CN102127416B - A kind of anionic surfactant type acidic fracturing fluid and preparation method thereof - Google Patents

Abstract

The invention relates to anionic surfactant type acid fracturing fluid and a preparation method thereof. The anionic surfactant type acid fracturing fluid is characterized by comprising the following components in part by mass: 22 to 32 parts of alkyl benzene sulfonic acid, 20 to 30 parts of sodium alkyl sulfate, 55 to 60 parts of cosolvent, 50 to 60 parts of cross-linking agent, 20 to 25 parts of water and 390 to 400 parts of acidic solvent, wherein the cosolvent is a mixture of short chain hydrocarbons which mainly include isooctane; the cross-linking agent is a linear chain alcohol having 12 to 16 carbon atoms; and the acidic solvent is 36 to 38-percent mixture of hydrochloric acid and water in a volume ratio of 1:9. The performance of the anionic surfactant type acid fracturing fluid is higher than the conventional high polymer fracturing fluid. According to test result, the PH value of the fracturing fluid system is about 1, the acidifying effect is high, the viscoelasticity is high, and the fluid carrying and gel breaking effects are high. The anionic surfactant type acid fracturing fluid can be used in fracturing exploitation of hypotonic oil fields, and has the characteristics of low cost, high backflow rate, no residue, cleanness, high efficiency and the like.

Description

A kind of anionic surfactant type acidic fracturing fluid and preparation method thereof

technical field

The invention relates to a method for preparing an anionic surfactant type acidic fracturing fluid used in fracturing and increasing production in the exploitation process of low-permeability oil and gas fields. the

Background technique

The oil recovery rate of low-permeability reservoirs in my country is low, and it is difficult to stabilize production. Fracturing technology, as the main method of increasing production and injection of oil and gas reservoirs, has developed rapidly. Fracturing fluid is an important part of fracturing technology. Water-based fracturing fluids are commonly used at home and abroad, including macromolecular fracturing fluids and viscoelastic surfactant (VES) fracturing fluids. the

With the advancement of hydraulic fracturing technology, in order to achieve deep penetration of proppant, foreign countries began to study macromolecular fracturing fluids in the late 1960s. This type of fracturing fluid has high viscosity and good sand-carrying effect, which better met the requirements of However, there are many disadvantages: for example, due to the large molecular weight of the main agent, the dispersion solubility in water is poor, and the utilization rate is low; after the fracturing is completed, a considerable part of insoluble matter and macromolecules that have not been completely broken remain in the formation In fractures, the permeability of the formation is reduced; the flowback rate of the polymer fracturing fluid is low, and the formation is seriously polluted. In the early 1990s, viscoelastic surfactants began to replace macromolecules as the main agent of fracturing fluids, which mainly consisted of VES and brine. Since VES is easily dissolved in brine, the system has little damage to the formation and can maintain good conductivity. the

In recent years, various viscoelastic surfactant fracturing fluid formulations have been emerging at home and abroad. The main ingredients are as follows: long-chain alkyl quaternary ammonium salt type cationic surfactant, betaine type amphoteric surfactant, nonionic Surfactants and anionic surfactants. Quaternary ammonium salt is widely used as the main thickening agent. This kind of fracturing fluid has good gelation and temperature resistance, mature synthesis technology and low price, so it has been widely used. the

With major oil and gas extraction companies attaching importance to environmental protection and increasing requirements for sustainable development of oil and gas fields, how to further reduce the damage of clean fracturing fluid to the formation has become an important research direction. With the deepening of application, researchers have found that cationic surfactants, especially long-chain quaternary ammonium salt surfactants, although they have excellent performance, also have some problems, such as easy to generate adsorption and retention in the formation, which seriously affects the recovery factor. It has certain biological toxicity and so on. Most anionic surfactants are difficult to form worm-like micelles in a strong acid environment, and the viscosity of the system is low, which cannot meet the requirements of fracturing. the

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the present invention proposes an anionic surfactant-type acidic fracturing fluid and a preparation method thereof. The fracturing fluid can increase flowback capacity while meeting conventional fracturing performance requirements, and avoid damage to ground damage. the

Thought of the present invention is: anionic surfactant alkylbenzenesulfonic acid is the amphiphilic molecule that is made up of lipophilic alkylbenzene and hydrophilic sulfonate, and alkyl sodium sulfate is composed of lipophilic long-chain alkyl and hydrophilic sulfuric acid. Amphiphilic molecules composed of roots, the lipophilic groups of the two substances are connected with short-chain alkanes, and the hydrophilic sulfonate and sulfate groups are connected with water to form micellar structures. The repulsion effect of the surfactant makes more surfactants enter the micelles, which promotes the growth of worm-like micelles, and the system appears viscoelastic. the

