RU2261397C1 - Method for batching of reagents - Google Patents

Abstract

FIELD: batching of reagents to the medium being extracted or transferred, applicable in oil collection and waste water sawaging systems.

SUBSTANCE: batching of reagents is carried out by way of their periodic interrupted introduction to the transferred or extracted medium, after damping of boreholes single delivery of reagent is accomplished until the ions of iron in deposit water is reduced to not more than 2 mg/l.

EFFECT: enhanced efficiency of batching of reagents and reduced degree of precipitation of salts and rate of corrosion.

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Description

The invention relates to the field of dosed supply of reagents in the extracted or pumped medium and can find application in oil gathering and waste water disposal systems.

There is a method of continuous or continuous dosing of reagents in a pumped or produced environment in the system of oil collection and disposal of wastewater (see G.Z. Ibrahimov, N. I. Khisamutdinov. Reference manual on the use of chemicals in oil production. M., Nedra, 1983 city, p.226).

The disadvantages of this method of dosing reagents is the high consumption of reagents, which requires significant costs for the protection of pipelines in the oil recovery system and disposal of wastewater.

There is also known a method of periodically introducing a reagent into a produced or pumped medium, which consists in the fact that according to the technology of periodic processing of an oil pipeline, an inhibitor in the form of a 1-10% aqueous dispersion is pumped in an amount of 500-1000 g / m ³ of a liquid volume for 24-48 h. Then this treatment is carried out after a certain period of time (after 1 month or more) (see Gusev V.I. et al. Chemistry and technology of using chemical products to intensify oil production. - M .: VNIIOENG, 1986).

The disadvantage of this method is the high consumption of reagents, low corrosion protection of oil gathering systems and waste water disposal.

The closest technical solution to the claimed invention is a method of dispensing reagents by periodically introducing them into a pumped or produced medium, and intermittently dispensing reagents by alternating dosing and stopping the input, while the dosing time (Tdose) and stopping time (Toast) are related by Toast = Tdoz K, where K is the coefficient (K = 0.5-1.5).

However, with a high content of iron ions in the produced waters of some wells, this dosing method will not give the desired result due to the interaction of iron ions contained in the killing fluid from the Devonian well and hydrogen sulfide contained in the formation water of a sulfur well.

The proposed invention solves the problem of increasing the efficiency of dosing of reagents, reducing the degree of deposition of salts and corrosion rate.

The problem is solved in that in the known method of dispensing reagents by periodically intermittently introducing them into a pumped or produced medium, according to the invention, after killing the wells, a single reagent is supplied to reduce iron ions in produced water not more than 2 mg / L.

With the right choice of reagent (inhibitor) and the appropriate technology for its use, inorganic salts can be prevented along the entire path of well production from the bottom to the oil and water treatment points. Positive results can be achieved only with the constant presence in the system of an effective inhibitor of salt deposition in the minimum necessary quantities. In this case, the best results are achieved if the inhibitor is introduced into the solution before crystallization of inorganic salts begins. The effectiveness of preventing salt deposits depends on the correct choice of inhibitor and its concentration. The choice of an inhibitor is carried out by experimental studies and in relation to the conditions of specific deposits.

The laboratory of NGDU Leninogorskneft analyzed the use of scale inhibitors in workshops: TsDNG-3 at 9 points (in one well in the annulus, in two wells in a line, in five gas pumps and for receiving a multiphase pump); TsDNG-4 at 14 wells in the annulus.

In accordance with their purpose, scale inhibitors (SNPCH-5312) protect oilfield equipment from calcium sulfite and SNPH-5313 deposits from iron sulfide deposits by binding calcium and iron ions and preventing their interaction with ions of other substances.

The effectiveness of the use of scale inhibitors can be traced by the change in the composition of the reservoir fluid before and after the start of supply.

Table 1 shows the experimental data on the content of iron ions in the produced water. From the data of table 1 it is seen that the iron ions disappear after 3-5 months of supply of the reagent.

Analysis of water samples carried out 2 months after the start of the inhibitor supply, and analysis of samples carried out to date, show that in the produced water there is a significant amount of iron ion associated with scaling. After the addition of the reagent (SNPCH-5313 inhibitor), a decrease in the content of iron ions is seen. The analyzes showed that at well No. 26491, the content of iron ions increased after underground well repair (ORS), where a killing fluid with an iron ion concentration of 185 mg / l was used (from well 15546).

Thus, we can conclude that the deposition of iron sulfide in sulfur wells occurs due to the interaction of iron ions contained in the killing fluid from the Devonian well and hydrogen sulfide contained in produced water of a sulfur well, according to the following scheme:

Fe + H ₂ S → FeS + H2 ↑

The average content of iron ions is

- Devonian formation water - 150 mg / l;

- formation water of coal-bearing horizons - 3 mg / l.

Studies have shown that calcium sulfide should be given priority in the fight against scaling, as its excess over iron ions in Devonian type formation water reaches 150 times, and in water of coal-bearing horizons - 250 times.

The data on the corrosion effect of reagents (SNPCH-5312, 5313 inhibitors) on the equipment are shown in Table 2, which shows the increase in the corrosion rate of equipment in formation water with the addition of SNPCH-5313 reagent.

Thus, when reaching iron ions of not more than 2 mg / l, it is necessary to stop the supply of the reagent, thereby achieving a decrease in the corrosion rate to oilfield equipment.

To do this, monthly, produced water at the wells where the reagent is supplied is checked for the presence of Fe ²⁺ iron ^ions , and when the iron ions are reduced to 2 mg / l, the reagent is stopped.

This will reduce salt deposition and corrosion rate.

Table 1. No. of wells The content of iron ions in the produced water. sampling date 06/28/2000 07/27/2000 09/25/2000 10/16/2000 11/30/2000 01/24/2001 03/15/2001 07/23/2003 iron ion content, mg / l. 131 0 2,8 0 0 0 0 0 1.7 133 0 5 0 0 prs 118 0 8.5 0 137 1 6.5 0 0 prs 125 33 0.5 11.2 15548 39 1 6.5 0 eleven 0 0 prs 26491 0 prs 149 0 0 no feed prs 209 0.5 26492 0 4 0 0 rush 54 4 26494 0 2,8 7.5 2 25 0 0 26523 8 0 3 0 4 nine no feed 0 35320 0 0 52 9.5 okrs

Table 2. Miscible Substances research Date The concentration of reagents, mg / l The corrosion rate, g / m ² · h Change in corrosion rate compared to saltwater corrosion rate Bottled water with DNS-10 with no inhibitor 07/17/2003 fifty 1,1057 Formation water with DNS-10s + SNPKh-5313 07/21/2003 fifty 1.9 Increased 1.72 times

Claims (1)

A method of dispensing reagents by periodically intermittently introducing them into a pumped or produced medium, characterized in that after killing the wells, a single reagent is supplied until the iron ions in the produced water are reduced to no more than 2 mg / l.