阅读说明：本技术 一种微生物泡沫排水剂及其在气井开采中的应用 (Microbial foam drainage agent and application thereof in gas well exploitation ) 是由 黄敏刚 杜海峰 于 2021-01-22 设计创作，主要内容包括：本申请提供微生物泡沫排水剂及其制备方法和用途。所述微生物泡沫排水剂包含芽孢杆菌以及任选地表面活性剂,所述微生物泡沫排水剂用于天然气开采或辅助天然气开采中。(The application provides a microbial foam drainage agent, a preparation method and application thereof. The microbial foam drainage agent comprises bacillus and optionally a surfactant, and is used in natural gas production or assisted natural gas production.)

1. A microbial foam drainage agent comprising a bacillus, preferably a culture comprising said bacillus;

optionally, the microbial foam drainage agent further comprises a surfactant.

2. The microbial foam drainage agent of claim 1, wherein the Bacillus is Bacillus subtilis; and/or

The bacillus culture consists of the bacillus and a culture medium; and/or

The effective viable count of the bacillus in the bacillus culture is not less than 5 multiplied by 10⁷cfu/mL, preferably ≥ 1X 10⁸cfu/mL, more preferably 1X 10 or more⁹cfu/mL; and/or

The culture medium is a liquid culture medium or a semi-solid culture medium.

3. The microbial foam drainage agent of claim 1 or 2, wherein the surfactant is a biosurfactant; preferably, the surfactant is selected from: lipopeptides, fatty acids, algal glycolipids and gramicidin; more preferably, the surfactant is a lipopeptide;

optionally, the concentration of the surfactant is 50-300g/L, preferably 75-200g/L or 75-250 g/L.

4. The microbial foam drainage agent of any one of claims 1 to 3, wherein the effective viable count of the Bacillus in the microbial foam drainage agent is 5 x 10 or more⁷cfu/mL, preferably ≥ 1X 10⁸cfu/mL, more preferably 1X 10 or more⁹cfu/mL; and/or

The concentration of the surfactant in the microbial foam drainage agent is 10-75g/L, preferably 15-50g/L or 18.75-50 g/L; and/or

Wherein the bacillus culture and the surfactant are in respective parts by volume based on the volume of the microbial foam drainage agent:

1-10 of the Bacillus culture

1-10 parts of the surfactant;

optionally, the ratio by volume of the bacillus culture to the surfactant is 1:1 to 1: 10; preferably, the ratio by volume of the bacillus culture and the surfactant is 1:1, 1:2, 1:3, 1:4, 1:5 or 1: 10; more preferably, the ratio of the bacillus culture to the surfactant is 1:3 or 1:4 by volume.

5. A method of preparing a microbial foam drainage agent, comprising:

culturing bacillus to obtain a culture of the bacillus; optionally, the method further comprises mixing the culture of bacillus with a surfactant to obtain the microbial foam drainage agent;

optionally, the culture is a liquid culture or a semi-solid culture.

6. The method of claim 5, wherein

The Bacillus is Bacillus subtilis; and/or

The effective viable count of the bacillus in the bacillus culture is not less than 5 multiplied by 10⁷cfu/mL, preferably ≥ 1X 10⁸cfu/mL, more preferably 1X 10 or more⁹cfu/mL; and/or

The surfactant is a biosurfactant; preferably, the surfactant is selected from: lipopeptides, fatty acids, algal glycolipids and gramicidin; more preferably, the surfactant is a lipopeptide;

optionally, the concentration of the surfactant is 50-300g/L, preferably 75-200g/L or 75-250 g/L.

7. The method of claim 5 or 6, wherein the microbial foam drainage agent isThe effective viable count of the bacillus is more than or equal to 5 multiplied by 10⁷cfu/mL, preferably ≥ 1X 10⁸cfu/mL, more preferably 1X 10 or more⁹cfu/mL; and/or

The concentration of the surfactant in the microbial foam drainage agent is 10-75g/L, preferably 15-50g/L or 18.75-50 g/L; and/or

Wherein the bacillus culture and the surfactant are in respective parts by volume based on the volume of the microbial foam drainage agent:

1-10 of the Bacillus culture

1-10 parts of the surfactant;

optionally, the ratio by volume of the bacillus culture to the surfactant is 1:1 to 1: 10; preferably, the ratio by volume of the bacillus culture and the surfactant is 1:1, 1:2, 1:3, 1:4, 1:5 or 1: 10; more preferably, the ratio of the bacillus culture to the surfactant is 1:3 or 1:4 by volume.

8. A method of draining or assisting in draining a gas well, comprising:

injecting into a gas well from 0.1% to 10% (w/w), preferably from 0.5% to 5% (w/w), more preferably from 0.5%, 1%, 2%, 3%, 4% or 5% (w/w) of the daily water production of the gas well, the microbial foam drainage agent of any one of claims 1 to 4 or the microbial foam drainage agent prepared by the method of any one of claims 5 to 7.

