RU2297436C2 - Composition of well-killing emulsion polysaccharide fluid and a method for preparation thereof - Google Patents

Abstract

FIELD: special-destination fluids in oil and gas production industry.

SUBSTANCE: invention, in particular, relates to compositions of drilling fluids, perforation and rock-filling fluids, which may also be used to restrict water inflow in oil and gas wells. Composition of well-killing emulsion polysaccharide fluid comprising fresh or mineralized water, polysaccharide thickener, and hydrocarbon phase is characterized by that said hydrocarbon phase is selected from kerosene, diesel, and commercial petroleum, and by that composition further contains diethanolamine, boric cross-linking agent (SP-RD), and water-soluble surfactant: Neftenol VVD, Neftenol K or Neftenol ML. Composition suitably contains, wt %: water 15.00-35.00, diethanolamine 0.00-5.00, surfactant 0.50-6.00, polysaccharide thickener 0.05-0.30, cross-linking agent 0.05-0.30, and hydrocarbon phase - the rest. Preparation procedure comprises dissolving surfactant or, consecutively, diethanolamine and surfactant in fresh or demineralized water, adding hydrocarbon phase to form emulsion, dissolving and hydrating polysaccharide thickener in resulting emulsion, and adding cross-linking agent.

EFFECT: reduced density and filtrate loss allowing killing of wells with abnormally low formation pressure and high formation permeability so that well repair time can be shortened.

2 cl, 2 tbl, 6 ex

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, and can also be used to limit water inflows into oil and gas wells.

The known composition of a polysaccharide gel for killing wells and a method for its preparation [1] containing fresh or mineralized water, a polysaccharide thickener, a boric crosslinker, diethanolamine, Quaternary ammonium compounds and a mixture of nonionic and anionic surfactants surfactant - VVD Neftenol, which is a mixture of water hydroxyethylated alkyl phenols and their sulfoethoxylates in the form of sodium salts or salts with triethanolamine.

A known method of preparing a polysaccharide gel [1], is to dissolve and hydrate the 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 a mixture Anionic surfactant - Neftenol VVD.

The prior art composition of emulsion polysaccharide liquid for killing wells, containing fresh or saline water, a polysaccharide thickener, a hydrocarbon phase, and a method for its preparation [2] are known.

However, when conducting operations in wells, they often encounter complicated geological and field conditions, such as low reservoir pressure and high permeability of formations. Under such conditions, the filtration of the polysaccharide liquid is too high, which leads to its significant absorption and subsequent difficulties associated with putting the wells into operation.

The technical result of the invention is the creation of a killing fluid based on an emulsion composition with a reduced density and a reduced filtrate recovery, which allows killing in wells with anomalously low reservoir pressure and high permeability of the reservoir and to reduce the time for the well to go into operation after the repair period.

The result is achieved by creating a direct-type emulsion composition having a reduced density, the external aqueous phase of which is a cross-linked polysaccharide gel.

The composition of the emulsion polysaccharide liquid for killing wells, containing fresh or mineralized water, a polysaccharide thickener, a hydrocarbon phase, contains kerosene or diesel fuel, or commercial oil and, additionally, diethanolamine, a boron crosslinker - a cross-linking agent SP-RD, a water-soluble surface-water, as the hydrocarbon phase active substance surfactant - Neftenol VVD or Neftenol K, or Neftenol ML in the following ratio of components, wt.%:

fresh or mineralized water 15.00-35.00 diethanolamine 0.00-5.00 specified surfactant 0.50-6.00 polysaccharide thickener 0.05-0.30 crosslinking agent SP-RD 0.05-0.30 specified hydrocarbon phase rest

A method of preparing the above emulsion polysaccharide liquid includes dissolving the specified surfactant or sequential diethanolamine and the specified surfactant in fresh or mineralized water, introducing the hydrocarbon phase into the resulting aqueous solution to obtain an emulsion, dissolving and hydrating the polysaccharide thickener in the emulsion obtained, adding a crosslinking agent SP-RD

Signs of the invention "the composition of the emulsion polysaccharide fluid for killing wells and the method of its preparation" are:

1. Fresh or mineralized water.

2. Diethanolamine.

3. Water soluble surfactants.

4. As a water-soluble surfactant - Neftenol VVD.

5. As a water-soluble surfactant - K. Neftenol

6. As a water-soluble surfactant - Neftenol ML.

7. Polysaccharide thickener.

8. Boric stapler.

9. As a boron crosslinker - a crosslinking agent SP-RD.

10. The hydrocarbon phase.

11. The hydrocarbon phase is kerosene.

12. As the hydrocarbon phase - diesel fuel.

13. The hydrocarbon phase is marketable oil.

14. A method of preparing an emulsion polysaccharide fluid for killing wells.

For research were used:

1. Fresh water

2. Mineralized water:

- formation water of the West Siberian, calcium chloride type, with a density of 1012 kg / m ³ with a content of Ca ⁺⁺ and Mg ⁺⁺ cations of 1000 mg / l.

