RU2257467C1 - Solid base of composition for acid treatment of critical area of formation - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: solid base 75.0-95.0% nitric acid-urea reaction products serving as acid reagent, 1.0-5.5% tertiary amines-hydrogen peroxide reaction product, 2.5-15.0% organic derivatives of phosphonic acid, e.g. nitrilotrimethylphosphonic acid or oxyethylidenephosphonic acid, and 1.5-4.5% nitrogen-containing corrosion inhibitor. Composition prepared on proposed base is more efficient owing to widened application area of composition including wells with formation temperature up to 100°C, successfully prevented, under these conditions, formation of stable oil emulsions with elevated iron-containing stabilizers level, removed water-oil emulsions from critical area of formation, preserved low corrosion activity, and excluded loss in active properties of base upon storage and transportation.

EFFECT: improved performance characteristics of formation critical area composition.

2 cl, 3 tbl

Description

The invention relates to the field of oil production, in particular to compositions for acid treatment of the bottom-hole formation zone (PZP), and can be used in the process of developing wells and their operation in order to intensify the flow of oil from the formation, composed mainly of carbonate reservoirs.

Currently, the vast majority of compositions for the acid treatment of PZP are liquid, which are prepared either directly at the well or in the factory. However, in the first case, when preparing the compositions (especially multicomponent ones), it is required to use a large amount of equipment, there are difficulties with the dosage (the exact observance of which depends on the qualifications of the service personnel), there is a possibility of unproductive losses of a number of components (due to the large volumes of use of acidic compounds at the well, it is quite difficult components in the amount required by the formulation, usually due to packaging characteristics, a number of components are in heel, which leads to their unjustified losses).

The preparation of liquid acid compositions in the factory eliminates the above disadvantages, but leads to increased costs during transport and storage of such a composition.

Based on this, the problem arose of creating a solid base of the composition for the acid treatment of PZP, which could be prepared in the factory and which would not lose its active properties during storage and transportation.

It is known to use in liquid compositions for the acid treatment of PPP as one of the components of organic derivatives of phosphonic acid: nitrilotrimethylphosphonic acid (NTP) [1] or hydroxyethylidenephosphonic acid (HEDP) [2]. However, compositions comprising these components are not without drawbacks, namely:

- the composition with NTF [1] does not provide a sufficient depth of processing of the BOP due to the low reaction rate of NTF with a carbonate rock, and also due to the modification of the surface of the rock with a surface-active substance (surfactant) present in the known composition along with NTF;

- composition with HEDP [2] is also characterized by a low dissolving ability in relation to carbonates and at the same time high corrosion activity (the dissolution rate of steel is 1.5-2.0 g / m ² · h).

Also known is a composition for treating PPP containing hydrochloric acid, the product of the interaction of tertiary amines with hydrogen peroxide, acetic acid and water [3]. The specified known composition at normal temperature is characterized by good penetration, provides dispersion of asphalt-resin-paraffin deposits (ARPD), eliminates the formation of iron-containing stabilizers of oil emulsions.

However, this known composition is characterized by a high rate of interaction with the carbonate rock at elevated temperatures, which reduces the depth of the formation, as well as low stabilizing ability against iron ions under the same conditions.

In addition, the disadvantages of this known composition are the high costs during transportation and its storage, associated with a high content of ballast (water) in the composition, and the rapid deterioration of its quality when stored in metal containers that are not equipped with special protection from the aggressive effects of an acid solution.

Along with liquid compositions for treating PPP, solid compositions containing one acid component are also known, namely:

chloroacetic acid [4] and the product of the interaction of nitric acid with urea [5], the first of which is pumped into the well in molten form, and the second in the form of a suspension.

The disadvantages of both are the low processing efficiency of carbonate rocks, which does not provide the required processing depth, as well as the technological difficulties of application. In the first case, it is required to use special smelters for the melting of chloroacetic acid (the melting temperature of the latter is ~ 62 ° C). And in the second, the difficulty of accurately simultaneously dosing three components, including corrosive nitric acid.

