RU2138616C1 - Compound for consolidation of bottom-hole zone of bed - Google Patents

Abstract

FIELD: oil and gas production industry. SUBSTANCE: compound is used for consolidation of bottom-hole zone of bed in fighting sand occurrences in oil and gas wells. Compound for consolidation of bottom-hole of bed has following components: 57-75 vol.% of distilled residue from rectification of furfuryl alcohol, 8-19 vol.% of concentrated technical muriatic acid, 2-4 vol.% of water solution of ammonia of 25% concentration, 2-4 vol.% of acetone, 10-12 vol. % of water. Application of aforesaid compound prolongs compound hardening period which allows for injecting it into given interval with ensuring required radius of treatment of bottom-hole zone of bed. It also increases deformative properties of sandstone with retention of its mechanical properties and permeability. This creates conditions for postrepair operation of wells at increased depressions without carrying-out of bed sand. EFFECT: higher efficiency. 5 dwg

Description

 The invention relates to the fastening of the bottomhole formation zone in the fight against sand occurrences in oil and gas wells.

Analysis of the current level of technology showed the following:
there is known a composition for attaching a bottomhole formation zone, consisting of furfuryl (furyl) alcohol and an acid catalyst selected from the group: hydrochloric acid, phosphoric acid, hypophosphoric acid (see US Pat. No. 4034811 of 11/20/1975 Continental Oil Company, publ. 07/12/1977 in the collection "Inventions in the USSR and abroad", N 3, 1978, p. 42). The process of polymerization of furfuryl alcohol is carried out directly in the reservoir.

 The disadvantage of this composition is the rapid curing and low deformability of the sandstone fixed by it. Curing occurs especially quickly when the pH decreases as a result of the introduction of an acid type catalyst, which limits the use of the composition for wells with elevated temperatures. In addition, the sequential injection of furfuryl alcohol and acid hardener into the reservoir does not allow us to obtain a bottomhole zone uniformly fixed in depth and processing interval as a result of a mismatch in the viscosities of the displaced and displacing fluids. The plastic-brittle nature of the destruction of the fixed rock when the limit of its mechanical strength from the loads arising during the operation of the well is exceeded determines the crack and channel formation due to low deformability, which does not exclude the removal of sand and rock particles from the well from deep-lying areas of the loose formation. The above reasons together lead to a decrease in the efficiency of processing the bottom-hole zone.

As a prototype taken composition for fastening the bottomhole formation zone, containing the following components, wt. %:
VAT residues of the production of furfuryl alcohol (COFS) - 55-90
Acid Hardener - 3-15
Water - Else
(see A.S. N 1694857 dated 06/21/89 according to class E 21 B 33/138, published in OB N 44, 1991). As the acid hardener, hydrochloric acid, or benzenesulfonic acid, or ferric chloride is used.

 The disadvantage of this composition is the rapid curing and low deformability of the sandstone fixed by it. Rapid curing is accompanied by an increase in the viscosity of the solution and makes it difficult for the latter to penetrate the formation to the required depth. The inability to treat the bottomhole formation zone in the required radius of sandy rock fixation due to its limited penetrating ability due to the fast set of structural viscosity reduces the effectiveness of repair work. Since the radius of treatment of the bottom-hole zone of the formation with this composition does not correspond to the required one, determined taking into account the degree of destruction of porosity and permeability of the rock, and is always smaller for the above reasons, the creation of depression on the formation during development of the well and the mode of forced gas extraction will lead to a rather rapid destruction of the fixed section of the formation the removal of solids from the well or the formation of sand plugs. At the same time, the plastic-brittle nature of the destruction of sandstone, bonded by this composition, which does not provide sufficient deformability, leads to the appearance of cracks and channels through which sand is removed from the destroyed sections of the bottomhole zone more remote from the wellbore. Thus, it is practically impossible to obtain an effective fixation of the bottomhole formation zone, which ensures the subsequent operation of the well without removing sand from it, with this composition.

