RU2344152C1 - Drilling agent - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: invention is related to the field of oil and gas industry, namely, to drilling agents for opening of producing reservoir bed. Drilling agent contains following components, wt %: biopolymer xanthan of brands "Saraksan-T" or "Saraksan" 0.2-0.7; α-glucan 0.2-0.8; salt or mixture of salts of univalent metals 1-55; defoaming agent of brand "Sofeksil-9056-20x" 0.01-0.2; bactericide of brand biocide B-2 0.006-0.008; bactericide of brand biocide SMB 0.1-0.5; water - the rest. As α-glucan, modified starch or dextran is used. As salts of univalent metals, chlorides or nitrates, or nitrites, or thiosulfates, or carbonates, or acetates, or bromides, or sodium or potassium formates, or their mixtures are used.

EFFECT: preparation of drilling agent with adjusted density without solid phase, which preserves its rheological properties for a long time.

4 cl, 4 tbl, 4 ex

Description

The invention relates to the field of the oil and gas industry, namely to drilling fluids for opening a productive reservoir.

The closest analogue to the claimed one is a drilling fluid containing a solid phase capable of creating a thixotropic structure with a low filtration rate. The drilling fluid includes a xanthan biopolymer, salts or a mixture of salts of monovalent or divalent metals (sodium chloride, potassium chloride, calcium chloride), α-glucan (starch modified by hydroxyl groups), solid phase (Palex bentonite, calcium carbonate, magnesia, barite) and water (see US patent No. 4422947, IPC C09K 007/02, publ. 12/27/83).

The known technical solution has the disadvantage that a solid phase is introduced into the drilling fluid to create the required density (Palex bentonite, calcium carbonate, magnesia, barite), and therefore it is not possible to control the density to create a drilling fluid without a solid phase.

When creating this technical solution, the technical problem of creating a drilling fluid with an adjustable density without a solid phase that retains its rheological properties for a long time was solved.

This technical problem is solved in that the drilling fluid consists of a xanthan biopolymer of the Saraksan or Saraksan-T grades, a salt or a mixture of monovalent metal salts, α-glucan (modified starch or dextran), Sofexil-9056-20x defoamer , bactericides of brands Biocide B-2 and Biocide-SMB and water, in the following ratio of components in the mixture, wt.%:

specified biopolymer 0.2-0.7 α-glucan 0.2-0.8 salt or mixture of monovalent salts of metals 1-55 specified antifoam 0.01-0.2 biocide B-2 0.006-0.008 SMB biocide 0.1-0.5 water rest

Chlorides or nitrates, or nitrites, or thiosulfates, or carbonates, or acetates, or bromides, or sodium or potassium formates, or mixtures thereof, can be used as monovalent metal salts.

As α-glucan, modified starch or dextran is used.

The solution has a density of from 1005 to 1700 kg / m ³ .

Xanthan biopolymer is a heteropolysaccharide synthesized by the bacteria Xanthomonas campestris. Xanthan biopolymer of the Saraksan or Saraksan-T grades (see RF patent No. 2252033, IPC 7 A61K 47/36, С12Р 19/06, published on 05/20/05) is allowed in oil production processes.

α-Glucan is a polysaccharide built only from D-glucose monosaccharide residues. Α-glucans include, for example, dextran or modified starch (see General Organic Chemistry. Volume 2. Edited by N.K. Kochetkov, Moscow: Chemistry, 1986, p.213). Hydroxyl-modified starch, built from D-glucopyranose residues, joined by α-1,4-glycosidic bonds, is a polysaccharide reagent for drilling fluids (see TU 6-55-221-147797). Dextran is a polysaccharide consisting of D-glucopyranose residues joined by α-1,6- and α-1,3-glycosidic bonds.

The silicone defoamer of the Sofexil 9056-20x brand is an aqueous emulsion of modified polydimethylsiloxane (TU 2251-009-4294526-00).

