RU2754527C1 - Grouting polymer composition for high temperatures - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention relates to the oil and gas industry, in particular to compositions for isolating or limiting water inflow, for leveling the input profile, eliminating absorption zones of high-temperature wells. The grouting polymer composition for high temperatures contains a copolymer of acrylamide and acrylic acid, water and crosslinkers: paraform and resorcinol, additionally contains a gelation regulator, the Kratol reagent, with the following component ratio, weight percentage: copolymer of acrylamide and acrylic acid 0.18-1.7; paraform 0.03-0.2; resorcinol 0.02-0.12; Kratol reagent 0.01-1.0; water is the rest. According to the second alternative, the grouting composition may contain paraform and resorcinol with aerosil as a crosslinker, water and additionally a gel formation regulator, which is used as a Kratol reagent, with the following component ratio, weight percentage : copolymer of acrylamide and acrylic acid 0.18-1.7; paraform 0.03-0.2; resorcinol 0.02-0.12; aerosol 0.01-0.03; Kratol reagent 0.01-1.0; water-the rest.

EFFECT: improved quality of insulation in high-temperature layers due to increasing the injection depth, the strength of the cross-linked polymer system formed in the watered zone, as well as expanding the temperature range of the application of the grouting polymer composition.

2 cl, 3 dwg, 3 tbl

Description

The invention relates to the oil and gas industry, in particular to compositions for isolating or limiting water inflow, for leveling the injectivity profile, eliminating absorption zones of high-temperature wells.

Known viscoelastic composition for insulation work in wells, containing polyacrylamide, a crosslinking agent chromium nitrate, a gelation regulator sulfamic acid, an organomineral reagent filler "APTON-RS", Monasil and water (RF patent No. 2356929, IPC S09K 8/04, E21 B 33 / 138, publ. 05/27/2009). The disadvantage of this composition is that at a temperature of 20 ° C, the gelation time is from 25 minutes to 7 hours 25 minutes, depending on the ratio of ingredients, which is not enough when working at higher reservoir temperatures. With a decrease in the concentration of the gelation regulator (sulfamic acid), the gelation time increases to 7 h 25 min at a temperature of 20 ° C, which also leads to a deterioration in the technological properties of the composition, such as plastic strength, adhesion to metal and formation rock. Therefore, this composition cannot be highly effective when performing isolation work in wells with increased reservoir temperature.

There is a known method for isolating water influx in high-temperature formations (RF patent No. 2272891, IPC Е21В 33/138, publ. 27.03.2006), including the injection into the formation of a composition from an aqueous solution of a crosslinker and polymer acrylamide with a molecular weight of no more than 1 million and a degree of hydrolysis of no more than 0.5% (nonionic polymer of acrylamide AK-631 grade N-50) capable of hydrolysis and formation of a strong gel in the presence of a crosslinker (chromium acetate or urotropin with hydroquinone) at a reservoir temperature of more than 70 ° C, as well as acting as a gelation regulator weak organic acids such as sulfosalicylic acid. The disadvantage of this composition is the long dissolution time of the low-hydrolyzed non-ionic polymer AK-631, grade P-50, in water, as a result, the complexity and duration of preparation of the composition during injection into the formation. In addition, metal ion crosslinking of carboxylic polymers such as partially hydrolyzed PAA is not suitable for use in high temperature formations. In such formations, excessive hydrolysis of the polymer gel will occur and, in addition, syneresis will occur due to undesirable crosslinking by divalent cations such as magnesium and calcium.

The closest solution, taken as a prototype, is a gel-forming composition that contains a copolymer of acrylamide and acrylic acid - 0.17-0.80 wt. %, paraform - 0.03-0.20 wt. %, resorcinol - 0.02-0.12 wt. %, water - the rest or a copolymer of acrylamide and acrylic acid - 0.17-0.80 wt. %, paraform - 0.03-0.20 wt. %, resorcinol -0.02-0.12 wt. %, aerosil - 0.01-0.03 wt. %, water - the rest (RF patent No. 2553816, IPC Е21В 33/13, С09К 8/504, Е21В 43/22, publ. 20.06.2015.). The disadvantage of the known composition is that its use is limited in temperature range. At temperatures above 70 ° C, within 20-30 minutes. there is a sharp increase in the viscosity of the gel, which reduces the depth of injection into the formation.