- a solution of potassium chloride, density 1150 kg / m ³

3. Polysaccharide - hydroxypropylguar brand Yaguar HP8FF.

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

5. 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

6. Integrated surfactant Neftenol K, TU 2483-065-17197708-2002, which is a multicomponent mixture of anionic and cationic surfactants of different chemical structures.

7. Detergent surfactant Neftenol® ML, TU 2481-056-17197708-00, which is a multicomponent mixture of anionic and non-inogenous surface-active substances of different chemical structures.

8. Crosslinking agent SP-RD, TU 2499-073-17197708-2003, which is a solution of various types of surfactants and activated boron compounds in polyhydric amino alcohols.

9. Kerosene, TU 38.401-58-10-90.

10. Diesel fuel, GOST 305-82.

11. Commodity oil of the Salym field with the following physico-chemical characteristics:

density at 20 ° C, kg / m ³ 826 content, wt.%: paraffins 4.2 sulfur 0.4 asphaltenes 0.4 silica gel resins 2.0 water traces viscosity, cP: at 20 ° C 5.5 at 50 ° C 2.7 temperature, ° С: solidification below -16 start boiling fifty fractional composition,%: up to 150 ° C twenty up to 200 ° C thirty up to 300 ° C 49

Examples of the preparation of emulsion formulations.

Example 1

5.0 g of a complex surfactant, VVP neftenol, was introduced into 150 g of fresh water with stirring on a paddle mixer. The surfactant was allowed to dissolve in water, 844 g of kerosene was slowly poured into the resulting solution for 3-5 minutes, after which the emulsion was further mixed for 10 minutes at a speed of rotation of the paddle mixer of 500-600 rpm. Then, 0.5 g of hydroxypropyl guar was introduced into the resulting emulsion without stopping stirring, after which the resulting emulsion composition was stirred for 30 minutes until the polysaccharide was completely hydrated, after which the stirring was not stopped, 0.5 g of the crosslinking agent SP-RD was introduced and the obtained emulsion composition for another 1-2 minutes until complete crosslinking.

Example 2

In 200 g of produced water with a density of 1012 kg / m ³ with a Ca ⁺⁺ and Mg ⁺⁺ ion content of 1000 mg / l with stirring on a paddle mixer, 12.5 g of diethanolamine was added, followed by the addition of 18.8 g of a water-soluble surfactant - neftenol K. After dissolving the introduced reagents in water, 766.5 g of diesel fuel was slowly poured into the resulting solution for 3-5 min, after which the emulsion was additionally mixed for 10 min at a rotational speed of the paddle mixer of 500-600 rpm. Then, 1.0 g of hydroxypropyl guar was introduced into the resulting emulsion without stopping stirring, after which the resulting emulsion composition was stirred for 30 minutes until the polysaccharide was completely hydrated, after which, without stopping stirring, 1.0 g of SP-RD crosslinking agent was added and mixed the resulting emulsion composition for another 1-2 minutes until complete crosslinking.

Example 3

In 250 g of a solution of potassium chloride with a density of 1150 kg / m ^3, 25 g of diethanolamine was added with stirring on a paddle stirrer, followed by the addition of 32.5 g of a washing surfactant, ML Neftenol. After dissolving the introduced reagents in water, 689 g of commercial oil was slowly poured into the resulting solution for 3-5 min, after which the emulsion was additionally mixed for 10 min at a rotational speed of the paddle mixer of 500-600 rpm. Then, 1.7 g of hydroxypropyl guar was introduced into the resulting emulsion without stopping stirring, after which the resulting emulsion composition was stirred for 30 minutes until the polysaccharide was completely hydrated, after which, without stopping stirring, 1.7 g of SP-RD crosslinking agent was added and mixed the resulting emulsion composition for another 1-2 minutes until complete crosslinking.

