CN104694114A

CN104694114A - Supermolecule clean fracturing fluid and preparation method and application thereof

Info

Publication number: CN104694114A
Application number: CN201510089194.1A
Authority: CN
Inventors: 杨江; 崔伟香; 管保山; 邱晓惠; 卢拥军
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2015-02-27
Filing date: 2015-02-27
Publication date: 2015-06-10
Anticipated expiration: 2035-02-27
Also published as: CN104694114B

Abstract

The invention provides a supermolecule clean fracturing fluid and a preparation method and application thereof. The fracturing fluid comprises, by weight, 0.1% -5% of an amphoteric surfactant, 0.1% -0.8% of an anionic polymer containing a hydrophobic group, 0-2% of an anionic surfactant, 0-4% of a salt and the balance of water, wherein: the amphoteric surfactant is one or the combination of two of amide amphoteric surfactants with two hydrophilic groups and one hydrophobic group and amide amphoteric surfactants with three hydrophilic groups and one hydrophobic group; the supermolecule clean fracturing fluid can be applied to oil-gas field fracturing, and can obtain higher consistency and viscoelasticity at lower concentration, so that better rheological property and sand carrying effect are obtained.

Description

Supermolecule clean fracturing fluid and preparation method and application thereof

Technical Field

The invention relates to a supermolecule clean fracturing fluid and a preparation method and application thereof, belonging to the field of petroleum.

Background

The reserves of low permeable layers of oil and gas fields in China are rich, but the natural productivity is low or no natural productivity exists at all, the single-well yield is improved without fracturing yield increase transformation, and the economic development value is difficult to obtain. The application of the fracturing fluid technology to the exploitation of such oil reservoirs is of great significance, and the fracturing fluid has the main functions of bringing the viscoelastic fluid and the propping agent into a fractured stratum and increasing the permeability so as to increase the yield of oil gas.

The residue after the hydration of the fracturing fluid directly influences the fracturing effect. The common fracturing fluid is macromolecular guanidine gum polysaccharide or a modified product thereof, and the residue content of the fracturing fluid is still high. The residues of the fracturing fluid are derived from insoluble substances of natural polymers and incomplete gel breaking products after the natural polymers are crosslinked with metals, and the residues can cause difficult-to-recover damage to the permeability of a fracturing fracture support band and the permeability of a stratum, so that the fracturing yield-increasing effect is seriously influenced.

Supramolecular materials are aggregates of molecules formed based on non-covalent intermolecular interactions. The components or building blocks with specific structures and functions are assembled into new supramolecular compounds in a certain way using intermolecular interaction forces as tools according to the principle of supramolecular self-assembly. The viscoelastic surfactant is also a result of molecular association aggregation, is applied to fracturing fluid of an oil-gas field, changes an aggregation state after meeting oil, becomes spherical low-viscosity liquid, breaks gel automatically, and has little damage to a stratum because of being micromolecule without residue; the viscoelastic surfactant fracturing fluid is simple in site construction, does not need excessive equipment, crosslinking agents, gel breakers and other auxiliaries, and therefore has unique advantages.

Us patent 5551516 discloses a viscoelastic surfactant based fracturing fluid in which water soluble inorganic salts such as potassium chloride or ammonium chloride and organic salts like sodium salicylate or alcohols are also used as stabilizers with cationic surfactants. Us patent 5964295, 6435277, 6412561 discloses the type of composition and method of use of viscoelastic surfactant based fracturing fluids. U.S. patent 6703352 discloses a formulation of a single-chain amphoteric surfactant having a carbon chain length of 12-24 with inorganic and organic salts.

CN1285700C discloses a formulation of clean fracturing fluid, which is prepared by mixing unsaturated fatty acid salt with eighteen carbon atoms and saline water or mixing fatty acid with eighteen carbon atoms, inorganic base and saline water. CN1752173A discloses a clean fracturing fluid additive, which comprises long-carbon-chain alkyl quaternary ammonium salt, long-carbon-chain alkyl dimethyl amine oxide, salicylate, glycol ether, low-carbon alcohol and water. CN101775276A discloses a preparation method of a fracturing fluid that can be used under higher formation temperature conditions, which comprises a Gemini cationic surfactant, an amphoteric surfactant, an electrolyte salt, a counter-ion salt, a cosolvent, water, and the like. CN102181279A discloses a cationic quaternary ammonium salt type surfactant fracturing fluid with multiple hydrophilic groups.