Biocide B-2 and biocide-SMB are bactericides. A bactericide is an organic substance of low molecular weight (an aqueous solution of formaldehyde, various derivatives of triazolinone, lower alcohols, amines, aromatic derivatives), which inhibits the activity of bacteria and allows you to save the rheological and filtration parameters of a drilling fluid based on biopolymer and α-glucan. In the present invention, two bactericides were used. B-2 biocide is a solution with the active substance 2,2-dibromo-3-nitrilo-propionamide in a solvent, inhibits mucus-forming and sulfide-reducing bacteria, yeasts, fungi and algae that cause viscosity changes, odors and corrosion (TU 9392-048- 42942526-2005). Biocide B-2 provides improved water quality in the preparation of biopolymer solution. Biocide-SMB is a liquid mixture of the active substances of chloromethyl-isothiazolinone and methyl-isothiazolinone, which has a wide spectrum of action against bacteria, fungi and yeast, chemically and thermally stable in the pH range from 2 to 9 and temperature exposure to 65 ° C ( TU 9392-049-42942526-2005). Biocide-SMB provides a longer life of polymer components with increasing temperature above 25 ° C (above this temperature, especially at 30-40 ° C, bacteria are active against polymer reagents, which is accompanied by the decomposition of biopolymer additives) and the time period of the solution in the well more than 2 weeks (up to two weeks, mineral salts dissolved in water act as a preservative agent). The concentration of the bactericide in the solution depends on the density of the solution and the temperature of the reservoir. The higher the density of the solution, the lower the concentration of the bactericide, with increasing temperature of the reservoir, the concentration of the bactericide increases. Typically, the concentration of the bactericide is in the range of 0.1-0.5 wt.%.

The pH of the drilling fluid, depending on the type and concentration of salts, ranges from 7 to 11.

Monovalent metal salts provide a drilling fluid density from 1005 to 1700 kg / m ³ , increase the thickening ability of xanthan biopolymer, minimize the external effect on the rheological properties of the drilling fluid, and at high levels in the solution (saline solutions) have preservative properties at temperatures up to 30 ° C ( above 30 ° C, a bactericide should be added), due to which the drilling fluid remains highly effective for a long time. Xanthan grades "Saraksan" or "Saraksan-T" provides high rheological properties due to its ability to dissolve with the formation of a minimum amount of microgels. α-Glucan provides low water loss and resistance to a high concentration of calcium ions with the compatibility of the drilling fluid with formation water of potassium chloride type. The amount of defoamer brand Sofexil-9056-20x (0.2 wt.%) Is sufficient to prevent the formation of foam of a solution with high density at an angular speed of up to 600 rpm, with a decrease in the density of the solution decreases the amount of defoamer brand Sofexil 9056-20x up to 0.01 wt.%

The amount of bactericide decreases with increasing density of the solution, since salts of monovalent metals are also a biocide with an increase in their concentration in the solution.

A feature of the present invention is to obtain a drilling fluid with a density of from 1005 kg / m ³ to 1700 kg / m ³ based on monovalent metal salts while maintaining the rheological and filtration parameters one month after preparation, even an increase in rheological parameters is observed, which makes it possible to reuse it. The invention is shown in the examples described below.

Preparation of biopolymer solution is carried out using standard equipment.

The drilling fluid preparation unit should include a mixing tank with hydraulic and mechanical stirrers for preparing a working drilling fluid.

The preparation of the solution according to the invention is illustrated by examples.

Example 1

Preparation of 1 m ^{3 of} drilling fluid ρ = 1100 kg / m ³ based on potassium carbonate K ₂ CO ₃ with a concentration of xaraxan biopolymer of the brand Saraksan or Saraksan-T 0.5 wt.% And modified starch 0.7 wt.% , defoamer brand Sofexil-9056-20x 0.022 wt.%, bactericide brand Biocide B-2 0.006 wt.%, bactericide brand Biocide-SMB 0.3 wt.%.

