RU2545582C1 - Composition and method for acid processing of bottom hole formation zone - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: composition for bottom hole formation zone processing comprises following elements in wt %: hydrochloric acid - 10.0-20.0, anionic surfactant, or non-ionic surfactant, or cationic surfactant, or mix thereof - 0.4-3.0, phosphorus compound AFON 300M - 0.01-15.0, solvent - 5.0-25.0, water making the rest. Proposed process comprises injection of said acid compound and its driving. Said compound is held to remove the reaction products. Note here that said acid compound is forced in pulse mode or in continuous mode in amount of 1-3 m³ per running meter of perforated depth of the bed at pressure allowable for this bed.

EFFECT: higher capacity of injection wells and fluid inflow due to decelerated reaction with bed rock, lower intensity of acid corrosion.

4 cl, 2 tbl, 17 ex

Description

The invention relates to the oil industry and can be used for acid treatment of the bottom-hole formation zone to increase the injectivity of injection wells and to intensify the flow of fluid from the reservoir with carbonate reservoirs.

A known composition for treating the bottom-hole zone of a carbonate formation, including in wt.%: Hydrochloric acid 10-20, non-inogenic surface-active substance (nonionic surfactant) 0.3-1.0, acetone 20-40 and the rest is water (see ed. certificate No. 1513131, MKI E21B 43/27, publ. 1989).

This composition does not provide the required depth of treatment of the bottomhole zone of the well due to the high dissolution rate of the rock.

Known surface-active acid composition for processing carbonate reservoirs, including in wt.%: Hydrochloric acid 6.0-24.0, alcohol-containing compound 5.0-30.0, technical detergent TMS "Zhenilen" 0.5-2, 0, the cationic surfactant is OxyPAS or Don-96 0.2-1.0, the iron stabilizer is 0.5-3.0 and the rest is water (see RF Patent No. 2494136, MKI C09K 8/74, publ. 2013, )

The disadvantage of this composition is the presence in the composition of the technical detergent "Zhenilen" sodium silicate. When the composition is injected into the carbonate formation, Ca ²⁺ and Mg ^{2+ ions are released} ; moreover, these ions are present in the formation waters in the form of CaCl ₂ and MgCl ₂ salts. The presence of these ions leads to the formation of insoluble precipitates of calcium silicate and magnesium.

The closest in technical essence and the problem to be solved with the claimed composition is an acid composition for treating the bottom-hole zone, including in wt.%: Hydrohalic acid 8.0-75.0, corrosion inhibitor 0.5-2.0, phosphonic acid and / or neonogenic oxyethylated surfactant 0.5-2.0, solvent - the rest (see RF Patent No. 2100587, MKI E21B 43/27, publ. 1997).

Laboratory studies have shown the non-selectivity of the use of the composition for oil and water-saturated layers of the reservoir.

A known method of oil recovery by injection into the reservoir of an acid composition containing in wt.%: Acid 97.5-99.9 and a moderator of the reaction with the formation rock 0.1-2.5, and a composition containing in wt.%: Surface active substance 5.0-16.0, liquid hydrocarbon 84.0-95.0, with a ratio of its volume to the volume of the acid composition from 2 to 4 (see RF Patent No. 2295635, MKI E21B 43/22, publ. 2007 g .).

This method has a significant drawback. The technology provides for the injection of two solutions: acid composition and hydrocarbon composition.

A known method of processing the bottom-hole zone of a well, which includes selling light hydrochloric acid solution of 5.0-20.0% concentration with a surfactant ML-81 into a zone of a productive formation previously prepared in distilled water at a temperature of 80-90 ° C B, holding a technological exposure of not more than 2 hours and a depressive effect (see RF Patent No. 2280154, MKI E21B 43/27, publ. 2006).

The known method involves pre-heating the acid composition to 80-90 ° C, which requires additional energy and does not provide the required processing depth.

A known composition for processing the bottom-hole zone of a carbonatonic reservoir, containing in wt.%: Hydrochloric acid 7.0-19.0, solvent 10.0-45.0, surfactant 0.1-3.0, phosphoric acid 4.0-14 , 0 and the rest - water, and the method of acid treatment of the bottom-hole zone of a carbonate oil reservoir, which involves injecting the above acid composition into a well and then selling it to the depth of the reservoir and carrying out technological aging (see RF Patent No. 2293101, MKI C09K 8/72, E21B 43/27, publ. 2007).

