RU2840462C1 - Composition for levelling well injectivity profile - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention relates to oil industry. Composition for balancing the well injectivity profile contains the following, wt.%: zwitterionic surfactant – cocamidopropyl betaine 0.7-9.5; anionic surfactant – sodium lauryl sulphate or sodium alkylbenzosulphonate 0.25-2.5; nonionic surfactant – neonol AF_9-10 0.84-12; precipitate-forming agent based on an alkaline solution of sodium salts of carboxylic and polycarboxylic acids 10-50; water – balance. Precipitate-forming agent based on an alkaline solution of sodium salts of carboxylic and polycarboxylic acids contains the following, wt.%: nonionic surfactant 0.02-12; anionic surfactant 0.02-5; sodium salts of carboxylic and polycarboxylic acids in terms of disodium adipate 1-30; mineral salts – potassium, sodium, calcium, magnesium and ammonium chlorides 0.02-10.

EFFECT: aligning the injectivity profile and increasing the sweep of the formation by flooding by isolating the highly permeable sections of the formation formed upon contact of the composition with mineralized formation water by a viscous finely dispersed colloidal system, and more complete displacement of oil due to washing from oil of low-permeable oil-saturated sections of formation.

1 cl, 5 tbl, 1 ex

Description

The invention relates to the oil-producing industry, in particular to sediment-forming compositions for regulating the development of oil fields, to compositions for regulating the injectivity profile of injection wells and can be used to level the injectivity profile of wells equipped with downhole pumping.

A composition for regulating the development of oil fields and a method for its preparation are known, containing polyacrylamide (PAA), bentonite clay and water [USSR Author's Certificate No. 1710708]. The disadvantage of this composition is the high dispersion of the clay minerals included in the composition, which limits the depth of penetration of the composition and reduces its effectiveness, especially in pore reservoirs.

A sediment-forming reagent for leveling the profile of well injectivity is known, containing sodium salt of naphthenic acids and water, additionally contains soapstock, saponified with sodium alkali, oxyalkylated alkylphenol and methanol [Patent RU No. 2527424]. The disadvantage of this composition is the formation of a screen of low-mobility, viscous-plastic mass in the bottomhole zone of the formation, which leads to an increase in injection pressure and a small depth of penetration of the sediment-forming composition into the formation.

A composition for increasing oil recovery from formations based on zwitterionic surfactants is known, containing a zwitterionic surfactant, sodium silicate, sodium chloride, and water [Patent RU No. 2716070]. The disadvantage of this composition is the low washing capacity of the solution for residual oil in the productive reservoir.

The closest, taken as a prototype, is a solution for oil extraction, containing a mixture of zwitterionic, anionic and nonionic surfactants and fresh water [Patent RU No. 2610952]. The disadvantage of the composition is the low values of the resistance factor and residual resistance factor of the resulting composition.

The technical task of the invention is to create a composition for redistributing filtration flows in a porous medium in order to regulate the flooding process and involve in the development of previously undrained oil reserves, which have increased values of the resistance factor and high values of the residual resistance factor during subsequent injection of water into an injection well.

The technical result of the invention is to increase the coverage of the formation by flooding due to an increase in the resistance factor and the residual resistance factor.

The set objective is achieved in that the composition containing a zwitterionic surfactant CPAV - cocamidopropyl betaine, an anionic surfactant APAV, a nonionic surfactant NPAV - neonol AF _9-10 and water, contains sodium lauryl sulfate or sodium alkylbenzenesulfonate as APAV and additionally a precipitate-forming reagent based on an alkaline solution of sodium salts of carboxylic and polycarboxylic acids, containing, by weight %: NPAV - 0.02-12; APAV - 0.02-5; sodium salts of carboxylic and polycarboxylic acids in terms of disodium adipate - 1-30; mineral salts - chlorides of potassium, sodium, calcium, magnesium, ammonium - 0.02-10, forming a finely dispersed solid phase upon contact with mineralized formation water, with the following ratio of components of the composition, wt. %:

- cocamidopropyl betaine - 0.7-9.5;

- specified APAV - 0.25-2.5;

- neonol AF _9-10 - 0.84-12;

- the specified sediment-forming reagent -10-50;

- water is the rest.

Reducing the content of the sediment-forming reagent based on sodium salts of carboxylic and polycarboxylic acids completely minimizes their impact on the properties of the composition, and increasing its content leads to an unjustified increase in the cost of the composition.

