RU2386665C1 - Heat-resistant viscoelastic composition for finishing and repairing wells - Google Patents

Abstract

FIELD: chemistry. ^ SUBSTANCE: invention relates to oil extraction, particularly to process compositions used in well finishing and workover and more specifically: as damping fluid; as a viscoelastic separator when cementing wells; temporary insulating compositions for production horizons without loss of permeability after breakdown of the composition. The heat-resistant viscoelastic composition contains the following in wt %: galactomannan type polysaccharide reagent 0.5-2.0, chromium acetate based compound 0.1-0.4, hydrocarbon-containing reagent 0.5-3.5, alkali metal hydroxide 0.1-0.35, water - the rest. The invention is developed in subclaims. ^ EFFECT: increased heat resistance of the composition with reduction of its the negative effect on the productive strata due to controlled gel time, with high processibility of the composition due to simplicity of its preparation in field conditions. ^ 8 cl, 2 tbl, 2 ex

Description

The invention relates to the field of oil production, in particular to technological compositions used in completion and overhaul of wells, namely: as a kill fluid; as a viscoelastic separator for well cementing; temporarily insulating composition of productive horizons without loss of permeability after the destruction of the composition and so on.

Viscoelastic compounds (hereinafter VUS) are intended for temporary protection of the reservoir from the influence of process fluids during the construction and development of wells, as well as during repair and insulation works, including when killing wells. A distinctive feature of the technology using WCS from traditionally used technologies (unstructured fluids treated with surfactants) is the significantly smaller volumes of fluid used to carry out this type of operation and, as a result, a decrease in the negative impact on the collector due to the low penetrating ability of the latter. The high structural properties of the viscoelastic composition and the ability to take the form of a filled volume make it possible to reliably block the overlapped interval of the formation and to exclude both the penetration of the process fluid into the formation and the flow of formation fluid from the formation, which is necessary for trouble-free and trouble-free operation.

Thus, the main requirements for kill fluids are: stability over time regardless of reservoir conditions (temperature, pressure, etc.), inadmissibility of disturbance of reservoir performance, environmental friendliness, explosion safety.

Known viscoelastic composition containing a polysaccharide-based reagent, alkali metal hydroxide, aluminum sulfate or copper sulfate, urea monoperoxyhydrate, and water with the following ingredients, wt.%:

polysaccharide reagent 1.0-3.0 alkali metal hydroxide 0.05-0.45 aluminum sulfate or copper sulfate 0.15-0.3 urea monoperoxyhydrate 0.1-0.2 and water rest

(see RF patent No. 2116433, class C09K 7/02, from 1996).

Known WCS has high structural and rheological properties (dynamic viscosity from 9540 to 12800 cps, shear stress from 160 to 200 g / cm ³ ), which helps to prevent the penetration of the composition into the interval of the reservoir by reducing the time of structure formation, lower filtration, increased viscosity and providing while non-shrinking and uniform destruction of the composition while maintaining low filtration of the composition after destruction while maintaining high gas-holding ability.

With all of the above positive characteristics, this composition has the disadvantage of low heat resistance. The known composition loses its physical and mechanical properties at a temperature of more than 45 ° C.

In addition, the known composition is not technologically advanced due to the fact that it is impossible to deliver the slurry prepared on the surface to the required interval of the well without using special devices, since the slurry can be delivered to the calculated interval of the formation by parallel injection of polymer and crosslinker solutions with the aim of further mixing both compositions in the pipes and only as a result of this, a known WUS with the required parameters is obtained.

Closest to the claimed technical solution according to the technical essence is a heat-resistant viscoelastic composition used in the implementation of the method of interval-wise acid treatment of the bottom-hole zone, mainly horizontal wells (RF patent No. 2208147, class E21B 43/27 from 2002). This composition contains, wt.%:

hydrocarbon liquid 4.8-8.8 alkaline emulsifier based hydroxyethylated ethanol or ethoxylated glycols 0.12-4.0 starch 2.5-4.5 alkali metal hydroxide 0.25-0.45 water soluble alkali metal borate 1-2-3.5 mineralized by potassium chloride and / or sodium water rest

The specified known composition has a relatively high heat resistance (up to 90 ° C), low values of the filtration rate, high insulating properties. However, the formation of this composition occurs in a very short period of time (gelation time 2-5 min), which requires additional equipment to deliver this composition to the required interval (interval killing, isolation, etc.). In addition, the known composition has limitations on the temperature factor (up to 90 °) and at higher formation temperatures, this composition loses its insulating properties, which is not always acceptable for work.

