A new type of biological fracturing fluid system

Abstract

A novel bio-fracturing fluid system of the present invention relates to the field of oil production technology. The novel bio-fracturing fluid system contains 0.3-0.5 parts by weight of a thickener, 0.1-0.3 parts by weight of a cross-linking agent, 1.0-2.0 parts by weight of a fracturing aid, and 97.2-98.6 parts by weight of water; the thickener is an isolated strain of Cossackia oryzae ( Cossaconia oryzae )The compound system of CY-117 fermentation broth and modified guar gum, the compound weight ratio of the fermentation broth of rice Corsacella to the modified guar gum is 1:1-9. The present invention uses biopolymer as the main functional substance to replace part of the guar gum polymer to develop and construct a new green and efficient biopolymer fracturing fluid system, which has good viscosity, thermal stability, salt resistance, viscoelasticity, safety and non-toxicity, good temperature resistance and shear resistance, and at 45℃~80℃, 100s ‑1 The viscosity is ≥50mPa.s at shear rate. For 30~50 mesh quartz sand, the suspended sand ratio can reach 20%~30%. It has strong sand suspension capacity, complete gel breaking, and low residue, which can improve the development effect of low permeability storage. From the cost comparison, the system cost can be reduced by about 16% compared with traditional guar gum fracturing fluid.

Description

Technical Field

[0001] The invention relates to the technical field of oil production, and in particular to a novel biological fracturing fluid system. Background Art

[0002] Low-permeability oil and gas reservoirs account for more than 60% of the production of new oil and gas reservoirs. For low-permeability oil and gas reservoirs, hydraulic fracturing technology is an important measure to increase production. Among them, water-based fracturing fluid is the most widely used fracturing fluid system because of its advantages such as easy construction, low cost and excellent performance.

[0003] Water-based fracturing fluid is prepared by adding thickeners, crosslinkers and other additives with water as solvent or dispersion medium. It has the advantages of high viscosity, good sand suspension performance, low filtration loss and low friction resistance. It can be used in oil and gas layers except water-sensitive formations. Water-based fracturing fluid additives mainly include thickeners, crosslinkers, and degelling agents. In addition, there are a variety of chemical additives such as filtration reducers, pH regulators, clay stabilizers, and bactericides. Thickeners are the main components that affect the performance of water-based fracturing fluids. They are used to provide the viscosity of the aqueous solution to facilitate the transportation of proppants.

[0004] At present, nearly 70% of the fracturing measures in the world use guar gum and hydroxypropyl guar gum as thickeners to prepare water-based fracturing fluids, and their foam fracturing fluids account for about 25% of the total number of fracturing wells, while oil-based fracturing fluids are rarely used, accounting for about 5%. Among water-based fracturing fluids, guar gum is used in large quantities, reaching 30-80%, and it relies on foreign imports, with large price fluctuations, resulting in high cost of use; in particular, the guar gum fracturing fluid system has a high content of residues after gel breaking, ranging from 300 to 600 mg / L, which causes great damage to the reservoir. Summary of the invention

[0005] The present invention aims to overcome the deficiencies of the prior art and provides a novel bio-fracturing fluid system to replace the guar fracturing fluid.

[0006] A novel bio-fracturing fluid system of the present invention comprises 0.3-0.5 parts by weight of a thickener, 0.1-0.3 parts by weight of a cross-linking agent, 1.0-2.0 parts by weight of a fracturing aid and 97.2-98.6 parts by weight of water; The thickener is an isolated strain of Cossackia oryzae ( Kosakonia oryzae ) A compound system of CY-117 fermentation broth and modified guar gum, wherein the compound weight ratio of the fermentation broth of Cossackia oryzae to the modified guar gum is 1:1-9.

[0007] As a further improvement of the present invention, the rice Cossackia ( Kosakonia oryzae)CY-117, the bacteria is deposited in the General Microbiology Center of China Microbiological Culture Collection Administration, the deposit address is No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, the deposit date is August 23, 2023, and its deposit number is CGMCC NO.28227.

[0008] As a further improvement of the present invention, the rice Cossackia ( Kosakonia oryzae )'s gene sequence is shown in SEQ ID NO.1.

[0009] As a further improvement of the present invention, the fracturing aid is selected from a mixture of one or more of a bactericide, a gel breaker, a clay stabilizer, a drainage aid and a pH regulator.

