RU2246609C2 - Well killing polysaccharide gel composition and method for producing the same - Google Patents

Abstract

FIELD: oil and gas producing industry, in particular composition for killing of well.

SUBSTANCE: claimed polysaccharide gel contains sweet or mineralized water, polysaccharide gelling agent, boron cross-linking agent, diethanolamine, quaternary ammonium compounds, and mixture of non-ionic and anionic surfactant (complex surfactant). Mixture of water soluble oxyethilated alkylphenols and their sulphoethoxylates in form of sodium salts or salts with triethanolamine is used as complex surfactant in amount of 0.1-0.5 kg on 1000 l of water being the gel base. Polysaccharide gel is obtained by dissolution and hydration of polysaccharide gelling agent in sweet or mineralized water (preferably monovalent ion solution) followed by treatment of obtained polysaccharide solution with aqueous solution including boron cross-linking agent, diethanolamine, quaternary ammonium compounds, and complex surfactant.

EFFECT: well killing composition of improved quality.

2 cl, 6 ex, 1 tbl

Description

The present invention relates to the oil and gas industry, in particular to compositions for killing and preserving wells and methods for their preparation and use, to compositions of drilling fluids, fluids for perforation and gravel packing, fluids for hydraulic fracturing, and can also be used to limit water inflows to oil and gas wells.

A known composition of a polysaccharide gel for hydraulic fracturing, containing fresh or saline water, a polysaccharide thickener, a boric crosslinker, diethanolamine and Quaternary ammonium compounds, which are used catamine AB, which is a 50% aqueous solution of alkyl dimethylbenzylammonium chloride with _{16 to 16} alkyl radical or a hydrophobizing agent Neftenol GF, which is a 50% aqueous solution of quaternary ammonium salts - products of the quaternization of tertiary alkyl dimethyl amines with alkyl a radical of _12-18 C and benzyl chloride in an amount of 0.05-1.0 kg per 1000 liters of water - gel bases. For gel destruction after the hydraulic fracturing process, the composition contains an oxidizing component taken from the group consisting of ammonium persulfate, persulfates, percarbonates and alkali metal perborates [1]. A similar composition without a destructor can be used as a kill fluid.

The disadvantage of this composition is that it cannot be successfully used as a kill fluid, because Due to the high adsorption of cationic surfactants on the rock, the interfacial tension at the boundary with the hydrocarbons of the filtrate of the liquid entering the reservoir increases, which can reduce the flow of oil after killing the well.

The invention is directed to creating a polysaccharide-based jamming fluid composition, the filtrate of which has a low interfacial tension at the hydrocarbon boundary, which will make it possible to more easily master a well after carrying out repair work in it.

The result is achieved by the addition of a mixture of nonionic and anionic surfactants to the polysaccharide gel, the Complex Surfactant Neftenol VVD, which is a mixture of water-soluble hydroxyethylated alkyl phenols and their sulfoethoxylates in the form of sodium salts or salts with triethanolamine.

The features of the invention "the composition of the polysaccharide gel for killing wells and the method of its preparation" is:

1. Fresh or mineralized water.

2. Polysaccharide thickener.

3. Boric stapler.

4. Diethanolamine.

5. Quaternary ammonium compounds.

6. Additive.

7. As an additive, a mixture of nonionic and anionic surfactants is used - Complex Surfactant Neftenol VVD.

8. The additive per 1000 l of the composition is 0.1-0.5 kg.

9. The method of preparation of the gel.

Signs 1-5 are common with the prototype, and signs 6, 7, 8, 9 are essential distinguishing features of the invention.