Another negative point is the fact that the lifetime of a given composition in reservoir conditions is determined by the time of thermal degradation of the polymer included in this composition, because this composition is not susceptible to shear degradation (after mixing, it restores its former properties, which under certain conditions can have a positive effect) and due to the fact that the known composition is acid-resistant, this composition does not deteriorate under acidic influence.

The technical result achieved by the present invention is to increase the heat resistance of the composition to 150 ° C while reducing its negative impact on the productive formation by providing an adjustable gelation time that allows the formation of WCS directly in the insulated formation, while ensuring high adaptability of the composition due to the simplicity of its preparation in fishing conditions.

An additional technical result is a decrease in the cost of the composition due to the use of better components and a decrease in their total quantity.

Another technical result is the provision of technologically required lifespan of the composition due to the ability to control the rate of its destruction.

The technical result is achieved by the inventive heat-resistant viscoelastic composition for completion and repair of wells, including a polysaccharide, hydrocarbon-containing reagent, alkali metal hydroxide and water, in which it is new that it additionally contains a compound based on chromium acetate, as a polysaccharide, the composition contains a polysaccharide reagent from class galactomannans, in the following ratio of components, wt.%:

Galactomannan polysaccharide reagent 0.5-20 Chromium Acetate Compound 0.1-0.4 Hydrocarbon-containing reagent 0.5-3.5 Alkali metal hydroxide 0.1-0.35 Water Rest

As a polysaccharide reagent from the class of galactomannans, the composition contains guar gum or Reoxan brand G.

As a hydrocarbon-containing reagent, the composition contains compounds based on a mixture of higher dioxane alcohols or diesel fuel.

As a compound based on a mixture of higher dioxane alcohols, it contains Burflub BT, or flotation reagent - oxal T-80, or a lubricating additive DSPB-BS.

As a compound based on chromium acetate, it contains chromium acetate or complexing agent BT-X.

The composition additionally contains additives with a complex effect: calcium chloride, or magnesium chloride, or sodium formate, or potassium formate, or a mixture of these formates.

Also, the composition additionally contains a destructor - an oxygen-containing reagent, in an amount of up to 5 wt.%:

As an oxygen-containing reagent, the composition contains hydrogen peroxide or urea monoperoxyhydrate.

The achievement of the specified technical result is ensured by the following.

The polysaccharide reagent from the class of galactomannans recommended for the proposed composition, in contrast to conventional polysaccharides, has a special spatial structure constructed from D-mannose and D-galactose residues, and glucomannans, consisting of D-mannose and D-glucose residues, which is a mannopyranose chain , to each second cycle of which galactopyranose residue is attached by ether bonds (EG Kister. Chemical treatment of drilling fluids, Moscow, Nedra, 1972, p.181).

Due to the introduction of the indicated polysaccharide reagent into the claimed composition in the proposed quantitative ratio together with a complexing compound based on chromium acetate, it is likely that a complex compound with a developed structure is formed, which, together with other components - a hydrocarbon-containing reagent and alkali metal hydroxide - allows to obtain a heat-resistant highly structured WCS, ensuring the preservation of the permeability of the rocks of the reservoir due to the formations composition with specified properties directly in reservoir conditions, where the ambient temperature (in this case, reservoir temperature) is an additional catalyst for the formation of structural reactions. The combined processing of the composition with compounds based on chromium acetate and a hydrocarbon-containing reagent, due to the synergistic action, gives the WCS additional plastic properties that allow the composition to restore its previous properties after shear deformation.

To obtain the proposed composition in laboratory conditions, the following substances were used:

Polysaccharide reagent from the class of galactomannans:

- guar gum for import;

- Reoxane brand G, TU 9189-002-409112231-2003.