The technical result that can be obtained by implementing the invention is reduced to the following:
the curing time of the composition increases, which allows it to be pumped to a predetermined interval and to provide the necessary radius of treatment of the bottom-hole formation zone;
the deformative properties of the fixed sandstone increase while maintaining its mechanical strength and permeability, which creates the conditions for the after-repair operation of the well with increased depressions without removal of formation sand.

The technical result is achieved using a known composition, including still bottoms of distillation of furfuryl alcohol, concentrated technical hydrochloric acid and water, in which acetone and a 25% aqueous solution of ammonia are added. We offer the following composition recipe, vol. %:
Distillation residues of distillation of furfuryl alcohol (COFS) - 57-75
Concentrated Technical Hydrochloric Acid - 8-19
Acetone - 2-4
An aqueous solution of ammonia 25% concentration - 2-4
Water - Else
COFS are used according to TU 64-5312-03-89, they have the following composition, wt. %:
Furfuryl alcohol - 63.79
Furfural - 2.06
Tetrahydrofurfuryl alcohol - 1.43
Sylvan - 0.58
Water - 0.14
Furan - 0.03
Diols - Else
technical hydrochloric acid of the highest grade, grade A, 35% concentration according to GOST 857-88, technical acetone - according to GOST 3760-79, aqueous ammonia 25% concentration - according to GOST 3760-79.

The combined use of acetone and ammonia can slow down the polymerization of furfuryl alcohol in the presence of an acid catalyst - hydrochloric acid, as well as the process of formation of furfural acetone oligomer, which helps to maintain high penetrating ability of the composition by preventing an increase in its rheological properties (viscosity, etc.) and generally increases the curing time of the composition. This is due to a change in the sequence of chemical reactions in a multicomponent system of the proposed composition:
1. Acetone interacts with ammonia to form a complex organic compound 4-amino-4-methyl-2-pentanone in accordance with the reactions proceeding in two stages: a and b (see reaction scheme, Fig. 1);
2. The resulting aminomethylpentanone reacts with hydrochloric acid (see Fig. 2);
3. Aldehyde reacts with ammonia to give acetaldimine (see Fig. 3);
4. Acetaldimine cyclizes to form aldehyde ammonia (see Fig. 4);
5. Aldehyde ammonia reacts with furfuryl alcohol to form a resinous substance of complex branched structure (see Fig. 5).

 Thus, the additional introduction of acetone and ammonia into the composition slows down the polymerization of furfuryl alcohol due to the binding of hydrochloric acid in accordance with the equation in FIG. 2, and by preventing the rapid interaction of the compounds of the furan ring present in COFS with acetone as a result of a change in the course of chemical processes in the direction described by the schemes in FIG. 1-5.

 In addition to slowing the onset of thickening and curing, this composition provides increased deformative properties of the cured sandstone, due to the combined effect of furfural-acetone resin and a complex vulcanized polymer compound obtained in accordance with the equation in FIG. 5. In this case, the complex of resinous compounds formed contributes to a better retention of sand particles in the bound state due to the variety of functional groups that determine the adhesive properties of the composition and are damping bridges between the fixed sand particles. As a result of the conjugate adsorption of resinous substances of various compositions on sand particles, the material to be fixed does not have a plastic-brittle, but an elastic-plastic nature of destruction under the influence of mechanical loads. This contributes to a significant reduction in the likelihood of cracking during the destruction of the fixed rock, which occurs in wells when the formation is subjected to both rock pressure and its mechanical strength is exceeded during forced gas withdrawals (increased depression). Cracks and channels appear during plastic-brittle fracture of samples of fixed sand using COFS and acid hardener (see prototype). In the case of the claimed composition, when the mechanical strength of the sand sample is exceeded, its initial shape changes, i.e. the sample is deformed and fracture has an elastic-plastic character, which helps to increase the resistance of the bonded rock to mechanical stress, to prevent sand from the loose zone of the formation during subsequent operation of the wells and to reduce the number of repair and restoration works.