[0010] As a further improvement of the present invention, the bactericide is selected from one of formaldehyde and glutaraldehyde bactericides or a mixture of the two in any proportion.

[0011] As a further improvement of the present invention, the breaker is ammonium persulfate.

[0012] As a further improvement of the present invention, the clay stabilizer is selected from one or more of potassium chloride, ammonium chloride and quaternary ammonium salt clay stabilizers, mixed in any proportion.

[0013] As a further improvement of the present invention, the drainage aid is selected from fatty alcohol polyethers.

[0014] As a further improvement of the present invention, the pH regulator is selected from one of sodium carbonate and sodium bicarbonate or a mixture of the two in any proportion.

[0015] As a further improvement of the present invention, the cross-linking agent is one of an organic zirconium cross-linking agent and an organic boron cross-linking agent, or a mixture of the two in any proportion.

[0016] In a novel bio-fracturing fluid system of the present invention, CY-117 fermentation liquid can be cross-linked into a strong glue that can be hung under the action of a cross-linking agent. The biopolymer structure of CY-117 fermentation liquid is generally composed of repeated polysaccharide units, and the repeating units contain a large number of hydroxyl groups and carboxyl groups, so a suitable cross-linking agent can be selected through the cross-linkable functional groups on the side chains for cross-linking.

[0017] A novel biological fracturing fluid system of the present invention is prepared by the following steps in parts: 1) At a stirring speed of 800-1000 r / min, slowly add a certain amount of CY-117 fermentation liquid and guar gum to clean water, stir evenly to form a thickener solution, add bactericide, clay stabilizer, drainage aid, pH adjuster in sequence, stir and mix evenly, then add degumming agent, stir again evenly to obtain base liquid; 2) The base fluid prepared in step 1 is placed in a mixer, stirring is started, a cross-linking agent is added, and the mixture is gelled uniformly, thereby obtaining the novel bio-fracturing fluid.

[0018] Compared with the existing water-based fracturing fluid, the present invention has the following advantages: 1. Using biopolymer as the main functional substance to replace part of guar gum polymer, develop and construct a new green and efficient biopolymer fracturing fluid system, which has good viscosity, thermal stability, salt resistance, viscoelasticity, environmental friendliness, safety and non-toxicity, and good temperature and shear resistance; 2. At 45℃~80℃, 100s -1 The viscosity at shear rate is ≥50mPa.s. For 30~50 mesh quartz sand, the suspended sand ratio can reach 20%~30%. It has strong suspended sand capacity, complete gel breaking, low residue (residue content 148mg / L~230mg / L), is environmentally friendly, and improves the development effect of low-permeability storage; 3. In terms of cost, the system cost can be reduced by up to about 16% compared with traditional guar gum fracturing fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 After the bacterial CY-117 fermentation liquid and guar gum are dissolved in water and a cross-linking agent is added, a jelly system with hanging ability can be formed. DETAILED DESCRIPTION

[0020] The experimental methods in the following examples and comparative examples, unless otherwise specified, are conventional methods, and are carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. The materials, reagents, etc. used in the following examples and comparative examples, unless otherwise specified, can be obtained from commercial channels.

[0021] The reagents used in the following examples and comparative examples are described: Modified guar gum LH-100 is a product produced by Guangrao Liuhe Chemical Co., Ltd. and was purchased; The drainage aid fatty alcohol polyether P-1 is a product produced by Tianjin Xiongguan Technology Development Co., Ltd. and was purchased; The organoboron crosslinking agent RS-2 is a product produced by Rongsheng Chemical Co., Ltd. and was purchased; Organic zirconium crosslinking agent JL-1 is a product produced by Beijing Shida Aode Technology Co., Ltd. and was purchased; The water used is clean water from Daqing area.

