阅读说明：本技术 植物胶压裂液微生物复合降粘体系及其在稠油开采领域的应用 (Vegetable gum fracturing fluid microorganism composite viscosity reduction system and application thereof in field of thick oil exploitation ) 是由 潘竟军 董景锋 李晓艳 怡宝安 于 2019-04-08 设计创作，主要内容包括：本发明提供了一种植物胶压裂液微生物复合降粘体系及其在稠油开采领域的应用。该植物胶压裂液微生物复合降粘体系包括植物胶、降粘微生物及水,降粘微生物选自假单胞菌、蜡样芽胞杆菌、枯草芽孢杆菌和嗜热脂肪地芽孢杆菌组成的组中的一种或多种。植物胶能够提供微生物生长所需的碳源。降粘微生物生长过程中能够代谢出生物表面活性剂、小分子有机溶剂及气体等,此类生物表面活性剂,一方面能够有效乳化稠油,降低稠油黏度,并提高稠油流动性；另一方面还有利于降低上述降粘体系中破胶剂等的用量,并减少破胶液残渣量,对提高稠油采收率具有重要意义。(The invention provides a vegetable gum fracturing fluid microorganism composite viscosity reduction system and application thereof in the field of thickened oil exploitation. The microbial composite viscosity reduction system of the vegetable gum fracturing fluid comprises vegetable gum, viscosity reduction microbes and water, wherein the viscosity reduction microbes are selected from one or more of the group consisting of pseudomonas, bacillus cereus, bacillus subtilis and geobacillus stearothermophilus. The plant gum can provide a carbon source for the growth of the microorganism. The biosurfactant, the small molecular organic solvent, the gas and the like can be metabolized in the growth process of the viscosity-reducing microorganisms, and on one hand, the biosurfactant can effectively emulsify the thick oil, reduce the viscosity of the thick oil and improve the fluidity of the thick oil; on the other hand, the method is beneficial to reducing the dosage of gel breakers and the like in the viscosity reduction system and reducing the residue of the gel breaker liquid, and has important significance for improving the recovery ratio of the thickened oil.)

1. The microbial composite viscosity reduction system for the vegetable gum fracturing fluid is characterized by comprising vegetable gum, viscosity reduction microbes and water, wherein the viscosity reduction microbes are selected from one or more of pseudomonas, bacillus cereus, bacillus subtilis and geobacillus stearothermophilus.

2. The vegetable gum fracturing fluid and microorganism composite viscosity reduction system of claim 1, further comprising 0.10 to 0.50 part of vegetable gum, 0.5 to 5 parts of viscosity reduction microorganism and the balance of water, based on 100 parts of the total weight of the vegetable gum fracturing fluid and microorganism composite viscosity reduction system.

3. The microbial composite viscosity reduction system of claim 2, wherein the vegetable gum is selected from one or more of the group consisting of guar gum, coumaric gum, sesbania gum and konjac gum.

4. The vegetable gum fracturing fluid microbial composite viscosity reducing system according to any one of claims 1 to 3, further comprising 0.5-2 parts of an anti-swelling agent, based on 100 parts of the total weight of the vegetable gum fracturing fluid microbial composite viscosity reducing system; preferably, the anti-swelling agent is selected from potassium chloride and/or ammonium chloride.

5. The vegetable gum fracturing fluid microbial composite viscosity reduction system of claim 4, wherein the vegetable gum fracturing fluid microbial composite viscosity reduction system further comprises 0.3-1 part of a cleanup additive, based on 100 parts of the total weight of the vegetable gum fracturing fluid microbial composite viscosity reduction system;

preferably, the cleanup additive is a fluorocarbon surfactant and/or a nonionic surfactant.

6. The vegetable gum fracturing fluid microbial composite viscosity reducing system of claim 5, wherein the vegetable gum fracturing fluid microbial composite viscosity reducing system further comprises 0.002-0.1 part of a gel breaker based on 100 parts of the total weight of the vegetable gum fracturing fluid microbial composite viscosity reducing system; preferably, the breaker is selected from sodium persulfate and/or ammonium persulfate.

7. The vegetable gum fracturing fluid microbial composite viscosity reducing system of claim 6, further comprising 0.20 to 0.50 parts of a cross-linking agent, based on 100 parts of the total weight of the vegetable gum fracturing fluid microbial composite viscosity reducing system; preferably, the crosslinking agent is selected from an organic boron crosslinking agent and/or an inorganic boron crosslinking agent.

