RU2464416C1 - Method of initiating inflow from bed - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: proposed method consists in creating pressure sink in bottomhole formation zone in drilled and cased wells with flow string by decreasing well fluid level by displacing fluid by system of air and water phases to be forced through head wall. Said head wall is arranged at wellhead and made up of T-bend, ejector or aerator. Flow string is arranged in well so that its bottom end is located 1.5-2 m under perforation interval. Then, well is completely filled with process fluid. Inflow from bed is initiated on feeding water phase of 4.5-7 l/s and water phase of 120-130 l/s. System of said phases is injected into flow string annulus. After foam circulation indications, water phase feed is decreased to 1-1.5 l/s, maintaining gas-fluid circulation to keep well pressure sink for at least 3 h. In injecting gas-fluid mix, water phase feed is increased by 10-15% to improve gas inflow by ejector.

EFFECT: simplified mounting, higher efficiency.

1 dwg

Description

The invention relates to the oil and gas industry, and in particular to methods of creating depression on the formation using separate phase systems pumped into the well.

There is a method of causing inflow from the reservoir (patent RU No. 2095560, published in Bulletin No. 31 of November 10, 1997), which consists in creating depression on the bottom-hole formation zone in a drilled and cased well with a tubing string in it by reducing the level of the borehole fluid by displacing it with a separate system, one of which is air, of the phases pumped into the annulus of the tubing string.

The disadvantage of this method is the mixing of borehole and reservoir fluids, which reduces the quality and efficiency of development (call inflow) of the reservoir.

The closest is the method of causing inflow from the reservoir (patent RU No. 2209948, IPC 43/18, published in Bulletin No. 22 of 08/10/2003), which consists in creating depression on the bottom-hole zone of the formation in a drilled and cased well with a pump string -compressor pipes in it by lowering the level of the borehole fluid by displacing it with a separate system, one of which is air, of phases pumped into the annulus of the tubing string, while the air and water phases are pumped into the annulus of the tubing string , Which is passed through the well head, while the volume of the aqueous phase is determined from the relationship:

,

,

where V _p - the required volume of the aqueous phase of the injected phase system to lower the level by a certain amount of H, m;

V _c is the volume of fluid in the well of a certain diameter and depth H, m, with a tubing string placed in it;

а - well filling factor with a system of separate air and water phases,% (а = 33% for production casing with a diameter of 146 mm, a = 46% for production casing with a diameter of 168 mm);

k _in - displacement coefficient, i.e. the volume of the borehole fluid displaced by 1 m ^{3 of the} aqueous phase of the injected system (k _in = 1.6).

The disadvantages of this method are:

- firstly, the head is placed in the well, which creates additional difficulties in the process of installing equipment in the well and with subsequent sealing of pipes at the mouth;

- secondly, in the process of implementation of the method, only the volumes of the water and air phases necessary to create depression on the formation are taken into account, and in the process of causing the inflow from the formation, the flow rate of the aqueous phase is not changed, i.e. do not control the density of the gas-liquid mixture in the process of causing inflow from the reservoir;

- thirdly, since the lower end of the tubing string is located above the bottom of the formation, it is possible to squeeze into the formation fluid that is formed due to the closure of the lower end of the tubing with sediment, which may fall both before the inflow and during the inflow of the formation ;

fourthly, when the water-air phase (gas-liquid mixture) is supplied into the annulus of the well, both the duration of the injection of foam with back pressure (repression) to the formation and the duration of the release of foam from the well increase, while the depression on the formation is sharp and not deep, which reduces Efficiency of calling formation fluid inflow from the reservoir as a whole.

The objective of the invention is to simplify the installation of equipment at the wellhead with the ability to adjust the supply of the aqueous phase of the gas-liquid mixture with a constant supply of the air phase (regulation of the density of the gas-liquid mixture) in the process of calling the inflow from the reservoir, as well as improving the efficiency of calling the inflow from the reservoir by feeding the gas-liquid mixture into the pipe space tubing strings (tubing) and the exclusion of crushing fluid into the reservoir both before and during the process of causing inflow from the reservoir.

The method of causing inflow from the formation is to create 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 well with liquid by displacing it with an air and water phase system, which are passed through the head.