[0022] CY-117 fermentation broth was obtained by fermentation of Daqing Huali Biotechnology Co., Ltd. Kosakonia oryzae ) is further explained: 1. Bacteria screening Collect wild lake mud and water samples from Daqing Oil Production Plant No. 2 and store them in sterile sample tubes. Mix the collected samples with sterile saline thoroughly, then transfer the sample solution to LB enrichment medium under sterile conditions and culture at 30°C and 150rpm for 24h. Dilute the enriched sample solution to 10 -1 ~10 -8 ; Take 100μL of the diluted sample solution, transfer it to the solid culture medium, and culture it at 30℃ for 48h; select single colonies with smooth and sticky surfaces, and separate pure bacteria by streaking. Transfer the single bacteria separated by streaking to the seed culture medium (500mL conical flask, 100mL liquid volume), culture it at 30℃, 150rpm for 18h, then transfer it to the fermentation medium (500mL conical flask, 100mL liquid volume) at 10% transfer volume, and culture it at 30℃, 150rpm for 72h. Select strains with high viscosity of the culture medium for further evaluation and identification; Solid culture medium (g / L): sucrose 30, peptone 3, KCl 0.5, K2HPO4 1, MgSO4·7H2O 0.5, FeSO4·7H2O 0.02, agar powder 20, pH 7.5, sterilized at 121 ℃ for 30 min; Seed culture medium (g / L): sucrose 30, peptone 3, K2HPO4 1, MgSO4·7H2O 0.5, KCl 0.5, FeSO4·7H2O 0.02, pH 7.5, sterilized at 121 °C for 30 min; Fermentation medium (g / L): sucrose 30, NaNO3 3, K2HPO4 1, MgSO4·7H2O 0.5, KCl 0.5, FeSO4·7H2O 0.02, pH 7.5, sterilized at 121 °C for 30 min; 2. Identification of bacterial species Take 1 mL of the bacterial solution after 16 hours of culture and mix it evenly with 1 mL of 50% glycerol in a sterile centrifuge tube and send it for identification of the bacterial species; The culture solution of the strain was diluted with physiological saline and centrifuged, and the bacterial precipitate was collected and 16S rRNA gene sequencing was performed as SEQ ID NO. 1 to obtain the base sequence of the strain (1447 bp). The results are as follows: The gene sequence amplified from the strain was compared with the NT database. The results showed that the strain had the highest homology with Kosakonia oryzae Strain Fo8A1, with a sequence homology of 99%, and was identified as Kosakonia oryzae. It was deposited in the General Microbiological Center of the China Microbiological Culture Collection Administration, with the deposit address at No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, on August 23, 2023, and its deposit number is CGMCC NO.28227; it is classified and named Kosakonia oryzae ( Kosakonia oryzae ); 3. Preservation of strains Slant storage: transfer the bacterial liquid after activation for 16 hours to slant agar medium, culture at 30℃ for 12 hours, and then store in a 4℃ refrigerator; Glycerol tube storage: Take 1 mL of activated seed solution and 1 mL of 50% glycerol in a sterile centrifuge tube in a clean bench, mix them evenly, seal them and store them in a -20℃ refrigerator; 4. Optimization of strain formula The final fermentation medium formula and the optimal culture conditions were obtained by using single factor and orthogonal experimental methods.

[0023] The fermentation broth of bacteria CY-117 is obtained by the following steps: 1. Pick a loop of bacteria from the slant, inoculate it into the sterilized seed culture medium, and culture it at 30°C for 16 hours; the seed culture medium is made of the following components by weight: sucrose 30g / L, tryptone 3g / L, potassium chloride 0.5g / L, potassium hydrogen phosphate 1g / L, magnesium sulfate 0.5g / L, pH 7.2-7.5; 2. The cultured seed culture fluid was inoculated into the sterilized fermentation medium at a 10% inoculation rate, and the fermentation fluid of CY-117 was obtained after culturing at 30°C and 150rpm for 48 hours. The fermentation medium was made of the following components by weight: sucrose 50g / L, sodium nitrate 4g / L, potassium chloride 1.2g / L, dipotassium hydrogen phosphate 0.5g / L, magnesium sulfate 0.5g / L, ferrous sulfate 0.01g / L (sterilized by 0.22μm filter membrane), pH 7.2-7.5.

[0024] Example 1

[0025] A novel biological fracturing fluid system of the present invention has the following main components and mass fractions: Thickener: 0.35 parts, which is a compound of CY-117 and LH100, with a ratio of CY-117:LH-100=1:9; Fungicide: 0.1 part, which is formaldehyde; Gel breaker: 0.06 parts, ammonium persulfate; Clay stabilizer: 1 part, potassium chloride; Drainage aid: 0.1 part, P-1; pH adjuster: 0.1 part, sodium bicarbonate; Cross-linking agent: 0.3 parts, RS-2; The clean water is 97.99 parts.

