RU2503702C1 - Method for obtaining acrylic reagent for insulation of water influxes in well (versions) - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: method for obtaining acrylic reagent for insulation of water influxes to a well involves hydrolysis of polyacrylonitrile raw material with liquid sodium glass in water mixture with pH=12-14 at the following mixture component ratio, wt %: polyacrylonitrile raw material 3.8 - 4.8, liquid sodium glass 48 - 59.5, water is the rest, in which mixture temperature at constant mixing is raised to 95-100°C, maintained during the period of time, which is required for formation of homogeneous viscous uniformly painted mass; obtained mass is exposed without any heating and mixing till it is separated into two layers; top layer - polymer solution is separated as the obtained acrylic reagent, and bottom layer - alkali solution that contains liquid sodium glass is used for hydrolysis of polyacrylonitrile raw material. Method for obtaining acrylic reagent for insulation of water influxes to a well involves mixing of several polymer solutions obtained by means of the above method.

EFFECT: obtaining reagent with considerably higher gel forming ability in combination with lower viscosity; stability of phase state of reagent.

2 cl, 2 tbl, 7 ex

Description

The invention relates to the field of the oil and gas industry, in particular to a technology for producing reagents for enhancing oil recovery, repair and insulation works and well drilling.

Known methods for producing water-soluble acrylic polymers by hydrolysis of polyacrylonitrile with alkaline reagents [Paus K.F. Drilling fluids. M .: Subsoil. 1973. p. 83-85. A.S. USSR No. 663709, C09K 7/02. 1983. RF patent №2021320, C09K 7/02, publ. 10/15/94}. The resulting products are water-soluble copolymers of acrylamide and acrylic acid, more precisely its salts, and can be used as components for the production of gelling compositions for isolating water inflows from productive formations that are not uniform in permeability. However, it should be borne in mind that polyacrylonitrile is produced for the production of demanding and responsible products (fiber, impact-resistant polymer materials, etc.) and its availability for the production of other large-capacity products (water-soluble acrylic polymers for oil and gas production) is limited, and the cost is high. As polyacrylonitrile raw materials, it is known to use wastes from the production of polyacrylonitrile fibers, threads, fabrics [RF Patent No. 2021320, C09K 7/02, publ. 10/15/94; RF patent No. 2064571, E21B 33/138, publ. 07/27/96; RF patent No. 2169754, C09K 7/02, publ. 06/27/2001}. The use of such raw materials is economically justified, and fiber or tissue wastes hydrolyzed in alkali contain aging stabilizers that provide increased heat resistance of polymer compositions used in gas and oil production processes. As alkaline reagents use solutions of alkali metal hydroxides [A.S. USSR No. 663709, C09K 7/02. 1983; RF patent №2021320, C09K 7/02, publ. 10/15/94; RF patent No. 2064571, E21B 33/138, publ. 07/27/96; RF patent No. 2169754, C09K 7/02, publ. 06/27/2001]. Common disadvantages of these technical solutions are technological difficulties due to the need to work with extremely aggressive solid alkali metal hydroxides (transportation, storage, preparation of solutions). According to the chemical composition, the resulting acrylic (co) polymers with salt groups can form gels when interacting with polyvalent metal ions. However, the disadvantage of such products as gelling agents is their low efficiency in terms of gelling, which requires their practical use in combination with other gelling agents, for example, silicates.

These drawbacks lack the closest in composition to the claimed invention (prototype 1) a method of producing a water-soluble acrylic reagent K-6 [Zainutdinov S, Akhmedov KS The study of mineral and plant materials of Uzbekistan. Tashkent: Publishing House of the Academy of Sciences of the Uzbek SSR. 1962. p.63-66], which is not used to isolate water inflows in the well, but an aqueous solution of sodium silicate is used as an alkaline reagent - it is safer since technologies for its use. The method includes hydrolysis of polyacrylonitrile with an aqueous solution of sodium silicate by heating in the following ratio of components (wt.%):

polyacrylonitrile 3.8 sodium silicate 19,2 water rest.