8. The vegetable gum fracturing fluid and microorganism composite viscosity reducing system of claim 7, further comprising 0.20 to 0.50 parts of the vegetable gum, 1 to 4 parts of the viscosity reducing microorganism, 0.2 to 0.4 parts of the crosslinking agent, 1 to 2 parts of the anti-swelling agent, 0.5 to 0.8 parts of the cleanup additive, 0.01 to 0.08 parts of the gel breaker and the balance of water, based on 100 parts of the total weight of the vegetable gum fracturing fluid and microorganism composite viscosity reducing system.

9. The application of the plant gum fracturing fluid microbial composite viscosity reduction system of any one of claims 1 to 8 in the recovery of thick oil, wherein the viscosity of the thick oil is 0.01-1.0 Pa-s.

10. The use of claim 9, wherein the weight ratio of the fracturing fluid to the heavy oil is (0.5-2): 1.

Technical Field

The invention relates to the field of thickened oil exploitation, in particular to a vegetable gum fracturing fluid microorganism composite viscosity reduction system and application thereof in the field of thickened oil exploitation.

Background

The thickened oil is rich in complex mixtures of multiple hydrocarbons such as colloid, asphaltene and the like, so that the thickened oil has high density, high viscosity and poor fluidity. How to effectively reduce the viscosity of crude oil becomes a key problem in the heavy oil recovery.

The microbial oil recovery technology is a technology for improving the yield and recovery ratio of crude oil by using microbes and metabolites thereof. In the process of extracting the thickened oil microorganism, a carbon source, a nitrogen source, a phosphorus source and the like are used as nutrients, and the surfactant-producing microorganism can produce surfactant substances. The surfactant can emulsify thick oil and reduce the viscosity of the thick oil, so the surfactant is often used for viscosity reduction exploitation of the thick oil. The microbial oil production technology has the characteristics of wide application range, simple process, good economic benefit, no pollution and the like, and has good application prospect.

As the heavy oil development gradually develops to low-porosity, low-permeability, heterogeneous and other difficultly-exploited reservoirs, part of heavy oil reservoirs need to improve the exploitation degree of the reservoirs by utilizing a hydraulic fracturing technology. The application range of the hydraulic fracturing as an important yield increasing measure for improving the recovery efficiency is continuously increased in the development of the thickened oil, and the vegetable gum fracturing fluid is pumped into a reservoir layer to form a high diversion channel, so that the recovery efficiency of the thickened oil is effectively improved. The viscous oil has high viscosity and poor fluidity, and the vegetable gum fracturing fluid is required to reduce the viscosity of the viscous oil, increase the fluidity of crude oil and improve the recovery ratio of the viscous oil while forming a high-flow-guide channel by fracturing. The plant gum is a plant polysaccharide polymer consisting of mannose and galactose, and can provide a nutrient source for microorganisms. Biosurfactant, small molecular organic solvent, gas and the like generated by the growth and metabolism of microorganisms can effectively reduce the viscosity of the thick oil and increase the flowability of the crude oil.

Introducing thick oil viscosity-reducing microorganisms into thick oil hydraulic fracturing: and adding a certain amount of thick oil viscosity-reducing microorganisms into the vegetable gum fracturing fluid, wherein the vegetable gum provides a microorganism growth carbon source and is supplemented with other nutrients. The biological surfactant, the small molecular organic solvent, the gas and the like can be metabolized in the growth process of the microorganism. The beneficial effects are as follows: (1) biological surfactant, small molecular organic solvent and gas generated by microbial metabolism can effectively emulsify crude oil, reduce viscosity of thick oil and improve fluidity of thick oil; (2) the microorganism takes the vegetable gum as a carbon source to realize growth and metabolism, effectively reduces the addition of additives (gel breakers, cleanup additives and the like) of the fracturing fluid, reduces the residue amount of the gel breaking fluid and achieves the purposes of cost reduction and efficiency improvement.

The existing literature provides a viscosity reduction bacterium for improving the oil recovery efficiency and application thereof, and provides streptococcus zooepidemicus which can effectively improve the property of crude oil, generate biogas and hyaluronic acid biological polysaccharide in the fermentation process, enable the crude oil to be easier to emulsify, wet and disperse, improve the oil layer pressure, reduce the viscosity of the crude oil and improve the flow capacity of the crude oil. However, the patent does not mention the thick oil fracturing technology and the viscosity reducing effect of the fracturing fluid on the thick oil.

