RU2808108C1 - Device for supplying reagent to well - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: devices for supplying and dosing chemical reagents into oil wells. The device includes a capillary tube lowered into the lift string with a reagent supply tip located after the descent at a depth below the beginning of the formation of deposits on the walls of the lift string to supply the reagent into the fluid flow produced by the downhole pump. When descending into the elevator column, the capillary tube is designed to be mounted on the column with rods equipped with external centralizers that prevent interaction of the capillary tube with the walls of the elevator column. The reagent supply tip is made in the form of a cylindrical body with identical nozzles, located evenly along the perimeter and height of the tip with a total cross-section that provides the required amount of reagent supplied to the elevator string in the form of corrosion inhibitors, solvents of paraffin deposits, scale deposits and/or demulsifiers, with a passage channel of the capillary tube is made with a cross section larger than the total cross section of the nozzles.

EFFECT: functionality of the device is expanded due to the possibility of pumping various liquid reagents, as well as using the device in inclined, horizontal and/or complex structured wells.

2 cl, 1 dwg

Description

The invention relates to the oil and gas industry, in particular to devices for supplying and dosing corrosion inhibitors, paraffin deposits, scale deposits and/or demulsifiers into oil wells.

There is a known method for supplying a reagent to a well (patent RU No. 2302513, MPK E21B 37/06, E21B 41/02, published July 10, 2007 Bulletin No. 19), including periodic controlled supply of a reagent into the annulus of the well using a dosing pump, and during underground repairs complicated well, the power cable for the electric motor of the centrifugal pump is replaced with a cable with a capillary tube, which is lowered on a tubing string into the well and a chemical reagent is supplied through its capillary channel, while the supply is carried out either to the intake of the well pump, or into the well perforation interval, for which a polyethylene capillary tube of estimated length is attached to the end of the capillary tube of the cable using a connecting nipple with a nozzle weight.

Including a device for supplying a reagent into the annulus of a well, including a capillary tube installed instead of a power cable for an electric motor of a centrifugal pump on the outer surface of a tubing string, with a polyethylene capillary tube of estimated length, equipped with a connecting nipple with a weight - nozzle, for location at the intake of a well pump or in the perforation interval of a well.

The disadvantages of this device are the complexity of implementation, which requires stopping the pump and replacing the cable with a capillary tube, low efficiency and high reagent costs associated with diluting the reagent with well fluid before pumping it through the tubing string, on the walls of which, having a much smaller area than the casing pipes, accumulation of corrosion, paraffin deposits, salt deposits and hardening emulsion, which leads to the need to use tripping operations to resuscitate the pump to clean or replace the tubing string, and a narrow scope of application due to the impossibility of use in inclined, horizontal and/or complexly structured (with wellbore deviation from the vertical by more than 4º-5º in zenith angle) wells, since it is possible that the integrity of the capillary tube may be violated during tripping operations and the polyethylene capillary tube with a nipple with a weight-nozzle will not reach the installation interval due to interaction with the walls of the well.

A device for dosing and supplying a chemical reagent into a well is also known, which includes a flexible capillary tube for supplying chemical reagents into a well (patent for PM RU No. 273100, IPC E21B 37/06, publ. 08/11/2017 Bulletin No. 23), made armored and fixed on the outer surface of the tubing, while the flexible capillary armored tube is attached to the outer surface of the tubing using a protector, and on the surfaces at the junction of the pump with the compressor pipe - using a protectorizer, and the flexible capillary armored tube is located in the protector covers and protectolizer together with a power electrical cable connected to the pump, and ends at the level of the pump inlet.

The disadvantages of this device are the low efficiency and high costs of the reagent associated with diluting the reagent with well fluid before pumping it through the tubing string, on the walls of which, having a much smaller area than the casing pipes, the accumulation of corrosion, paraffin deposits, scaling and hardening emulsion, which leads to the need to use tripping operations to resuscitate the operation of the pump to clean or replace the tubing string, and a narrow scope of application due to the impossibility of use in inclined, horizontal and/or complexly structured wells, since the integrity of the flexible capillary tube may be damaged during tripping operations due to interaction with the walls of the well.

The closest to the technical essence is a method of combating paraffin deposits in oil and gas wells (patent RU No. 2438006, IPC E21B 37/00, publ. December 27, 2011 Bulletin No. 36), including lowering a device for heating the produced fluid into the pump and compressor pipes, moreover, as a device for heating the produced liquid, a technological column with a check valve at the end is used, which is lowered to a depth below the beginning of the deposition of paraffins on the walls of the pipes, the coolant is pumped into the column while the well is operating, introducing the coolant into the flow of the produced liquid until the produced liquid reaches a temperature of the wellhead is not lower than the melting temperature of paraffins.