Although viscoelastic surfactant fracturing fluids have the advantages of no residue, less damage to the formation, etc., their higher use concentrations, and corresponding higher costs, require further improvement.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide the supermolecule clean fracturing fluid which can obtain higher consistency and viscoelasticity at lower concentration and has better rheological property and sand carrying effect.

In order to achieve the purpose, the invention provides a supermolecular clean fracturing fluid which comprises, by weight, 0.1% -5% of an amphoteric surfactant, 0.1% -0.8% of an anionic polymer containing a hydrophobic group, 0-2% of an anionic surfactant, 0-4% of a salt and the balance of water, wherein:

the amphoteric surfactant is one or the combination of two of amide amphoteric surfactants with two hydrophilic groups and one hydrophobic group and amide amphoteric surfactants with three hydrophilic groups and one hydrophobic group.

In the fracturing fluid, the amphoteric surfactant preferably has a molecular structure represented by the following formula I

In the formula I, x is 2 or 3;

R₁is C24-54 and contains x-CO-groups;

R₂is a methylene group with carbon number of C2-5;

R₃is an alkyl group having a carbon number of C1-4, -CH₂CH₂COO-or-CH₂CH₂OH；

R₄Is an alkyl group having a carbon number of C1-4, -CH₂CH₂COO-or-CH₂CH₂OH；

R₅is-CH₂-or-CH₂CH₂-。

In the above supramolecular clean fracturing fluid, preferably, R is₁Has a structure as shown in any one of the following formulas II-IV:

in the supramolecular cleaning fracturing fluid, preferably, the amphoteric surfactant comprises one or a combination of two of DIBT and TDIBT; the DIBT is a dimeric amidopropyl betaine surfactant, and the molecular structure of the DIBT contains two hydrophilic groups and a hydrophobic group (the hydrophobic group is an acyl group with carbon number of 36 and containing two-CO-); the TDIBT is a dimeric and trimeric amidopropyl betaine mixed surfactant, wherein the TDIBT comprises 80% of DIBT and 20% of amidopropyl betaine in percentage by weight, and the amidopropyl betaine comprises three hydrophilic groups and one hydrophobic group (the hydrophobic group is an acyl group with the carbon number of 54 and contains three-CO-); namely:

DIBT is one or the combination of two of the structures shown in formula (a) and formula (b);

TDIBT is a mixture of 80% DIBT and 20% of a structure shown in a formula (c) in percentage by weight; wherein the structures shown in the formulas (a), (b) and (c) are as follows:

in the supramolecular cleaning fracturing fluid, preferably, the anionic polymer containing the hydrophobic group is partially hydrolyzed polyacrylamide, the polyacrylamide comprises a hydrophobic group and an anionic group, and the molecular weight of the polyacrylamide is 10-500 ten thousand; the hydrophobic group comprises a straight chain or branched chain hydrocarbon chain group with the carbon number of C12-22, and is connected with the main chain through an amido bond or an ester bond; the anionic group is carboxyl or sulfo; more preferably, the molecular weight of the polyacrylamide is 20-200 ten thousand, and the molecular weight of the hydrophobic group accounts for 0.5-2% (mole ratio) of the whole polyacrylamide molecular weight.

In the supramolecular clean fracturing fluid, preferably, the addition amount of the anionic surfactant is 0.01-2% in percentage by weight of the supramolecular fracturing fluid, the anionic surfactant comprises one or more of alkyl carboxylate, alkyl sulfate, alkyl fatty polyoxyethylene ether sulfate, alkyl sulfonate, alkylbenzene sulfonate and alkyl alcohol polyether sulfosuccinic acid monoester salt, and the number of carbon atoms of the alkyl group is C8-22; more preferably, the anionic surfactant comprises one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sodium alkyl sulfonate.

In the supramolecular clean fracturing fluid, preferably, the salt is added in an amount of 0.1-2% in percentage by weight of the supramolecular clean fracturing fluid, and comprises one or more of potassium chloride, ammonium chloride and quaternary ammonium salt, and the salt is added to prevent clay swelling.

In the supramolecular clean fracturing fluid, preferably, the fracturing fluid further comprises one or more of a combination of a nonionic surfactant, a cationic surfactant and an alcohol solvent; the addition amount of the non-ionic surfactant is 0.1-2%, the addition amount of the cationic surfactant is 0.01-0.5%, and the addition amount of the alcohol solvent is 0.1-1% by weight percentage of the supramolecular clean fracturing fluid; more preferably, the nonionic surfactant comprises one or a combination of several of alkyl fatty alcohol polyoxyethylene ether, alkyl glycoside and alkyl amide; the cationic surfactant comprises alkyl quaternary ammonium salt surfactant; the alcohol solvent comprises one or more of methanol, ethanol, isopropanol, ethylene glycol and propylene glycol. The nonionic surfactant and the cationic surfactant are added into the fracturing fluid, so that the dissolving speed of the fracturing fluid can be adjusted, and the shear resistance of the fracturing fluid is improved.