Another document introduces a low-temperature shallow heavy oil reservoir, develops a heavy oil field fracturing non-flowback technology, analyzes the performance index of the fracturing fluid and performs comparative analysis with the conventional fracturing fluid, and can meet the industrial standard and the fracturing suspended sand requirement. Provides an economic and effective technical means for exploiting the shallow layer thick oil. But the technology does not mention the viscosity reduction effect of the fracturing fluid on the thick oil in the thick oil fracturing process.

Disclosure of Invention

The invention mainly aims to provide a vegetable gum fracturing fluid microorganism composite viscosity reduction system and application thereof in the field of thickened oil exploitation, so as to solve the problem that the conventional fracturing fluid has poor effect in the process of viscosity reduction of thickened oil.

In order to achieve the above object, one aspect of the present invention provides a composite viscosity reducing system for a plant gum fracturing fluid microorganism, which comprises a plant gum, a viscosity reducing microorganism and water, wherein the viscosity reducing microorganism is one or more selected from the group consisting of pseudomonas, bacillus cereus, bacillus subtilis and geobacillus stearothermophilus.

Further, the composite viscosity reducing system of the vegetable gum fracturing fluid and the microorganism comprises 0.10-0.50 part of vegetable gum, 0.5-5 parts of viscosity reducing microorganism and the balance of water, wherein the total weight of the composite viscosity reducing system of the vegetable gum fracturing fluid and the microorganism is 100 parts; preferably, the vegetable gum is selected from one or more of the group consisting of guar gum, coumarone gum, sesbania gum and konjac gum.

Further, the total weight of the vegetable gum fracturing fluid and microorganism composite viscosity reduction system is 100 parts, and the vegetable gum fracturing fluid and microorganism composite viscosity reduction system also comprises 0.5-2 parts of an anti-swelling agent; preferably, the anti-swelling agent is selected from potassium chloride and/or ammonium chloride.

Further, the total weight of the vegetable gum fracturing fluid and microorganism composite viscosity reduction system is 100 parts, and the vegetable gum fracturing fluid and microorganism composite viscosity reduction system also comprises 0.3-1 part of a cleanup additive; preferably, the cleanup additive is a fluorocarbon surfactant and/or a nonionic surfactant.

Further, the total weight of the plant gum fracturing fluid and microorganism composite viscosity reduction system is 100 parts, and the plant gum fracturing fluid and microorganism composite viscosity reduction system further comprises 0.002-0.1 part of a gel breaker; preferably, the breaker is selected from sodium persulfate and/or ammonium persulfate.

Further, the total weight of the vegetable gum fracturing fluid and microorganism composite viscosity reduction system is 100 parts, and the vegetable gum fracturing fluid and microorganism composite viscosity reduction system further comprises 0.20-0.50 part of a cross-linking agent; preferably, the crosslinker is selected from an organic boron crosslinker and/or an inorganic boron crosslinker.

Further, the composite viscosity reducing system of the plant gum fracturing fluid and the microorganism comprises, by taking 100 parts of the total weight of the composite viscosity reducing system of the plant gum fracturing fluid and the microorganism, 0.20-0.50 part of plant gum, 1-4 parts of viscosity reducing microorganism, 0.2-0.4 part of cross-linking agent, 1-2 parts of anti-swelling agent, 0.5-0.8 part of cleanup additive, 0.01-0.08 part of gel breaker and the balance of water.

The invention also provides application of the plant gum fracturing fluid microorganism composite viscosity reduction system in thickened oil exploitation, wherein the viscosity of the thickened oil is 0.01-1.0 Pa.s.

Furthermore, the weight ratio of the fracturing fluid to the thick oil is (0.5-2): 1.