Each oil field has its own geological and physical characteristics. The composition of oil and reservoir rocks, oil viscosity, formation water salinity, reservoir temperatures and pressures vary over a fairly wide range. For example, the reservoir temperatures of most fields in Western Siberia vary from 50 to 100 ° C. Therefore, the use of gel technologies for enhanced oil recovery, limitation or isolation of water inflow requires the creation of gel-forming systems with controlled properties.

Gelation time at temperatures above 70 ° C can be adjusted with inorganic and organic additives, adjusting to specific reservoir conditions. Therefore, it is important to expand the possibility of using crosslinked polymer systems to manually control the time of their crosslinking by changing the content of both polyacrylamide and crosslinker. With the same content of components in the mixture, the composition will have different properties at 70 ° C and at 90 ° C, incl. gelation time, rheological properties and strength characteristics.

The possibility of using structure-forming compositions in waterproofing technologies under conditions of elevated reservoir temperatures is mainly determined by two factors:

- stability of structures at elevated temperatures;

- controlled kinetics of structure formation, which allows pumping the required volumes of the composition.

The objective of the invention is to improve the quality of insulation in high-temperature formations by increasing the injection depth, the strength of the crosslinked polymer system formed in the flooded zone, as well as expanding the temperature range of using the grouting polymer composition.

The problem is solved by the fact that the proposed grouting polymer composition for high temperatures containing a copolymer of acrylamide and acrylic acid, water and crosslinkers - paraform and resorcinol, according to the invention, additionally contains a gelation regulator reagent Krathol, with the following ratio of components, wt. %:

copolymer of acrylamide and acrylic acid - 0.18-1.7

paraform - 0.03-0.2

resorcinol - 0.02-0.12

reagent Krathol - 0.01-1.0

water - the rest,

Or, as a crosslinker, it contains paraform and resorcinol with aerosil and additionally contains a gelation regulator - Krathol reagent, with the following ratio of components, wt. %:

copolymer of acrylamide and acrylic acid - 0.18-1.7

paraform - 0.03-0.2

resorcinol - 0.02-0.12

aerosil - 0.01-0.03

reagent Krathol - 0.01-1.0

water is the rest.

In addition, the grouting polymer composition for high temperatures as a copolymer of acrylamide and acrylic acid, according to the invention, contains a copolymer of acrylamide and acrylic acid with a molecular weight of 3-18 million and a degree of hydrolysis of 5-30%.

Chemical technologies for oil production use a wide range of acrylamide polymers, differing in molecular weights and degrees of hydrolysis. Varying the molecular characteristics and concentration of the polymer in the composition allows you to select the optimal composition in relation to the specific geological and physical conditions of the fields.

The technology using crosslinked polymer systems is based on the injection of polymer solutions containing a crosslinking agent into a reservoir with a heterogeneous permeability and oil saturation. The preliminary selection of a polymer for waterproofing is carried out on the increased strength characteristics of the compositions, which are possessed by compositions based on polymers with a molecular weight of 3-18 million. which allows you to form a screen that provides effective waterproofing.

In the prototype, copolymers of acrylamide and acrylic acid with a molecular weight of 5-18 million and a degree of hydrolysis of 5-30% are used as a polymer, which is not enough for the formation of stable crosslinked gels under conditions of elevated reservoir temperatures and a significantly short gelation time at elevated temperatures, in the claimed technical The solution proposed to expand the range of polymers used to copolymers of acrylamide and acrylic acid with a molecular weight of 3-18 million and a degree of hydrolysis of 5-30%.

An equally important factor in the successful and high-quality performance of insulation works, incl. elimination of zones of lost circulation of drilling mud during well drilling is the choice of the optimal concentration of polymers and crosslinkers in water.

In the claimed composition, it is proposed to expand the range of concentration of polymer components in water, namely from 0.18 to 1.7%, which will certainly improve the rheological, physicochemical and filtration characteristics of the grouting polymer composition. In addition, an increase in concentration and the use of a low molecular weight polymer makes it possible to create more durable waterproof screens, which ultimately affects the quality of the work carried out.

