SU1735574A1 - Compound for oil-field development control - Google Patents

Abstract

The composition contains, wt%: polyacrylamide 0.15-1.0; chromium substance 0.005-0.04; cationic surfactant 0.000001-1.0; water - the rest. The formulation is prepared by serially dissolving, with mechanical stirring, a polyacrylamide solution, an aqueous solution of a cationic surfactant, and an aqueous solution. After soaking the prepared formulations for 16-24 hours, the rheological properties of the formed gels are determined on a Hepler reoviscometer. 1 h. the item f., 2 tab.

Description

The invention relates to the oil and gas industry, in particular, compositions for regulating the development of oil fields, including the regulation of the injectivity profile of injection wells and (or) the isolation of water inflow from oil wells.

Known regulation of mining using an aqueous solution of polyacrylamide.

However, this method is ineffective in fields with fissured or highly permeable rock (above 2 µm), since polyacrylamide molecules do not effectively resist the flow of water in such a porous medium even at high concentrations in solution (0.3-0.5%) .

A composition for regulating formulation is known, containing 0.3-1% polyacrylamide, 0.001-0.03% chromic alum as a crosslinking agent, and water.

However, the known composition has low rheological properties and low thermal stability, which leads to its low efficiency in regulating the development of deposits by flooding.

The purpose of the invention is to improve the rheological properties and increase the thermal stability of the composition.

The goal is achieved by the fact that the composition for regulating the development, containing polyacrylamide, a chromium-containing substance as a crosslinking agent and water, additionally contains a cationic surfactant in the following ratio, wt.%:

Polyacrylamide 0.15-1.0

Cationic surfactant0, 000001-1.0

vi you ate

SL VI

Chromium-containing

substance0.005-0.04

Water Rest

As the cationic surfactant (CPAS), the use of quaternary ammonium salts and salts of fatty amines, and as chromium-containing substances, chromic alum, chromium salts, chromates and bichromates of monovalent cations.

In the known composition, the rheological properties of the polymer solution are improved by the interaction of the carboxyl groups of polyacrylamide with the chromium cation due to the formation of the three-dimensional structure of the cross-linked polyacrylamide. However, the introduction of even microquantities (less than 0.001%) of the cationic surfactant into the polymer and chromium cation solution improves its geological properties due to the interaction of the surfactant cation with the carboxyl group of polyacrylamide and the formation of surface-active polyacrylamide, which, in turn, reacts with the chromium cation, the image of the three-dimensional structure of the surface-active cross-linked polymer, the rheological properties of which are further improved due to the hydrophobic interaction of the alkyl targets of the cationic surfactant molecules with each other.

In addition, the use of active surfactants in polyacrylamide-containing compositions increases their thermal stability due to the binding of oxygen dissolved in the aqueous composition and catalyzing the thermal destruction of polyacrylamide molecules (in the absence of cationic surfactants), cationic surfactants with the formation of amine oxides inert to the polyacrylamide molecule.

EXAMPLE 1. The rheological properties of the known and proposed compositions are determined on a Hepler reoviscometer based on the ball immersion time (g, s) under the action of an applied load (P, g / cm) and are expressed by the dynamic viscosity of the composition mPa-s), which is calculated by the formula t K, where K is the constant of the measuring node of the reoviscometer.

Polyacrylamide mol. m. MM 15 million and degree of hydrolysis (SG) 15% (P-1), million and (P-2) and million and (P-3), as a cationic surfactant - dimethyl-benzylalkylammonium chloride (DBACH) of the general formula KY (CH3) 2CH2CbH5 + C1-, where R is CicrCis, and the soloxyl salt of fatty amines of the brand GIPH-1 (RNH2-HCI, where R is Syu-Cte), containing 50% of the active substance; as a chlorine-containing substance (HSV) - chromium potassium alum (XKKJ, waste

chromium alum (OHK) containing 2.7-5.0% of trivalent chromium, and potassium dichromate (BHC).