The disadvantage of this invention is the use of phosphoric acid, which, when the concentration of hydrochloric acid is reduced due to its interaction with the carbonate rock, forms insoluble precipitates of calcium and magnesium phosphates with the rock of the formation, which leads to a decrease in processing efficiency.

The closest in technical essence the achieved effect to the claimed method is a method of treating the bottom-hole zone of an oil reservoir, including the flow of acid reagent through the well into the zone of the reservoir in volumes that ensure that the filtration resistance in the zone of the reservoir remote from the well exceeds those in its bottom-hole zone, holding and removal of waste products by depressing the well depending on the injectivity of the wells As well as squeezing the liquid take fresh water or process water or process water with added detergent composition or oil with an oil soluble emulsifier (see. Russian Patent №2346153, IPC E21B 43/27, C09K 8/74, publ. 2009 YG).

This method is applicable for processing only terrigenous reservoirs and the absence of a moderator in the reagent does not provide the required depth of treatment of the bottomhole zone.

The aim of the invention is to develop a composition for the acid treatment of the bottom of the formation and the method of acid treatment of the bottom of the formation using it, which is highly effective by slowing down the reaction rate of the acid with the formation rock, reducing the rate of acid corrosion, preventing the formation of secondary sediments and the formation of an emulsion and providing the washing action of the composition.

This goal is achieved by creating a composition for the acid treatment of the bottomhole formation zone containing hydrochloric acid, a surfactant - nonionic surfactant, or anionic surfactant, or surfactant, or a mixture thereof, Athos 300M, solvent and water, in the following ratio, wt.%:

hydrochloric acid 10.0-20.0 APAS, nonionic surfactants, KPAV or their mix 0.4-3.0 Athos 300M 0.01-15.0 solvent 5.0-25.0 water rest,

moreover, the composition may additionally contain a corrosion inhibitor in an amount of 0.5-2.0 wt.%, and in the method of acid treatment of the bottomhole formation zone, the above acid composition is injected, followed by its sale and technological exposure, and the injection is carried out in a pulsed or continuous mode in the amount of 1-3 m ³ per linear meter of perforated formation thickness at a pressure not exceeding the allowable on the treated formation.

In an embodiment of the method, the acid composition is injected into the treated formations at intervals, which makes it possible to control the volume and mode of injection depending on the filtration properties of the formation.

Hydrochloric acid is used according to TU 2122-131-05807960-97 with rev. 1-3, TU 2458-017-12966038-2002, TU 2458-264-05765670-99 as amended. 1, TU 2458-526-05763441-2010, TU 2122-252-05763441-99 as amended. 1-4, GOST 3118-77, GOST 857-95.

As surfactants can be used anionic surfactants, nonionic surfactants, cationic surfactants, or a mixture thereof, such as: Volgonate alkyl sulfonate according to TU 2481-308-05763458-2001; Neftenol K (RD-1K) according to TU 2483-065-17197708-2002; emulsol NGL-205 grade A according to TU 0253-050-7035181853-2008; alkapav 16.30 according to TU 2482-004-04706205-2005; neonol AF ₉ -6, AF ₉ -12 according to TU 2483-077-05766801-98; oxanol KD-6, O-18, TsS-21 according to TU 2483-328-05763441-2000; OP-10 according to GOST 8433-81; syntamide-5 according to TU 6-02-640-91; syntanol DS-10, DT-7 according to TU 6-14-577-88. Introduction to the composition of surfactants helps to reduce interfacial tension at the border with hydrocarbons, prevents the formation of water-oil emulsions and ensures compatibility of composition and reservoir fluid, as well as provides easier removal of spent reaction products and formation contamination.

Athos 300M is a mixture of sodium salts of phosphonic and hydrochloric acids and is produced according to TU 2499-540-05763441-2012 with rev. 2. Introduction to Athos 300M helps to slow the dissolution rate of carbonate rock (table 1, example 16) due to the formation of a film on the interface: carbonate rock - acid composition.