The inventive plugging polymer composition contains the Kratol reagent as a gelation regulator. The use of the Kratol reagent in oil production for the purpose of regulating the gelation of polymer systems is not known.

The Krathol reagent contains sulfamic acid, alkyldiethylbenzylammonium chloride and sodium alkylbenzenesulfonate. The presence of additives allows the Kratol reagent in the inventive grouting polymer composition to play the role of a gelation time regulator in high-temperature formations, which ultimately makes it possible to solve the problem of improving the quality of insulation by increasing the injection depth and the strength of the crosslinked polymer system formed in the watered zone. By varying the concentration of the Krathol reagent, it is possible to regulate the required gelation time for specific geological and physical conditions of a particular field, including high reservoir temperatures. The introduction of the Krathol reagent into the grouting polymer composition prevents the premature rapid gelation of crosslinked polymer systems that occurs at elevated temperatures. In addition, the Krathol reagent has a complex effect: in addition to regulating gelation, it exhibits the properties of a bactericide and a corrosion inhibitor, which also has a positive effect on the state of equipment under conditions of active use of sulfamic acid.

Studies have established that, under high temperature conditions, aerosil, along with paraform and resorcinol, acts as a crosslinker for a copolymer of acrylamide and acrylic acid. Since both of the claimed gel-forming compositions - both without Aerosil and with Aerosil - have equal technical advantages by simplifying the preparation of the gel-forming composition without Aerosil and increasing the gelation time by about 10-20% in its presence, each invention of the claimed group of inventions is characterized by the applicant by a set of features using the alternative “or”.

As part of the proposed technical solution, the following reagents are used.

Copolymer of acrylamide and acrylic acid - for example, partially hydrolyzed polyacrylamide grades A345, SD-6800, AN-132, FP-107, A523, etc. with a molecular weight of 3-18 million and a degree of hydrolysis of 5-30%. These grades of polyacrylamides are used for the purification of natural and industrial wastewater, intensification of the clarification, thickening and filtering of process brines, suspensions, flotation concentrates and flotation waste, for the processes of increasing oil production and drilling.

Paraform (paraformaldehyde) TU 6-09-141-03-89 is a product of formaldehyde polymerization. It is a white, loose powder with a formaldehyde odor. It is used as a disinfectant, used in the preparation of resorcinol-formaldehyde, phenol-formaldehyde, urea-formaldehyde and other resins, as well as in the production of chemicals for oil drilling, additives to petroleum oils, adhesive resins and molded materials of electrical components.

Resorcinol GOST 9970-74 - meta-dioxybenzene, white or yellowish crystalline powder with a weak characteristic odor. They are used in the production of medicines for the treatment of skin diseases, in the production of explosives, resorcinol-aldehyde resins, azo dyes, stabilizers and plasticizers of high molecular weight compounds.

Krathol TU 2121-415-05800142-2014 is a sulfamic acid-based product manufactured by PJSC Pigment, is a white crystalline powder, readily soluble in water, containing sulfamic acid (from 90%), alkyldimethylbenzylammonium chloride (1-5% ) and sodium alkylbenzenesulfonate (1-5%). It is used in the oil industry for acid treatment of the bottomhole formation zone, it is used as the main component of dry acid compositions.

Alkyldimethylbenzylammonium chloride belongs to the class of quaternary ammonium compounds, is a highly effective disinfectant with a powerful antimicrobial, bactericidal, algicidal, fungicidal, virucidal effect.

Sodium alkylbenzenesulfonate is currently the main surfactant in the composition of synthetic detergents and complex reagents, widely used in the oil industry, as an inhibitor of hydrogen sulfide and acid corrosion.

Aerosil GOST 14922-77 is a highly dispersed, highly active, amorphous, pyrogenic silicon dioxide (SiO ₂ ). It is used for thickening, imparting thixotropic properties to liquids and active filling of rubbers and sealants. It is also widely used to impart flowability to powdery products, prevent clumping, adsorb excess moisture and increase their shelf life. It acts as a stabilizer, acts as an anti-sediment additive for multicomponent systems. It is thermally stable and retains its properties at temperatures above 200 ° C.