The following reagents are used to prepare the composition:

As a precipitating reagent, a reagent based on an alkaline solution of sodium salts of carboxylic and polycarboxylic acids is used (TU 20.59.59-001-59994272-2023) (https://inipe.ru/wp-content/uploads/2024/06/TU-20.59.59_001_59994272_2023.pdf

As zwitterionic surfactants, surfactants from the alkyl betaine series are used - cocamidopropyl betaine (CAPB) - trade mark BETAPAV® NPO "NIIPAV" (TU 2480-002-04706205-2004)

(1. https://reestrinform.ru/reestr-sgr/reg-RU.61.%D0%A0%D0%A6.10.008.%D0%95.000344.07.11.html?ysclid=lxvpq172ai739119271

2. http://docum.ru/tu.asp?cl=349950 ).

The following are used as anionic surfactants:

- sodium lauryl sulfate (SLS) - sodium salt of lauryl sulfuric acid LLC "Polikhim".

- sodium alkylbenzenesulfonate (sulfanol) is a mixture of isomers of sodium salts of alkylbenzenesulfonic acids, the Himpek group of companies (TU 2481-009-14331137-2011), (http://skfsamara.ru/catalog/?product=%D1%81%D1%83%D0%BB%D1%8C%D1%84%D0%BE%D0%BD%D0%BE%D0%BB-%D0%BF%D0%BE%D1%80%D0%BE%D1%88%D0%BE%D0%BA-%D0%BE%D1%82%D0%B1%D0%B5%D0%BB%D0%B5%D0%BD%D0%BD%D1%8B%D0%B9-%D1%84%D0%B0%D1%81%D0%BE%D0%B2%D0%BA&ysclid=lxvs0071ol958391140)

As a non-ionic surfactant, oxyethylated monoalkylphenols are used, trade name NEONOL, grades AF _9-10 , AF _9-12, manufactured according to TU 2483-077-05766801-98 by JSC NIZHNEKAMSKNEFTEKHIM. (https://elarum.ru/info/standards/tu-2483-077-05766801-98/?ysclid=lxvrjlxknu326793604)

Example of preparation of compositions.

Place 66 g of fresh water in a 250 ml glass beaker. Then, while stirring on a paddle stirrer (450-500 rpm), 10 g of sediment-forming reagent, 12 g of neonol AF _9-10 , 2.5 g of sodium alkylbenzenesulfonate, and 9.5 g of cocamidopropyl betaine are successively added to the beaker with water.

After mixing for 10-15 minutes at a paddle mixer speed of 300-350 rpm, the composition is kept under static conditions for 15-20 minutes to remove the bulk of the bubbles in the volume. As a result, a composition is obtained with the following component content, % by weight: sediment-forming reagent based on sodium salts of carboxylic or polycarboxylic acids - 10; neonol AF _9-10 - 12; sodium alkylbenzenesulfonate - 2.5; cocamidopropyl betaine - 9.5 and fresh water is the rest.

The component composition and concentrations of the claimed compositions and prototype are presented in Table 1 (see in the graphic section).

The essence of the proposed invention is as follows. The composition for regulating the injectivity profile, penetrating into a water-saturated interlayer and mixing with formation water containing Ca ²⁺ , Na ⁺ , K ⁺ , Mg ²⁺ ions, on the one hand significantly increases the viscosity of the mixture, which is associated with the transition of micelles from a spherical shape to a cylindrical one and their subsequent growth due to ionic crosslinking with the formation of viscoelastic surfactants, on the other hand, due to the chemical reaction of the injected alkaline solution containing sodium salts of carboxylic and polycarboxylic acids, forms a solid finely dispersed phase of a colloidal suspension, according to the following reaction:

During the reactions, a solid phase of calcium salts of mono-, di- and polycarboxylic acids is formed. As a result, a rim of viscous, sedimentation-resistant finely dispersed colloidal system is formed in the washed water-saturated intervals, which facilitates deep penetration and decreases the permeability of water-saturated intervals of the formation. As a result, the injected water begins to flow into less permeable zones and sections of the formation not covered by flooding, which leads to an increase in the coverage of the flooding process and an increase in the efficiency of work on leveling the profile of the well intake capacity.