 An indicator of the deformation properties is the relative deformation of the specimens upon cracking. The methodology for testing cylinder specimens for splitting was developed at SevKavNIPIgaz (see Sat. Scientific Works of VNIIgaz, "Theory and Practice of Construction of Production Gas Wells", Moscow, 1983, p. 111 1-115).

 When processing sand cores of the claimed composition, their mechanical strength and permeability practically does not differ from these parameters for samples of the prototype. This is due to the fact that the content of the main substance, furfuryl alcohol, which gives resinous compounds, in the chemical waste used in both cases is approximately the same, and only the speed and sequence of polymerization processes change, which is described in detail above.

 The content of COFS in the composition in an amount of less than 57 vol.% Reduces the curing time, reduces the mechanical strength and deformability of the samples of bonded sand in an amount of more than 75 vol.% - it is impractical, because practically no improvement in composition properties.

 The content of hydrochloric acid in the composition in an amount of less than 8 vol.% Reduces the mechanical strength, the permeability of the samples and their deformation properties in an amount of more than 19 vol.% - reduces the curing time of the composition.

 The content of acetone and aqueous ammonia in the composition in an amount of less than 2 vol.% Reduces the curing time and reduces the deformability of the samples, and their content in the composition of more than 4 vol.% Negatively affects the mechanical strength, which is due to a decrease in the content of hydrochloric acid per unit volume ammonia solution.

Например: 40 мл (4 об.%) ацетона соответствуют его количеству, равному 32 г (G_ац = V_ац•d_ац = 40•0,8 = 32). На 32 г ацетона необходимо около 9 г аммиака (32: 3,4= 9,4) или при его 25%-ной концентрации в растворе - 36 г (9•100: 25= 36). Плотность 25%-ного раствора аммиака равна 0,9 г/см³ тогда необходимый объем раствора аммиака равен 40 мл (V_ам=G_ам:d_ам= 36:0,9=40), т. е. соотношение объемов ацетона и водного раствора аммиака равно 1:1.The volume ratio of acetone and aqueous ammonia, equal to 1: 1, is due to the following. From equations 1-3 it follows that for the formation of acetaldimine, which is involved in the processes of cyclization, and then polymerization, 2 ammonia molecules are needed for 2 acetone molecules. Given their molecular weight, the ratio of the mass parts of acetone and ammonia is:

For example: 40 ml (4 vol.%) Of acetone corresponds to its amount equal to 32 g (G _ac = V _ac • d _ac = 40 • 0.8 = 32). For 32 g of acetone, about 9 g of ammonia is needed (32: 3.4 = 9.4) or, at its 25% concentration in solution, 36 g (9 • 100: 25 = 36). The density of a 25% ammonia solution is 0.9 g / cm ³ then the required volume of ammonia solution is 40 ml (V _am = G _am : d _am = 36: 0.9 = 40), i.e. the ratio of the volumes of acetone and aqueous ammonia is 1: 1.

 The volume ratio of acetone and aqueous ammonia in the composition, equal to 1: 1.5, reduces the mechanical strength of the bonded sand, due to the partial neutralization of hydrochloric acid with free ammonia, and the ratio of acetone and ammonia, equal to 1.5: 1, reduces the curing time of the composition as a result of the formation of furfural acetone oligomer.