All the compositions were prepared in the following sequence: in fresh water (mineralization less than 1 g / l) with stirring on a magnetic stirrer was introduced successively the reagent Krathol, then after complete dissolution paraform crosslinkers, resorcinol, aerosil (in compositions containing aerosil) were introduced, then the copolymer was introduced and continued stirring until complete dissolution. Dissolution time at room temperature and gel time at high temperature were determined. In parallel, tests were carried out at a temperature of 70 ° C and 90 ° C. When the relaxation time (filament lifetime) was more than 120 sec, the polymer system was considered to have reached the required degree of crosslinking. Further, the viscosity and rheological characteristics of crosslinked gels were determined using a Haake Viscotesteri Q rotary viscometer.

An example of a specific implementation

In 98.7 ml of fresh water (mineralization less than 1 g / l), a solution was prepared containing 1.0 g (1.0%) of grade A 345 polyacrylamide, 0.18 g (0.18%) of Krathol reagent, 0.09 g. (0.09%) paraform, 0.03 g (0.03%) resorcinol and 0.005 g (0.005%) aerosil

The dissolution time at room temperature and the gel time at 90 ° C were determined. The dissolution time was 90 minutes. Gelation time 285 min. (see table 1 line 25). The viscosity and rheological characteristics of the crosslinked gel, measured on a Haake Viscotesteri Q viscometer, are shown in FIG. 1.

Further, similarly to an example of a specific embodiment, compositions with different content of components were obtained and their dissolution time, crosslinking time at temperatures of 70 ° C and 90 ° C were investigated. All results are shown in Table 1.

Experiments Nos. 1-15 were carried out using as a copolymer of acrylamide and acrylic acid partially hydrolyzed polyacrylamide grade AN 132, Nos. 16-32 - partially hydrolyzed polyacrylamide grade A 345, Nos. 33-49 - partially hydrolyzed polyacrylamide grade A 523, No. 50-54 - partially hydrolyzed polyacrylamide FP 107 The time of dissolution and gelation at different temperatures depending on different concentrations of the components of the grouting polymer mixture for copolymers A345, A523, FP107, AN132 are presented in Table 1.

Examples 16, 33 and 50 without the Kratol reagent are given for comparison with the prototype (RF patent No. 2553816). In fresh water (mineralization less than 1 g / l), a solution is prepared containing polyacrylamide grade A 345, paraform crosslinkers and resorcinol.

It can be seen from the examples given that the composition according to the prototype (line 55) at a temperature of 70 ° C is crosslinked in 30 minutes, at 90 ° C in 13 minutes, which is not enough for trouble-free delivery of the composition to the formation for further repair and isolation works. The introduction of the gelation regulator Krathol both without aerosil and in its presence makes it possible to lengthen the crosslinking time from 30 to 1200 minutes, depending on the temperature.

The selected concentration range of partially hydrolyzed polyacrylamide from 0.18 to 1.7% in the presence of crosslinkers makes it possible to obtain strong crosslinked gels Nos. 3-14. At a concentration of 0.15% PAA, the gel does not cross-link (No. 1) or it is weakly cross-linked (No. 2), which does not allow creating a durable waterproof screen. At a concentration above 1.7%, the described PAA (No. 15) are poorly soluble in water, form a thick, highly pumpable solution, which can lead to emergency consequences in the well.

A smooth increase in the concentration of Kratol in polymer compositions (No. 16-32) and (No. 33-49) allows you to select the optimal time for gelant crosslinking while maintaining the rheological characteristics.

For grouting polymer compositions prepared according to the examples of tables 1, marked with *, a study of rheological properties was carried out.

To assess the rheological properties of the compositions, the dependences of the effective viscosity on the shear rate were recorded and the ultimate shear stress was calculated.

The viscosity and rheological properties of crosslinked gels in the presence of gelation regulator, and without, were determined in a rotary viscometer Haake Viscotesteri Q. For the studied samples shear test was used when changing a shear rate in the range of 0.1 to 300 s ^-1, wherein determined the dependence of the shear stress and viscosity on the shear rate. In this case, the increase in the shear rate was carried out stepwise, with a given step on a logarithmic scale.