To prepare 1 m ^{3 of the} solution, 0.97 m ^{3 of} water is taken. It is advisable to treat industrial water with a fast-acting bactericide of the Biocide B-2 brand in an amount of 58.2 g. When stirring, 117.7 kg of potassium carbonate K ₂ CO ₃ is added, the mixing temperature is not more than 20 ° C (since the salt dissolution reaction is exothermic, it precipitates heat). With vigorous stirring and a temperature of at least 20 ° C (if the temperature is lower, the polymers will not dissolve well and insoluble lumps of polymers may form) 5.57 kg of Saraksan or Saraksan-T biopolymer (xanthan gum) is not slowly introduced less than 15 minutes. If less than 15 minutes, the formation of polymer lumps will occur, which in the future will not be able to completely dissolve in an aqueous solution of salts. Due to the possibility of foam formation after the introduction of the biopolymer, it is necessary to introduce 0.22 l of defoamer of the Sofexil-9056-20x brand.

After the introduction of the Sofexil-9056-20x defoamer, with intensive stirring, 7.79 kg of α-glucan, which is used as modified starch, is slowly introduced for at least 15 minutes and the resulting solution is stirred until the reagents are completely dissolved and the desired rheological properties are obtained system. To preserve fluid for a period of more than 2-3 weeks, 3 kg of Biocide-SMB bactericide are administered.

Example 2

Preparation of 1 m ^{3 of} drilling fluid ρ = 1100 kg / m ³ based on potassium chloride KCl with a concentration of xanthan biopolymer of the Saraksan or Saraksan-T brand 0.55 wt.%, Dextran 0.25 wt.%, Antifoam brand Sofexil-9056-20x "0.022 wt.%, Bactericide of the brand Biocide B-2 0.006 wt.%, Bactericide of the brand Biocide-SMB 0.3 wt.%.

To prepare 1 m ^{3 of the} solution, 0.927 m ^{3 of} water is taken. It is advisable to treat industrial water with a fast-acting bactericide of the brand Biocide B-2 in an amount of 55.62 g. 165.5 kg of potassium chloride KCl is added with stirring, the mixing temperature is at least 20 ° C (not all the salt can dissolve when the temperature is lowered). With vigorous stirring and a temperature of at least 20 ° C (if the temperature is lower, the polymers will not dissolve well and insoluble lumps of polymers may form), 6.06 kg of Saraksan or Saraksan-T biopolymer (xanthan gum) are not slowly introduced less than 15 minutes. If less than 15 minutes, the formation of polymer lumps will occur, which in the future will not be able to completely dissolve in an aqueous solution of salts. Due to the possibility of foam formation after the introduction of the biopolymer, it is necessary to introduce 0.22 l of defoamer of the Sofexil-9056-20x brand.

After the introduction of Sofexil-9056-20x antifoam, 2.75 kg of α-glucan, which is used as dextran, is slowly added with vigorous stirring for at least 15 minutes and the resulting solution is stirred until the reagents are completely dissolved and the desired rheological properties of the system are obtained . To preserve fluid for a period of more than 2-3 weeks, 3 kg of Biocide-SMB brand bactericide is administered depending on the temperature of the reservoir.

Example 3

Preparation of 1 m ^{3 of} drilling fluid ρ = 1390 kg / m ³ based on sodium nitrate NaNO ₃ with a concentration of xaraxan biopolymer of the Saraksan or Saraksan-T brand 0.35 wt.%, Modified starch 0.4 wt.%, Antifoam brand Sofeksil-9056-20x 0.1% wt., bactericide brand Biocide B-2 0.008 wt.%, bactericide brand Biocide-SMB 0.2 wt.%.

To prepare 1 m ^{3 of the} solution, 0.73 m ^{3 of} water is taken. It is advisable to treat industrial water with a quick action bactericide of the brand Biocide B-2 in the amount of 58.4 g. 651.14 kg of sodium nitrate NaNO ₃ is added with stirring, the stirring temperature is at least 20 ° C (not all the salt can dissolve with decreasing temperature). With vigorous stirring and a temperature of at least 20 ° C (if the temperature is lower, the polymers will not dissolve well and insoluble lumps of polymers may form) 4.85 kg of Saraksan or Saraksan-T biopolymer (xanthan gum) are not slowly introduced less than 15 minutes. If less than 15 minutes, the formation of polymer lumps will occur, which in the future will not be able to completely dissolve in an aqueous solution of salts. Due to the possibility of foam formation after the introduction of the biopolymer, it is necessary to introduce 1 l of defoamer of the Sofexil-9056-20x brand.

