RU2301248C1 - Base of composition for oxygen treatment of terrigenous reservoir and declaying of bottomhole formation zone - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention can be employed in well development and operation targeted to intensify oil inflow from formation constituted preferably by terrigenous reservoirs, including those with carbonate inclusions. Base of above-indicated composition contains, wt %: sulfamic acid 4-40, ammonium fluoride or ammonium bifluoride, or ammonium bifluoride-fluoride 4-40, nitric acid-urea reaction product 10-90, phosphonic acid organic derivatives 0.5-10, and corrosion inhibitor 0.5-5. Use of such base prevents formation of sediments, including secondary ones, both at normal and at elevated (above 90°C) formation temperatures; provides dissolution of terrigenous reservoir, including those with carbonate inclusions, resulting in high-degree declaying of formation due to increased degree of dissolution and dispersion of clay material; enables preparation of working fluids from base with fresh and mineralized water; and also prevents formation of stable emulsions and settling of iron-containing sediments into bottomhole zone of formation. Invention in more details is reflected in dependent claims.

EFFECT: improved performance characteristics of composition.

4 cl, 2 tbl

Description

The invention relates to the field of oil production, in particular to compositions for acid treatment and wedging of the bottomhole 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 reservoir, composed mainly of terrigenous reservoirs and terrigenous reservoirs with carbonate inclusions.

Currently, the vast majority of compositions for the acid treatment of terrigenous reservoirs 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 due to the presence of ballast - water.

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

A known composition for thermochemical acid treatment of the formation, the base of which contains the product of the interaction of nitric acid with urea and sodium nitrite (Auth. Certificate of the USSR No. 1739014, class B21V 43/27, from 1989).

However, this known composition is designed to remove sediment deposits and can chemically affect (dissolve) only materials that make up the carbonate reservoir. Aluminosilicates and quartz materials that are part of the terrigenous collector, the aforementioned known composition can not dissolve.

Also known is the basic base of the acidic composition for treating PZP, which is sulfamic (amidosulfonic) acid (Auth. USSR Certificate No. 314883, class E21B 43/27, dated 1966). It is pumped into the well in the form of a crystalline suspension or in the form of an aqueous 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 base base in water is also intended for carbonate reservoirs and is ineffective in claying and dissolving terrigenous reservoirs. In addition, it cannot be used at reservoir temperatures above + 60 ° C due to hydrolysis of sulfamic acid with the formation of hydrosulfate and sulfate ions, which reduces the processing efficiency, since it leads to the precipitation of sparingly soluble sulfates in the PPP.

Known solid base for acid treatment of PPP, containing the product of the interaction of nitric acid with urea, the product of the interaction of tertiary amines with hydrogen peroxide - a complex cationic surfactant, organic derivatives of phosphonic acid and a nitrogen-containing corrosion inhibitor (RF Patent No. 2252567, class E21B 43/27, 2004).

Working solutions of this known base showed high efficiency when used in carbonate reservoirs, however, when working with terrigenous rocks, the dissolution rates of the latter are very low. In addition, these working solutions are heat-resistant only at temperatures up to + 100 ° C.

Closest to the proposed technical solution in technical essence is the basic base of the acid composition for treating terrigenous reservoirs containing ammonium fluoride or bifluoride, or ammonium bifluoride-fluoride and sulfamic acid, taken in an equimolar ratio. In addition, the known base base of the acid composition may additionally contain a water-soluble surfactant (RF Patent No. 2101482, CL. E21B 43/27, from 1996).

Working solutions prepared by dissolving the specified base base in water have several disadvantages, namely:

- the formation of precipitation when used at temperatures above + 85 ° C, as well as when used in terrigenous reservoirs with carbonate inclusions;

- the inability to use for the dissolution of formation mineralized water;

- a low degree of loosening of the bottomhole formation borehole.

The technical result consists in eliminating the formation of precipitation, including secondary, both at normal and at elevated temperature in the formation (above 90 ° C), when dissolving terrigenous reservoirs, including those with carbonate inclusions, with a high degree of clay formation by increasing the degree of dissolution and dispersion of clay material, while at the same time making it possible to prepare working solutions from the base on fresh or mineralized water.

An additional technical result is the prevention of the formation of persistent emulsions and the precipitation of iron-bearing sediments in the bottomhole formation zone.

The use of a dry powder base base also reduces transport costs, increases the convenience of transportation and storage, improves working conditions during the preparation of working solutions.

The specified technical result is provided by the basic composition for acidizing the terrigenous reservoir and wedging out the bottom of the formation containing sulfamic acid, ammonium fluoride or ammonium bifluoride, or ammonium bifluoride, and additionally it contains the product of the interaction of nitric acid with urea, organic derivatives of phosphonic acid and corrosion inhibitor in the following ratio of ingredients, wt.%:

sulfamic acid 4-40 ammonium fluoride or ammonium bifluoride or ammonium fluoride bifluoride 4-40 product of nitrogen interaction acids with urea 10-90 organic phosphonic acid derivatives 0.5-10 corrosion inhibitor 0.5-5

Also, the base base, when used in low-permeability reservoirs, may contain a cationic or nonionic surfactant surfactant, or a mixture thereof in an amount of 0.5-5 wt.%.