As a corrosion inhibitor can be used:

Katasol 18-3 according to TU 2482-005-49811-247-2010; methane-2 according to SPT-500-2006; KI-1 MR according to TU 2482-033-42942526-2002; PB-5 according to TU 6-01-28-92; PKU-E according to TU 6-02-1299-85; Sinol IKK according to TU 2482-002-48482528-98; BA-6 according to TU 6-02-1192-79; KI-1 according to TU 6-046-89-381.006-97. A corrosion inhibitor is formulated using non-inhibited hydrochloric acid.

Organic solvents are used as a solvent, such as: isopropyl alcohol according to GOST 9805-84; propyl alcohol according to TU 2632-106-4449379-07; methyl alcohol according to GOST 2222-95; technical ethyl alcohol in accordance with GOST 17299-78. The use of monohydric alcohols reduces interfacial tension at the border with hydrocarbons, which contributes to the creation of a homogeneous system in contact and mixing of reservoir and injected reagents and prevents the formation of emulsions that block filtration channels.

The proposed composition for acid treatment can be prepared both in industrial production and immediately before use by sequential dissolution of the components in the claimed amounts. The ratio of the components in the composition is determined experimentally as the most optimal for solving the problem.

The proposed composition is a liquid from colorless to brown in color, stable during transportation and storage.

The proposed processing method consists in injecting an acid composition into the well in a volume of 1-3 m ³ per meter of perforated formation thickness at a pressure not exceeding the permissible level for the treated formation. At low injectivity, the wells are first exposed to the bath mode. The injection of the acid composition can be performed in a pulsed mode, which allows to increase the processing depth at low permeability, or in a constant mode, which provides continuous movement in the bottomhole zone. To treat zones of the formation with different permeability, a funnel for injecting the acid composition is set at the level of the lower perforation holes. After injection of the acid composition, it is forced into the formation by industrial water or an oil-water emulsion or oil in the volume of tubing and then technological exposure is carried out for 4-6 hours depending on the temperature of the formation. In the case of high heterogeneity of the filtration properties of the treated zones of the formation, the acid composition is injected intervalwise. This injection allows you to adjust the volume and mode of injection of the acid composition. The extraction of the reaction products of the acid composition with carbonate rock is carried out by the swabbing method.

To prove the conformity of the proposed proposal to the criterion of "industrial applicability", we give examples of the preparation of the composition for the acid treatment of the bottomhole formation zone and the effectiveness of the impact on the bottomhole zone using known and claimed compositions. The research results are shown in table 1.

Example 1 (the claimed composition).

In 64.2 g of water, 12.0 g of Athos 300M, 0.8 g of oceanol KD-6, 13.0 g of isopropyl alcohol and 10.0 g of hydrochloric acid are added with stirring (see table 1, example 1).

Examples 2-6 are carried out analogously to example 1, changing the types of components used and their content in the composition.

Example 7

To 73.1 g of water, 0.9 g of Athos 300M are added with stirring, a mixture of 1.0 g of syntanol DT-7 and 1.0 g of alkapava 16.30, 11.0 g of methyl alcohol, 2.0 g of corrosion inhibitor - KI-1 and 11.0 g of hydrochloric acid (see table 1, example 7).

Examples 8-15 are carried out analogously to example 7, changing the types of components used and from the content in the composition.

Example 16

To 58.9 g of water, 2.1 g of syntamide-5, 25.0 g of isopropyl alcohol and 1.0 g of corrosion inhibitor, methane, are added with stirring (see table 1, example 16).

Example 17 (prototype).

In 60.0 g of hydrochloric acid of 25% concentration, 2.0 g of KI-1 corrosion inhibitor is added with stirring, then 2.0 g of nitrilotrimethylphosphonic acid, 1.0 g of neonol AF _9-12 and 3.0 g of acetone (cm table 1, example 17).

To study the kinetics of the interaction of the composition with carbonate, a technique is used based on the measurement in time of the volume of carbon dioxide released during the interaction of the proposed composition with calcium carbonate (marble).

The installation consists of a flask in which an interaction reaction occurs, connected by a flexible hose to a Drexel placed in a vessel with water. The emitted carbon dioxide displaces water from the vessel, which flows through a flexible hose into a receiving measuring tank.