SUMMARY OF THE INVENTION

A composition of a polysaccharide gel for killing wells is proposed, which contains fresh or mineralized water, a polysaccharide thickener, a boron crosslinker, diethanolamine, quaternary ammonium compounds, characterized in that it additionally contains a mixture of nonionic and anionic surfactants - Complex surfactant Neftenol VVD, which is an alkylene hydroethylen mixture and their sulfoethoxylates in the form of sodium salts or salts with triethanolamine, in an amount of 0.1-0.5 kg per 1000 l of water - the basis of the gel;

and a method for preparing a polysaccharide gel, comprising dissolving and hydrating a polysaccharide thickener in fresh or mineralized water, represented mainly by solutions of monovalent cations, followed by processing the resulting polysaccharide solution with an aqueous solution including a boron crosslinker, diethanolamine, quaternary ammonium compounds and an anionic nonionic mixture of anionic anionic Surfactant Neftenol VVD.

For research were used:

1. The water is fresh.

2. Mineralized water:

- a solution of potassium chloride with a density of 1,150 g / cm ³ ;

- formation water of the West Siberian, calcium chloride type, with a density of 1.012 g / cm ³ with a content of Ca ⁺⁺ and Mg ⁺⁺ cations of 1000 mg / l.

3. Polysaccharide:

- hydroxypropylguar brand Yaguar HP8FF.

4. Boric crosslinker - a solution of sodium tetraborate of ten-water, GOST 4199-76.

5. Diethanolamine (h), TU 6-09-2652-91.

6. Water repellent neftenol GF, TU 2484-035-17197708-97.

7. A mixture of nonionic and anionic surfactants:

- Complex surfactant Neftenol VVD, TU 2483-015-17197708-97, which is a mixture of water-soluble hydroxyethylated alkyl phenols and their sulfoethoxylates in the form of sodium salts or salts with triethanolamine.

Examples of the preparation of gels.

Example 1

From 1000 ml of the total amount of fresh water - the gel base - 40 ml was cast to prepare a solution of boron crosslinker, diethanolamine, hydrophobizing agent Neftenol GF and a mixture of nonionic and anionic surfactant - Complex surfactant Neftenol VVD. 4 g of hydroxypropyl guar was introduced into 960 ml of fresh water with stirring on a paddle mixer, after which the resulting solution was stirred for 30 minutes until the polysaccharide was completely hydrated, and then, without stopping mixing, an aqueous solution containing 40 ml of fresh water was introduced, 0.4 g boron crosslinker, 0.2 g of diethanolamine, 0.5 g of the hydrophobizing agent Neftenol GF and 0.1 g of a mixture of nonionic and anionic surfactant - Complex surfactant Neftenol VVD, after which the resulting gel was stirred for another 1-2 minutes until complete crosslinking.

Example 2

From 1000 ml of the total amount of potassium chloride solution - gel base - with a density of 1,150 g / cm ^3, 40 ml was poured to prepare a solution of boron crosslinker, diethanolamine, hydrophobizing agent Neftenol GF and a mixture of nonionic and anionic surfactants - Complex surfactants Neftenol VVD. 4 g of hydroxypropyl guar was introduced into 960 ml of a potassium chloride solution with stirring on a paddle stirrer, after which the resulting solution was stirred for 30 minutes until the polysaccharide was completely hydrated, and then, without stopping mixing, an aqueous solution containing 40 ml of potassium chloride solution with a density of 1.150 g was introduced / cm ³ , 0.4 g of boron crosslinker, 0.2 g of diethanolamine, 0.5 g of hydrophobizing agent Neftenol GF and 0.25 g of a mixture of nonionic and anionic surfactant - Complex surfactant Neftenol VVD, after which the resulting gel was stirred for 1- 2 min d full crosslinking.

Example 3

From 1000 ml of the total amount of produced water — the gel base — with a density of 1.012 g / cm ³ containing Ca ⁺⁺ and Mg ⁺⁺ ions, 1000 ml / l was poured to prepare a solution of boron crosslinker, diethanolamine, hydrophobizing agent Neftenol GF and a mixture of nonionic and anionic Surfactant - Integrated surfactant Neftenol VVD. 4 g of hydroxypropyl guar was introduced into 960 ml of produced water with stirring on a paddle mixer, after which the resulting solution was stirred for 30 minutes until the polysaccharide was completely hydrated, and then, without stopping mixing, an aqueous solution containing 40 ml of produced water was added, 0.4 g boron crosslinker, 0.2 g of diethanolamine, 0.5 g of the hydrophobizing agent Neftenol GF and 0.5 g of a mixture of a nonionic and anionic surfactant - Complex surfactant Neftenol VVD, after which the resulting gel was stirred for another 1-2 minutes until complete crosslinking.