When the composition penetrates into the oil-saturated interlayer and mixes with the formation oil, the ionic bonds of the composition micelles are destroyed and the viscosity of the mixture decreases, and the alkaline solution reacts with organic acids in the crude oil, thereby forming secondary surfactants in the formation, which allow for an even greater reduction in the interfacial tension between the injected liquid and the oil. The wettability of the rock by the alkaline solution also changes due to the adsorption of organic acid salts on the rock surface from the oil. As a result, the porous medium is hydrophilized, due to which the adsorption of surfactants on the formation rock decreases and the efficiency of the washing composition increases.

The use of the composition in flooding control technology is characterized by a simultaneous increase in both the displacement coefficient and the reservoir coverage coefficient, which leads to regulation of the development of flooded reservoirs.

The efficiency of the compositions is determined experimentally using the methods described below. The dynamic viscosity was determined by rheological tests of the compositions presented in Table 1, prepared on fresh water and their mixtures in a volume ratio of 1:1 with formation mineralized water with a total mineralization of 258.62 g/ ^dm3 . The tests were carried out using a Modular Compact Rheometer MCR52 (AntonPaar GmbH, Austria) according to the instructions for the device, at a shear rate of 40 s- ¹ . The test results are presented in Table 2 (see in the graphic section).

The results of the experiments conducted to determine dynamic viscosity indicate that the claimed compositions have more viscous systems compared to the existing prototype.

The sedimentation capacity of the reagent included in the composition for leveling the injectivity profile was estimated over 12 hours based on the sedimentation curve obtained on a torsion balance at different values of the ratios of the commercial form of the sedimentation reagent - formation water. The results of the volume and mass of the sediment are given in Table 3 (see in the graphic section).

According to the research results, it is evident that sediment is formed in all ranges of mixing of the commercial form of the reagent with formation water, and at a ratio of 1:1, a stable, non-stratifying, finely dispersed, highly concentrated colloidal system is formed in full.

To determine the efficiency of the developed compositions, filtration studies were carried out on a single core sample at a constant filtration rate. A single core sample saturated with formation water was placed in a rubber cuff and installed in a core holder. During the experiment, a formation water model was filtered through a single core sample in an amount exceeding 3 pore volumes (Vpore) until a steady-state flow regime was achieved. At the next stage, one of the provided compositions was injected in an amount of 0.5 pore volumes at a constant flow rate of 0.1 ^cm3 /min. After the core sample was kept for 30 minutes, an additional 0.5 pore volume of the composition was pumped, then the injected water model was filtered through the core sample at a flow rate of 0.1 ^cm3 /min until a steady-state filtration regime was achieved. Based on the data obtained, the values of the resistance factor (R) and the residual resistance factor (R _res ) were calculated. The resistance factor is described by the ratio of the mobility of water to the mobility of the injected compositions, and is determined by:

(1)

Where , , , - respectively, the viscosity and permeability coefficient for water and the tested compositions.

The residual resistance factor is described by the ratio of mobility for water before and after filtration of the injected compositions, and is determined by:

(2)

Where , , , - respectively, the viscosity and permeability coefficient for water before and after filtration of the test compositions.

The results of filtration studies on high-permeability core models are presented in Table 4, and on low-permeability cores are presented in Table 5 (see the graphic section).

Analysis of the data in tables 4 and 5 shows that the use of compositions based on a mixture of nonionic, anionic and zwitterionic surfactants and a sediment-forming reagent based on sodium salts of carboxylic and polycarboxylic acids leads to an increase in the values of the resistance factor and residual resistance factor. Thus, the obtained data confirm the high efficiency of the claimed composition.

The use of the composition in the oil industry will allow:

- carry out work on injection wells equipped with downhole pumping;

- to increase the efficiency of oil displacement from heterogeneous formations at a late stage of development.

Claims (2)

A composition for leveling the injectivity profile of wells, containing a zwitterionic surfactant CPAV - cocamidopropyl betaine, an anionic surfactant APAV, a nonionic surfactant NPAV - neonol AF _9-10 and water, characterized in that it contains sodium lauryl sulfate or sodium alkylbenzenesulfonate as APAV and additionally a precipitate-forming reagent based on an alkaline solution of sodium salts of carboxylic and polycarboxylic acids, containing, wt.%: NPAV 0.02-12; APAV 0.02-5; sodium salts of carboxylic and polycarboxylic acids in terms of disodium adipate 1-30; mineral salts - chlorides of potassium, sodium, calcium, magnesium, ammonium 0.02-10, with the following ratio of composition components, wt.%: cocamidopropyl betaine 0.7-9.5 specified APAV 0.25-2.5 neonol AF _9-10 0.84-12 the specified precipitation-forming reagent 10-50 water rest