Compound based on chromium acetate:

- complexing agent BT-X, TU 2432-023-40912231-2004;

- chromium acetate TU 6-00-204-147-267-07.

Hydrocarbon-containing reagent:

- Burflyub BT TU 2452-018-40912231-2003;

- DSPB-BS, TU 2452-002-52412574-00;

- flotoreagent-oxal T-80, TU 2452-029-05766801-94;

- diesel fuel GOST 305-82 or diesel fuel EURO GOST R 52340-2005 (EN 590: 2004);

Alkali metal hydroxide.

- technical caustic soda, GOST 2263-79 (caustic soda);

- potassium hydroxide GOST 305-82.

Complex action additives:

- sodium formate technical TU 2432-01R00203803-98;

- potassium formate, by import;

- crystalline magnesium chloride, TU 92 2110-05800308-02-97;

- technical calcium chloride, GOST 451-77;

Destructor:

- technical urea monoperoxyhydrate, TU 6-00-04691277-186-97;

- hydrogen peroxide GOST R 24363-80

- process water with a hardness of not more than 5 mEq / l.

The essence of the invention is illustrated by the following examples.

Example 1 (composition 5, table 1). To obtain the claimed composition, the following reagents were successively added to 833.5 g of industrial water: 100 g of sodium formate — stirred until dissolved, 10 min; 15 g of Reoxane brand G was stirred for 30 minutes; 30 g of 10% chromium acetate and mixed until a uniform color of the composition for 15 minutes; 1.5 g of caustic soda and 20 g of DSPB-BS, the mixture was additionally mixed until homogeneous and a viscoelastic composition was obtained with the following ratio of ingredients, wt.%: Polysaccharide reagent Reoxan G - 1.5; sodium formate - 10; chromium acetate - 0.3; caustic soda - 0.15; DSPB-BS - 2 hydrocarbon-containing reagent; water - 86.05.

Example 2 (composition 2, table 1). To obtain the claimed composition, the following reagents were successively added to 927 g of industrial water: 7 g of Reoxane grade G was stirred for 30 minutes; 30 g of 10% chromium acetate and mixed until a uniform color of the composition for 15 minutes; 1 g of potassium hydroxide and 35 g of flotation reagent oxal-80, the mixture was additionally mixed until homogeneous and a viscoelastic composition was obtained with the following ratio of ingredients, wt.%: Polysaccharide reagent Reoxan G - 1.5; chromium acetate - 0.3; potassium hydroxide - 0.1; DSPB-BS hydrocarbon-containing reagent - 3.5; water - 95.4.

Similarly prepared the other inventive compositions with a different ratio of components.

Data on the component content of the studied viscoelastic compositions are shown in table 1.

In laboratory conditions, the following properties of the claimed and known prototype viscoelastic compositions were analyzed:

- filtration rate (F, cm ³ at a pressure drop of 0.7 MPa) through a porous filter with a permeability of 400 mD, was measured on a OFI dynamic filter press;

- dynamic viscosity (Pa) was measured on a Hepler instrument;

- thermal stability was measured in special bombs of a roller furnace without movement, at temperatures of 60 ° C, 110 ° C, 150 ° C and at a pressure of 0.7 and 1.5 MPa in bombs during heating, after which the rheological characteristics of the composition were measured ;

- to determine the insulating ability of the claimed composition on an NTI OFI dynamic filter press device at temperatures of 60 ° C, 110 ° C, 150 ° C, the following studies were carried out: a composition with a volume of 200 ml was interfered with test bombs (which is about 7-8 in height) cm), from above the composition was poured with mineralized water with a density of 1100 kg / m ³ (water mineralization by salts of monovalent metals Na, K), the bomb was installed in the device and heated to a predetermined temperature and at the same time repression was created at 1.5 MPa and then measured for 1 hour filter uw.

The research results are shown in table 2.

The results of the study, presented in tables 1 and 2, showed that the inventive WCS is characterized by an adjustable rate of structure formation, because the greatest increase in structure occurs under the influence of the temperature factor. Thus, the formation of the composition can occur directly in the interval of the installation of WCS in the well. At the same time, the proposed WCS retains its strength properties in a wide temperature range up to + 150 ° C for a long time (by introducing the destructor into the composition, this time can be adjusted) (over 20 Pa); has almost zero filtering; does not pass oil, gas and water; with shear deformations it is able to restore the original properties.