The invention also provides a method for preparing the supermolecule clean fracturing fluid, which comprises the following steps: mixing an amphoteric surfactant, an anionic surfactant and salt, adding the mixture into an anionic polymer aqueous solution containing a hydrophobic group, and uniformly stirring to obtain the supermolecule clean fracturing fluid.

In the above method, preferably, the method for preparing the amphoteric surfactant comprises the steps of: reacting the initial acid with organic amine at 160-180 ℃ for 3-8 hours to obtain a first reaction intermediate; distilling off water and residual organic amine in the first reaction intermediate to obtain a second reaction intermediate; reacting the second reaction intermediate with sodium chloroacetate aqueous solution at 70-80 ℃ for 4-6 hours to obtain an amphoteric surfactant; wherein the starting acid is dimeric octadecanoic acid and/or trimeric octadecanoic acid; the organic amine is N, N-dimethyl-1, 3-propane diamine.

Obtained by reacting polybasic acid as a starting material with organic amine₁For structurally corresponding intermediates, dimer or trimer acids can be prepared from U.S. Pat. Nos. 5001260 and 6187903Unsaturated fatty acid, and the structures shown in formulas II and III are possible isomers, or commercial compounds can be directly used. The molar ratio of the dimer acid to the amine is 1:2, the dimer acid and the amine react to generate diamide, and the molar ratio of the trimer acid to the amine is 1:3 to generate the triamide by the same principle. The polyamide is further reacted with a carboxyl-containing group to form a betaine-type active agent.

In the above method, preferably, the method further comprises the step of adding one or a combination of several of a nonionic surfactant, a cationic surfactant and an alcohol solvent thereto as required.

The invention also provides application of the supermolecule clean fracturing fluid in oil-gas field fracturing, and the application can be carried out by referring to application modes of other fracturing fluids in the prior art.

The supermolecule clean fracturing fluid provided by the invention has the following beneficial effects: compared with the traditional surfactant fracturing fluid, the fracturing fluid provided by the invention can obtain higher consistency and viscoelasticity at lower concentration, and obtain better rheological property and sand carrying effect.

Detailed Description

The technical solutions of the present invention will be described in detail below in order to clearly understand the technical features, objects, and advantages of the present invention, but the present invention is not limited to the practical scope of the present invention.

Example 1

The embodiment provides a preparation method of a supramolecular clean fracturing fluid, which comprises the following steps:

1) synthesis of dimeric octadecyl amide or dimeric, trimeric mixed octadecyl amide

Taking 100g of high-purity dimer acid (the content of C36 dimeric octadecanoic acid is more than 95 percent), or dimeric and trimeric mixed acid (the content of C36 dimeric octadecanoic acid is 80 percent, and the content of C54 trimeric octadecanoic acid is 20 percent), adding the 100g of dimeric and trimeric mixed acid into N, N-dimethyl-1, 3-propane diamine (38.3g, 0.38mol), uniformly mixing, heating to 160-180 ℃, preserving heat for 3-8 hours, distilling off water generated by the reaction, and finishing the reaction when the acid value is less than 6; and distilling to remove redundant N, N-dimethyl-1, 3-propane diamine to obtain high-purity dimeric octadecyl amide or dimeric and trimeric mixed octadecyl amide.

2) Synthesis of betaine type amphoteric surfactant

Adding sodium chloroacetate (15.7g, 0.135mol) into 137mL of water, mixing and heating to 80 ℃, then adding the high-purity dimeric octadecyl amide or dimeric and trimeric mixed octadecyl amide 50g, reacting for 4-6 hours at 70-80 ℃, and obtaining a product with the active matter content of 30% by mass concentration after the reaction is finished when the mass concentration of NaCl reaches 98% of theory; the final product structure may be homologues as shown in formula (a) to formula (c):

3) preparation of supramolecular clean fracturing fluid

The components and the code numbers are as follows:

HMPAM: the hydrophobic modified polyacrylamide is anionic partially hydrolyzed polyacrylamide containing hydrophobic groups, the carbon number of the hydrophobic groups is C16, and the hydrophobic groups are connected with the main chain through amide bonds; the molecular weight is 100 ten thousand;

DIBT: dimeric amidopropyl betaine surfactant (amide structure II, III): the molecular structure of the compound contains two hydrophilic groups and a hydrophobic group (the hydrophobic group is an acyl group with carbon number of 36 and containing two-CO-);

TDIBT: dimeric, trimeric amidopropyl betaine mixed surfactant (amide structure II, III, IV mixture): the amidopropyl betaine mixture contains 80% of DIBT and 20% of amidopropyl betaine with three hydrophilic groups and one hydrophobic group (the hydrophobic group is C54 acyl containing three-CO-);

SDS (sodium dodecyl sulfate): sodium lauryl sulfate;

ABS: sodium dodecylbenzenesulfonate.