In each experiment, a 1 × 1 × 1 cm cube is used, cut from a single marble sample, which is placed in a flask with the test composition. The volume of the composition is 50 cm ³ , the experimental temperature is 20 ± 2 ° C, and the pressure is atmospheric. The reaction rate of the interaction of calcium carbonate with the composition is monitored by the change in the volume of released carbon dioxide over time. The solubility coefficient of calcium carbonate is calculated for half dissolution of the cube, based on the time of allocation of 50% of the total volume of gas released:

where γ is the weight of the cube, g;

τ ₅₀ - time for the allocation of 50% of the volume of carbon dioxide, hour;

S is the surface area of the cube, cm ² .

Table 1 The content of the components of the composition, wt.% The solubility coefficient of the rock, g / cm ² · h №№ Hydrochloric acid in terms of HCl Athos 300M Corrosion inhibitor Solvent Surfactant Water one 2 3 four 5 6 7 8 one 10.0 12.0 - 13.0 isopropyl alcohol 0.8 oxanol KD-6 64,2 3.45 2 12.0 0.5 - 7.0 methyl alcohol 1.4 emulsol NGL-205 grade A 79.1 3,50 3 14.0 1,5 - 9.0 technical ethyl alcohol 0.4 alkapav 16.30 75.1 3.56 four 16,0 5,0 - 15.0 isopropyl alcohol 0.9 neonol AF _9-6 63.1 4.40 5 18.0 0.01 - 16.0 ethyl alcohol technical 2.5 neonol AF _9-12 63.49 3.26 6 20,0 11.0 - 5.0 propyl alcohol 3.0 neonol AF _9-10 61.0 4.00 7 11.0 0.9 2.0 KI-1 11.0 methyl alcohol 1,0 syntanol DT-7 + 1,0 alkapav 16.30 73.1 3.46 8 18.0 0.04 1.4 BA 14.0 propyl alcohol 1.5 OP-10 65.06 4.12 9 14.0 15.0 1.0 CI 22.0 methyl alcohol 1.5 syntanol DS-10 + 1.5 emulsol NGL-205 grade A 45 3.11 10 15.0 6.0 2.0 synol 10.0 isopropyl alcohol 0.5 oxanol TsS-21 66.5 4,55 eleven 15.0 1,1 2.0 PB-5 12.0 ethyl alcohol technical 1.1 neftenol K (RD-1K) +1.1 OP-10 67.7 3.12 12 17.0 0.3 0.5 PKU-E 8.0 propyl alcohol 0.6 alkyl sulfonate Volgonate 73.5 3.90 13 20,0 0.5 2.0 methylane 12.0 isopropyl alcohol 1.6 oxanol O-18 63.9 4.15

Continuation of table 1 one 2 3 four 5 6 7 8 fourteen 19.0 0.1 1.6 Katasol 10.0 ethyl alcohol technical 1.0 Neonol AF _9-6 68.3 3.15 fifteen 13.0 0.7 1,0 methylane 25.0 isopropyl alcohol 2.1 syntamide-5 58.2 4.70 16 13.0 - 1,0 methylane 25.0 isopropyl alcohol 2.1 syntamide-5 58.9 15.7 Prototype 17 60.0 2.0 NTF 2.0 KI-1 35.0 acetone 1.0 Neonol AF _9-12 - 5,6

C is the concentration of acid, a fraction of a unit.

From the data shown in table 1, it is seen that the dissolution rate of the rock when using the inventive composition is lower compared with the composition of the prototype. When using the composition without the Athos 300M component, the dissolution rate of marble increases from 3.11-4.55 g / cm ² · h to 15.7 g / cm ² · h, which indicates that the use of the Athos 300M component in the composition leads to slowing down the rate of dissolution of carbonate rock when using the inventive composition.

To determine the change in filtration resistance, model tests are carried out. Bulk models with a length of 3.0-3.3 cm and a cross section of 1.54 cm ² filled with quartz sand with the addition of 10% calcium carbonate are taken. The models are saturated with water, then they are displaced with oil, after which the test composition is pumped from the reverse side, aged and displaced with oil. In water-saturated models, the test composition is pumped after water, aged and displaced with water. The change in filtration resistance is determined by the formula:

$$Q=\frac{K_{2(\mathrm{at},n)}-K_{\mathrm{one}(\mathrm{at},n)}}{K_{2(\mathrm{at},n)}}\cdot \mathrm{one\; hundred}\%,$$

