RU2260677C1 - Method for chemical protection of downhole equipment against corrosion, paraffin and salt deposits and against sulfate-reducing bacteria - Google Patents

Abstract

FIELD: oil and gas production, particularly inhibition of corrosion, paraffin and salt deposition and sulfate-reducing bacteria growth in boreholes or wells.

SUBSTANCE: method involves metered supplying chemical reagents of different types simultaneously or serially for different predetermined depths in dependence of production and technical conditions of well operation. Chemical reagents are supplied through capillary hose including capillary pipes, protective cushion and shell. Chemical reagent flow regulation is performed by metering electric plant at well head.

EFFECT: increased efficiency of downhole equipment protection due to provision of free metered chemical reagent supplying for necessary depth during pumping equipment operation.

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Description

The invention relates to methods and devices for chemical protection of downhole equipment, including in-depth, against corrosion, paraffin deposition and scaling, as well as for chemical treatments of the extracted well fluid and the bottomhole formation zone and can be used in various industries, including oil.

A known method of dispensing a reagent into a well [1], which includes periodic injection of a reagent into the annulus and its supply through a dispensing unit to a stream of well production extracted from a tubing string at a pump intake, the reagent is supplied through a dispensing unit by continuously transferring part of the product from tubing string (tubing) through a calibrated channel made in the tubing string above the dynamic level of the well fluid. As a metering unit, an annulus annunciator is used with annular elements of elastic material sequentially installed with a gap relative to each other, while the thickness of the annular elements is not higher than the gap, and their diameter is chosen not less than the diameter of the well.

The disadvantages of this method are the small penetration of fluid into the well, the inability to supply reagents to the bottomhole zone, the difficulty of dosing the reagent into the well.

Closest to the claimed one is a method of supplying reagents to the well [2], including lowering the dispenser to the bottom at the pump and tubing, periodically pumping the reagent into the dispenser through an armored hose and feeding the reagent into the liquid.

The disadvantage of this method is the inability to control the flow of the reagent in the process of pumping formation fluid, the check valve is in the well, which increases the risk of an accident. This method of supplying reagents to the well does not provide effective protection for running equipment throughout the depth of the well, it does not allow for the simultaneous dosed supply of various chemicals to various depths of the well.

The problem and the expected technical result solved by the invention is to increase the efficiency of chemical protection of downhole equipment against corrosion, paraffin deposition, scaling and SSC by unimpeded dosing of chemicals to the required depth during the operation of pumping equipment, the flow rate of the regents is carried out at the wellhead.

The problem is solved in that in the method of chemical protection of downhole equipment against corrosion, paraffin deposition and sulfate-reducing bacteria by means of a dosed supply of a chemical reagent according to the invention, an adjustable dosed supply of various reagents is carried out simultaneously or sequentially at different predetermined depths depending on the technological and technical features of the operation of the well, capillary hose along the borehole, consisting of capillary tubes, a protective pad and armor, moreover, the adjustment of the flow rate of the reagents is carried out at the wellhead by the installation of a metered electric pump UDE.

A significant difference is that the capillary hose is lowered into the well, the capillary hose being connected on the surface through the check valves with UDE, and in the well, the ends of the capillaries of the hose are located at predetermined depths, which are the points of supply of metered chemical reagents. UDE consists of a metering pump and chemical tanks.

In Fig 1 is a schematic diagram of the implementation of the proposed method for protecting downhole equipment and chemical treatments of wells, where

1 - tubing;

2 - a three-capillary hose;

3 - supply points of metered chemical reagents;

4 - check valves;

5 - electric dosing pump installation (UDE);

Figure 2 is a schematic diagram of a three-capillary hose, where

6 - capillary tubes;

7 - a protective pillow;

8 - armor.

A comparative analysis of the essential features of the proposed technical solutions and prototype allows us to conclude that the claimed inventions meet the criterion of \ novelty \.

Since the distinguishing features of the claimed technical solutions are new, they, according to the authors, meet the criterion of \ inventive step \.

The claimed technical solution works as follows.

A three-capillary hose (2) is lowered into the well on the tubing (1), the ends of the capillaries of which are installed at the required depths, which corresponds to the feed points of the dosed chemical reagents (3). At the wellhead, a three-capillary hose (2) through check valves (4) is connected to the UDE (5) for the dosed supply of chemicals.

In the proposed three-capillary hose (figure 2) for supplying chemicals as capillaries (6), polyethylene insulation of the conductive conductors of the CPBP cable, protected by a protective pillow (7), and armor (8) from steel metal tape are used.