Technical solutions

An anionic surfactant type acidic fracturing fluid, characterized in that the components are 22-32 parts of alkylbenzenesulfonic acid, 20-30 parts of alkyl sodium sulfate, 55-60 parts of cosolvent, and 50-60 parts of crosslinking agent , 20-25 parts of water and 390-400 parts of an acidic solvent; the co-solvent is a short-chain hydrocarbon mixture based on isooctane; the cross-linking agent is a straight-chain alcohol with 12-16 carbon atoms; The acidic solvent is a mixture of 36%-38% hydrochloric acid and water, the volume ratio of hydrochloric acid and water is 1:9; the parts are parts by mass. the

The short-chain hydrocarbon mixture mainly composed of isooctane is 90# gasoline, 93# gasoline or 97# gasoline. the

The number of carbon atoms in the alkylbenzenesulfonic acid is 10-13. the

The number of carbon atoms of the alkyl sodium sulfate is 10-13. the

A method for preparing anionic surfactant type acidic fracturing fluid, characterized in that the steps are as follows:

Step 1: Mix the alkylbenzenesulfonic acid, sodium alkylsulfate and co-solvent weighed according to the mass ratio, and store them sealed at room temperature for 90-100 hours;

Step 2: Add 50-60 parts of cross-linking agent and 20-25 parts of water, mix well and set aside for 40-50 hours;

Step 3: adding 390-400 parts of an acidic solvent to obtain an anionic surfactant type acidic fracturing fluid. the

A method for using an anionic surfactant-type acidic fracturing fluid, characterized in that: the anionic surfactant-type acidic fracturing fluid is uniformly mixed with 140-150 parts by mass of an acidic solvent, and then 15%-30% by mass of ceramic granules and 1%-3% by weight of the wrapped gel breaker, stirred evenly and injected into the well; the steps of the wrapped gel breaker are: weigh 85% cyclohexanol, 3% Anhydrous calcium oxide or calcium chloride, put it in a container, stir until it is completely dissolved, then add 12% magnesium oxide, mix evenly, dry it in the air for 50-80 hours in the room until it is completely dry, crush and sieve to obtain the packaged broken Glue. the

The cyclohexanol in the packaged breaker is replaced by isobutanol or tert-butanol. the

Beneficial effect

An anionic surfactant type acidic fracturing fluid and its preparation method proposed by the present invention, the anionic surfactant type fracturing fluid is combined with acid fracturing technology, the system not only has a series of advantages of clean fracturing fluid, but also because of the anionic surface The active agent has the same charge as the silicate substances in most oil reservoirs, and the fracturing fluid has little adsorption to the formation and little damage. the

The fracturing fluid in the present invention has the following characteristics:

1. The operation is simple, the source of raw materials is abundant, and the cost is low. the

2. Good acid resistance, the viscosity remains above 100mpa.s in strong acid environment;

3. Good temperature and shear resistance, 70°C, 170S ^-1 shear rate for 90min, viscosity maintained at 100mpa.s;

4. Excellent sand-carrying performance, easy to break glue and flow back. the

5. The amount of raw materials required by the formula is small and the cost is low. the

Detailed ways

Now in conjunction with embodiment the present invention will be further described:

Example 1:

Preparation of anionic surfactant-type acidic fracturing fluid: weigh 2.4g of dodecylbenzenesulfonic acid, 2.1g of sodium dodecylsulfate, and 5.5g of 93# gasoline in a container according to mass ratio, mix well, and store in a sealed container at room temperature After 96 hours, 5 g of dodecanol and 2 g of water were added to the above sample; after 48 hours, 39.7 g of an acidic solvent was added to obtain a spare anionic surfactant-type acidic fracturing fluid. the

Packaged gel breaker: Measure and weigh 85% cyclohexanol, 3% anhydrous calcium oxide or calcium chloride, put them in a container, stir until they are completely dissolved, then add 12% magnesium oxide, mix well , aired indoors for 50-80 hours until completely dry, crushed and sieved to obtain a wrapped gel breaker; the cyclohexanol is replaced by isobutanol or tert-butanol. the

