, including the use of nitrogen, helium or argon as injected into the liquid-filled annulus of the tubing string of a neutral gas well. 3. The method according to claim 1, including the additional injection of pre-pumped into the well "pillow" of neutral oil gas until the neutral gas reaches the shoe of the tubing and obtain "trapping", while the pressure of the column of injected oil (Rzh) is calculated by the formula Рж = 0,1 · ρ · H, where H is the height of the oil column.