A feature of the proposed WCS is the ability to degrade after a certain time by introducing a small amount of a destructive substance into the composition (its amount is determined by the required lifetime of the WCS). Moreover, after degradation, the composition has a minimum viscosity (1.5-2 cPs) and retains minimal filtration, therefore, it is easily and completely removed from the installation interval.

Thus, due to its properties, the proposed composition will ensure high-quality work when completing and overhauling wells.

table 2 Data on the results of the study of the proposed and known prototype viscoelastic compounds Composition No. from table 1 Structuring time, h-min at a temperature of ° C The rate of filtration through an oxide disk, cm ³ at a temperature of ° C Dynamic viscosity, MPa · C at ° C Isolating ability to measure filtration,
cm ³ at ° C 22 60 110 150 60 110 150 60 110 150 60 110 150 one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen For the proposed WMR one 24 0-40 0-20 0-20 0 0.1 0.9 108475 100454 96357 0 0.4 2.0 2 24 0-45 0-27 0-23 0 0 0.4 104532 100001 94568 0 0.25 1.8 3 twenty 0-38 0-24 0-15 0 0 0.2 121431 113584 108544 0 0.2 1,6 four twenty 0-35 0-20 0-13 0 0 0 134731 128756 120041 0 0 1,5 5 eighteen 0-34 0-15 0-10 0 0 0 125678 118329 110120 0 0 1.4 6 twenty 0-30 0-10 0-05 0 0 0 154543 141518 134703 0 0 1,2 7 eighteen 0-20 0-08 0-05 0 0 0.1 184613 183983 165418 0 0 0.4 8 twenty 025 0-10 0-07 0 0 0.2 143562 132517 130874 0 0 0.5 9 24 0-25 0-15 0-10 0 0 0.2 138431 124532 120431 0 0 0.8 10 twenty 0-30 0-18 0-10 0 0 0 129516 109156 100852 0 0 0.6 eleven 24 0-18 0-10 0-06 0 0 0 138519 174431 153123 0 0 0.5 For the well-known prototype VUS 12 0-03 - - - 0 0.4 1,5 116,090 112 504 78 514 0 1,5 4.8

Claims (8)

1. Heat-resistant viscoelastic composition for completion and repair of wells, including a polysaccharide, a hydrocarbon-containing reagent, an alkali metal hydroxide and water, characterized in that it additionally contains a compound based on chromium acetate, as a polysaccharide, the composition contains a polysaccharide reagent from the class of galactomannans in the following ratio of components , wt.%:
Galactomannan polysaccharide reagent 0.5-2.0 Chromium Acetate Compound 0.1-0.4 Hydrocarbon-containing reagent 0.5-3.5 Alkali metal hydroxide 0.1-0.35 Water Rest 2. The composition according to claim 1, characterized in that as the polysaccharide reagent from the class of galactomannans, the composition contains guar gum or Reoxane brand G. 3. The composition according to claim 1, characterized in that as the hydrocarbon-containing reagent, the composition contains compounds based on a mixture of higher dioxane alcohols or diesel fuel. 4. The composition according to claim 3, characterized in that, as a compound based on a mixture of higher dioxane alcohols, it contains Burflub BT, or flotation reagent - oxal T-80, or a lubricating additive DSPB-BS. 5. The composition according to claim 1, characterized in that, as a compound based on chromium acetate, it contains chromium acetate or complexing agent BT-X. 6. The composition according to claim 1, characterized in that it further comprises additives having a complex effect: calcium chloride, or magnesium chloride, or sodium formate, or potassium formate, or a mixture of these formates. 7. The composition according to claim 1, characterized in that it further comprises a destructor - an oxygen-containing reagent in an amount of up to 5.0 wt.%. 8. The composition according to claim 7, characterized in that as the oxygen-containing reagent, the composition contains hydrogen peroxide or urea monoperoxyhydrate.