Example 4 (prototype).

Of 1000 ml of the total amount of fresh water - the base of the gel - 40 ml was cast to prepare a solution of boron crosslinker, diethanolamine and water-repellent Neftenol GF. 4 g of hydroxypropyl guar was introduced into 960 ml of fresh water with stirring on a paddle mixer, after which the resulting solution was stirred for 30 minutes until the polysaccharide was completely hydrated, and then, without stopping mixing, an aqueous solution containing 40 ml of fresh water was introduced, 0.4 g boron crosslinker, 0.2 g of diethanolamine and 0.5 g of hydrophobizing agent Neftenol GF, after which the resulting gel was stirred for another 1-2 minutes until complete crosslinking.

Example 5 (prototype).

Of 1000 ml of the total amount of a solution of potassium chloride — gel base — with a density of 1.150 g / cm ^3, 40 ml was cast to prepare a solution of boron crosslinker, diethanolamine, and Neftenol GF water repellent. In a 960 ml solution of potassium chloride with a density of 1.150 g / cm ^3, 4 g of hydroxypropyl guar was introduced on a paddle with stirring, after which the resulting solution was stirred for 30 minutes until the polysaccharide was completely hydrated, and then, without stopping mixing, an aqueous solution containing 40 ml was introduced a solution of potassium chloride with a density of 1.150 g / cm ³ , 0.4 g of a boron crosslinker, 0.2 g of diethanolamine and 0.5 g of a hydrophobizing agent Neftenol GF, after which the resulting gel was stirred for another 1-2 minutes until complete crosslinking.

Example 6 (prototype).

From 1000 ml of the total amount of produced water — the base of the gel — with a density of 1.012 g / cm ³ containing Ca ⁺⁺ and Mg ^++, 1000 mg / l was poured into a solution of boron crosslinker, diethanolamine and hydrophobizing agent Neftenol GF. 4 g of hydroxypropyl guar was introduced into 960 ml of produced water with stirring on a paddle mixer, after which the resulting solution was stirred for 30 minutes until the polysaccharide was completely hydrated, and then, without stopping mixing, an aqueous solution containing 40 ml of produced water was added, 0.4 g boron crosslinker, 0.2 g of diethanolamine and 0.5 g of hydrophobizing agent Neftenol GF, after which the resulting gel was stirred for another 1-2 minutes until complete crosslinking.

The resulting compositions were investigated as follows:

the filter press of high pressure and temperature (FANN) studied the filtration of the obtained gels at a temperature of 80 ° C and a pressure of 0.7 MPa. In the obtained filtrate, the interfacial tension at the boundary with kerosene was determined using a stalagmometer. 3 wt.% Bentonite clay was added to the filtrate, and the resulting mixture was left for a day to adsorb surfactants, after which the clay was filtered through filter paper, and the obtained filtrate was again examined on a stalagmometer.

Table 1 presents the results of the studies.

Table 1 Composition number Liquid gel base The amount of Neftenol VVD, kg per 1000 l of gel base water The filtrate volume after 30 min, ml Interfacial tension of the filtrate before clay treatment, mN / m Interfacial tension of the filtrate after clay treatment, mN / m 1. Fresh water 0.1 30.3 3.9 4,5 2 potassium chloride solution with a density of 1,150 g / cm ³ 0.25 15.8 2,8 3,1 3. formation water with a density of 1.012 g / cm ³ 0.50 21.7 2,8 2.9 4. Fresh water - 31,0 4.8 8.3 5. potassium chloride solution with a density of 1,150 g / cm ³ - 15.6 5.1 9.0 6. formation water with a density of 1.012 g / cm ³ - 22.0 4.9 8.5

From the table it follows that the addition to the composition of 0.1-0.5 kg per 1000 l of water of the gel base of a mixture of nonionic and anionic surfactants - Complex surfactant Neftenol VVD - significantly reduces the interfacial tension of the filtrate, while it also remains low after addition to the filtrate clay, while in compositions without a mixture of nonionic and anionic surfactants - Complex surfactants Neftenol VVD - with the addition of clay, the interfacial tension increases significantly.