 It is known to use acetone as a solvent in grouting compositions for isolating permeable formations (see cl. RF N 2046180 dated 1.07.1992, class E 21 B 33/138, publ. In OB N 29, 1995, p. RF N 2002038 dated 06/17/1991 according to class E 21 B 33/138, published in OB N 39-40, 1993; Blazhevich V.A. et al. Methods of isolation of a formation during drilling and operation of wells. foreign patents, VNIIOENG, M., 1972, p. 6), in the method for processing the borehole zone of a formation (see A.S. N 1508630 of 07.30.1987, class E 21 B 33/138), in adhesive compositions (see, for example, A.S. N 702059 dated 05/10/1978 according to class C 09 J 3/14, published in OB N 45, 1979-, A.S. N 18337880 from 07/26/1990 according to class C 09 J 163/02, published in OB N 30, 1993; A.S. N 1578173 dated 06/15/1987 according to class C 09 J 161/10, publ. in OB N 26, 1990; ac N 599535 dated 01.03.1977 according to class C 09 J 3/14, publ. in OB N 22, 1980, etc.).

 It is known to use ammonia (25% aqueous solution) in a mixture with pentahydrate copper sulfate, hydrol (molasses) and water as a retarder for setting cement slurries (see ac N 646033 of 07.15.1977, class E 21 B 33 / 138, published in OB N 5, 1979). The known composition is an additive in cement slurry, which is an alkaline suspension. The mechanism of cement hardening slowdown described below with the participation of this complex moderator is possible only in alkaline environments and does not work in environments with high acidity, as, for example, in the claimed composition. An aqueous solution of ammonia alone does not have a retarding effect on the setting time of the cement mortar, but only increases the effectiveness of the reagent based on copper sulfate and hydrol due to the formation of a copper-ammonia complex that oxidizes the hydrochlor sugar. The resulting products are inhibitors of the hardening of the solution.

 The use in the claimed composition of only an aqueous solution of ammonia (without acetone) does not have a retarding curing effect, because ammonia is almost instantly neutralized by hydrochloric acid.

 It is known to use ammonia as a hydrophilizing additive in a water-insulating composition mixed with heavy hydrocarbons and an inorganic additive (see ac N 1422971 dated 06/12/1985 according to class E 21 B 33/138, chipboard), in a water-insulating composition as an additive ( see ac N 1153042 dated 04/21/1983 according to class E 21 B 33/138, OB N 16, 1985), as well as in all kinds of adhesive compositions mixed with other reagents, for example, for the purpose of increasing the initial adhesion and expansion of functionality (see clause of the Russian Federation N 2022992 of 11.29.1990 according to class C 09 J 161/24, published in OB N 21, 1994), as a catalytic converter an interaction reaction of organic polymers (see clause of the Russian Federation N 2002787 dated March 26, 1990 according to class C 09 J 175/08, published in Rev. N 41-42, 1993, and A.S. N 1309557 dated 13.02 .1985 according to class C 09 J 131/04, published in OB N 35, 1995, etc.), for the purpose of increasing the adhesive strength, viability and reducing the drying time (see A.S. N 812818 from 02.23.1979, class C 09 J 3/16, published in OB N 10, 1981), to improve the washability and the recovery of adhesive properties after wetting (see A.S. N 937498 from 09/25/1980 according to class C 09 J 3/16, publ. in OB N 23, 1982), as a plasticizer (see A.S. N 223691 dated 6.01.1965 according to class C 09 J 3/16, publ. in OB N 24, 1968) and etc.

 It is known to use furfural (the reagent is a part of bottoms) in the method of processing cement mortars for fixing wells in order to increase mechanical strength and increase the retardation time of setting (see A.S. N 323543 dated January 31, 66, class E 21 B 33/138, publ. In OB N 1, 1971), in compositions for fixing wells in order to increase the stability of the compositions to the effects of reservoir fluids at elevated temperatures (see A. S. N 1629479 from 06.06.87, class E 21 B 33/138, published in OB N 7, 1991), adhesives in order to increase adhesion to wet surfaces and non-hardening sealing mastics and increasing the strength of the adhesive joint (see AS No. 724546 of 09/09/1977 according to class C 09 J 3/12, publ. in OB N 12.1980).