New is that the tip is placed at the wellhead and is made in the form of a tee, ejector or aerator, and the tubing string in the well is placed so that its lower end is 1.5-2 m below the perforation interval, then the wellbore is completely filled with technological liquid, and the inflow from the reservoir begins when supplying: an aqueous phase of 4.5-6 l / s and an air phase of 120-130 l / s, and the system of air and water phases is pumped into the pipe space of the tubing string, after the appearance of foam circulation, reduce the flow aqueous phase up to 1-1.5 l / s, continue with circulation of the gas-liquid mixture to maintain depression on the formation for at least 3 hours, and when injecting the gas-liquid mixture using an ejector, the flow of the aqueous phase is increased by 10-15% (to improve gas suction by the ejector).

The figure shows a diagram of an implementation of the proposed method of causing inflow from the reservoir.

The way to call the inflow from the reservoir 1 (see the figure) is to create a depression on the bottom-hole zone of the reservoir (PZP) 2 in the drilled and cased well 3 with a string of tubing 4 in it.

Depression on the reservoir 1 is created by lowering the level of the borehole fluid by displacing it with an air and water phase system (gas-liquid mixture), which are passed through tip 5.

The tubing string 4 in the well is placed so that its lower end 6 is at a distance of h = 1.5-2 m below the perforation interval.

Then, at the wellhead 3, a faceplate 7 is installed on the upper end of the tubing string 4 and is equipped with a pipe valve 8, which is connected to the head 5 by the injection line (gas-liquid mixture) 9. The head 5 is placed on the wellhead 3 and is made in the form of a tee, ejector, or aerator.

For example, the tip 5 is made in the form of an aerator (see the figure), to which the air phase is fed through the pipe 10 through its perforated holes 10 ', i.e. air (gas) produced by the compressor 11, and through the pipe 12 serves the aqueous phase, which is used as an aqueous solution of a surfactant, using a pump 13.

As the pump 13 can be used, for example, cementing unit CA-320 M, providing a change in the supply of the aqueous phase from 1 to 6 l / s. This is achieved by equipping the cementing unit CA-320 with bushings of the smallest diameter, for example 90 mm. In the measuring tank of the cementing unit or in the tank of the water carrier (not shown in the figure) of the pump 13, the aqueous phase of the mixture is prepared in the form of an aqueous solution with a surfactant. Surfactants are used as a foaming agent. For example, surfactants are added to fresh water with a density ρ = 1000 kg / m ³ , for example, sulfanol (at a concentration of 0.1-0.3% of the content in water) according to TU 6-01-862-73 or other surfactants, for example OP-7 , OP-10 (at a concentration of 0.3-0.6% of the content in water) according to TU 8433-81.

An annular valve 14 of a well 3 by a flow line 15 is connected with a trough 16. A pipe 8 and an annular valve 14 are opened and, by means of a pump 13, completely fill the borehole 3 (pipe 17 and annular 18 of the tubing string 4 space) with a process fluid, for example, fresh water ρ = 1000 kg / m ³ .

After that, the call of the inflow from the formation 1 begins, for this, first turn on the pump 13, and then start the compressor 11, i.e. feed starts: the aqueous phase with a flow rate of 4.5-6 l / s and the air phase with a flow rate of 120-130 l / s, through pipes 12 and 10, respectively.

Air and water phases are directed to head 5, where they are mixed and a gas-liquid mixture is formed. Then, through the injection line 9, the gas-liquid mixture through the open pipe valve 8 enters the inner space 17 of the tubing string 3. When injecting the gas-liquid mixture using an ejector, the aqueous phase is increased by 10-15% (to improve gas suction by the ejector), i.e. (1.1-1.15%) × (4.5-6) l / s = 4.95-6.9 l / s.

As the gas-liquid mixture is injected, the pressure in the pipe space 17 of the tubing string 3 gradually increases, reaching a certain value, and for some time it remains at the same level. This increase in pressure is explained by the fact that when moving downward, the density of the well fluid located in the pipe space 17 of the tubing string 4 in the initial period exceeds the density of the gas-liquid mixture displacing it, which creates additional pressure.