The process is carried out with stirring in a flask under reflux in a boiling water bath. Upon completion of the reaction, the product is obtained in the form of a 16-17% aqueous solution containing hydrolyzed polyacrylonitrile and sodium silicate. The product is proposed for use as a soil builder for the formation of agglomerated agglomerated soil particle aggregates. The use of this product to isolate water inflows into a well is not known. However, for a number of indicators, the use of K-6 reagent for these purposes has significant drawbacks. First, for the hydrolysis process to proceed efficiently, the claimed sodium silicate content in the reaction mixture is really necessary. According to [Kurenkov V.F., Gerkin R.V., Ivanov B.C., Lukyanov B.C. University News. Chemistry and chemical technology. 1998. Vol. 41, issue 2, pp. 73-77] high degrees of hydrolysis of polyacrylonitrile with sodium silicate solution (> 70% in 4 hours at 95 ° C) are achieved when the concentration of the latter in the reaction mixture (respectively in the product) is not less than 17 mass%. At the same time, this sodium silicate content is much higher than that required for effective gelling mixtures used to isolate water inflows from productive formations that are heterogeneous in permeability (0.3-10 mass% in the composition) [RF Patent No. 2064571, E21B 33 / 138, publ. 07/27/96. A.S. USSR No. 1416669, E21B 33/138. 1986}. A high content of sodium silicate causes gelation to be too rapid, which creates significant difficulties when injecting reagents into the formation and reduces the efficiency of its distribution in porous rock. Secondly, in an experimental study of the process at various ratios of polyacrylonitrile / sodium silicate (the content of the latter is 5-60 wt.%), Including the ratio of prototype 1, it was found that the product formed under these conditions is divided into two phases within 24 hours - transparent, tan, the polymer solution phase (upper) and the alkaline reagent phase (lower). Unstable, with t.z. the reagent phase state creates big problems in its practical application (transportation, storage, use).

Closest to the claimed invention for use as a water-insulating reagent (prototype 2) is a method for producing acrylic reagent "Givpan" [RF Patent No. 2169754, C09K 7/02, publ. 06/27/2001}, including the hydrolysis of polyacrylonitrile raw materials (waste from the production of acrylonitrile fibers) by mixing the calculated amount of polyacrylonitrile raw materials with alkali previously dissolved in water to obtain pH values of 12-14, and stirring the reaction mixture with a stepwise temperature rise mode. However, this reagent does not have sufficient gelling ability to isolate water inflows in the well.

The technical problem solved in this invention is a new method for producing an acrylic reagent for isolating water inflows in a well according to the first embodiment, including hydrolysis of polyacrylonitrile feedstock with liquid sodium glass in an aqueous mixture with pH = 12-14 in the following ratio of mixture components, wt.%: Polyacrylonitrile raw materials 3.8-4.8, liquid sodium glass 48-59.5, the rest water, in which the temperature of the mixture is brought to 95-100 ° C with constant stirring, it is maintained for the time required to form a uniform viscous uniformly colored mass, maintain the resulting mass without heating and stirring until it is divided into two layers, separate the upper layer - a polymer solution - as the obtained acrylic reagent, and the lower layer - an alkaline solution containing liquid sodium glass, then used for hydrolysis of polyacrylonitrile raw materials. The method for producing an acrylic reagent for isolating water inflows into a well according to the second embodiment involves mixing several polymer solutions obtained by the method described above.

As polyacrylonitrile raw materials can be used, for example:

1) waste polyacrylonitrile fibers ("tows");

2) polyacrylonitrile filaments and their wastes;

3) a copolymer of acrylonitrile with methyl acrylate.

As the alkaline reagent can be used liquid sodium glass with a mass fraction of SiO ₂ - 22.7-36.7%, mass fraction of Na ₂ O - 8.7-13.8%.

Comparative analysis with prototype 1 shows that the inventive method differs from the known using liquid sodium glass in relation to polyacrylonitrile raw materials, significantly larger than in prototype 1 or than described in the scientific and technical literature [Kurenkov V.F., Gerkil R. V., Ivanov BC, Lukyanov BC University News. Chemistry and chemical technology. 1998. v. 41, issue 2, p. 73-77}.

