RU2291288C1 - Method for fighting corrosion caused by sulfate-restoring bacteria - Google Patents

Abstract

FIELD: oil industry, possible use for suppressing growth of sulfate-restoring bacteria and inhibiting corrosion in systems for collecting and processing oil.

SUBSTANCE: method for fighting corrosion caused by sulfate-restoring bacteria including forcing a volume of bactericide solution into inter-tubular space of oil well, at outlet of which pipe corrosion has been detected caused by sulfate-restoring bacteria, forcing of bactericide solution is performed into inter-tubular space of working oil well under pressure of 0,5-2,5 MPa with flow of 5-6 liters per second, while volume of bactericide solution is computed on basis of actual debit of liquid of oil well from formula V=A·C·D, where V - bactericide solution volume being forced in, m³, A - value, received from concentration calculation, kg/m³, of bactericide solution being used, m³/kg, C - suppressing concentration for adhesion forms of sulfate-restoring bacteria, kg/m³, D - actual well debit for 1 day, m³.

EFFECT: simplification of method due to execution of operations in working well.

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Description

The invention relates to the oil industry and may find application in suppressing the growth of sulfate-reducing bacteria and inhibiting corrosion in oil collection and treatment systems.

A known method of combating corrosion caused by sulfate-reducing bacteria, which includes determining the well of the active biocenosis zone of sulfate-reducing bacteria, the volume of the bactericide solution necessary to suppress the vital activity of sulfate-reducing bacteria, injecting the bactericide solution into the formation through the well and stopping it for a time necessary to completely suppress the sulfate-reducing activity bacteria starting up a stopped well. A solution of a bactericide, prepared on high density water, is injected through an idle oil well, at the outlet of which pipe corrosion caused by sulfate-reducing bacteria was detected by feeding it at atmospheric pressure into the annulus of the well in the indicated volume. During this stop, the used bactericide solution is additionally poured into the annulus, saturating the active biocenosis of sulfate-reducing bacteria in the bottomhole zone of the well. The saturated bottom-hole zone of the well is used as a reservoir for storing and spending the indicated bactericide solution in the flow line during operation of the indicated well (RF Patent No. 2233973, 08/10/2004).

The known method is difficult to manufacture and is not always justified, because the used bactericide solution is lost in the bottomhole zone of the well and often does not fulfill its functions as a suppressor of the growth of sulfate-reducing bacteria.

Closest to the proposed invention in technical essence is a method of combating corrosion caused by sulfate-reducing bacteria, which includes injecting a volume of a solution of a bactericide prepared on water into an oil-producing well, at the outlet of which pipe corrosion caused by sulfate-reducing bacteria is detected. As a solution of the bactericide use 1.5-2.5% by weight of a solution of the bactericide, prepared on mineralized water with a density of up to 1.15 g / cm ³ . Before pumping the bactericide solution through the well, mineralized water used to prepare the bactericide solution is pumped in a volume not less than the volume of the well. The used bactericide solution fill the pipe and annular space (the space between the casing string and the tubing string) of the well. The annulus is closed and the stopped oil production well is put into operation (RF Patent No. 2263201, October 27, 2005 prototype).

The method provides a reduction in the used volume of the bactericide solution. However, the method is complex, requires a mandatory shutdown of the well.

The proposed invention solves the problem of simplifying the method by performing work on a working well.

The problem is solved in that in a method of combating corrosion caused by sulfate reducing bacteria, which includes injecting the volume of a bactericide solution into the annulus of an oil producing well, at the outlet of which pipe corrosion caused by sulfate reducing bacteria is detected, the volume of the bactericide solution is injected into the annulus of a working oil well 0.5-2.5 MPa with a flow rate of 5-6 l / s, and the volume of the bactericide solution is calculated depending on the actual oil flow rate Extractive wells formula:

where V is the injected volume of the bactericide solution, m ³ ,

And - the value obtained from the calculation of the concentration, kg / m ³ used the solution of the bactericide, m ³ / kg,

C is the inhibitory concentration for the adhered forms of sulfate reducing bacteria, kg / m ³ ,

D is the actual flow rate of the well for 1 day, m ³ .

The features of the invention are:

1) injection of the volume of the bactericide solution into the annulus of the oil producing well, at the outlet of which pipe corrosion caused by sulfate-reducing bacteria was detected;

2) injection of the volume of a solution of bactericide - is carried out in the annulus of a working oil well;

3) the same under pressure not more than 2.5 MPa;

4) the same with a flow rate of 5-6 l / s;

5) the calculation of the volume of the solution of the bactericide depending on the actual flow rate of the liquid of the oil producing well according to a special formula.

Sign 1 is common with the prototype, signs 2-5 are the salient features of the invention.

SUMMARY OF THE INVENTION

When developing an oil reservoir in a reservoir, conditions are created for the production of sulfate-reducing bacteria, which in turn cause equipment corrosion. Existing methods to combat pipe corrosion caused by sulfate-reducing bacteria are not always able to fully protect oil equipment. In addition, existing methods are complex, require a mandatory shutdown of the well. The proposed invention solves the problem of simplifying the method by performing work on a working well. The problem is solved as follows.