By applying the technical scheme of the invention, in the plant gum fracturing fluid microorganism composite viscosity reduction system provided by the application, the plant gum can provide a carbon source required by microorganism growth. The biosurfactant, the small molecular organic solvent, the gas and the like can be metabolized in the growth process of the viscosity-reducing microorganisms, and the biosurfactant can effectively emulsify the thick oil, reduce the viscosity of the thick oil and improve the fluidity of the thick oil on one hand; on the other hand, the method is beneficial to reducing the dosage of gel breakers and the like in the preparation process and reducing the residue of gel breakers, and has important significance for improving the recovery ratio of the thickened oil. On the basis, the plant gum fracturing fluid microorganism composite viscosity reduction system has excellent viscosity reduction performance on thick oil, and has the advantages of low residue and the like.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

As described in the background art, the existing fracturing fluid has the problem of poor effect in the process of viscosity reduction of thick oil. In order to solve the technical problems, the application provides a composite viscosity reduction system of a vegetable gum fracturing fluid microorganism, which comprises vegetable gum, viscosity reduction microorganisms, a cross-linking agent and water, wherein the viscosity reduction microorganisms comprise one or more of the group consisting of pseudomonas, bacillus cereus, bacillus subtilis and geobacillus stearothermophilus.

In the composite viscosity reduction system for the plant gum fracturing fluid microorganisms, the plant gum can provide a carbon source required by the growth of the microorganisms. The biosurfactant, the small molecular organic solvent, the gas and the like can be metabolized in the growth process of the viscosity-reducing microorganisms, and the biosurfactant can effectively emulsify the thick oil, reduce the viscosity of the thick oil and improve the fluidity of the thick oil. The method is beneficial to reducing the dosage of the auxiliary agent in the preparation process or not adding the auxiliary agent at all, thereby being beneficial to reducing the residue amount of the gel breaking liquid and having important significance for improving the recovery ratio of the thickened oil. On the basis, the plant gum fracturing fluid microorganism composite viscosity reduction system has excellent viscosity reduction performance on thick oil, and has the advantages of low residue and the like.

The addition of the viscosity-reducing microorganism into the plant gum fracturing fluid microorganism composite viscosity-reducing system is beneficial to improving the emulsifying property and viscosity-reducing property of the fracturing fluid on the thick oil. In a preferred embodiment, the composite viscosity-reducing system for the vegetable gum fracturing fluid microorganisms further comprises 0.10-0.50 part of guar gum, 0.5-5 parts of viscosity-reducing microorganisms and the balance of water, based on 100 parts of the total weight of the composite viscosity-reducing system for the vegetable gum fracturing fluid microorganisms. The dosage of each component in the above-mentioned vegetable gum fracturing fluid microbial composite viscosity-reducing system includes but is not limited to the above-mentioned range, and the limitation of the dosage in the above-mentioned range is favorable for further improving the viscosity-reducing performance and emulsifying performance of the thick oil.

In order to further improve the overall performance of the viscosity reduction system, the vegetable gum used in the present application preferably includes one or more of but not limited to guar gum, coumar gum, sesbania gum and konjac gum.

The plant gum fracturing fluid microorganism composite viscosity reduction system with the composition has excellent viscosity reduction performance and emulsifying performance on thick oil, and simultaneously has the advantages of low gel breaking residue and the like. In a preferred embodiment, the vegetable gum fracturing fluid microorganism composite viscosity reduction system further comprises 0.5-2 parts of an anti-swelling agent based on 100 parts of the total weight of the vegetable gum fracturing fluid microorganism composite viscosity reduction system. The addition of the anti-swelling agent is beneficial to improving and inhibiting hydration swelling and dispersion transfer of clay minerals in the oil reservoir. The anti-swelling agent includes, but is not limited to, the above range, and the limitation of the anti-swelling agent to the above range is advantageous for further inhibiting the hydration swelling and dispersion transfer of the clay mineral in the petroleum reservoir. Preferably, the anti-swelling agent includes, but is not limited to, potassium chloride and/or ammonium chloride. The antiswelling agent may be of the kind commonly used in the art. The anti-swelling agents are low in price and easy to adsorb on the surface of the reservoir, so that the selection of the anti-swelling agents is beneficial to further improving the inhibition effect of the fracturing fluid on the hydration swelling and dispersion transfer of the clay minerals in the reservoir.