After the introduction of the Sofexil-9056-20x antifoam, 5.55 kg of α-glucan, using modified starch, is slowly introduced with vigorous stirring for at least 15 minutes and the resulting solution is stirred until the reagents are completely dissolved. To preserve fluid for a period of more than 1 month, 2 kg of Biocide-SMB bactericide is administered, depending on the temperature of the reservoir.

Example 4

Preparation of 1 m ^{3 of} drilling fluid ρ = 1610 kg / m ³ based on a mixture of salts of potassium nitrate KNO ₃ and sodium nitrite NaNO ₂ with a concentration of xanthan biopolymer of the brand Saraksan or Saraksan-T 0.22 wt.%, Dextran 0, 2 wt.%, Defoamer brand Sofexil-9056-20x 0.2 wt.%, Bactericide brand Biocide B-2 0.006%, bactericide brand Biocide-SMB 0.1 wt.%.

To prepare 1 m ^{3 of the} solution, 0.421 m ^{3 of} water is taken. It is advisable to treat industrial water with a fast-acting bactericide of the brand Biocide B-2 in an amount of 24.9 g (0.006 wt.%). With stirring, 481 kg of potassium nitrate KNO ₃ and 708 kg of sodium nitrite NaNO _{2 are} added, the stirring temperature is at least 20 ° C (not all the salt can dissolve with decreasing temperature). With vigorous stirring and a temperature of at least 20 ° C (if the temperature is lower, the polymers will not dissolve well and insoluble lumps of polymers may form) 3.55 kg of Saraksan or Saraksan-T biopolymer (xanthan gum) is not slowly introduced less than 15 minutes. If less than 15 minutes, the formation of polymer lumps will occur, which in the future will not be able to completely dissolve in an aqueous solution of salts. Due to the possibility of foam formation after the introduction of the biopolymer, it is necessary to introduce 2 l of defoamer of the Sofexil-9056-20x brand.

After the introduction of the Sofexil-9056-20x defoamer, 1.71 kg of α-glucan, which is used as dextran, is slowly introduced with vigorous stirring for at least 15 minutes and the resulting solution is stirred until the reagents are completely dissolved. To preserve fluid for a period of more than 1 month, 1 kg of Biocide-SMB brand of bactericide is administered.

The invention is shown in the examples.

The properties of the proposed drilling fluid are presented in tables 1-4. Rheological and mechanical parameters and water loss were determined one day and 30 days after the preparation of the solution. Water loss was determined at a pressure of 0.1013 MPa. Viscosity characteristics were determined using a Fann viscometer. The effective viscosity was determined at 600 rpm. Due to the selected combination of polymers (xanthan and α-glucan), the solution has a high viscosity at low shear rates, and at high shear rates the viscosity of the solution approaches the viscosity of water. When the flow stops, a gel-like thixotropic structure is instantly formed, which is determined at a shear rate of 3 rpm on a Fann viscometer.

The invention is shown in the examples.

Example 1: composition: 0.5 wt.% Xanthan (used xanthan grades "Saraksan-T" or "Saraksan", the amount of the latter - in terms of dry product), as α-glucan used modified starch 0.7 wt.% , 0.006 wt.% Biocide B-2 bactericide, 0.3 wt.% Biocid-SMB bactericide, 0.022 wt.% Defoaming agent Sofexil-9056-20x, potassium carbonate K ₂ CO ₃ 117.7 kg, providing density 1100 kg / m ³ .

Indicators of rheological and mechanical properties and fluid loss of the drilling fluid according to example 1 are presented in table 1.