As organic derivatives of phosphonic acid, the base base contains nitrilotrimethylphosphonic acid (NTP) or hydroxyethylidene phosphonic acid (OEDP).

In this case, the working solutions of the base base contain fresh or saline water.

As a surfactant, cationic surfactant Kama-03 is used in the experiments, nonionic surfactant Neonol AF _9-12 , the product of the interaction of tertiary amines with hydrogen peroxide, for example, OxyPAS.

The achievement of the specified technical result is ensured through the use of effective, well-combined with each other ingredients.

During the interaction of the working solution prepared from the claimed base stock with a terrigenous reservoir, the following chemical reactions proceed. When dissolving the specified base base in water, in addition to the processes of dissolving the ingredients included in the base, additional free nitric acid and urea are released

CO (NH ₂ ) ₂ · HNO ₃ = CO (NH ₂ ) ₂ + HNO ₃ ,

and hydrofluoric acid is released from ammonium bifluoride NH ₄ F · HF = NH ₄ F + HF.

The resulting ammonium fluoride is in equilibrium with hydrofluoric acid in accordance with the following reactions:

NH ₄ F + NH ₂ SO ₃ H = NH ₂ SO ₃ NH ₄ + HF,

NH ₄ F + HNO ₃ = NH ₄ NO ₃ + HF

Thus, as a result of dissolution of the base base in an aqueous medium, three acids with different chemical nature are simultaneously found - nitric, sulfamic and hydrofluoric (hydrofluoric) acids, as well as urea (urea), complexones (NTF or OEDF), corrosion inhibitor, surfactant (if it was introduced), as well as a large number of ammonium cations in the form of ammonium salts of the above acids.

The formation of significant amounts of ammonia (and in the acidic environment of ammonium cations) in addition to its presence in ammonium bifluoride (fluoride) occurs during the hydrolysis of sulfamic acid and urea (urea), which is part of its complex (reaction product) with nitric acid according to the reactions:

NH ₂ SO ₃ H + H ₂ O = NH ₃ + H ₂ SO ₄ ,

СО (NH ₂ ) ₂ + Н ₂ О = 2NH ₃ + СО ₂

The above hydrolysis processes occur especially rapidly at elevated temperatures. Moreover, one ammonia molecule forms two ammonia molecules and a carbon dioxide molecule.

The terrigenous reservoir, as is known, consists of quartz materials (SiO ₂ ), and clay materials (Al ₂ O ₃ · (0.3-8) SiO ₂ (0.5-19) H ₂ O), often with inclusions of metal oxides : K ₂ O, MgO or carbonate inclusions (CaMg) CO ₃ .

Below are the main chemical reactions that occur during the interaction of a working solution prepared from the proposed base base, and rocks of a terrigenous reservoir. Dissolution of quartz materials:

SiO ₂ + HF = SiF ₄ + H ₂ O

Decomposition of clay materials:

Al ₂ O ₃ · (0.3-8) SiO ₂ (0.5-19) H ₂ O + HF = AlF ₃ + SiF ₄ + H ₂ O

Interaction with carbonate rocks:

(CaMg) СО ₃ + HNO ₃ -Са (NO ₃ ) ₂ + Mg (NO ₃ ) ₂ + Н ₂ О

MgO + 2HNO ₃ = Mg (NO ₃ ) ₂ + H ₂ O

(CaMg) CO ₃ + 3NH ₂ SO ₃ H = Ca (NH ₂ SO ₃ ) ₂ + Mg (NH ₂ SO ₃ ) ₂ + H ₂ O

In a medium containing a lot of ammonia (in an acidic environment - ammonium ions), the formation of ammonia, complex compounds that do not precipitate, and thus prevent the formation of insoluble precipitates.

For example, calcium fluoride:

CaF ₂ + 2NH ₃ = [Ca (NH ₃ ) ₂ ] F ₂

In addition, ammonium cations prevent clay swelling, and carbon dioxide, dissolving in oil hydrocarbons, reduces its viscosity, all this increases the permeability of terrigenous rocks and terrigenous rocks with carbonate inclusions, and the reaction rate with the rock slows down at elevated formation temperatures.

After neutralizing the acid reagent and iron-containing stabilizers of oil emulsions, organic derivatives of phosphonic acid react to prevent the formation of precipitation and preserve these properties at high formation temperatures.

Due to the fact that effective surfactants are used in the composition, the interfacial tension at the interface “acid composition - oil” is reduced, which ensures high permeability of the composition in low-permeability parts of the reservoir and thereby increases the coverage of the treatment zone.

The corrosion inhibitor performs the function of a corrosion inhibitor of steel after dissolving the inventive base in water.

