RU2312880C1 - Stabilizer for collector properties of oil formation - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: stabilizer is composed of, wt %: nitrilotrimethylphosphonic acid 2.5-20, oxyethylenediphosphonic acid 2.5-60, cationic surfactant 1.0-40, hydrophobic organosilicon liquid (oil wetting agent) 0.5-10.0, and moisture absorbent 5-50. Use of stabilizer prevents precipitation of salts in formation pores, removes capillary bound water from formation pores, removes reaction products, asphaltenes, tars, and paraffins from bottomhole zones of injection and production wells, and enhances oil wetting properties of treated surfaces.

EFFECT: increased oil recovery from production wells.

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Description

The invention can be used in the oil industry.

It is known from the prior art to use nitrilotrimethylphosphonic acid (NTP) as a component of the composition to prevent the inorganic salts from precipitating in the bottomhole formation zone during oil production - see, in particular, a.s. USSR No. 1224277. This composition allows to increase the time of its inhibition while maintaining the properties of the complete prevention of scaling.

It is known to use a hexane fraction (GF) as a cationic surfactant in a reagent that improves oil recovery.

It is known to use a hydrophobic organosilicon liquid (GCR) as a water repellent in the composition of fluids for killing wells. The use of GKZH allows to reduce the performance of oil well filtration.

It is known to use hydroxyethylidene diphosphonic (OEDP) acid as a component of a composition that prevents the deposition of salts and sand during oil production.

In addition, in the oil industry, the above components are used separately. However, their use is fraught with certain difficulties. In particular, at temperatures of -25 ° C and lower, typical for the conditions of Western Siberia, most cationic surfactants and hydrophobizators freeze or turn into a porridge mass that is not amenable to dissolution, and at a temperature of -35 ° C and below, all surfactants and water-repellents freeze.

Known difficulties have led to the creation of the claimed reservoir properties stabilizer - the Axis multifunctional composition — used as a component in water-soluble formulations used: for killing wells with the goal of not degrading the reservoir's productive properties and stabilizing the bottom-hole zone characteristics; during acid treatment of the bottom-hole zone of producing wells; during acid treatment of injection wells in order to increase the level of injectivity and / or alignment of injectivity profiles; as a surface-active component of an aqueous composition injected into an injection well to disperse reaction products through the formation. The technical result achieved by the implementation of the present invention is to prevent the precipitation of salts in the pores of the formation due to a shift in thermodynamic equilibrium when the formation waters come into contact with injected, aqueous formulations containing the claimed stabilizer, to remove capillary-bound water from the formation pores, to remove reaction products, asphaltenes , resins and paraffins from the bottom-hole zone of production and injection wells, hydrophobization of the treated surface.

To achieve the technical result, a reservoir stabilizer of reservoir properties is proposed, consisting of a mixture of scale inhibitors, surfactants, hydrophobizing agents and a moisture absorber, while nitrilotrimethylphosphonic (NTF) and hydroxyethylidene diphosphonic (oEDF) are used as scale inhibitors. as a surfactant, a cationic surfactant, and as a hydrophobizing agent, a hydrophobic organosilicon liquid, while these components may be contained in the stabilizer in the following amounts, wt.%:

water repellent 0.5 ÷ 10.0 NTF 2.5 ÷ 20 OEDF 2.5 ÷ 60 Surfactant 1,0 ÷ 40 moisture absorber 5.0 ÷ 50

The proposed stabilizer of the reservoir properties of the reservoir of an oil well includes the following components:

water-soluble acids - scale inhibitors of OEDP and NTF acids; their presentation is powder; cationic surfactant (for example, GF) and GKZH water repellent, their presentation is a liquid having an alkaline reaction; moisture absorber.

The listed components are opposite in chemical nature, their direct mixing to obtain a complex composition is impossible, because acids, dissolving in alkalis, immediately react with them and the result is the product of this reaction, and not a complex composition containing all the necessary components. The consequence of this was the need to solve the problem of compounds in the composition of the above heterogeneous chemical nature of the substances. The result of the solution was the conclusion that to prevent a chemical reaction between the components of the stabilizer, they should all be in a solid state, since in this state the substance is most chemically inert. To achieve this result, a technological process was developed for the increment of liquid surfactants and water repellents in dry forms of the same substances. After obtaining dry forms of all stabilizer components, their quantitative composition was developed, which ensures inhibition of scaling processes even when scaling inhibitors are contained in the aqueous mixture in an amount of up to 5 mg / L and a decrease in interfacial tension due to the introduction of a cationic surfactant.

Introduction to the composition of the claimed stabilizer of the reservoir properties of the NTF and OEDF reservoir as scale inhibitors is due to the following: it is known that, for example, when a kill fluid is mixed with sodium bicarbonate and potassium chloride water, salt formation occurs from the well for mixing produced water with the components of the killing solution. In particular, the formation water of oil fields in the West Siberian region contains salt-forming cations of calcium, barium and strontium, which precipitate with bicarbonate and sulfate anions. Ability loss of calcite in the derivation of the well killing associated with a reduction of dissolved carbon dioxide (carbon dioxide) contained in the water reservoir, due to mixing with a solution of jamming and reaction equilibrium shift to the right - Ca (HCO _{3) 2} + H ₃ ↔SaSO ₂ O + CO ₂ . In addition, during the mixing of formation water of oil fields, in particular the Noyabrsk region with killing solutions, salt formation of calcite, celestine and barite is possible in the well.