 It is known to use furfuryl alcohol (the reagent is a part of bottoms) in cement slurry in order to increase the strength of cement stone in the early stages of hardening as an antifoam (see A.S. N 675169 of 04/17/1978 according to class E 21 B 33 / 138, published in OB N 27, 1979), with the aim of obtaining cement slurry at low water yield and increased strength as a defoamer (see AS No. 684129 of 04/25/1978 according to class E 21 B 33/138, published in OB 33, 1979), in adhesive compositions mixed with organic reagents for the purpose of increasing the bonding strength and acceleration contact setting (see A.S. N 642348 dated 10.01.1977 according to class C 09 J 3/14, published in OB N 2, 1979).

 Furfural in a mixture with acetone is used in mastics for fixing polystyrene tiles with the aim of durability of the mastic and improving its adhesive properties (see A.S. N 159586 dated 3.12.62, published in OB N 1, 1964). Furfurolacetone monomer (formed as a result of the interaction of reagents according to the above chemical reaction schemes) is used in adhesive compositions (see A. S. N 642350 dated 10/10/1976 according to CL C 09 J 3/16, publ. In OB N 2 , 1979, A.S. N 958461 dated 3.11.80 according to CL C 09 J 3/16, published in OB N 34, 1982, A.S. N 1446137 dated 05/29/1987 according to CL C09 J 3/16, published in OB N 47, 1988).

 Thus, the use of acetone in a mixture with an aqueous solution of ammonia according to the claimed technical result in the compositions for fastening the bottom-hole zone of the formation has not been identified by available sources of fame.

 The inventive composition has an inventive step.

In more detail, the essence of the claimed invention is described by the following examples:
Example N 1. To 57 ml (57 vol.%) COFS pour 19 ml (19 vol.%) Of technical hydrochloric acid 35% concentration, 3 ml (3 vol.%) 25% aqueous ammonia solution, 3 ml (3 vol.%) Acetone and 18 ml (18 vol.%) Of water.

The resulting composition is stirred for 3 minutes, saturate it with a sand core using the installation UIPK-1M, and left for 24 hours in an thermostat at 20 and 60 ^o C for curing and curing.

The sand fixed by the composition has the following properties: curing time at 20 ^o C 140 min, at 60 ^o C - 75 min; relative deformation - 2.7 • 10 ^-3 , tensile strength at cracking - 2.04 MPa, gas permeability - 2.25 μm ² .

Example No. 2. Prepare a mixture of solutions of the following composition, vol.%:
COFS - 75
Concentrated Technical Hydrochloric Acid - 8
Acetone - 2
Aqueous solution of ammonia 25% concentration - 2
Water - 13
and then carry out all operations as described in example No. 1.

The sand fixed by the composition has the following properties: curing time at 20 ^o C - 390 min, at 60 ^o C - 220 min, relative deformation - 4.2 • 10 ^-3 , breaking strength - 1.86 MPa, gas permeability - 2, 86 μm ² .

Example No. 3. A mixture of solutions of the following composition is prepared, vol.%:
COFS - 67
Concentrated Technical Hydrochloric Acid - 15
Acetone - 4
Aqueous solution of ammonia 25% concentration - 4
Water - 10
and then carry out all operations as described in example No. 1.

The sand fixed by the composition has the following properties: the start time of curing at 20 ^o C is 240 min, at 60 ^o C - 90 min, relative deformation - 6.7 • 10 ^-3 , tensile strength at cracking - 1.85 MPa, gas permeability - 3 , 27 μm ² .

Example No. 4. Prepare a mixture of solutions of the following composition, vol.%:
COFS - 57
Concentrated technical hydrochloric acid - 20 (max transcendent value)
Acetone - 3
An aqueous solution of ammonia 25% concentration - 3
Water - 17
and then carry out all operations as described in example No. 1.

The sand fixed by the composition has the following properties: curing start time at 20 ^o C - 95 min, at 60 ^o C - 50 min, relative deformation - 3.5 • 10 ^-3 , tensile strength at cracking - 1.98 MPa, gas permeability - 3 25 μm ² .