The inventive base framework was investigated in laboratory conditions. The following substances were used for its preparation, as well as for the preparation of working solutions:

- 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 brand name Nitrol, characterized by a mass fraction of acids in terms of nitric acid, not less than 4-6%, mass fraction of moisture 5-8 %;

- 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

- sulfamic acid TU 2121-278-00204197-2001

- ammonium bifluoride GOST 9546-75

- ammonium fluoride GOST 4518-75

- ammonium bifluoride fluoride TU 113-08-54483

- Surfactants:

- oksiPAV is issued according to TU 2413-008-48482528-99

- neonol AF9-12, TU 2483-077-05766801-98

- Surfactant "Kama-03", TU 2482-038-53501222-2004

- Corrosion inhibitors:

- SNPCH-6501 is produced according to TU 39-0576570-OP-216-95

- Naming is produced according to TU 2499-037-53501222-2003

- KI-1 is produced according to TU 6-01-4689387-34-90

- technical fresh water with a hardness of 12 mEq / l

- mineralized water with a density of 1.02-1.03 g / cm ³ .

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

Example 1. In a laboratory double-shaft mixer with a volume of 3 l, 118 0 g of Nitrol, 260 g of ammonium bifluoride, 440 g of sulfamic acid, 50 g of complexon-oxyethylidenephosphonic acid, 30 g of corrosion inhibitor Nating, 40 g of surfactant were loaded sequentially with stirring "Kama-03." After stirring for 20-25 minutes, a basic base was obtained with the following content of ingredients, wt.%: The product of the interaction of nitric acid with urea - 59, ammonium bifluoride - 13, sulfamic acid - 22, corrosion inhibitor "Nating" -1.5, surfactant "Kama-03" - 2, an organic derivative of phosphonic acid OEDP - 2.5.

Basic bases with different contents of ingredients were prepared in a similar way.

Working solutions using the basic composition for acidizing terrigenous reservoirs and loosening PZP were prepared by dissolving the latter in fresh or mineralized water to a concentration of 10-15 wt.%. The resulting working solution is hereinafter referred to as the "acid composition".

During laboratory tests, the following properties of acid formulations prepared using the proposed base base were determined:

1) the effect of the acid composition on the permeability of terrigenous rocks and terrigenous rocks with carbonate inclusions,

2) the effect of the acid composition on the clay and rock clasticification

3) interfacial tension at the oil-acid composition phase boundary

4) corrosion rate through the dissolution rate of steel.

The effect of acid compositions on the permeability of terrigenous rocks of terrigenous rocks with carbonate inclusions was studied using the UIPK-1Ms installation using cylinders machined from core material taken from wells with terrigenous reservoirs. The processing efficiency was evaluated by the residual resistance factor f _OS :

F _OS = K ₂ / K ₁ ,

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 effect of the acid composition on the decontamination of terrigenous rocks was determined by determining the solubility of a core material model containing 20 wt.% Bentonite clay, 5% carbonates and 75% quartz sand. Solvent capacity (P) was determined by the formula

P = (ΔM · 100) / M,%

where ΔМ is the change in the mass of the sample of the core material model after exposure to the acid composition, M is the initial mass of the model sample (dried to constant mass at a temperature of 120 ÷ 150 ° C).

The formation of secondary sediments was determined visually when exposed to the core material model with the acid composition at a temperature of 95-110 ° C. Observation time 3 hours

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

σ = V · K · (ρ _to -ρ _n ),

where σ is the magnitude of the 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 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 ingredient content of the proposed base base, as well as on the above properties of acidic compositions prepared on this basis, are shown in tables 1 and 2.

The results shown in tables 1 and 2 show that the acid compositions for the acid treatment of PPP prepared on the basis of the claimed base have the following advantages over the known compositions:

- characterized by high dissolving ability in relation to clay materials;

lack of secondary precipitation even at high temperatures;

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

These advantages confirm the high efficiency of acid formulations prepared on the proposed base basis (with both fresh and mineralized water), when used to increase the productivity of production wells and to increase the injectivity of injection wells drilled in terrigenous reservoirs.

Claims (4)

1. The basic basis of the composition for the acid treatment of the terrigenous reservoir and wedging of the bottomhole formation zone, containing sulfamic acid, ammonium fluoride, or ammonium bifluoride, or ammonium bifluoride, characterized in that it additionally contains the product of the interaction of nitric acid with urea, organic derivatives of phosphonic acid and corrosion inhibitor in the following ratio of ingredients, wt.%: sulfamic acid 4-40 ammonium fluoride, or ammonium bifluoride, or ammonium fluoride bifluoride 4-40 product of nitrogen interaction acids with carbamide 10-90 organic phosphonic acid derivatives 0.5-10 corrosion inhibitor 0.5-5 2. The base base according to claim 1, characterized in that when used in low-permeability reservoirs it additionally contains a cationic or nonionic surfactant or a mixture thereof in an amount of 0.5-5 wt.%. 3. The basic basis according to claim 1, characterized in that as organic derivatives  phosphonic acid, it contains nitrilotrimethylphosphonic acid or hydroxyethylidenephosphonic acid. 4. The basic base according to claim 1, characterized in that its working solutions contain fresh or saline water.