To determine the ultimate shear stress, the rheological curve was plotted in a controlled shear stress (CS) mode.

The dependence of the shear stress on the shear rate (flow curves) for crosslinked polymer systems is approximated by the Herschel-Bulkley equation describing the behavior of a plastic fluid:

where τ is the shear stress, Pa;

K is the consistency, Pa⋅s is a measure of the consistency of the liquid;

- скорость сдвига, с^-1;

- shear rate, s ^-1 ;

n is an indicator of the degree of non-Newtonian behavior of the liquid - the more n differs from 1, the higher the manifestation of the non-Newtonian properties of the solution;

τ ₀ - limiting shear stress, Pa - characterizes the magnitude of the external influence required for the beginning of the fluid flow.

_{The ultimate shear stress τ 0} can be used as a parameter for assessing the effectiveness of grouting compositions. The ultimate shear stress of a system, to a certain extent, characterizes the presence of the properties of a solid - for deformation to begin, it is necessary to apply some shear stress. The higher τ ₀ , the greater the resistance of the system at low shear rates and the higher its insulating capacity.

FIG. 1 shows the rheological curves of the dependence of the effective viscosity on the shear rate of compositions 16 and 25 at 90 ° C, FIG. 2 - compositions 33 and 45 at 90 ° C.

All compositions are non-Newtonian fluids, that is, their flow does not obey Newton's law and the viscosity changes with a change in the shear rate (applied deformation).

The obtained rheological curves (Fig. 1 and Fig. 2) indicate that the introduction of the crosslinking regulator does not affect the viscosity and strength characteristics of the crosslinked polymer compositions (Table 2)

Investigated the time of gelation of the compositions in the presence of partially hydrolyzed polyacrylamide FP107 without Aerosil (No. 51) and in the presence of Aerosil 0.01; 0.02, 0.03% (No. 52-54, respectively).

The use of Aerosil in concentrations from 0.01 to 0.03% makes it possible to further increase the gelation time of the grouting polymer composition by about 10-20%, which is an advantage of using this composition. The use of aerosil in a concentration higher than 0.03% is impractical, since with an increase in aerosil concentration, a significant increase in the crosslinking time is not observed (No. 52-54).

Additional introduction of Aerosil does not affect the rheological characteristics of crosslinked polymer systems, which is confirmed by the obtained viscosity curves (Fig. 3 and Table 3.

The advantages of the inventive grouting polymer composition for high temperatures are:

- the possibility of regulating the gelation time depending on the specific conditions of the formation, the depth of the well, the required injection volumes;

- at elevated temperatures, the properties of the crosslinked polymer systems are preserved for a long time, the strength of the crosslinked polymer system formed in the watered zone increases;

- an increase in the injection depth into high-temperature formations due to an increase in the gelation time;

- prevention of a sharp formation of plugs at elevated temperatures, leading to emergency situations.

The end result of using the invention is to improve the quality of the insulation works in high-temperature formations, expand the temperature range of using the grouting composition and expand the range of polymer grouting compositions.

Claims (14)

1. Grouting polymer composition for high temperatures containing a copolymer of acrylamide and acrylic acid, water and crosslinkers - paraform and resorcinol, characterized in that it additionally contains a gelation regulator reagent Krathol, with the following ratio of components, wt. %: copolymer of acrylamide and acrylic acid - 0.18-1.7 paraform - 0.03-0.2 resorcinol - 0.02-0.12 reagent Krathol - 0.01-1.0 water - the rest, or as a crosslinker contains paraform and resorcinol with aerosil and additionally contains a gelation regulator - reagent Krathol, with the following ratio of components, wt. %: copolymer of acrylamide and acrylic acid - 0.18-1.7 paraform - 0.03-0.2 resorcinol - 0.02-0.12 aerosil - 0.01-0.03 reagent Krathol - 0.01-1.0 water is the rest. 2. The grouting polymer composition for high temperatures according to claim 1, characterized in that, as a copolymer of acrylamide and acrylic acid, it contains a copolymer of acrylamide and acrylic acid with a molecular weight of 3-18 million and a degree of hydrolysis of 5-30%.

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