RU2458959C1 - Clayless drilling mud - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: clayless drilling mud that includes fluorine-containing acrylamide copolymer and acrylic acid and water contains copolymer of general expression:

molecular weight 1.2·10⁶ with fluorine content up to 2%, with the following components ratio, wt %: said copolymer 0.1-0.15, water the rest.

EFFECT: stability of operating parameters up to 120 days at low temperatures.

1 tbl, 1 ex

Description

The invention relates to the field of drilling oil and gas wells, namely, non-clay drilling fluids used in drilling, mainly when drilling drilling productive formations in winter at temperatures up to minus 22 ° C.

Known clay-free drilling fluid (RF Patent No. 1556099, C09K 7/02, publ. 1995), comprising an acrylic polymer, a salt of a trivalent metal and water, characterized in that, in order to increase the ability to restore technological properties after removal of cuttings while increasing speed flocculation, it additionally contains cellulose ether in the following ratio of ingredients, wt.%:

Acrylic polymer 0.001-0.035 Trivalent metal salt 0.003-0.030 Cellulose ether 0,100-0,300 Water Rest

The disadvantages of the known clay-free drilling fluid include its increased hydrodynamic pressure during circulation, which reduces the efficiency of the flushing process and adversely affects the permeability of the bottom-hole formation zone.

A well-known drilling fluid (RF Patent No. 2243984, C09K 7/02, publ. BI No. 1, 2005) containing hydroxyethyl cellulose (OEC) or carboxylmethyl cellulose (CMC), oil product as a builder, a powdery finely divided filler with associated gas (air , nitrogen) in the following ratio of ingredients:

Hydroxyethyl cellulose (OEC) or carboxyl methyl cellulose (CMC) 0.2 ÷ 0.3 Oil product (commercial oil, diesel fuel, oil) 5 ÷ 30 Surfactant (sulfanol, OP-10) 0.02 ÷ 0.05 Fine filler (modified concrete, lignosulfonates) 0.9 ÷ 1 Air-gas mixture - air, nitrogen (volumetric) 2 ÷ 20 Water Rest

The disadvantages of the known drilling fluid include its high cost, toxicity, fire hazard, the possibility of environmental pollution by drilling waste, the problems of their safe disposal.

Known drilling fluid (RF Patent No. 2362793, C09K 8/08, publ. BI No. 21, 2009) containing polyacrylamide, soda ash and water, while it additionally contains carboxylmethyl cellulose (CMC) and the biopolymer "Saraksan" or "Saraksan-T "In the following ratio of ingredients, wt.%:

Polyacrylamide (PAA) 0.15-0.3 Carboxyl methyl cellulose 0.3-0.5 Soda ash Na ₂ CO ₃ 0.3-0.5 Biopolymer "Saraksan" or "Saraksan-T" 0.1-0.2 Water Rest

The disadvantages of this non-clay drilling mud are the high content of PAA, the inclusion of expensive chemicals in the formulation and the inability to use it at low ambient temperatures (minus 22 ° C).

Known clay-free drilling fluid (US Patent No. 4780517, C08F 20/58, publ. 1988) containing from about 50 to 98 mol.% Acrylamide, from about 1.9 to 49.9 mol.% Alkali metal salt or ammonium salt acrylic acid and from about 0.1 to 5 mol.% copolymerizable ionic surfactants.

The disadvantages of this clayless mud include the increased polymer content, the need for the introduction of ionic surfactants.

A well-known drilling fluid (RF Patent No. 2301244, C09K 8/12, publ. BI No. 17, 2007), which is obtained by mixing fresh water, saline or sea water and from about 0.3 pounds to about 2.5 pounds per active polymer compounds of one or more anionic dispersed polymers. Anionic dispersed polymers consist of from about 2 to about 98 mol% of one or more anionic monomers and from about 98 to about 2 mol% of one or more nonionic monomers.

The disadvantages of this clay-free drilling fluid include the increased polymer content, as well as the need for the introduction of saline or sea water.