Comparison with other technical solutions shows that a significant result of the invention is to obtain an acrylic reagent for isolating water inflows in a well that differs in chemical composition from known ones. It is believed that acrylic reagents obtained by exhaustive hydrolysis of polyacrylonitrile with alkali metal hydroxides are random copolymers of acrylamide (-CH ₂ -CH (CONH ₂ ) -) and acrylic acid, more specifically alkali metal acrylate (-CH ₂ -CH (COONa) -) [Zilberman E.N. The success of chemistry. 1986, vol. 60, issue 1, pp. 62-78. Kurenkov V.F., Gerkin R.V., Ivanov VS, Lukyanov BC Izvestia VUZov. Chemistry and chemical technology. 1998. v. 41, issue 2, p. 73-77}. Although in accordance with the general laws of polymer-analogous reactions, a certain amount of unreacted nitrile groups and the products of their intermediate transformations may probably be present in the final copolymer [Zilberman E.N. The success of chemistry. 1986, vol. 60, issue 1, pp. 62-78. Akhmedov K.S., Aripov E.A., Virskaya E.A. et al. Water-soluble polymers and their interaction with disperse systems. Tashkent: Fan Publishing House 1969. p.16-30]. At the same time, an elemental analysis of the polymer of an acrylic reagent for isolating water inflows in a well obtained by the proposed method, isolated from an aqueous solution separated from the phase of an alkaline solution of sodium silicate and twice reprecipitated with alcohol from aqueous solutions, shows the presence of 62.9-63 in it. 2 wt.% Ash. This may mean that in the process of hydrolysis in the polymer, imidosilicate ester units —CH ₂ —CH (CNH-SiO ₂ OH) - form, some of which are not further hydrolyzed and remain in the copolymer [KA Akhmedov, EA Aripov. , Virskaya E.A. et al. Water-soluble polymers and their interaction with disperse systems. Tashkent: Fan Publishing House 1969. p.16-30]. In the IR spectrum of the obtained polymer there is an absorption band of 1022.77 cm ^-1 related to vibrations of the Si-O group. By simply mixing a solution of hydrolyzed polyacrylonitrile with an aqueous solution of sodium silicate, for example, this is done to obtain gelling compositions for isolating water inflows from productive formations that are not uniform in permeability [RF Patent No. 2064571, E21B 33/138, publ. July 27, 1996], such a reaction, according to the data of elemental analysis and IR spectroscopy, does not occur.

Thus, the claimed technical solution meets the criteria of the invention of "novelty."

Separated from the reaction mass of the water-silicate phase of an alkaline reagent, has a pH value of 12-14. The IR spectrum of the alkaline reagent layer is completely identical to the IR spectrum of liquid sodium glass in liquid paraffin - in both spectra there is a strong absorption band in the region of 900-1100 cm ^-1 , which is typical for vibrations of the Si-O group. Thus, there is a stratification of the system into two liquid phases - a concentrated polymer solution and a solution of liquid sodium glass. The latter can be used repeatedly for the hydrolysis of new batches of polyacrylonitrile raw materials, which, combined with the lower cost of liquid sodium glass compared with sodium alkali, provides an economic advantage of the proposed method compared to the known ones.

Thus, in terms of features, the proposed method meets the criteria of "inventive step" and "industrial applicability".

The proposed method for producing an acrylic reagent for isolating water inflows in a well is illustrated by the following examples.