The following oilfield equipment is used to prepare a polysaccharide gel for killing wells in the field:

- cementing unit ЦА-320 (1 pc.) *;

- PPU;

- a tanker truck for 6-8 m ³ (1 pc.) *;

- an ejector for introducing reagents;

- additional capacity.

*) The cementing unit and tanker can be replaced by an acid tank (SIN-32 unit).

Fresh water, or a solution of potassium chloride or sodium, or produced water of the required density is loaded into the tanker. Part of the prepared fresh water or solution is taken into an additional container of a smaller volume, at the rate of 40 l per 1000 l of solution - the basis of the gel.

Fresh or mineralized water in the tanker with the help of PUF is heated to 18-30 ° С, then, with stirring with the help of ЦА-320, the calculated amount of polysaccharide thickener is uniformly introduced through the ejector through the ejector, after which the resulting solution is mixed (2 -3 cycles of mixing).

Boron crosslinker, diethanolamine, quaternary ammonium compounds and a mixture of nonionic and anionic surfactants - Complex surfactants Neftenol VVD - in an amount of 0.1-0.5 kg per 1000 l of water - the gel base are successively dissolved in an additional container in pre-selected fresh or mineralized water.

The reagent solution prepared in an additional container using CA-320 and an ejector is uniformly mixed for 1 cycle with a solution of a polysaccharide thickener prepared in a tank truck, resulting in a hemmed polysaccharide aqueous gel of low viscosity.

It is possible to apply several options for jamming:

- with complete replacement of the well fluid with a polysaccharide kill fluid;

- with the replacement of well fluid with polysaccharide kill fluid 200-300 meters above the perforation interval, and above with formation or saline water.

With the complete replacement of the fluid with a polysaccharide killing fluid, the killing technology is similar to that using water systems and differs in that no absorption occurs in the reservoir. Therefore, the flow rate of the killing polysaccharide fluid does not exceed the wellbore volume.

With the combined replacement of the well fluid, the flow rate of the polysaccharide kill fluid is 3-4 times less than with a complete replacement. The volume of the killing polysaccharide liquid is determined by calculation, taking into account the volume of the sump and leaving a glass covering the perforation interval by 100-200 m.

A necessary condition of this technology is the density of the polysaccharide kill fluid should exceed the density of the basic kill fluid (saline) by 20-50 kg / m ³ .

A new set of claimed essential features allows to obtain a new technical result, namely to create an effective composition of the fluid for killing wells and a technological method for its preparation.

Sourse of information

1. RF patent No. 2173772, E 21 In 43/26 - prototype.

Claims (2)

1. The composition of the polysaccharide gel for killing wells containing fresh or mineralized water, a polysaccharide thickener, a boric crosslinker, diethanolamine, quaternary ammonium compounds, characterized in that it additionally contains a mixture of nonionic and anionic surfactants - a complex surfactant Neftenol VVD, which is a mixture of water-soluble alkyl phenols and their sulfoethoxylates in the form of sodium salts or salts with triethanolamine, in an amount of 0.1-0.5 kg per 1000 l of water - the basis of the gel. 2. The method of preparing the polysaccharide gel composition according to claim 1, comprising dissolving and hydrating the polysaccharide thickener in fresh or saline water, which is predominantly solutions of monovalent cations, followed by processing the resulting polysaccharide solution with an aqueous solution including a boron crosslinker, diethanolamine, quaternary ammonium compounds and a mixture nonionic and anionic surfactants - complex surfactants Neftenol VVD.