[0026] Example 2

[0027] A novel biological fracturing fluid system of the present invention has the following main components and mass fractions: Thickener: 0.35 parts, compounded with CY-117 and LH100, the ratio is CY-117:LH-100=1:9; Bactericide: 0.1 part, glutaraldehyde; Gel breaker: 0.06 parts, ammonium persulfate; Clay stabilizer: 1 part, ammonium chloride; Drainage aid: 0.1 part, P-1; pH adjuster: 0.1 part, sodium carbonate; Cross-linking agent: 0.3 parts, JL-1; The clean water is 97.99 parts.

[0028] Example 3

[0029] A novel biological fracturing fluid system of the present invention has the following main components and mass fractions: Thickener: 0.35 parts, compounded with CY-117 and LH100, the ratio is CY-117:LH-100=2:8; Bactericide: 0.2 parts, including 0.1 parts of formaldehyde and 0.1 parts of glutaraldehyde; Gel breaker: 0.1 part, ammonium persulfate; Clay stabilizer: 1.3 parts, ammonium chloride; Drainage aid: 0.2 parts, P-1; pH adjuster: 0.1 part, sodium carbonate; Cross-linking agent: 0.1 parts, RS-2; The amount of clean water is 97.65 parts.

[0030] Example 4

[0031] A novel biological fracturing fluid system of the present invention has the following main components and mass fractions: Thickener: 0.35 parts, compounded with CY-117 and LH100, the ratio is CY-117:LH-100=3:7; Bactericide: 0.2 parts, glutaraldehyde; Gel breaker: 0.05 parts, ammonium persulfate; Clay stabilizer: 0.65 parts, including 0.4 parts of potassium chloride and 0.25 parts of ammonium chloride; Drainage aid: 0.15 parts, P-1; pH adjuster: 0.2 parts, including 0.1 parts of sodium carbonate and 0.1 parts of sodium bicarbonate; Cross-linking agent: 0.2 parts, JL-1; The amount of clean water is 98.2 parts.

[0032] Example 5

[0033] A novel biological fracturing fluid system of the present invention has the following main components and mass fractions: Thickener: 0.35 parts, compounded with CY-117 and LH100, the ratio is CY-117:LH-100=4:6; Fungicide: 0.15 parts, which is formaldehyde; Gel breaker: 0.1 part, ammonium persulfate; Clay stabilizer: 1 part, potassium chloride; Drainage aid: 0.1 part, P-1; pH adjuster: 0.1 part, sodium bicarbonate; Cross-linking agent: 0.2 parts, of which JL-1 is 0.1 parts and RS-2 is 0.1 parts; The amount of clean water is 98 parts.

[0034] Example 6

[0035] A novel biological fracturing fluid system of the present invention has the following main components and mass fractions: Thickener: 0.30 parts, compounded with CY-117 and LH100, the ratio is CY-117:LH-100=5:5; Fungicide: 0.15 parts, which is formaldehyde; Gel breaker: 0.1 part, ammonium persulfate; Clay stabilizer: 1 part, ammonium chloride; Drainage aid: 0.2 parts, P-1; pH regulator: 0.12 parts, sodium carbonate; Cross-linking agent: 0.3 parts, RS-2; The amount of clean water is 97.83 parts.

[0036] Comparative Example 1 The main components and mass fractions of the existing guar gum fracturing fluid system are as follows: Thickener: 0.35 parts, LH100; Fungicide: 0.1 part, which is formaldehyde; Gel breaker: 0.06 parts, ammonium persulfate; Clay stabilizer: 1 part, potassium chloride; Drainage aid: 0.1 part, P-1; pH adjuster: 0.1 part, sodium carbonate; Cross-linking agent: 0.3 parts, RS-2; The clean water is 97.99 parts.

[0037] The debonding performance of the above-mentioned Examples 1-6 and Comparative Example 1 was tested as follows: including debonding liquid viscosity, surface tension, and residue content, see Table 1:

[0038] From the analysis of Table 1, it can be concluded that Examples 1 to 6 and Comparative Example 1 completely broke the gel within 12 hours, and the apparent viscosity of the broken gel liquid after breaking the gel was 1.5 mPa.s, and the surface tension was less than 32 mN / m, which fully met the requirements of the industry standards. In particular, the overall residue content of the system after breaking the gel was less than 240 mg / L, which was much lower than other existing fracturing fluid systems such as guar gum, meeting the index requirements. At the same time, as the proportion of CY-117 fermentation liquid increased, compared with Comparative Example 1, its residue content was reduced by up to 52.2%, meeting the low residue requirements.