The method is carried out by the following sequence of operations (figure 1):

1. Installation at the wellhead UDE (5), consisting of metering pumps with tanks equipped with check valves (4).

2. The descent into the well of the pump on the tubing (1) with a three-capillary hose (2), the ends of the capillaries of which are set at the required depths (3), which are technologically justified depending on the task and correspond to the supply points of the dosed chemical reagents.

3. Connecting a three-capillary hose (2) at the wellhead to the UDE (5).

4. Depending on the task, the types of chemicals are selected and the volume and dosage regimen are set.

The method is illustrated by the following examples.

Example 1. Determination of the necessary depths for the injection of chemical reagents (points of supply of metered chemical reagents).

In fields that have entered the late stage of development and the water cut of which has exceeded 70%, corrosion of all underground well equipment is observed, serious damage of which is associated with aggressive environments. The increase in the aggressiveness of the oil-water environment is due to the vital activity of bacteria. It has been unequivocally established that the biological component of the corrosion process significantly affects the corrosion rate of metal equipment [3].

So, in NGDU \ Ufaneft \ studies were conducted in the well. No. 1344 of the South Sergeevskaya area of the Sergeevsky field. The results of the analysis of scrapings from the outer surface of the tubing along the well of the investigated well for the quantitative accounting of microorganisms are presented in Table 1.

Table 1
Analysis of scrapings along the well bore. No. 1344 of South Sergeevskaya Square Depth, m Bioinfection, cells / g SVB GTB TB 10 units 460 fifty 143 thirty 260 thirty 286 units 260 thirty 372 units 200 twenty 430 fifty 480 fifty 572 units 1250 130 715 units 200 twenty 860 units 230 twenty 1000 units 1830 180 1145 units 320 thirty 1288 units 200 twenty 1402 units 1500 150

Based on the processed results, where an increased content of heterotrophic (GTB) and thionic (TB) bacteria is observed, three points of dosing of the bactericide are established, which correspond to: 1st - 572 m - static level; 2nd - 1000 m - to the dynamic level; 3rd - 1402 m - pump intake. Based on the results obtained, the treatment is carried out according to the proposed method of chemical protection of downhole equipment with bactericidal corrosion inhibitors according to the scheme shown in figure 3.

Example 2. The implementation of the method of chemical protection of downhole equipment from corrosion, paraffin deposition, scaling and SBR.

The method of chemical protection of downhole equipment from corrosion, paraffin deposition and scaling, chemical treatment of wells is carried out in NGDU \ Ufaneft \ according to the scheme shown in figure 1.

Dosing points of chemical reagents (3) correspond to: lower - bottomhole zone of the well; medium - pump intake; upper - to a static or dynamic level. To carry out chemical treatment of the well, one of the capillaries of the three-capillary hose (2) is periodically injected into the lower supply point with the necessary chemical reagent (hydrochloric acid, solvent, surfactant, etc.). Depending on the task, it is possible to inject corrosion inhibitors instead of chemical treatment or, after chemical treatment, a corrosion inhibitor should be injected.

Depending on the problem being solved, either a solvent or a demulsifier is supplied to the pump intake (middle supply point) through another capillary of a three-capillary hose (2).

A hydrogen sulfide neutralizer is pumped to the depth of the static or dynamic level (upper feed point) through the third capillary of the three-capillary hose (2).

Thus, the inventive method of chemical protection of downhole equipment from corrosion, paraffin deposition, scaling and SSC allows to increase the effectiveness of chemical protection of downhole equipment from corrosion, paraffin deposition and scaling, as well as simultaneously with chemical protection to conduct chemical treatments of the bottomhole formation zone. The method is not laborious, efficient and industrially applicable, because for their implementation use available equipment and materials.

Sources of information

1. A.S. 1 810 498 A1. A method of dispensing a reagent into a well.

2. A.S. 883343 A1. Device for supplying reagent and water to the bottom of the well.

3. Lipovich RN, Gonik AA, Nizamov K.R. and others. Microbiological corrosion and methods for its prevention. - M.: VNIIOENG, 1977.

Claims (1)

A method of chemical protection of downhole equipment from corrosion, paraffin deposition, scaling and sulfate-reducing bacteria by means of a dosed supply of a chemical reagent, characterized in that the controlled dosed supply of various types of chemical reagents is carried out simultaneously or sequentially at different predetermined depths depending on the technological and technical features of well operation through capillary a hose consisting of capillary tubes, a protective pillow and armor, and adjustment reagent consumption is performed on the wellhead installation dosage electropump.

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