Example 1 (according to the invention). In a 1 L flask equipped with a thermometer, a mechanical stirrer, a reflux condenser and placed in a water bath, the reaction mixture of the composition (wt.%) Was loaded: polyacrylonitrile - 3.8; liquid sodium glass - 59.5; water - the rest, namely: 14.25 g “Polyacrylonitrile polymer for the preparation of drilling fluids” manufactured by Saratovorgsintez LLC with indicators corresponding to TU 2216-016-47773778-2005, 222.6 g of liquid sodium glass with indicators corresponding to GOST 13078 -81, and 138 ml of water. With constant stirring, the temperature of the reaction mixture was brought to 95 ° C, which was established when the water bath was boiling, and it was maintained for the time required to form a uniform (without PAN fiber inclusions), viscous mass uniformly colored from brownish yellow to pale yellow. After completion of the chemical process, the reaction mass was held without heating and stirring for 24 hours until it was separated into two layers. The upper layer was separated as an acrylic reagent, and the lower layer as an alkaline reagent. The total yield of products was 337.3 g (90% of the taken raw materials). The volume of the product was 276.2 ml. After separation, the obtained: acrylic reagent - 158.2 ml, alkaline reagent - 118 ml. The concentration of acrylic reagent for the polymer was 10.3% of the mass. The pH value of the lower layer is 14. The characteristics of the acrylic regent for isolating water inflows in the well are given in Table 1. 6 cm ^{3 of} acrylic reagent and 6 cm ^{3 of a} 20% solution of CaCl _{2 were} thoroughly mixed in a measuring cylinder. After settling for 1 hour, the volume of the gel formed and the total volume of the solution were measured. Gelling ability was evaluated by the ratio of the volume of the gel to the total volume of the solution. After 24 hours, the measurements were repeated. The results are shown in table.2.

Example 2 (according to the invention). They took the reaction mixture of the products specified in example 1, composition (wt.%): Polyacrylonitrile - 4.8, liquid sodium glass - 48, water - the rest, namely: "Polyacrylonitrile polymer ..." - 15 g, liquid sodium glass - 150 g, water - 147.5 ml. The synthesis of an acrylic reagent for isolating water inflows in a well as in Example 1. After separation, the following was obtained: an acrylic reagent for isolating water inflows in a well — 138 ml, an alkaline reagent — 92 ml. The pH value of the alkaline reagent layer was 14. The characteristics of the obtained acrylic regent for isolating water inflows in the well are given in Table 1, data on the gel-forming ability in Table 2.

Example 3 (according to the invention). The polymer solutions obtained in Examples 1 and 2 were mixed. After mechanical stirring without heating, an averaged product was obtained with the characteristics given in Table 1 and Table 2.

Example 4 (according to the invention). A reaction mixture of the composition (wt.%) Was prepared: polyacrylonitrile — 3.8, alkaline reagent — liquid sodium glass isolated from the reaction mass obtained in Example 1 — 59.3, water — the rest, namely: “Polyacrylonitrile polymer ...” - 9.5 g, alkaline reagent - 148.4 g, water - 92 ml. The synthesis was carried out under the conditions as in example 1. After separation of the layers, the following was obtained: acrylic reagent for isolating water inflows in the well — 105.6 ml, alkaline reagent — 78.8 ml. The pH value of the alkaline reagent layer was 14. The characteristics of the obtained acrylic regent for isolating water inflows in the well are given in Table 1, data on the gel-forming ability in Table 2.

Example 5 (according to the invention). The reaction mixture of the composition (wt.%) Was prepared: polyacrylonitrile - 3.8, alkaline reagent isolated from the reaction mass according to example 4 - 59, water - the rest, namely: "Polyacrylonitrile polymer ..." - 20 g, alkaline reagent - 310 5 g, water - 195.8 ml. The synthesis was carried out under the conditions as in example 1. After separation of the layers, the following was obtained: acrylic reagent for isolating water inflows in the well — 259 ml, alkaline reagent — 172.4 ml. The characteristics of the obtained acrylic reagent for isolating water inflows in the well are given in Table 1, data on the gel-forming ability in Table 2.

Example 6 (prototype 1). In a 1 L flask equipped with a thermometer, a mechanical stirrer, a reflux condenser and placed in a water bath, the reaction mixture of the composition (wt.%) Was loaded: polyacrylonitrile - 3.8; liquid sodium glass - 19.2; water - the rest, namely: 14.25 g of "Polyacrylonitrile Polymer ...", 72 g of liquid sodium glass and 288.7 ml of water. The mixture was kept with constant stirring in a boiling water bath for 6 hours. Received 337.5 ml of the product, painted in yellow-brown color, which shows a significant content of the remainder of the unreacted fibers. Product characteristics are given in table 1, data on the gel-forming ability in table 2.