Example 4

37.5 g of diethanolamine was added to 300 g of fresh water with stirring on a paddle mixer, followed by the addition of 46.0 g of a water-soluble surfactant, VVD neftenol. After dissolving the introduced reagents in water, 611.5 g of kerosene was slowly poured into the resulting solution for 3-5 min, after which the emulsion was additionally mixed for 10 min at a rotational speed of the paddle mixer of 500-600 rpm. Then, 2.4 g of hydroxypropyl guar was introduced into the resulting emulsion without stopping stirring, after which the resulting emulsion composition was stirred for 30 minutes until the polysaccharide was completely hydrated, after which the stirring was not stopped, 2.4 g of the crosslinking agent SP-RD were introduced and the obtained emulsion composition for another 1-2 minutes until complete crosslinking.

Example 5

In 350 g of a solution of potassium chloride with a density of 1150 kg / m ^3, 50 g of diethanolamine was introduced with stirring on a paddle mixer, followed by the addition of 60 g of a washing surfactant, ML Neftenol. After dissolving the introduced reagents in water, 534 g of commercial oil was slowly poured into the resulting solution for 3-5 minutes, after which the emulsion was additionally mixed for 10 minutes at a rotational speed of the paddle mixer of 500-600 rpm. Then, 3.0 g of hydroxypropyl guar was introduced into the resulting emulsion without stopping stirring, after which the resulting emulsion composition was stirred for 30 minutes until the polysaccharide was completely hydrated, after which, without stopping stirring, 3.0 g of SP-RD crosslinking agent was added and mixed the resulting emulsion composition for another 1-2 minutes until complete crosslinking.

Example 6 (known from [1])

4 g of hydroxypropyl guar was introduced into 1000 g 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 stirring, 0.5 g of hydrophobizing agent, 0.2 g of diethanolamine were successively introduced. 0.1 g of a complex surfactant of VVD neftenol and 0.4 g of ten-sodium sodium tetraborate in a glycerol solution, after which the resulting gel was stirred for another 1-2 minutes until complete crosslinking.

The composition of the obtained kill fluids described in examples 1-6 are presented in table 1.

Table 1
Component composition of kill fluids No. composition a aqueous phase, wt.% water soluble surfactant, wt.% hydrocarbon phase, wt.% fresh reservoir potassium chloride solution diethanols, wt.% Neftenol VVD Neftenol K Neft enol ML kerosene diesel fuel commercial oil polysaccharide, wt.% crosslinking agent SP-RD, wt.% one fifteen - - - 0.5 - - 84,4 - - 0.5 0.05 2 - twenty - 1/9 - - 76.65 - 0.1 0.1 3 - - 25 2,5 - - 3.26 - - 68.9 0.17 0.17 four thirty - 3.75 4.62 - - 61.15 - - 0.24 0.24 5 - - 35 5 - - 6 - - 53,4 0.3 0.3 6 composition according to [1]: fresh water 1000 ml; diethanolamine 0.2; Neftenol VVD 0.1; hydrophobizer neftenol GF 0.5 g; ten-sodium tetraborate in a solution of glycerol 0.4 g; hydroxypropyl guar 4 g.

As a polysaccharide thickener can be used: guar gum, hydroxypropylguar, carboxymethylhydroxypropylguar.

The resulting compositions were investigated as follows:

1. The density of the compositions was determined pycnometrically at 20 ° C.

2. The viscosity of the compositions was determined on a Farm 35 SA viscometer at 100 rpm (170 sec ^-1 ) and a temperature of 20 ° C.

3. The filtrate recovery of the obtained compositions was studied on a high-pressure and temperature filter press (FANN) at a temperature of 80 ° C and a pressure of 0.7 MPa.

4. Thermostability was evaluated visually by stratification of the obtained compositions at a temperature of 80 ° C for 10 days.

Physico-chemical properties of the obtained emulsion polysaccharide kill fluids in comparison with the prototype are presented in table 2.

table 2
Physico-chemical properties of the obtained emulsion polysaccharide kill fluids in comparison with the prototype Composition number density at 20 ° C, kg / m ³ dynamic viscosity at 100 rpm, cP filtrate volume after 30 min, ml Thermostability at 80 ° C one 805 260 7 no stratification 2 873 180 7 - "- 3 908 145 7 - "- four 858 120 10 - "- 5 958 90 16 - "- 6 1000 40 32 - "-

From the table it follows that the claimed compositions have a lower density due to the introduction of the hydrocarbon phase; higher viscosity due to the smaller amount of the aqueous phase in the composition of the emulsion; lower filtrate recovery, which allows the use of these compositions in various technologies of killing, as well as used in wells with abnormally low reservoir pressure and high permeability of the reservoir. The presence of diethanolamine in the compositions will absorb the released hydrogen sulfide.