In which a device is used for heating the produced liquid, including a process column with a check valve at the end, lowered into the tubing to a depth below the beginning of paraffin deposition on the pipe walls, for pumping coolant into the column in the form of steam when the well is operating, introducing steam into the flow of the produced liquid until the produced liquid reaches a temperature at the wellhead not lower than the melting point of paraffins.

The main disadvantage of this device is its narrow scope of application due to its ability to combat paraffin deposits only and the impossibility of use in inclined, horizontal and/or complexly structured wells, since the integrity of the process column (capillary tube) and/or valve at the end may be damaged when hoisting operations due to interaction with the walls of the tubing.

The technical result is the creation of a device for supplying a reagent into a well, which allows expanding functionality due to the possibility of injecting various liquid reagents to reduce the formation of corrosion, paraffin deposits, scale deposits and hardening emulsion on the pipe walls, as well as use in inclined, horizontal and/or complexly structured wells , thanks to the descent of a capillary tube fixed from the outside on a column of rods equipped with external protective centralizers, eliminating interaction with the internal walls of the pipe during hoisting operations.

The technical solution is a device for supplying a reagent to a well, including a capillary tube lowered into the lift string with a reagent supply tip located after descent at a depth below the beginning of the formation of deposits on the walls of the lift string to supply the reagent into the fluid flow produced by the downhole pump.

What is new is that the capillary tube, when descending into the elevator column, is designed to be mounted on the column with rods equipped with external centralizers that exclude interaction of the capillary tube with the walls of the elevator column; the reagent supply tip is made in the form of a cylindrical body with identical nozzles located evenly along the perimeter and height a tip with a total cross-section that provides the required amount of reagent supplied to the lift column in the form of corrosion inhibitors, solvents of paraffin deposits, scale deposits and/or demulsifiers, while the passage channel of the capillary tube is made with a cross-section larger than the total cross-section of the nozzles.

What is also new is that when lowering into inclined or horizontal wells, the lower centralizer is installed directly above the reagent supply tip, and the distance between the centralizers is selected the smaller, the smaller the turning radius that passes through the section of the rod string with the capillary tube.

The drawing shows a diagram of the proposed device lowered into a horizontal well.

The device for supplying the reagent to the well 1 includes a capillary tube 5 lowered into the lift string 2 of the well pump 3 and lowered on the rod string 4 with a reagent supply tip 6 located after lowering at a depth below the beginning of the formation of deposits (not shown) on the walls of the lift string 2 for supplying a reagent corresponding to deposits (corrosion, paraffin deposits, salt deposits and/or hardening emulsion) into the fluid flow produced by the well pump 3. Fixing the capillary tube 5 on the rod string 4 can be carried out by any known mechanisms (clamps, protectors, spring clips, etc. . – the author does not claim this). In this case, the rod column 4 is equipped with external centralizers 7, which exclude interaction of the capillary tube 5 with the walls of the lift column 3. The reagent supply tip 6 is made in the form of a cylindrical body with identical nozzles 8 located evenly along the perimeter and height of the tip 6 with a total cross-section that provides the required amount reagent supplied to the lift column 3 in the form of corrosion inhibitors, solvents of paraffin deposits, scale deposits and/or demulsifiers.

Downhole pump 3 for work in horizontal or inclined wells is most often used in the form of an electric centrifugal pump (ESP), a gerotor pump (GP) for shallow wells (100 - 200 m) or a screw pump (SC) for shallow wells (20 - 100 m) , including an electric motor 9, powered by a power cable 10, a hydraulic protection 11, an input module 12 and pumping sections 13 (all shown conditionally).

The centralizers 7 can be installed (by welding, adhesive bonding, factory production - the author does not claim this) on the couplings (not shown) of the rod columns 4, on clamps or protectors (the author does not claim this, since this is known from open sources).

Tip 6 for supplying the reagent is adjusted in laboratory conditions or in special workshops. Initially, the total cross-section of the nozzles 8 necessary to supply the required amount of reagent into the flow of the produced liquid is determined based on the performance of the well pump 3 (according to the passport), the wellhead pump feeding the capillary tube 5 (not shown - according to the passport), the type of deposits (determined by monitoring the wells ), reagent concentration (by sample analysis) (the author does not claim this). Then, using a drill of the required diameter on the tip, the required number of holes - nozzles 8 - is made to achieve the total cross-section evenly along the height and perimeter of the nozzle 6 for uniform supply of the reagent into the fluid flow pumped by the well pump 3 along the lift string 2. For different deposits, the number and diameter of nozzles 8 of the tip 6 can be changed accordingly; for this purpose, the tip can be made removable (threaded, interference fit, hot melt adhesive, etc.) from the capillary tube 5 for quick replacement (the author does not claim this). In this case, the passage channel (not shown) of the capillary tube 4 is made with a cross-section larger than the total cross-section of the nozzles 8 to achieve the desired result. The author does not claim the types of reagents, quantities and methods of their supply, since they are determined by the technical personnel servicing the well.