Closest to the proposed technical solution according to the technical essence is a solid base of an acidic composition for treating PPP, which is sulfamic (amidosulfonic) acid [6]. It is pumped into the well in the form of a crystalline suspension or in the form of a solution. Crystalline sulfamic acid is safe to handle, transport and store. Its application allows to increase the productivity of wells and reduce corrosion of oilfield equipment.

However, the acid composition obtained by dissolving the specified solid base in water is characterized by the following disadvantages:

- the inability to use at formation temperatures above + 60 ° C due to hydrolysis of sulfamic acid with the formation of hydrosulfate and sulfate ions, which reduces the processing efficiency and may lead to the precipitation of sparingly soluble sulfates in the BCP;

- the formation of oil-acid emulsions or stable industrial layers upon contact of oil and the specified composition, in particular with an increased content of iron ions in the reaction medium;

- low efficiency when exposed to the bottomhole zone containing water-oil emulsions as colmatants.

The technical problem solved by the invention is to increase the efficiency of the composition prepared on the basis of the invention, by expanding the scope of application of the composition to wells with reservoir temperature up to + 100 ° C, effectively preventing the formation of persistent oil emulsions under these conditions with an increased content of iron-containing stabilizers, destruction and removal of water-oil emulsions from the BCP while maintaining low corrosivity and eliminating the loss of active properties of the base when its storage and transportation.

The specified technical problem is provided by the solid basis of the composition for the acid treatment of the bottom-hole zone of the formation, including an acid reagent, while new is that it additionally contains the product of the interaction of tertiary amines with hydrogen peroxide, organic derivatives of phosphonic acid and a nitrogen-containing corrosion inhibitor, moreover, as an acid reagent the base contains the product of the interaction of nitric acid with urea, in the following ratio of components, wt.%:

nitric acid reaction product

with carbamide 75.0-95.0

product of the interaction of tertiary amines

with hydrogen peroxide 1.0-5.5

organic derivatives of phosphonic acid 2.5-15.0

the specified corrosion inhibitor of 1.5-4.5.

As organic derivatives of phosphonic acid, the solid base of the invention comprises nitrilotrimethylphosphonic acid or hydroxyethylidenephosphonic acid.

The stability of the solid base during storage is provided by the claimed combination of components in their specific ratio and the exception of the formation of corrosive substances.

The function of each component in the proposed framework is as follows.

The product of the interaction of nitric acid with urea in a composition prepared on the basis of the invention serves as an acid reagent that dissolves the components of carbonate rocks with an increase in their permeability and is characterized by a slowed reaction rate with carbonates at elevated reservoir temperatures.

The product of the interaction of tertiary amines with hydrogen peroxide acts as a hydrophobizing agent for a porous medium and a demulsifier, reducing the interfacial tension at the acid-oil interface, and also preventing the formation of emulsions or industrial layers upon contact of the oil with the acid composition and destroying water-oil emulsions even with an increased content of iron-containing stabilizers , and unexpectedly it turned out that he performs this function at elevated temperature. Apparently, this is due to the influence of other components present in the proposed framework.

Organic derivatives of phosphonic acid prevent the formation of precipitation after neutralizing the acid reagent and iron-containing stabilizers of oil emulsions, while maintaining these properties at temperatures up to 100 ° C.

Nitrogen-containing corrosion inhibitor acts as a corrosion inhibitor of steel after dissolution of the inventive base in water and at the same time has a synergistic effect on other properties of the composition. The latter is apparently due to the chemical affinity of the corrosion inhibitor and the acid reagent used.