K _{2 (c, n)} and K _{1 (c, n)} —permeability of the model before and after injection of the composition, μm ² . The test results of the compositions are shown in table 2.

table 2 No. p.p. Permeability, μm ² Number of the uploaded composition Change in filtration resistance,% Before processing after processing one 2 3 four 5 Water saturated model one 0.16 0,094 2 -41.0 2 0.31 0.24 9 -22.6 Prototype 3 0.17 0.42 17 +147.0 Oil saturated model four 0,026 0,112 5 +330.8 5 0,035 0.266 fifteen +660.0 Prototype 6 0,029 0.004 17 -86.2

From the data of table 2 it is seen that when using the proposed composition decreases the filtering resistance for oil and increases the filtering resistance for water, which ensures the selectivity of the impact on the formation rock.

We give an example of a specific application of the method of acid treatment of the bottomhole formation zone using the proposed composition.

Bottom-hole treatment of a producing well in order to intensify oil production. The depth of the well is 1700 m, the diameter of the casing string is 146 mm. The interval of the productive carbonate formation is 1611-1635 m, the perforation intervals are 1611-1615 m and 1630-1635 m.The calculated volume of the reagent for processing the first layer is 8.0 m ³ , the second 10.0 m ³ . Allowable pressure on the first layer is 4.0 MPa, on the second - 3.0 MPa.

Processing the lower interval. A tubing casing equipped with a funnel is lowered to a depth of 1635 m and a packer to a depth of 1620 m. With an open annular valve, the tubing is filled with reagent (4.9 m ³ ). Close the annular valve, plant the packer and pump the remaining reagent (5.1 m ³ ). Reagent is sold with oil in a volume of 5.0 m ³ at a pressure of not more than 3.0 MPa. When the injection pressure rises above the permissible one, the injection is temporarily stopped and resumed after its decrease. Carry out technological exposure for 6 hours. Mastering after processing is carried out by swabbing the plunger along the tubing string until depression at the bottom of 3.0 MPa with a sealed annular space in the volume to a neutral pH of the produced product.

Upper Interval Processing. The funnel is installed at a depth of 1615 m, the packer at a depth of 1600 m. With an open annular valve, the tubing is filled with reagent (4.9 m ³ ). Close the annular valve, plant the packer and pump the remaining reagent (3.1 m ³ ). The reagent is sold with oil in a volume of 5.0 m ³ at a pressure of not more than 4.0 MPa. Carry out technological exposure for 6 hours. Mastering after processing is carried out by swabbing the plunger along the tubing string until depression at the bottom of 3.0 MPa with a sealed annular space in the volume to a neutral pH of the produced product. The pumping equipment is lowered and the well is put into operation. As a result of processing, the oil production rate increased from 1.5 to 7.0 tons / day.

When using the proposed composition for the acid treatment of the bottom-hole formation zone and the acid treatment method using it, in comparison with the prototype, the reaction rate of the interaction of the acid composition with the formation rock is reduced, the penetration ability of the acid composition in low-permeability oil-saturated zones is increased, and the coverage of the formation by exposure increases, which ultimately ultimately, leads to an increase in oil production.

Claims (4)

1. The composition for the acid treatment of the bottom zone of the formation containing hydrochloric acid, a surfactant surfactant, a phosphorus-containing compound and a solvent, characterized in that the composition as a surfactant contains an anionic surfactant or nonionic nonionic surfactant, or cationic surfactant, or a mixture thereof, as phosphorus-containing compounds - Athos 300M and additionally water in the following ratio of components, wt.%:
hydrochloric acid 10.0-20.0 ACAS or nonionic surfactants, or CPAS, or their mixture 0.4-3.0 AFON 300M 0.01-15.0 solvent 5.0-25.0 water rest 2. The composition according to claim 1, characterized in that it further comprises a corrosion inhibitor in an amount of 0.5-2.0 wt.%. 3. A method of treating the bottom-hole zone of a formation, including injecting an acid composition followed by selling it, carrying out technological aging and removing reaction products, characterized in that the composition according to claim 1 or 2 is injected as an acid composition, the acid composition is injected in a pulsed or continuous mode in the amount of 1-3 m ³ per linear meter of perforated reservoir thickness at a pressure not exceeding the permissible for this reservoir. 4. The method according to claim 3, characterized in that the injection of the acid composition is carried out at intervals in oil formations.