When lowering into inclined or horizontal wells 1, the lower centralizer 14 is installed directly above the reagent supply tip 6, and the distance between the centralizers 7 and 14 - L is selected, the smaller the smaller the turning radius R, which passes through the section of the rod string 4 with the capillary tube 5. Distance L is selected empirically, for example, in the fields of the Republic of Tatarstan (RT) with a radius R = 35-40 m (wells 1 with casing pipes 102 mm or 114 mm - shown conditionally) for a section of rod string 4 passing through this radius R, it is recommended install centralizers 14 and 7 through L=5–6 m; with a radius R = 60-70 m (wells 1 with casing pipes 146 mm or 168 mm are shown conditionally) to the section of the rod string 4 passing through this radius R - centralizers 14 and 7 through L = 9–11 m; to the section of the rod string 4 located above this radius R - centralizers 7 through L = 20-30 m. In complex structured vertical wells 1 it is recommended to install centralizers 14 and 7 through L = 20-30 m, and in simple vertical wells 1 - through L =30-50 m.

Structural elements, process connections, seals, etc. that do not affect the performance of the device for supplying the reagent to the well are not shown in the drawing or are shown conditionally.

The device for supplying the reagent to the well operates as follows.

Into a lift string 2 previously lowered into well 1 with a cable 10 and a well pump 3, a string of rods 4 is lowered with a capillary tube 5 attached to it with a nozzle 8 selected for the corresponding deposits, below the formation of which on the walls of the lift string 2 and this nozzle 6 is placed for reagent supply. Deposits in RT fields are most intensively formed on the walls of lift pipes 3 in the range of fluid level fluctuations in well 1, where the temperature constantly changes depending on the presence or absence of well fluid. When lowering, the rod string 4 is equipped from the outside with centralizers 7 and 14 at a distance L depending on the radius R of the turn through which the corresponding section of the rod string 4 with the capillary tube 5 passes to prevent interaction of the capillary tube 5 with the walls of the lift string 2. Wellhead (not shown) of the well 1 is isolated by a wellhead seal (not shown), cable 10 is connected to a control unit (not shown) of a well pump 3, and a capillary tube 5 is connected to a wellhead feed pump (not shown), which selects the appropriate reagent (corrosion inhibitor, solvents of paraffin deposits, scale deposits and /or demulsifier) from a container (not shown).

The well pump 3 is put into operation by supplying electrical energy via cable 10. As a result, the electric motor 9 of pump 3 begins to rotate, transmitting rotation through hydraulic protection 11 to pumping sections 13, which, through the input module 12, take liquid from well 1 and supply it to the surface through the lift string 2. In this case, the feed pump supplies the reagent into the capillary tube 5 and through the nozzles 8 of the nozzle 6 in the required quantity is distributed in the flow of liquid pumped by the well pump 3 along the lift string 2, slowing down or completely eliminating the process of formation of corrosion, paraffin deposits, scaling and/or hardening in it emulsions.

Removing the device occurs in the reverse order after stopping the operation of the well pump 3.

The proposed device for supplying a reagent into a well allows expanding functionality due to the possibility of injecting various liquid reagents to reduce the formation of corrosion, paraffin deposits, scale deposits and hardening emulsion on the pipe walls, as well as using the device in inclined, horizontal and/or complexly structured wells, thanks to the descent a capillary tube fixed externally on a rod column equipped with external protective centralizers, excluding interaction with the internal walls of the pipe during hoisting operations.

Claims (2)

1. A device for supplying a reagent to a well, including a capillary tube lowered into the lift string with a reagent supply tip located after lowering at a depth below the beginning of the formation of deposits on the walls of the lift string to supply the reagent into the fluid flow produced by the well pump, characterized in that the capillary the tube when descending into the elevator column is made with the possibility of attaching rods to the column equipped with external centralizers that exclude interaction of the capillary tube with the walls of the elevator column; the reagent supply tip is made in the form of a cylindrical body with identical nozzles located evenly along the perimeter and height of the tip with a total cross-section , providing the required amount of reagent supplied to the lift column in the form of corrosion inhibitors, solvents of paraffin deposits, scale deposits and/or demulsifiers, while the passage channel of the capillary tube is made with a cross-section larger than the total cross-section of the nozzles. 2. A device for supplying a reagent to a well according to claim 1, characterized in that when lowering into inclined or horizontal wells, the lower centralizer is installed directly above the tip of the reagent supply, and the distance between the centralizers is selected the smaller, the smaller the turning radius that passes through the section of the column rods with a capillary tube.