[0039] It can be seen that the new bio-fracturing fluid system formed by biopolymer CY-117 and modified guar gum LH-100 has stronger sand suspension and wall building ability than slick water fracturing fluid or linear gel fracturing fluid, and is suitable for high sand ratio operations. Compared with traditional guar gum and chemical polymers, the new bio-fracturing fluid system has a lower residue content after gel breaking, which can be reduced from the general 300 mg / L to about 150 mg / L, reducing damage to the reservoir.

[0040] In terms of cost, the system cost is reduced by about 16.1% compared with the traditional guar gum fracturing fluid. The system cost calculation is shown in Table 2:

[0041] The performance of the above embodiments 1-6 is tested below: Evaluation of heat and shear resistance: According to Q / SH 0351-2010 Technical Requirements for Crosslinking Agents for Water-Based Fracturing, 50 g of the new bio-fracturing fluid system was taken and tested at 80 °C for 100 s using a high-temperature and high-pressure coaxial cylinder rotational viscometer (model TC-150MX, manufacturer Brookfield). -1 Temperature and shear resistance test under .

[0042] The shear viscosity of Examples 1 to 6 is shown in Table 3 below:

[0043] From the analysis in Table 3, it can be concluded that the shear viscosity of the new bio-fracturing fluid is greater than 80 mPa·s, which is better than the industry standard specified in Q / SH 0351-2010 (90 min shear viscosity greater than 50 mPa.s), forming a series of systems with different strengths.

[0044] Evaluation of sand suspension performance: The static sand suspension capacity of 20-60 mesh quartz sand at a sand ratio of 30% was evaluated in a 100 mL measuring cylinder, see Table 4:

[0045] From the analysis of Table 4, it can be concluded that the static suspended sand performance of Examples 1 to 6 is good, the suspended sand-to-sand ratio can reach 30%, and there is basically no sedimentation within 120 minutes.

[0046] The description of the above embodiments 1 to 6 and comparative example 1 is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A novel bio-fracturing fluid system, characterized in that: The novel bio-fracturing fluid system contains 0.3-0.5 parts by weight of a thickener, 0.1-0.3 parts by weight of a cross-linking agent, 1.0-2.0 parts by weight of a fracturing aid, and 97.2-98.6 parts by weight of water; The thickener is an isolated strain of Cossackia oryzae ( Kosakonia oryzae ) A compound system of CY-117 fermentation broth and modified guar gum, wherein the compound weight ratio of the fermentation broth of Cossackia oryzae to the modified guar gum is 1:1-9.

2. A novel bio-fracturing fluid system according to claim 1, characterized in that: The oryzae bacteria ( Kosakonia oryzae )CY-117, the bacteria is deposited in the General Microbiology Center of China Microbiological Culture Collection Administration, the deposit address is No. 3, Yard No. 1, Beichen West Road, Chaoyang District, Beijing, the deposit date is August 23, 2023, and its deposit number is CGMCC NO.28227.

3. A novel bio-fracturing fluid system as claimed in claim 2, characterized in that: The oryzae bacteria ( Kosakonia oryzae )'s gene sequence is shown in SEQ ID NO.

1.

4. A novel bio-fracturing fluid system according to claim 1, characterized in that: The fracturing aid is selected from a mixture of one or more of a bactericide, a gel breaker, a clay stabilizer, a drainage aid and a pH adjuster.

5. A novel bio-fracturing fluid system according to claim 4, characterized in that: The bactericide is selected from formaldehyde and glutaraldehyde bactericides or a mixture of the two in any proportion.

6. A novel bio-fracturing fluid system according to claim 4, characterized in that: The debonding agent is ammonium persulfate.

7. A novel bio-fracturing fluid system according to claim 4, characterized in that: The clay stabilizer is selected from one or more of potassium chloride, ammonium chloride and quaternary ammonium salt clay stabilizers, mixed in any proportion.

8. A novel bio-fracturing fluid system according to claim 4, characterized in that: The drainage aid is selected from fatty alcohol polyethers.

9. A novel bio-fracturing fluid system according to claim 4, characterized in that: The pH regulator is selected from sodium carbonate and sodium bicarbonate, or a mixture of the two in any proportion.

10. A novel bio-fracturing fluid system according to claim 1, characterized in that: The crosslinking agent is one of an organic zirconium crosslinking agent and an organic boron crosslinking agent, or a mixture of the two in any proportion.

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