Example No. 5. Prepare a mixture of solutions of the following composition, vol.%:
COFS - 56 (min beyond value)
Concentrated Technical Hydrochloric Acid - 19
Acetone - 3
An aqueous solution of ammonia 25% concentration - 3
Water - 19
and then carry out all operations as described in example No. 1.

The sand fixed by the composition has the following properties: curing start time at 20 ^o C - 100 min, at 60 ^o C - 50 min; relative deformation - 1.7 • 10 ^-3 , tensile strength at cracking - 1.02 MPa, gas permeability - 2.18 μm ² .

Example N 6. Prepare a mixture of solutions of the following composition, vol.%:
COFS - 76 (max outrageous value)
Concentrated Technical Hydrochloric Acid - 8
Acetone - 2
Aqueous solution of ammonia 25% concentration - 2
Water - 12
and then carry out all operations as described in example No. 1.

The sand fixed by the composition has the following properties: curing start time at 20 ^o C - 225 min, at 60 ^o C - 75 min, relative deformation - 2.6-10 ^-3 , tensile strength at cracking - 1.81 MPa, gas permeability - 1 98 μm ² .

 Example No. 7. Prepare a mixture of solutions of the following composition, vol.%:.

COFS - 75
Concentrated technical hydrochloric acid - 7 (min transcendent value)
Acetone - 2
Aqueous solution of ammonia 25% concentration - 2
Water - 14
and then carry out all operations as described in example No. 1.

The sand fixed by the composition has the following properties: curing start time at 20 ^o C - 230 min, at 60 ^o C - 85 min; relative deformation - 1.8 • 10 ^-3 , tensile strength at splitting - 1.12 MPa, gas permeability - 1.25 μm ² .

Example N 8. Prepare a mixture of solutions of the following composition, vol.%:
COFS - 70
Concentrated Technical Hydrochloric Acid - 12
Acetone - 1 (min overwhelming value)
Aqueous solution of ammonia of 25% concentration - 1 (min beyond value)
Water - 16
and then carry out all operations as described in example No. 1.

The sand fixed by the composition has the following properties: curing start time at 20 ^o C - 85 min, at 60 ^o C - 20 min, relative deformation - 0.9 • 10 ^-3 , tensile strength at cracking - 2.13 MPa, gas permeability - 2 , 26 μm ² .

Example No. 9. Prepare a mixture of solutions of the following composition, vol.%:
COFS - 70
Concentrated Technical Hydrochloric Acid - 12
Acetone - 5 (max outrageous value)
An aqueous solution of ammonia of 25% concentration - 5 (max outrageous value)
Water - 8
and then carry out all operations as described in example No. 1.

The sand fixed by the composition has the following properties: curing start time at 20 ^o C - 120 min, at 60 ^o C - 55 min; relative deformation - 2.0 • 10 ^-3 , tensile strength at cracking - 1.57 MPa, gas permeability - 2.19 μm ² .

Compared with the prototype of the claimed composition provides an increase in curing time at 20 ^o C 1.2-3.3 times, at 60 ^o C - 1.3-3.7 times, increase the deformability of 3.4-8.4 times while maintaining satisfactory strength properties and gas permeability.

 Preparation of the composition in the field does not require the use of special equipment. The composition can be prepared in the measuring unit of the cementing unit. Mixing of the composition in the measuring units of the units is provided by the main or auxiliary pump.

Claims (1)

Composition for fixing the bottom-hole zone of the formation, including bottoms of distillation of furfuryl alcohol, concentrated technical hydrochloric acid and water, characterized in that it additionally contains acetone and 25% aqueous ammonia solution with respect to volume parts equal to 1: 1, in the following ratio components, vol.%:
Distillation residues of distillation of furfuryl alcohol - 57 - 75
Concentrated Technical Hydrochloric Acid - 8 - 19
Acetone - 2 - 4
Aqueous solution of ammonia 25% concentration - 2 - 4
Water - Else

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