When the concentration of the aqueous phase is less than 15.0 wt.%, The viscosity of the emulsion composition increases, which complicates the process of its preparation, as well as the technology of killing wells. An increase in the concentration of the aqueous phase of more than 35.0 wt.% Leads to the formation of unstable emulsion systems - stratified into aqueous and hydrocarbon phases.

The selected concentration range of diethanolamine is determined by the absorption capacity of the composition with respect to hydrogen sulfide. Theoretically, 50 kg of diethanolamine contained in 1 m ^{3 of the} emulsion polysaccharide kill fluid allow 15 kg of hydrogen sulfide to be absorbed. At the same time, for the Astrakhan gas condensate field containing the maximum amount of hydrogen sulfide among Russian fields, up to 25% of hydrogen sulfide is contained in gas well production, and the absorption capacity of the silencing solution should be from 6 to 10 kg / m ³ , therefore, a high concentration of diethanolamine in the composition is not economically feasible. Moreover, since the density of diethanolamine is 1096.6 kg / m ³ , its increase in composition leads to an increase in density.

The lower concentration of water-soluble surfactant 0.5 wt.% Due to the possibility of obtaining a thermostable emulsion. An increase in the concentration of a water-soluble surfactant of more than 6.0 wt.% Is not economically feasible.

At concentrations of the cross-linking agent SP-RD and hydroxypropylguar below 0.05 wt.%, The volume of filtrate recovery increases. At concentrations of the cross-linking agent SP-RD and hydroxypropylguar more than 0.3 wt.%, The viscosity of the emulsion polysaccharide killing fluid is significantly increased, which complicates the process of its preparation, as well as the technology of killing wells.

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

- Cementing unit ЦА-320 (2 pcs.);

- PPU;

- Tank truck for 6-8 m ³ (2 pcs.);

- tee;

- Ejector for the introduction of reagents.

Fresh or mineralized water is poured into the first tanker, the solution is heated to 18-30 ° C using PUF, then, with stirring using the first CA-320 through an ejector, for one cycle of mixing, the calculated amount of water-soluble surfactant or diethanolamine and water-soluble surfactant is introduced . Then, the hydrocarbon phase: kerosene, or diesel fuel, or commercial oil is slowly introduced into the resulting solution with constant stirring using the first CA-320, the second CA-320, from the second tank truck using a tee: The resulting composition is mixed until a homogeneous emulsion. A polysaccharide thickener is uniformly introduced into the prepared emulsion through the unit chunk or ejector, after which the prepared composition is mixed for 30 minutes, after which the cross-linking agent SP-RD is uniformly introduced.

It is possible to apply several options for jamming:

- with complete replacement of the well fluid with an emulsion polysaccharide kill fluid;

- with the replacement of the well fluid with an emulsion polysaccharide killing fluid 100-200 meters higher than the perforation interval, and higher with a hydrocarbon fluid with a density of 20-50 kg / m ³ less than the density of the emulsion polysaccharide killing fluid.

When the fluid is completely replaced with an emulsion polysaccharide kill fluid, the kill technology is similar to that using water systems and differs in that no absorption occurs by the reservoir. Therefore, the flow rate of the emulsion polysaccharide kill fluid does not exceed the volume of the wellbore.

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

A necessary condition of this technology is the density of the emulsion polysaccharide kill fluid should exceed the density of the main kill fluid 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.

Information sources

1. RF patent №2246609, 02.20.2005.

2. RF patent No. 2196164, 01/10/2003 - the closest analogue.

Claims (2)

1. The composition of the emulsion polysaccharide liquid for killing wells, containing fresh or mineralized water, a polysaccharide thickener, a hydrocarbon phase, characterized in that it contains kerosene, or diesel fuel, or commercial oil and additionally diethanolamine, a boron crosslinker - a crosslinking agent SP-RD, a water-soluble surfactant surfactant - Neftenol VVD, or Neftenol K, or Neftenol ML in the following ratio of components, wt.%: Fresh or saline water 15.00-35.00 Diethanolamine 0.00-5.00 Indicated Pav 0.50-6.00 Polysaccharide thickener 0.05-0.30 Crosslinking agent sp-rd 0.05-0.30 The specified hydrocarbon phase Rest 2. The method for preparing the emulsion polysaccharide liquid according to claim 1, comprising dissolving the specified surfactant or diethanolamine and the specified surfactant in fresh or mineralized water, introducing the hydrocarbon phase into the resulting aqueous solution to obtain an emulsion, dissolving and hydrating the polysaccharide thickener in the emulsion obtained, adding a crosslinker agent SP-RD.