The preparation process is as follows: after HMPAM is fully dissolved, one or a combination of more of DIBT, TDIBT, SDS and ABS is added according to the proportion shown in the table 1 under the stirring condition to form uniform liquid systems of different series.

Example 2

This example was performed on a Harke RS6000 rheometer at 100s^-1The viscosity of the liquids of different compositions was measured at 70 ℃ at shear rate and the results are shown in table 1 (concentration is the content of active substance).

Table 1 results of viscosity measurements

Serial number	Composition (in weight percent)	Viscosity, mPas
			1	0.25％HMPAM	5
2	0.2％DIBT	4
			3	0.25％HMPAM+0.2％DIBT	70
4	0.2％DIBT+0.03％SDS	20
			5	0.2％DIBT+0.03％SDS+0.25％HMPAM	90
6	0.15％HMPAM	3
			7	1％TDIBT+0.03％ABS	31
8	1％TDIBT+0.03％ABS+0.15％HMPAM	92

As can be seen from table 1: in different series of uniform liquids, the viscosity obtained by compounding the amphoteric surfactant containing two or three hydrophilic groups with the anionic polymer containing the hydrophobic groups is higher than the sum of the viscosities of the amphoteric surfactant and the anionic polymer when the amphoteric surfactant and the anionic polymer are used independently, and the viscosity can be further improved by compounding the amphoteric surfactant with the anionic surfactant.

Example 3

This example tests the dynamic viscoelasticity of the compounded sample containing HMPAM and surfactant of example 2 on a Haake Mars rheometer, with the results shown in table 2.

TABLE 2 viscoelastic Properties (40 ℃, 0.01rad/s)

Serial number	Composition in weight percent	G' (storage modulus), Pa	G "(loss modulus), Pa
				1	0.25％HMPAM+0.2％DIBT	0.42	0.31
2	0.2％DIBT+0.03％SDS+0.25％HMPAM	0.36	0.21
				3	1％TDIBT+0.03％ABS+0.15％HMPAM	5.20	1.41

As can be seen from table 2: at very low frequency (0.1rad/s), the G '(storage modulus) of the compounded sample (serial numbers 1-3) is greater than G' (loss modulus), which shows that the compounded sample has higher viscoelastic property and is beneficial to sand carrying performance.

Example 4

In this example, a static sand-carrying performance test experiment was further performed on the supramolecular clean fracturing fluid provided in example 1: 20% of ceramsite (20/40 mesh ceramsite) was put into a measuring cylinder containing 100mL of liquid, stirred and dispersed uniformly, and then the settling time was observed and compared with the conventional guanidine gum fracturing fluid, and the results are shown in Table 3.

Preparing a conventional guanidine gum fracturing fluid: the water content is 100%, 0.25% of hydroxypropyl guar gum (produced by Kun mountain Jinguken oilfield chemical technology development company), 0.12% of sodium carbonate and 4% of potassium chloride are added into a certain amount of water according to the weight percentage of the water, stirred for 5min, added with an organic boron crosslinking agent (20%) according to the crosslinking ratio of 100:0.6, and stirred for 1min to form the guar gum jelly.

TABLE 3 Sand Total settling time (60 ℃ C.)

Serial number	Composition (in weight percent)	Sand settling time (minutes)
			1	0.25％HMPAM+0.2％DIBT	32
2	0.2％DIBT+0.03％SDS+0.25％HMPAM	40
			3	1％TDIBT+0.03％ABS+0.15％HMPAM	55
4	0.25% guanidine jelly	21

As can be seen from table 3: compared with the traditional 0.25% guanidine jelly, the supermolecule clean fracturing fluid provided by the invention has long settling time and better static sand carrying effect.

Example 5

This example further performed a residue test experiment on the supramolecular clean fracturing fluid provided in example 1, with reference to "SY/T5107-1995 water-based fracturing fluid performance evaluation method 6.6 fracturing fluid residue content determination", and the results are shown in table 4.