Prepare 0.1-1.0% solutions of polyacrylamide on water that simulates fresh and mineralized (waste, formation) water, with a total salt content of sodium chloride, calcium and magnesium -0.34; 13, 120 and 240 g / l, 1% aqueous solutions of HKKI OCC, 1% hydrochloric acid solution of BHC with the addition of a reducing agent — a non-ionic surfactant of the brand SNO and 0.0001-10% aqueous solutions of a cationic surfactant.

These compositions are prepared by the sequential introduction with mechanical stirring in 100 ml of a 0.1-1.0% solution of PAA with the required amounts of 0.0001-10% aqueous solution of CPAS and 1% aqueous solution of HSV for obtaining their content in the composition of 0.000001-1.0 and 0.0002- 0.004%, respectively.

Known formulations are prepared in the same manner as proposed, but without adding cationic surfactant to the PAA solution.

After holding the prepared compositions at room temperature for 16-24 hours, the rheological properties of the gels formed are determined on a Hepler reoviscometer,

The results of the determination of their rheological properties are given in Table. one.

From tab. 1, it can be seen that by introducing cationic surfactant into an aqueous solution of polyacrylamide and a chromium-containing substance, the rheological properties of the proposed formulations improve mainly more than twofold compared with the known composition. However, when the content of the cationic surfactant is less than wt.%, Polyacrylamide less than 0.15% and the chromium-containing substance is less than 0.005% in this composition, the rheological properties of its composition are insignificantly different from the rheological properties of the composition of the prototype. Therefore, the lower limit of the content of the components in this composition is for the cationic surfactant 1-10% by weight, polyacrylamide 0.15% by weight and the chromium-containing substance 0.005% by weight. We take the upper limit of the content of components in the composition, based on technical and economic considerations (high composition cost, high viscosity of the initial mixture of components and high consumption of components) for cationic surfactant 1.0, polyacrylamide 1.0 and chromium-containing substance 0.04 wt. %

Thus, the introduction of a cationic surfactant into a known composition containing polyacrylamide and a chromium-containing substance significantly improves its rheological properties.

EXAMPLE 2 The thermal stability of the proposed and known is determined by keeping them at 70 and 90 ° C in a heating cabinet for several days. At the same time, after each day of the compositions, their rheological properties are determined on a Hepler resiscometer.

Thermal stability of the compositions (TS) is estimated by the following formula:

Vehicle

100

/ 4) -1

where to and /; g is the viscosity of the composition of the initial (at 20 ° С) i-t after holding it at the required temperature for a certain time t. The larger the vehicle, the higher the thermal stability of the composition.

The results of the study of the thermal stability of the compositions after 3 days of exposure at 70 and 90 ° C are given in Table. 2,

From the above data on the thermal stability of the compositions it is clear that the introduction of a small amount of cationic surfactant in the composition of the prototype dramatically increases its thermal stability from 0-24 to 58-90%.

Thus, the introduction into the known compositions of a small amount of cationic surfactant significantly improves the rheological properties and increases their thermal stability.

The technology for applying the proposed formulations is simple and consists in pumping them into the reservoir, until the well intake is reduced by 20-50%, the composition is pumped out of the wellbore into the reservoir with water or oil, held in the reservoir for 16-24 hours, and oil wells or water injection for injection wells.

The use of the proposed formulations to control the development of oil fields and isolate the flow of water into wells leads to an increase in oil production (with a simultaneous decrease in water production).

Claims (2)

1. The composition for regulating the development of oil fields, including polyacrylamide, a chromium-containing substance and water, characterized in that, in order to improve the rheological properties and increase the thermal stability of the composition up to 90 ° C, it additionally contains a cationic surfactant in the following ratio of components, wt.%: Polyacrylamide 0.15-1.0 Chromium-containing substance 0,005-0,04 Cationic surfactant 0, 00001-1,0 Water Else 2. A composition according to claim 1, characterized in that quaternary ammonium salts and salts of fatty amines are used as a cationic surfactant. -J ate -four L