When carrying out work to protect oilfield equipment from corrosion caused by sulfate-reducing bacteria, the volume of the bactericide solution is injected into the annulus of the oil producing well, at the outlet of which pipe corrosion caused by sulfate-reducing bacteria is detected. The volume of the bactericide solution is injected into the annulus of a working oil well at a pressure of 0.5 - 2.5 MPa at a flow rate of 5-6 l / s. The volume of the bactericide solution is calculated depending on the actual flow rate of the oil well by the formula:

V = A · C · D,

where V is the injected volume of the bactericide solution, m ³ ,

And - the value obtained from the calculation of the concentration, kg / m ³ used the solution of the bactericide, m ³ / kg,

C is the inhibitory concentration for the adhered forms of sulfate reducing bacteria, kg / m ³ ,

D is the actual flow rate of the well for 1 day, m ³ .

In formula A, the concentration of the bactericide solution is most often equal to 0.05 m ³ / kg, because obtained from the calculation that they use a 2% solution of the bactericide, that is, 20 kg / 1 m ^{3 of} water. The dosage of the bactericide is determined on the basis of the inhibitory concentration of 0.5 kg / m ³ for the adhered forms of sulfate reducing bacteria.

The injection pressure of the bactericide solution of 0.5-2.5 MPa and the flow rate of 5-6 l / s were selected empirically. With such injection parameters, the well operating mode is not violated, there is no withdrawal of the injected fluid from the annulus to the bottomhole zone, and there is no entry of the bactericide solution into the produced products.

Adhesive forms of sulfate-reducing bacteria form colonies of cells coated with polysaccharide mucous membranes, which protect bacteria from adverse environmental conditions, including from the action of chemicals that suppress their vital activity - bactericides. Slaughter concentrations of bactericides in relation to the adhered forms of sulfate reducing bacteria differ by an order of magnitude from the same concentrations in relation to planktonic forms. The presence of a protective biofilm also prevents the access of corrosion inhibitors to the surface of pipelines and oilfield equipment, as a result of which their protective effectiveness is reduced. The danger of corrosion caused by sulfate-reducing bacteria is not only to increase the aggressiveness of the environment due to the appearance of hydrogen sulfide and other waste products, but also to localize it under adhesive colonies. The rate of biocorrosion can be several times higher than the rate of hydrogen sulfide corrosion of non-bacterial origin. The most effective way of inhibiting the growth and development of microorganisms and protecting pipelines and oilfield equipment from biocorrosion is the use of bactericides. The bulk of the bactericides used are organic compounds.

Measures to combat corrosion caused by sulfate-reducing bacteria are carried out in an oil well, at the outlet of which pipe corrosion caused by sulfate-reducing bacteria is detected. As a solution of a bactericide, prepared on water of increased density, use a 1.5-2.5% solution of a bactericide, prepared on the basis of water with a density of 1.04-1.07 g / cm ³ up to a maximum of 1.15 g / cm ³ . When preparing the solution, bactericide is first pumped into the container, and then water. Mixing the entire volume of the solution is carried out by a centrifugal pump at least 2 times. The bactericidal solution is pumped into the annulus of a working well, after which the well remains in operation. As a bactericide, reagents SNPCH-1004, sulfane, Head-1007, etc. are used.

Regardless of the calculation results, the minimum solution volume during well treatments is at least 1 m ³ .

An example of a specific implementation of the method

Measures to combat corrosion caused by sulfate-reducing bacteria are carried out in an oil well, the output of which is corrosion of pipes caused by sulfate-reducing bacteria, with the following characteristics: diameter of the column 146x8 mm, length -1200 m, diameter of the column of tubing 73x8 mm, length - 1000 m. As a solution of bactericide, prepared on water of high density, use a 2% solution SNPCH-1004, prepared on produced water with a density of 1.07 g / cm ³ .

Calculate the volume of injected bactericide solution according to the formula (1):

V = A · C · D = 0.05 m ³ / kg · 0.5 kg / m ³ · 105 m ³ = 2.625 m ³

The calculated volume of the bactericide solution is injected into the annulus of a working oil well under a pressure of 2.5 MPa with a flow rate of 5.6 l / s. The used bactericide solution fill the annulus of the well, close the annulus and continue to operate the oil well.

Previously, for the fight against corrosion caused by sulfate-reducing bacteria, at least 15 m ³ of a bactericide solution was required. According to the proposed method for carrying out such work requires 2.5-3.0 m ^{3 a} solution of the bactericide. Success of work, i.e. guaranteed protection of the well and flow lines from corrosion caused by sulfate-reducing bacteria was 95% versus 90% according to previously used technology.

The application of the proposed method will allow to solve the problem of increasing the efficiency of protection against corrosion caused by sulfate-reducing bacteria, to reduce the volume of the used bactericide solution and to carry out work without stopping the oil producing well.

Claims (1)

A method of combating corrosion caused by sulfate-reducing bacteria, which includes injecting the volume of a bactericide solution into the annulus of an oil producing well, at the outlet of which pipe corrosion caused by sulfate-reducing bacteria is detected, characterized in that the volume of the bactericide solution is injected into the annulus of a working oil-producing well, 0 oil-producing well 5-2.5 MPa with a flow rate of 5-6 l / s, and the volume of the bactericide solution is calculated depending on the actual flow rate of the oil ayuschey wells formula: V = A · C · D, where V is the injected volume of the bactericide solution, m ³ ; And - the value obtained from the calculation of the concentration, kg / m ³ , the used solution of the bactericide, m ³ / kg; C - inhibitory concentration for adhered forms of sulfate-reducing bacteria, kg / m ³ ; D is the actual flow rate of the well for 1 day, m ³ .