When using fracturing construction, take the spare fluid and add 14.2g of acidic solvent, then add 15%-30% by mass of ceramsite and 1%-3% by mass of wrapped gel breaker, stir well and inject well use. the

The laboratory performance test results of the above fracturing fluid are as follows:

Testing instrument: 2NN-D6S six-speed rotational viscometer, Qingdao Haitongda Special Instrument Factory. the

(1) Determination of the relationship between temperature and viscosity

Table 1 Determination of the relationship between temperature and viscosity

temperature Viscosity (unit mpa.s) 30℃ 245 40℃ 245 50℃ 230 60℃ 225 70℃ 220

( 2), determination of high temperature resistance

Table 2 Determination of temperature resistance under static conditions

Temperature (°C) 70(30min) 70(60min) 70(90min) Viscosity (mpa.s) 220 215 215

(3) Determination of shear resistance performance

Table 3 Determination of temperature resistance under shear conditions

Temperature (°C) 70 70 70 70 Tolerance time (min) 30 60 90 120 Shear rate (170S ^-1 ) 170 170 170 170 Viscosity (mpa.s) 240 230 220 220

The viscosity of the acidic fracturing fluid is kept above 200mpa.s during the heating process from normal temperature to 70°C. The acidic fracturing fluid was kept at 70°C for 90 minutes, and the viscosity remained above 200mpa.s. The acidic fracturing fluid was sheared at 70°C for 90 minutes, and the viscosity remained above 200mpa.s. The above properties meet the sand-carrying requirements of conventional fracturing fluids. the

Example 2:

Preparation of anionic surfactant-type acidic fracturing fluid: weigh 3.2g of dodecylbenzenesulfonic acid, 3.0g of sodium dodecyl sulfate, and 6.0g of 93# gasoline in a container according to mass ratio, mix well, and store in a sealed container at room temperature After 96 hours, 5 g of dodecanol and 2 g of water were added to the above sample; after 48 hours, 39 g of an acidic solvent was added to obtain a spare anionic surfactant type acidic fracturing fluid. the

Packaged gel breaker: Measure and weigh 85% cyclohexanol, 3% anhydrous calcium oxide or calcium chloride, put them in a container, stir until they are completely dissolved, then add 12% magnesium oxide, mix well , aired indoors for 50-80 hours until completely dry, crushed and sieved to obtain a wrapped gel breaker; the cyclohexanol is replaced by isobutanol or tert-butanol. the

When using fracturing construction, take the spare fluid and add 14.2g of acidic solvent, then add 15%-30% by mass of ceramsite and 1%-3% by mass of wrapped gel breaker, stir well and inject well use. the

The laboratory performance test results of the above fracturing fluid are as follows:

(1) Determination of the relationship between temperature and viscosity

Table 4 Determination of the relationship between temperature and viscosity

temperature Viscosity (unit mpa.s) 30℃ 255 40℃ 255 50℃ 240 60℃ 235 70℃ 230

(2) Determination of high temperature resistance

Table 5 Determination of temperature resistance under static conditions

Temperature (°C) 70(30min) 70(60min) 70(90min) Viscosity (mpa.s) 230 220 220

(3) Determination of shear resistance performance

Table 6 Determination of temperature resistance under shear conditions

Temperature (°C) 70 70 70 70 Tolerance time (min) 30 60 90 120 Shear rate (170S ^-1 ) 170 170 170 170 Viscosity (mpa.s) 250 240 230 230

The viscosity of the acidic fracturing fluid is kept above 200mpa.s during the heating process from normal temperature to 70°C. The acidic fracturing fluid was kept at 70°C for 90 minutes, and the viscosity remained above 200mpa.s. The acidic fracturing fluid was sheared at 70°C for 90 minutes, and the viscosity remained above 200mpa.s. The above properties meet the sand-carrying requirements of conventional fracturing fluids. Compared with example (1), due to the increase of the consumption of anionic surfactant and co-solvent, the viscosity of the system increases. the

Implementation 3:

Preparation of anionic surfactant-type acidic fracturing fluid: Weigh 3.0 g of dodecylbenzenesulfonic acid, 2.8 g of sodium lauryl sulfate, and 5.8 g of 93# gasoline in a container according to the mass ratio, mix them evenly, and seal them at room temperature for storage After 96 hours, 5 g of dodecanol and 2 g of water were added to the above sample; after 48 hours, 39 g of an acidic solvent was added to obtain a spare anionic surfactant-type acidic fracturing fluid. the

