RU2283854C2 - Formation permeability control composition - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: in a formation permeability control composition comprising aluminum salt solution (20-40 vol %) and alkali reagent, the latter is liquid zeolite production waste, namely mother liquor MP-X or MP-Y containing sodium silicate and admixture of corresponding zeolite NaX or NaY, pH of solution being 12-14.

EFFECT: enhanced plugging capability of composition due to increased volume of precipitate and reduced solubility thereof in formation water.

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Description

The present invention relates to the oil industry, in particular to compositions for enhancing oil recovery.

It is known the use of various compositions based on sedimentation to reduce the permeability of the formation by water and increase oil recovery, for example, silicate-alkaline with various additives (RF patent 2023142, E 21 B 43/22, op.15.11.94).

However, the known compounds are not effective enough.

It is known to use aluminum sulfate, the plugging ability of which is associated with the formation of sediment in the highly permeable (flooded) part of the formation from interaction with formation water (Ibragimov GZ et al. Use of chemical reagents to intensify oil production. Handbook. M .: Nedra, 1991. S.168-170, patent of the Russian Federation 2166622, 43/22 op.10.05.2001).

The disadvantages of the known composition is the low efficiency due to the formation of a fine precipitate with low adhesion to the surface of the collector.

The closest of the analogues is the composition for regulating the permeability of the formation, containing aluminum chloride and alkali (see M. Christian et al. Increasing the productivity and injectivity of wells. M: Nedra, 1985, pp. 73-74, 96).

The mechanism of formation of a clogging screen using the proposed composition is due to the ability of aluminum salts to form a gel-like precipitate of aluminum hydroxide when interacting with alkalis.

The disadvantages of the known composition is the lack of effectiveness of water isolation, due to the rapid erosion of a weak gel-like precipitate.

The technical result is an increase in the plugging ability of the composition by increasing the volume of sediment and reducing its solubility in formation water.

The composition for regulating the permeability of the reservoir, including a solution of aluminum salt and an alkaline reagent, as an alkaline reagent, it contains liquid waste from the production of zeolite - a master liquor grade MP-X or MP-Y containing sodium silicate and an admixture of the corresponding zeolite NaX or NaY, pH of the solution is 12-14, with the following ratio of components, vol.%:

solution of aluminum salt 20-40,

specified waste - the rest.

In the inventive composition as an aluminum salt was used:

- aluminum hydroxyl chloride (aluminum chloride solution) TU-38.302163-94, obtained from the spent catalyst complex of the benzene alkylation process with propylene. This liquid is light yellow in color with a greenish tint with the content of the main substance in terms of AlCl ₃ 200-300g / dm ³ , the pH of the solution is 0.8-2.0, the freezing temperature is minus 40 ° C;

- aluminum sulfate technical GOST 12966-85 in the form of a 20% solution;

- sodium aluminate solution, STP 01.01.01-401-401, alkaline module (the ratio of Na ₂ O / Al ₂ O ₃ is 1.4-2.0).

As liquid waste from the production of zeolites, solutions were used uterine brands MP-X and MP-Y, TU 2163-118-05-76-65-75-2004, which are weakly concentrated solutions containing sodium silicate and an admixture of the corresponding zeolites (NaX and NaY ), the pH of the solutions is 12-14.

A significant difference of the proposed composition is that the aluminum salt solution, when interacting with liquid waste from the production of zeolites containing sodium silicate, forms a water-insoluble volume precipitate of aluminum silicate by the reaction:

Al ³⁺ + Na ₂ SiO ₃ → Al ₂ (SiO ₃ ) ₃ ↓

The proposed composition for controlling the permeability of the formation can be used both in carbonate and terrigenous reservoirs, and regardless of the degree of mineralization of formation water.

The ability of the proposed composition to sedimentation was investigated in laboratory conditions. For this, the components of a precipitate-forming composition consisting of an aqueous solution of an aluminum salt and a mother liquor of the corresponding zeolite were mixed in glass cylinders in different ratios.

As a result of the studies (see the table), it was found that the maximum sediment volume (100%) is formed by the interaction of 20 vol.% Aluminum hydroxyl chloride and 80 vol.% Mother liquor MP-Y.

In the known composition, the volume of precipitate formed is 72%.

Table
The results of laboratory studies of sedimentation composition No. p / p Sedimentary composition,% vol. The volume of precipitate formed,% of the total volume of the mixture aluminum salt solution zeolite liquid waste hydroxychloride aluminum sodium aluminate solution 20% aluminum sulfate solution stock solution MP-Y uterine solution MP-X one twenty 80 one hundred 2 thirty 70 95 3 40 60 83 four prototype composition 72

The effectiveness of the proposed composition was evaluated by reducing the permeability of the reservoir model; bulk core 300 mm long, 50 mm in diameter, filled with quartz sand, was used as a reservoir model. The initial core permeability of 0.68-2.51 μm ^{2 was} selected by changing the sand fractions in the range of 0.05-1.20 mm. Saturation and determination of permeability were carried out by filtering wastewater. The pressure drop remained constant.

The isolation effect was calculated as follows:

Data on the clogging ability of the artificial model of the proposed and known compositions are shown in examples 1-4.

Example 1. A bulk core was saturated with wastewater with a density of 1118 kg / m ³ , then 20 ml of aluminum hydrochloride and 80 ml of mother liquor MP-Y were successively pumped into it, squeezed with wastewater. Filtration was stopped for 24 hours to react, then permeability was determined and the effect of isolation was calculated. It amounted to 97.5%. The high insulation effect is due to the formation of a volumetric clogging screen, consisting of insoluble silicates (Al ₂ SiO ₃ , MgSiO ₃ , CaSiO ₃ ) formed as a result of the interaction of the mother liquor MP-Y with aluminum hydrochloride, and with wastewater containing magnesium cations and calcium.

Example 2. The core was saturated with wastewater with a density of 1027 kg / m ³ and its initial permeability was determined, then 30 ml of sodium aluminate solution and 70 ml of mother liquor MP-Y were sequentially pumped, after the reagents were forced through the wastewater, the core was left for 24 hours to react. The insulation effect was 93%.

Example 3. In an artificial core saturated with fresh water, 40 ml of a 20% solution of aluminum sulfate and 60 ml of a mother liquor MP-X were successively pumped, pressed through with fresh water. Filtration was stopped for sedimentation, after 24 h, the permeability of the artificial model was determined and the effect of isolation was calculated. Its value was 85%.

Example 4. The initial permeability of the artificial core saturated with waste water with a density of 1118 kg / m ^{3 was} determined. In sequence, 20 ml of a 20% solution of aluminum chloride and 80 ml of a 20% solution of sodium hydroxide (composition according to the prototype) were pumped, pumped into a core, filtration was stopped for 24 hours for reaction. The insulation effect during filtration of known composition was 64%.

Thus, the proposed sediment-forming composition provides a higher isolation effect (by 21-33.5%) compared to the known one, which is due to the formation of a larger in volume (11-28%) water-insoluble precipitate - aluminum silicate.

The use of the proposed composition in the field can be carried out by conventional technological methods and technical means used in the repair and operation of production wells.

Claims (1)

The composition for regulating the permeability of the reservoir, including a solution of aluminum salt and an alkaline reagent, characterized in that it contains a liquid waste from the production of zeolite as an alkaline reagent - a mother liquor grade MP-X or MP-Y containing sodium silicate and an admixture of the corresponding zeolite NaX or NaY, the pH of the solution is 12-14 in the following ratio of components, vol.%: Aluminum salt solution 20-40 Indicated waste Rest