If the pressure on the compressor 11 increases to the maximum permissible for it or the inner walls of the well 3 (for example, 9 MPa), it is necessary to stop the injection of gas (air) for a short time, for 2-3 minutes, while continuing to pump the aqueous surfactant solution.

When the gas-liquid mixture moving down the pipe space 17 of the tubing string 4 reaches the lower end 6 of the tubing string 4, then it enters the annulus 18 of the tubing string 4, the density difference gradually disappears, and the pressure drops.

Air (gas) from the mixture enters the annulus 18 of the tubing string 4 and causes the discharge of fluid located in the annular space 18 of the tubing string 4 through the flow line into the groove tank. The density of the gas-liquid mixture in the annulus 18 of the tubing string 3 gradually decreases, and the pressure in the discharge line 10 begins to drop.

At a certain point in time, circulation of the gas-liquid mixture in the form of foam appears through the annular valve through the flow line in the trough behind the borehole fluid.

After that, the supply of the aqueous phase (aqueous surfactant solution) is reduced to 1-1.5 l / s (decrease the density of the gas-liquid mixture) until the calculated value of depression is reached, for example, 4 MPa and the gas-liquid mixture continues to circulate for at least 3 hours to maintain the achieved Depression on the reservoir. Maintaining the achieved depression on the reservoir is ensured by reducing the density of the gas-liquid mixture, which is regulated over a wide range, for example, when the initial flow rate of the aqueous phase is 4.5-6 l / s, the density of the gas-liquid mixture is 800 kg / m ³ , and with a subsequent decrease in the flow of water phase to 1-1.5 l / s the density of the gas-liquid mixture is 200 kg / m ³ and is determined empirically.

During the circulation of the gas-liquid mixture, the influx from the well begins, i.e. the work of formation 1 begins and the PZP 2 is cleaned from sludge and dirt.

The presence of inflow from the formation 1 is determined visually by the volumetric output of the formation fluid from the annular space 18 of the tubing string 4 through the annular valve 14 and flow line 15 into the groove capacity 16. When the formation 1 is in operation, well 3 is switched to a spare line (not shown in Fig.) for practicing.

When the inflow from the reservoir is called according to the proposed method, the gas-liquid mixture is injected into the inner space of the tubing string and its output through the annular space of the tubing string into the gutter, while the duration of pumping the gas-liquid mixture with back pressure (repression) onto the reservoir is sharply reduced, and a more smoothly increasing deeper depression on the reservoir, the duration of the release of the gas-liquid mixture from the well sharply decreases, all this in general allows improving the efficiency of the call when eye from the formation.

When lowering the tubing string 4 below the perforation interval by 1.5-2 meters, the liquid is crushed into the reservoir, the formation of which is possible due to the closure of the lower end of the tubing by sediment, which can fall both before and during the inflow from the reservoir. In addition, the proposed method of causing inflow from the formation is simple in installing equipment at the wellhead and allows you to control the flow of the aqueous phase of the gas-liquid mixture with a constant supply of the air phase, i.e. the density of the gas-liquid mixture is regulated, due to which a calculated depression on the formation is created in the process of causing inflow from the formation.

Claims (1)

The method of causing inflow from the formation, which consists in creating a depression on the bottom-hole zone of the formation in a drilled and cased hole with a string of tubing - tubing in it by lowering the level of the borehole fluid by displacing it with an air and water phase system, which is passed through a head characterized in that the head is placed at the wellhead and is made in the form of a tee, ejector or aerator, and the tubing string in the well is placed so that its lower end is 1.5-2 m below the perforation interval, then completely behind the wellbore is filled with process fluid, and the inflow from the formation begins when supplying: an aqueous phase of 4.5-6 l / s and an air phase of 120-130 l / s, and the system of air and water phases is pumped into the pipe space of the tubing string, after the circulation of the foam reduces the flow of the aqueous phase to 1-1.5 l / s, continues the circulation of the gas-liquid mixture to maintain depression on the formation for at least 3 hours, and when pumping the gas-liquid mixture using an ejector, the flow of the aqueous phase is increased by 10-15% for Improvement of gas suction by ejector.

Images