The inventive solid base was prepared in laboratory conditions, while the following substances were used:

- The product of the interaction of nitric acid with urea is a crystalline powder from white to gray, produced according to TU 27081564.042-98 under the trademark "Netrol", characterized by a mass fraction of acids in terms of nitric acid, not less than 46%, mass fraction of moisture 5-8 %;

- The product of the interaction of tertiary amines with hydrogen peroxide (hereinafter referred to as “amine oxide”) is a transparent or slightly yellowish liquid, produced according to TU 2413-008-48482528-99;

Organic derivatives of phosphonic acid: NTF is produced according to TU 2439-347-05763441-2001; OEDF is produced according to TU 2439-363-05763441-2002;

- Nitrogen-containing corrosion inhibitors:

- The corrosion inhibitor SNPCH-6501 is produced according to TU 39-05765670-OP-216-95;

- Corrosion inhibitor Nating, produced according to TU 2499-037-53501222-2003;

- The corrosion inhibitor KI-1 is produced according to TU 6-01-4689387-34-90.

An example of the preparation of the proposed framework in laboratory conditions.

438.5 g of netrol, 36.65 g of HEDP, 7.35 g of corrosion inhibitor SNPCH-6501 and 17.5 g of amine were sequentially loaded into a 1 liter laboratory double-shaft mixer with stirring.

After stirring for 20-25 minutes, a solid base was obtained with the following content of components, wt.%: The product of the interaction of nitric acid with urea - 87.7; OEDP, an organic derivative of phosphonic acid, 7.33; corrosion inhibitor - 1.47; the product of the interaction of tertiary amines with hydrogen peroxide is 3.5.

Bases with different component contents were prepared in a similar manner.

The composition for the acid treatment of the PPP using the proposed solid base was prepared by dissolving the latter in fresh water to a concentration of 10-15 wt.%. The resulting composition is hereinafter referred to as the “acid composition”.

In the course of laboratory tests, the following properties of acid compositions for the acid treatment of PZP prepared on the basis of the invention were determined:

- corrosion rate through the dissolution rate of steel;

- the effect of acid composition on the permeability of carbonate rocks;

- interfacial tension at the oil – acid composition interface;

- the effect of the acid composition on the formation of an emulsion with oil.

These properties were determined immediately after preparation of the composition and again after heating the composition to 35-90 ° C and cooling it. These studies were necessary to confirm the stability of the properties of the composition prepared using the proposed framework at elevated temperatures.

The effect of acid compositions on the permeability of carbonate rocks was investigated using the UIPK-1M installation using cylinders machined from core material taken from wells with carbonate reservoirs (limestones). Processing efficiency was evaluated by the residual resistance factor

where K ₁ , K ₂ is the coefficient of permeability of a cylindrical core sample in oil before and after pumping the acid composition, respectively.

The interfacial tension at the oil-acid composition interface was determined on a Stalagmometer instrument using a glass capillary by the volume of an oil drop squeezed from the capillary into an aqueous solution of the inventive solid base. The magnitude of interfacial tension was calculated by the formula:

σ = V · K · (ρ _to -ρ _n ), where

σ is the magnitude of interfacial tension, mN / m;

V is the volume of a drop of oil squeezed through the capillary into the acid composition;

K is the capillary constant;

ρ _to , ρ _n - the density of the acid composition and oil, respectively, g / cm ³ .

The effect of the acid composition on the formation of an emulsion with oil was studied as follows. A mixture of 50 ml of oil (anhydrous or irrigated) and 50 ml of the acid composition was placed in a glass beaker, stirred for 30 s on a mechanical stirrer at a shaft rotation speed of at least 2000 rpm, and then kept for 1 hour at a temperature of 20-90 ° C. Visually determined the formation of an emulsion in the interaction of oil and acid composition; the presence of industrial layers, clots, etc. determined by the residue on a sieve with a mesh size of 0.315 mm after filtering through it a mixture of oil and acid composition. The viscosity of the oil layer after interaction with the acid composition was determined on a VPZh viscometer according to GOST 33-82. At high viscosity of oil emulsions (over 100 mPa.s), the viscosity of the latter was measured with a Viscostar L re-viscometer.

The dissolution rate of steel in acid compositions was determined by the weight loss of steel plates St.3 or 08 KP with dimensions of 10 × 10 × 2 mm after exposure to the compositions for 24 hours, cleaning from corrosion products and drying.