The introduction of a hexane fraction as a surfactant into the stabilizer is due to the fact that during the oil production, due to the violation of thermodynamic equilibrium in the near-wellbore zone, asphaltene-resinous and paraffin deposits are deposited on the walls of the well and in the pores of the formation, which, clogging the pores of the formation, impede the flow oil. For their effective removal and use of GF. In addition, the presence of HF in the killing solution allows it to exert an additional effect on the bottomhole formation zone by removing not only contaminants, but also capillary bound water from it.

The use of GKZH as a water repellent for the well surface is due to the need to facilitate the passage of oil in the pores of the reservoir by reducing interfacial tension at the oil / water interfaces.

Below are a few examples that display specific applications of the claimed stabilizer.

Example 1. In OJSC "Surgutneftegas" used the stabilizer of the reservoir properties of the oil reservoir of the following composition, wt.%:

- hydrophobic organosilicon liquid (GKZh-11) - 2.0;

- nitrilotrimethylphosphonic acid - 16.0;

- hydroxyethylidene diphosphonic acid - 34.0;

- surfactant (GF-1) - 10;

- moisture absorber (unosil) - 38.0.

The stabilizer of this composition was used as an additive to the solution of killing wells based on technical table salt. The concentration of the stabilizer was 0.05 wt.%. Silencing was carried out in wells with a sufficiently high permeability (above 50 mD, BS-10 layer), low clay content and a high risk of the formation of insoluble sediments in the pore space and working bodies of the downhole pumping equipment. The use of a stabilizer made it possible to preserve the reservoir properties of the reservoir as much as possible, which resulted in an increase in fluid flow rate by 5–7%; an increase of 1.5 ÷ 2 times the period of the wells without reducing the flow rate of the fluid; reduction by 20 ÷ 25% of the time to reach the steady state.

Example 2. At OAO Sibneft-Noyabrskneftegaz, the reservoir stabilizer of the oil reservoir was used in the following composition, wt.%:

- hydrophobic organosilicon liquid (Penta 811) - 4.0;

- nitrilotrimethylphosphonic acid - 15.0;

- hydroxyethylidene diphosphonic acid - 33.0;

- surfactant (Neftenol K) - 12.0;

- moisture absorber (KSM silica gel) - 36.0.

The stabilizer was used as an additive to well killing solutions based on technical table salt. The concentration of the stabilizer was 0.055 wt.%. Silencing was carried out in wells with a sufficiently high permeability (40-60 mD, BS 0, BS 6, BS 10-1 formations), a low clay content and a high probability of the formation of insoluble sediments in the pore space and working bodies of the downhole pumping equipment. Using a stabilizer allowed to increase oil production by 8%; fluid flow rate by 19.3%; productivity ratio of 4%.

Example 3. In OAO Yuganskneftegaz, the reservoir stabilizer of the oil reservoir was used in the following composition, wt.%:

- hydrophobic organosilicon liquid (GKZh-10) - 7.0;

- nitrilotrimethylphosphonic acid - 8.0;

- hydroxyethylidene diphosphonic acid - 14.0;

- surfactant (Don 96) - 30;

- moisture absorber (aerosil) - 41.0.

The stabilizer was used as an additive to well killing solutions based on technical table salt. The concentration of the stabilizer was 0.057 wt.%. Silencing was carried out in wells with medium permeability (30 mD), significant clay content and an average probability of formation of insoluble sediments. The result of the use of a stabilizer was a reduction in the time of well completion at an average rate of 1.5 days, an increase in productivity by an average of 9%.

Example 4. In OJSC "Yuganskneftegas" also used the stabilizer of the reservoir properties of the oil reservoir of the following composition, wt.%:

- hydrophobic organosilicon liquid (IVV-1) - 9.5;

- nitrilotrimethylphosphonic acid - 3.0;

- hydroxyethylidene diphosphonic acid - 7.0;

- surfactant (sulfanol) - 38.5;

- moisture absorber (ammonium chloride) - 42.0.

The stabilizer was used as an additive to well killing solutions based on a mixture of sodium chloride and potassium chloride. The concentration of the stabilizer was 0.058 wt.%. Silencing was carried out in wells with low permeability (up to 8 mD, Jurassic deposits), high mudness of the reservoir and low probability of the formation of insoluble sediments. The result of the use of a stabilizer was a reduction in the time of well completion at an average rate of 1.0 day, an increase in productivity by an average of 6%.

The generalized data on the commercial use of the stabilizer are presented in the following table.

The boundary values of the content of the components of the proposed stabilizer are due to the characteristics of productive oil reservoirs, such as permeability, clay content in the reservoir, the probability of the formation of insoluble sediments.

The use of the inventive stabilizer as a component of a silencing fluid ensures, due to the synergistic addition of all the described effects, that the filtration characteristics of oil reservoirs remain unchanged, and in some cases an increase in such characteristics as oil permeability, leading to an increase in well debit.

Claims (1)

Stabilizer of reservoir properties of the reservoir, consisting of a mixture of scale inhibitors - nitrilotrimethylphosphonic NTF and hydroxyethylidene diphosphonic HEDP acids, a cationic surfactant surfactant, a hydrophobizing agent - hydrophobic silicone liquid GKZH and a moisture absorber in the following quantities: GKZH 0.5-10.0 NTF 2,5-20 OEDF 2,5-60 cationic surfactant 1,0-40 moisture absorber 5-50