TABLE 4 residue content

Serial number	Composition (in weight percent)	Residue content (mg/L)
			1	0.25％HMPAM+0.2％DIBT	28
2	0.2％DIBT+0.03％SDS+0.25％HMPAM	31
			3	1％TDIBT+0.03％ABS+0.15％HMPAM	52
4	0.25% guanidine jelly	280

As can be seen from table 4: the insoluble residue of the supermolecule clean fracturing fluid provided by the invention is far lower than that of the traditional 0.25% guanidine jelly glue, and belongs to clean fracturing fluid.

Claims

1. The supermolecular clean fracturing fluid comprises, by weight, 0.1% -5% of an amphoteric surfactant, 0.1% -0.8% of an anionic polymer containing a hydrophobic group, 0-2% of an anionic surfactant, 0-4% of a salt and the balance of water, wherein:

2. The supramolecular cleaning fracturing fluid of claim 1, wherein: the amphoteric surfactant has a molecular structure represented by the following formula I:

in the formula I, x is 2 or 3;

R₁is C24-54 and contains x-CO-groups;

R₂is a methylene group with carbon number of C2-5;

R₅is-CH₂-or-CH₂CH₂-。

3. The supramolecular cleaning fracturing fluid of claim 2, wherein: the R is₁Has a structure as shown in any one of the following formulas II-IV:

4. the supramolecular cleaning fracturing fluid of any one of claims 1-3, wherein: the amphoteric surfactant comprises one or a combination of two of DIBT and TDIBT;

the DIBT is a dimeric amidopropyl betaine surfactant; the surfactant contains two hydrophilic groups and one hydrophobic group; the hydrophobic group is an acyl group with the carbon number of 36 and containing two-CO-;

the TDIBT is a dimeric, trimeric amidopropyl betaine mixed surfactant, wherein the TDIBT comprises 80% of DIBT and 20% of amidopropyl betaine in percentage by weight; the amidopropyl betaine contains three hydrophilic groups and one hydrophobic group; the hydrophobic group is an acyl group having a carbon number of 54 and containing three-CO-.

5. The supramolecular cleaning fracturing fluid of claim 1, wherein: the anionic polymer containing hydrophobic groups is partially hydrolyzed polyacrylamide, the polyacrylamide comprises hydrophobic groups and anionic groups, and the molecular weight of the anionic polymer is 10-500 ten thousand; the hydrophobic group comprises a straight chain or branched chain hydrocarbon chain group with the carbon number of C12-22, and is connected with the main chain through an amido bond or an ester bond; the anionic group comprises a carboxyl group or a sulfo group.

6. The supramolecular cleaning fracturing fluid of claim 1, wherein: the adding amount of the anionic surfactant is 0.01-2% in percentage by weight of the supramolecular clean fracturing fluid, the anionic surfactant comprises one or a combination of alkyl carboxylate, alkyl sulfate, alkyl fatty polyoxyethylene ether sulfate, alkyl sulfonate, alkylbenzene sulfonate and alkyl polyether sulfosuccinic acid monoester salt, and the carbon number of the alkyl is C8-22;

preferably, the anionic surfactant comprises one or more of sodium dodecyl sulfate, sodium dodecyl benzene sulfonate and sodium alkyl sulfonate.

7. The supramolecular cleaning fracturing fluid of claim 1, wherein: the addition amount of the salt is 0.1-2% by weight of the supermolecule clean fracturing fluid, and the salt comprises one or a combination of potassium chloride, ammonium chloride and quaternary ammonium salt.

8. A method of preparing the supramolecular cleaning fracturing fluid of any one of claims 1-7, comprising the steps of:

mixing an amphoteric surfactant, an anionic surfactant and salt, adding the mixture into a hydrophobic group-containing anionic polymer aqueous solution, and uniformly stirring to obtain the supermolecule clean fracturing fluid.

9. The method of claim 8, wherein: the preparation method of the amphoteric surfactant comprises the following steps:

reacting the initial acid with organic amine at 160-180 ℃ for 3-8 hours to obtain a first reaction intermediate;

distilling off water and residual organic amine in the first reaction intermediate to obtain a second reaction intermediate;

reacting the second reaction intermediate with sodium chloroacetate aqueous solution at 70-80 ℃ for 4-6 hours to obtain an amphoteric surfactant; wherein,

the starting acid is dimeric octadecanoic acid and/or trimeric octadecanoic acid; the organic amine is N, N-dimethyl-1, 3-propane diamine.

10. Use of the supramolecular cleaning fracturing fluid of any one of claims 1-7 in fracturing of oil and gas fields.