A well-known drilling fluid (Patent CN No. 1528797, C08F 220/56, publ. 2004), which is highly effective for hydrophobic association, where the average molecular weight of 15,000,000-25,000,000, has a low freezing point and resistance to salt deposits, is capable of apply in areas such as tertiary oil production.

The disadvantages of this drilling fluid include an increased polymer content of 15 to 35%, as well as the failure to provide a long operating time at low temperatures to minus 22 ° C.

The problem to which the invention is directed, is to develop a composition of clay-free drilling fluid, which is characterized by a reduced polymer consumption, a reduced cost of drilling fluid, provides long-term stability of the operating parameters under normal and difficult drilling conditions when exposed to low temperatures (temperature to minus 22 ° C) .

The technical result is to obtain a clay-free drilling fluid with stable operating parameters up to 120 days when exposed to low temperatures of minus 22 ° C.

The technical result is achieved by a clay-free drilling fluid containing a fluorine-containing copolymer of acrylamide and acrylic acid and water, characterized in that a copolymer of the general formula is used

a molecular weight of 1.2 · 10 ⁶ with a fluorine content of up to 2%, in the following ratio of ingredients, wt.%:

The specified copolymer 0.1 Water Rest

The data given in the table show that a higher content of ingredients is not economically feasible, since with an increase in the content of the copolymer the viscosity of the solution increases, and the freezing temperature does not change.

Analysis results The concentration of fluorine-containing copolymer in solution, wt.% Water, wt.% Expiration time, sec Freezing temperature, ° С 0.6 99,4 31 minus 22 0.3 99.7 eighteen minus 22 0.15 99.85 12 minus 22 0.1 99.9 8 minus 22

Example. To obtain a fluorine-containing copolymer, a copolymer of acrylamide and acrylic acid and octofluoropentane chlorosulfite are used, the reagent ratio is 1: 5. 1 g of copolymer is introduced into the stirred reactor and 20 ml of benzene are added, then 5 g of octofluoropentanol is added. The temperature was raised to 120 ° C and the reaction was carried out for about 120 minutes. At the end of the reaction, benzene is distilled off from the product, the residue is filtered off and the residue is dried.

The structural formula of the obtained copolymer

The molecular weight of 1.2 · 10 ⁶ , x = 60%, y = 40%. The fluorine content of 2%, in the following ratio of ingredients, wt.%:

The specified copolymer 0.1 Water 99.9

Melting point 160 ° C. IR data: 2916 cm ^-1 , 2368 cm ^-1 , 1660 cm ^-1 , 1417 cm ^-1 , 1250 cm ^-1 , 1094 cm ^-1 .

To prepare the drilling fluid, water and a fluorine-containing copolymer are used. In order to obtain a uniform gel-like mass, the preparation time of the solution is 24 hours with constant stirring.

Ready for use when drilling a well, the drilling fluid has the following rheological characteristics:

Density (ρ) 1010 kg / m ³ Conditional viscosity (V) 8 sec Freezing temperature minus 22 ° C Hydrogen indicator pH 7

Tests of the inventive drilling fluid show that it is universal and does not contain expensive reagents, such as CMC. The solution retains its stability up to 120 days, the conditional viscosity does not change at the same time and is 8 seconds at normal and at low temperatures (minus 22 ° C).

The inventive drilling fluid has a set of useful qualities:

- has a high endurance;

- maintains its stability for a long time, up to 120 days;

- improves the quality of fastening wells by eliminating the formation of clay crust on the walls of the well;

- prevents pollution of the reservoir;

- can be operated at low temperatures.

The proposed drilling fluid meets all the requirements for clay-free drilling fluids, therefore, completely eliminates the consumption of clay powder.

The widespread use of drilling fluid will provide tangible economic benefits.

Claims (1)

A clay-free drilling fluid containing a fluorine-containing copolymer of acrylamide and acrylic acid and water, characterized in that a copolymer of the general formula is used:

a molecular weight of 1.2 · 10 ⁶ with a fluorine content of up to 2% in the following ratio of ingredients, wt.%:
The specified copolymer 0.1-0.15 Water Rest