Data on the component content of the proposed framework, as well as on the above properties of acidic compositions prepared on this basis, are shown in tables 1-3.

The results are shown in tables 1-3, show that the compositions for the acid treatment of PPP prepared on the basis of the invention have the following advantages over the known compositions:

- characterized by stability of properties at temperatures up to + 100 ° С (the characteristics of the acid composition remain unchanged both during heating and during cooling);

- effectively prevent the formation of oil-acid emulsions and their iron-containing stabilizers, including at elevated temperatures up to + 100 ° C and an increased concentration of iron ions;

- provide a more significant compared with the prototype increase in the permeability of carbonate cores in oil, i.e. increase the efficiency of processing PZP.

These advantages confirm the high efficiency of acid compositions prepared on the proposed basis, when used to increase the productivity of producing wells and to increase the injectivity of injection wells.

SOURCES OF INFORMATION

1. RF patent No. 2047757, cl. E 21 B 43/27, 1993

2. RF patent No. 2153579, class. E 21 B 43/27, 1998

3. RF patent №2138634, cl. E 21 B 43/27, 1999

4. Copyright certificate of the USSR No. 775300, cl. E 21 B 43/27, 1979

5. Copyright certificate of the USSR No. 1739014, cl. E 21 B 43/27, 1989

6. Copyright certificate of the USSR No. 314883, cl. E 21 B 43/27, dated 1966

Table 1
Physico-chemical properties of acid compositions prepared from the proposed solid base (mass fraction of solid base in the composition - 12.5%) No. of composition The content of components in a solid base, wt.% Density,
g / cm ³ The dissolution rate of steel at 20 ° C, g / m ² · h Netrol Oxide
amine OEDF NTF Corrosion inhibitor 1 87.7 3,5 7.33 - 1.47 1,048 0,203 2 90 3.0 - 5.5 1,5 1,047 0.209 3 90 3.0 4,5 - 2,5 1,052 0.197 4 86 4.0 8.0 - 4.0 1,057 0.186 5 90 - 7.5 - 2.0 1,055 0.215 6 93.5 4.0 - - 2.5 1.06 0.151 7 90 4.0 - 6.0 - 1,057 62.5 8 87.7 3,5 7.33 - 1.47 1,047 0.26 nine 89 4.0 5.5 - 1,5 1,052 0.24 10 prototype Technical sulfamic acid of improved quality (solution with a mass fraction of 10%) 1.06 0.206 Note: “Corrosion inhibitor” was used in experiments 1-7 as a corrosion inhibitor; in experiment 8 - SNPCH-6501; in experiment 9 - KI-1.

table 2
The results of pumping the acid composition prepared from the proposed solid base (2V _pores ) through oil-saturated carbonate core samples No. of composition according to the table. 1 Permeability to processing K ₁ , MD Permeability after treatment K ₂ , MD F _OS = K ₂ / K ₁ d.ed. Note 1 161.4 573.1 3,55 Without formation of a filtration channel 2 22.4 13460 600.9 Filtration Channel Formation 3 1.9 7.0 3,7 Without formation of a filtration channel 4 1.8 300.9 167.2 Filtration channel formation without oil breakthrough 8
prototype 56.8 70,4 1.24 Without formation of a filtration channel

Claims (2)

1. A solid base composition for acidizing the bottom of the formation, including an acid reagent, characterized in that it further comprises the product of the interaction of tertiary amines with hydrogen peroxide, organic derivatives of phosphonic acid and a nitrogen-containing corrosion inhibitor, and the base contains the product of the interaction of nitrogen as an acid reagent acids with urea, in the following ratio, wt.%: The product of the interaction of nitric acid with carbamide 75.0-95.0 The product of the interaction of tertiary amines with hydrogen peroxide 1.0-5.5 Organic Phosphonic Acid Derivatives 2.5-15.0 The specified corrosion inhibitor is 1.5-4.5. 2. The solid base according to claim 1, characterized in that, as organic derivatives of phosphonic acid, it contains nitrilotrimethylphosphonic acid or hydroxyethylidenephosphonic acid.