The addition of the cleanup additive is beneficial to improving the discharge speed of the viscosity reduction system and reducing the residual quantity of the viscosity reduction system in the flowback process. In a preferred embodiment, the composite viscosity reducing system for vegetable gum fracturing fluid microorganisms further comprises 0.3-1 part of cleanup additive based on 100 parts of the total weight of the composite viscosity reducing system for vegetable gum fracturing fluid microorganisms. The amount of the cleanup additive includes, but is not limited to, the above range, and limiting the amount to the above range is advantageous for further reducing the residual amount of the complex viscosity reducing system for the plant gum fracturing fluid microorganisms. Preferably, the cleanup additive is a fluorocarbon surfactant and/or a non-ionic surfactant. The nonionic surfactant has good compatibility with the guanidine gum, viscosity-reducing microorganisms and other components, and the nonionic surfactant is further favorable for further improving the discharge aiding effect.

In a preferred embodiment, the composite microbial viscosity reducing system for the vegetable gum fracturing fluid further comprises 0.002-0.1 part of a gel breaker based on 100 parts of the total weight of the composite microbial viscosity reducing system for the vegetable gum fracturing fluid. More preferably, breakers include, but are not limited to, sodium persulfate or ammonium persulfate. The selection of the gel breakers is beneficial to further improving the flowback performance of the viscosity reduction system.

For a reservoir with a small crack, the cross-linking agent can not be added into the plant gum fracturing fluid microorganism composite viscosity reduction system, and only the fracturing fluid with low viscosity can meet the requirement. For reservoirs with larger cracks, a cross-linking agent needs to be added so that the fracturing fluid forms gel, and the fracturing performance of the fracturing fluid is improved. In a preferred embodiment, the composite viscosity reducing system for vegetable gum fracturing fluid microorganisms further comprises 0.20-0.50 part of a cross-linking agent, based on 100 parts of the total weight of the composite viscosity reducing system for vegetable gum fracturing fluid microorganisms. The amount of the cross-linking agent includes, but is not limited to, the above range, and the limitation thereof is advantageous for further improving the fracturing performance of the fracturing fluid.

The cross-linking agent in the plant gum fracturing fluid microorganism composite viscosity reduction system can adopt the type commonly used in the field. In a preferred embodiment, the crosslinking agent includes, but is not limited to, an organic boron crosslinking agent and/or an inorganic boron crosslinking agent. The types of the cross-linking agents include, but are not limited to, the above-mentioned ones, which are selected to be beneficial to improving the fracturing performance of the above-mentioned vegetable gum fracturing fluid microbial composite viscosity reduction system.

In order to further improve the comprehensive performance of the plant gum fracturing fluid and microorganism composite viscosity reduction system, the plant gum fracturing fluid and microorganism composite viscosity reduction system further comprises 0.20-0.50 part of plant gum, 1-4 parts of viscosity reduction microorganisms, 0.2-0.4 part of cross-linking agent, 1-2 parts of anti-swelling agent, 0.5-0.8 part of cleanup additive, 0.01-0.08 part of gel breaker and the balance of water, wherein the total weight of the plant gum fracturing fluid and microorganism composite viscosity reduction system is 100 parts.

The application also provides an application of the fracturing fluid formed by the plant gum fracturing fluid microorganism composite viscosity reduction system in the exploitation of thick oil, wherein the viscosity of the thick oil is 0.01-1.0 Pa.s.

The thick oil with the viscosity has the characteristics of high density, high viscosity, poor fluidity and the like, so that the problem of poor viscosity reduction effect of the fracturing fluid exists when the viscosity reduction treatment is carried out on the thick oil by adopting the conventional fracturing fluid. When the vegetable gum fracturing fluid microorganism composite viscosity reduction system is used for treating thick oil, vegetable gum can provide a carbon source required by microorganism growth, and the viscosity reduction microorganism can metabolize a biological surfactant, a small molecular organic solvent, gas and the like, so that the emulsification effect of the vegetable gum fracturing fluid microorganism composite viscosity reduction system on the thick oil can be greatly improved, the viscosity of the thick oil is reduced, the fluidity of the thick oil is improved, the dosage of a gel breaker and the like in the process of preparing fracturing fluid can be reduced, and the residue quantity of the gel breaker is reduced.

In a preferred embodiment, the weight ratio of the fracturing fluid to the thick oil is (0.5-2): 1. The weight ratio of the fracturing fluid to the heavy oil includes but is not limited to the above range, and the limitation of the weight ratio to the heavy oil in the above range is beneficial to further reduce the viscosity and the fracturing effect of the microbial composite viscosity reduction system of the vegetable gum fracturing fluid.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.