Table 1 Day η _pl , MPa · s η _eff , MPa · s τ ₀ , dPa SNA _10s , dPa SNA _10min, dPa Water loss, cm ³ one 13 27.5 141.52 78.08 85,4 2,8 thirty fourteen 29.2 148.54 80.52 87.84 2.6

where η _PL - plastic viscosity,

η _eff - effective viscosity, calculated at 600 rpm,

τ ₀ - dynamic shear stress,

СНС _10с - static shear stress after 10 s,

SNS _10min - static shear stress after 10 min.

Example 2: composition: 0.55 wt.% Xanthan (used xanthan grades "Saraksan-T" or "Saraksan", the amount of the latter - in terms of dry product), as α-glucan used dextran 0.25 wt.%, 0.006 wt.% Biocide B-2 bactericide, 0.3 wt.% Biocid-SMB bactericide, 0.022 wt.% Defoaming agent Sofexil-9056-20x, potassium chloride KCl 165.5 kg, providing a density of 1100 kg / m ³ .

Indicators of rheological and mechanical properties and fluid loss of the drilling fluid according to example 2 are presented in table 2.

table 2 Day η _pl , MPa · s η _eff , MPa · s τ ₀ , dPa CHC _10s , dpa SNA _10min, dPa Water loss, cm ³ one fifteen 29th 136.64 61 87.84 2,3 thirty 16 30.5 141.2 63,44 90.28 2

Example 3: composition: 0.35 wt.% Xanthan (used xanthan grades "Saraksan-T" or "Saraksan", the amount of the latter - in terms of dry product), as α-glucan used modified starch 0.4 wt.% , 0.008 wt.% Biocide B-2 bactericide, 0.2 wt.% Biocide-SMB bactericide, 0.1 wt.% Defoaming agent Sofexil-9056-20x, sodium nitrate NaNO ₃ 651.14 kg, providing density 1390 kg / m ³ .

Indicators of rheological and mechanical properties and fluid loss of the drilling fluid according to example 3 are presented in table 3.

Table 3 Day η _pl , MPa · s η _eff , MPa · s τ ₀ , dPa CHC _10s , dPa SNA _10min, dPa Water loss, cm ³ one 28 45 165.92 72 91.2 2.5 thirty 29th 47.5 169.84 75.64 95.16 2,3

Example 4: composition: 0.22 wt.% Xanthan (used xanthan grades "Saraksan-T" or "Saraksan", the amount of the latter - in terms of dry product), as α-glucan used dextran 0.2 wt.%, 0.006 wt.% Biocide B-2 bactericide, 0.1 wt.% Biocid-SMB bactericide, 0.2 wt.% Defoaming agent Sofexil-9056-20x, potassium nitrate KNO ₃ 481 kg and sodium nitrite NaNO ₂ 708 kg, providing a density of 1610 kg / m ³ .

Indicators of rheological and mechanical properties and fluid loss of the drilling fluid according to example 4 are presented in table 4.

Table 4 Day η _pl , MPa · s η _eff , MPa · s τ ₀ , dPa SNA _10s , dPa SNA _10min, dPa Water loss, cm ³ one 42 58 170.8 65.88 80.52 3 thirty 43.5 59 172.7 68.32 82.96 2.9

Claims (4)

1. A drilling fluid comprising a xanthan biopolymer, α-glucan, a salt or a mixture of monovalent metal salts and water, characterized in that it contains a Saraxan-T or Saraksan brand xanthan biopolymer, Sofexil-9056-20x defoamer , a bactericide of the brand Biocide SMB in the following ratio of components, wt.%:
Specified Biopolymer 0.2-0.7 α-glucan 0.2-0.8 Salt or mixture of salts of monovalent metals 1-55 Specified Antifoam 0.01-0.2 Biocide B2 0.006-0.008 Biocide SMB 0.1-0.5 Water Rest 2. The drilling fluid according to claim 1, characterized in that the modified starch is used as α-glucan. 3. The drilling fluid according to claim 1, characterized in that dextran is used as α-glucan. 4. The drilling fluid according to claim 1, characterized in that the salts of monovalent metals use chlorides, or nitrates, or nitrites, or thiosulfates, or carbonates, or acetates, or bromides, or sodium or potassium formates, or mixtures thereof.