Packaged gel breaker: Measure and weigh 85% cyclohexanol, 3% anhydrous calcium oxide or calcium chloride, put them in a container, stir until they are completely dissolved, then add 12% magnesium oxide, mix well , aired indoors for 50-80 hours until completely dry, crushed and sieved to obtain a wrapped gel breaker; the cyclohexanol is replaced by isobutanol or tert-butanol. the

When using fracturing construction, take the spare fluid and add 14.2g of acidic solvent, then add 15%-30% by mass of ceramsite and 1%-3% by mass of wrapped gel breaker, stir well and inject well use. the

The laboratory performance test results of the above fracturing fluid are as follows:

(1) Determination of the relationship between temperature and viscosity

Table 7 Determination of the relationship between temperature and viscosity

temperature Viscosity (unit mpa.s) 30℃ 250 40℃ 250 50℃ 235 60℃ 225 70℃ 220

(2) Determination of high temperature resistance

Table 8 Determination of temperature resistance under static conditions

Temperature (°C) 70(30min) 70(60min) 70(90min) Viscosity (mpa.s) 220 220 215

(3) Determination of shear resistance performance

Table 9 Determination of temperature resistance under shear conditions

Temperature (°C) 70 70 70 70 Tolerance time (min) 30 60 90 120 Shear rate (170S ^-1 ) 170 170 170 170 Viscosity (mpa.s) 240 235 225 220

The viscosity of the acidic fracturing fluid is kept above 200mpa.s during the heating process from normal temperature to 70°C. The viscosity of the acidic fracturing fluid is kept above 200mpa.s under the condition of standing at 70°C for 90 minutes and shearing for 90 minutes. The above properties meet the sand-carrying requirements of conventional fracturing fluids. Compared with example (1) (2), because the consumption of anionic surfactant and co-solvent is in the middle, the viscosity of the system is between the two. the

Claims (7)

1. an anionic surfactant type acid fracturing fluid is characterized in that component is alkyl benzene sulphonate (ABS) 22-32 part, sodium alkyl sulfate 20-30 part, solubility promoter 55-60 part, linking agent 50-60 part, water 20-25 part and acid solvent 390-400 part; Described solubility promoter is as main short hydrocarbon mixture take octane-iso; Described linking agent is the straight chain alcohol of 12-16 carbon atom; Described acid solvent is the hydrochloric acid of 36%-38% and the mixture of water, and the volume ratio of hydrochloric acid and water is 1: 9; Described part is mass parts.

2. anionic surfactant type acid fracturing fluid according to claim 1 is characterized in that: described take octane-iso as main short hydrocarbon mixture as 90# gasoline, 93# gasoline or 97# gasoline.

3. anionic surfactant type acid fracturing fluid according to claim 1, it is characterized in that: the carbonatoms of described alkyl benzene sulphonate (ABS) is 10-13.

4. anionic surfactant type acid fracturing fluid according to claim 1, it is characterized in that: the carbonatoms of described sodium alkyl sulfate is 10-13.

5. method for preparing described any anionic surfactant type acid fracturing fluid of claim 1～4 is characterized in that step is as follows:

Step 1: the alkyl benzene sulphonate (ABS) that will take by weighing in mass ratio, sodium alkyl sulfate and solubility promoter mix, and preserve 90-100 hour in the normal temperature sealing;

Step 2: the water that adds 50-60 part linking agent and 20-25 part mixes rearmounted 40-50 hour;

Step 3: add again acid solvent 390-400 part and obtain anionic surfactant type acid fracturing fluid.

6. a right to use requires the method for 1～4 described any anionic surfactant type acid fracturing fluid, it is characterized in that: the acid solvent of anionic surfactant type acid fracturing fluid and 140-150 mass parts is mixed, add the gel breaker that the parcel of the haydite of 15%-30% mass parts and 1%-3% mass parts is processed, the rear notes well that stirs uses again; The step of the gel breaker that described parcel is processed is: metering takes by weighing 85% hexalin, 3% anhydrous calcium oxide or calcium chloride, place container, be stirred to its whole dissolvings, add again 12% magnesium oxide, be mixed, indoor airing 50-80 hour to complete drying, broken, sieving obtains wrapping up the gel breaker of processing.

7. the using method of anionic surfactant type acid fracturing fluid according to claim 6 is characterized in that: hexalin is replaced by isopropylcarbinol or the trimethyl carbinol in the gel breaker that described parcel is processed.