Example 7 (prototype 2). In a measuring cylinder, 2.5 cm ^{3 of} acrylic reagent “Givpan” was thoroughly mixed with indicators corresponding to TU 2216-001-04693227-99, and 5 cm ^{3 of a} 5% CaCl ₂ solution. After settling for 1 hour, the volume of the gel formed and the total volume of the solution were measured. Gelling ability was evaluated by the ratio of the volume of the gel to the total volume of the solution. After 24 hours, the measurements were repeated. The results are shown in table.2.

Table 1. No pp Product Density, g / cm ³ at 20 ° C Conditional viscosity, s PH value Notes one Acrylic reagent according to example 1 1.13 112 fourteen 2 Acrylic reagent according to example 2 1.09 115 fourteen 3 Acrylic reagent according to example 3 1,11 113 fourteen four Acrylic reagent according to example 4 1.12 109 fourteen 5 Acrylic reagent according to example 5 1.13 111 fourteen 6 Acrylic reagent according to example 6 (prototype 1) 1.10 - fourteen The product contains fiber residues and is divided into two layers within 24 hours. 7 Acrylic reagent "Givpan" (prototype 2) 1.13 180 12-14 8 Acrylic reagent "Givpan" ^** (prototype 2) 1.10 140 fourteen Note: ^* conditional viscosity is determined by the time of expiration of a 100 ml sample of the product through the opening of a calibrated funnel of the B3-246 viscometer (nozzle No. 4) at 20 ° C; ^** reagent diluted to a polymer concentration in solution of 11% of the mass.

Table 2. No pp Product Gelling ability Notes After 1 hour after 24 hours one Acrylic reagent according to example 1 0.83 0.81 Single phase solution 2 Acrylic reagent according to example 2 0.85 0.83 Single phase solution 3 Acrylic reagent according to example 3 0.84 0.82 Single phase solution four Acrylic reagent according to example 4 0.83 0.82 Single phase solution 5 Acrylic reagent according to example 5 0.85 0.83 Single phase solution 6 Acrylic reagent according to example 5 (prototype 1) 0.86 0.85 Biphasic composition 7 Acrylic reagent "Givpan" (prototype 2) 0.30 0.27 Single phase solution

From table 1 it is seen that in terms of density, the resulting reagents are not inferior to the product of prototype 1 and prototype 2. In terms of viscosity for solutions of the same concentration, the resulting reagents have a lower viscosity than the Givpan reagent. It is incorrect to compare the obtained products by viscosity with the K-6 reagent (prototype 1), because the latter is not an aqueous polymer solution, but a two-phase system, additionally containing a viscous component - liquid glass. Comparison with prototype 2 shows that, with a comparable polymer content, the products of the invention are not inferior to Givpanu. From the data of table 2 shows that the gelling ability of acrylic reagents of a new chemical composition obtained by the proposed method are not inferior to that of prototype 1 containing liquid sodium glass, and significantly exceed that of prototype 2 - a product obtained by hydrolysis of polyacrylonitrile raw materials with sodium alkali. Thus, the proposed method for producing an acrylic reagent for isolating water inflows in a well provides a product with undoubted advantages compared with reagents used for the same purpose — significantly higher intrinsic gelling ability in combination with lower viscosity, which reduces energy consumption when injecting the reagent into layer.

Claims (2)

1. A method of producing an acrylic reagent for isolating water inflows into a well, comprising hydrolysis of polyacrylonitrile feedstock with liquid sodium glass in an aqueous mixture with pH = 12-14 in the following ratio of mixture components, wt.%:
polyacrylonitrile feed 3.8-4.8 liquid sodium glass 48-59.5 water rest,
in which the temperature of the mixture with constant stirring is brought to 95-100 ° C, maintain it for the time required to form a homogeneous viscous uniformly colored mass, maintain the resulting mass without heating and stirring until it is divided into two layers, the upper layer is polymer solution - as the obtained acrylic reagent, and the bottom layer is an alkaline solution containing liquid sodium glass, further used for the hydrolysis of polyacrylonitrile raw materials. 2. A method of producing an acrylic reagent for isolating water inflows into a well, comprising mixing several polymer solutions obtained by the method of claim 1.