9. The method of claim 8, further comprising injecting the microbial foam drainage agent of any one of claims 1 to 4 or prepared by the method of any one of claims 5 to 7 into the gas well every 3 to 20 days, preferably every 5 to 15 days, more preferably every 5, 7, 10 or 15 days with a daily water production of the gas well of 0.1% to 10% (w/w), preferably 0.5% to 5% (w/w), more preferably 0.5%, 1%, 2%, 3%, 4% or 5% (w/w).

10. Use of the microbial foam drainage agent of any one of claims 1-4 or prepared by the method of any one of claims 5-7 in natural gas extraction or assisted natural gas extraction.

Technical Field

The application belongs to the technical field of natural gas exploitation. In particular, the present application relates to microbial foam drainage agents for gas well foam drainage to enhance natural gas production and their use in natural gas production or assisted natural gas production.

Background

In the middle and later stages of the development of the natural gas well, the stratum energy is reduced, the daily gas production is less than the critical liquid carrying gas quantity of the well, liquid accumulation occurs in a shaft of the well, and if the liquid is not discharged out of the well in time, the liquid accumulation in the shaft is too much, so that the yield of the gas well is reduced and even the gas well is drowned by water. At present, methods for removing accumulated liquid at the bottom of a well mainly comprise foam drainage and mechanical drainage. The foam drainage gas production process is a drainage-assisting process for adding foam drainage foaming agent into a well, and the foam drainage gas production process is fully mixed with bottom hole accumulated liquid by means of stirring of natural gas, so that the surface tension of the liquid is reduced, and a large amount of low-density water-containing foam is generated, and the bottom hole accumulated liquid can be completely taken out. The foam drainage gas production is an economic, high-efficiency and convenient-to-construct drainage gas production technology, has the characteristics of simple equipment, easy construction, quick response, low cost and no influence on gas well production, and the number of applied wells is more than 80 percent, so that the foam drainage gas production is the most effective means for maintaining stable production of the water-producing gas well.

At present, domestic foam drainage agents mainly take chemical surfactants such as petroleum byproducts, anionic surfactants and the like as main components, and the application of the foam drainage agents mainly has the following problems: (1) the biodegradation is slow, the high temperature resistance, the high salt content and the high condensate oil difference are achieved; (2) a large amount of foams are generated in the drainage and gas production process, the foams are difficult to eliminate after reaching the ground, and even if a defoaming agent is added, the problems of slow defoaming, incomplete defoaming and the like exist; (3) the chemical foam drainage agent has poor compatibility with formation water, and is easy to denature to cause formation blockage; (4) due to the existence of condensate oil, emulsion is easily generated in produced liquid, which brings many problems for post-treatment.

The microbe foam water drainage gas production technology is that microbes grow and propagate by using organic matters in a gas well and inorganic salt ions in formation water as nutrient substances to generate secondary metabolites, and the secondary metabolites are fully contacted with bottom hole accumulated liquid by means of stirring of natural gas flow to generate a large amount of stable low-density water-containing foams, so that the bottom hole accumulated liquid is more easily carried to the ground by the gas flow from the bottom hole, and the purpose of water drainage and gas production is achieved.

Therefore, the exploration and development of new microbial foam drainage agents are of great significance in natural gas extraction or auxiliary natural gas extraction.

Disclosure of Invention

In a first aspect, the present application provides a microbial foam drainage agent comprising a bacillus; optionally, the microbial foam drainage agent further comprises a surfactant.

In some embodiments of the first aspect, the Bacillus is Bacillus subtilis.

In some embodiments of the first aspect, the bacillus culture consists of the bacillus and a culture medium.

In some embodiments of the first aspect, the effective viable count of the Bacillus in the Bacillus culture is ≥ 5X 10⁷cfu/mL。

In some embodiments of the first aspect, the medium in which the bacillus is cultured is a liquid medium or a semi-solid medium.

In some embodiments of the first aspect, the surfactant is a biosurfactant.

In some embodiments of the first aspect, the concentration of the surfactant is from 50 to 300 g/L.

In some embodiments of the first aspect, the effective viable count of the Bacillus in the microbial foam drainage agent is 5X 10 or more⁷cfu/mL。

In some embodiments of the first aspect, the concentration of the surfactant in the microbial foam drainage agent is from 10 to 75 g/L.

In some embodiments of the first aspect, wherein the bacillus culture and the surfactant are each in parts by volume, based on the volume of the microbial foam drainage agent:

1-10 of the Bacillus culture

1-10 parts of surfactant.

In a second aspect, the present application provides a method of preparing a microbial foam drainage agent, comprising:

culturing bacillus to obtain a culture of the bacillus; optionally, the method further comprises mixing the culture of bacillus with a surfactant to obtain the microbial foam drainage agent.

In some embodiments of the second aspect, the culture is a liquid culture or a semi-solid culture.

In some embodiments of the second aspect, the Bacillus is Bacillus subtilis.

In some embodiments of the second aspect, the effective viable count of the Bacillus in the Bacillus culture is ≥ 5X 10⁷cfu/mL。

In some embodiments of the second aspect, the surfactant is a biosurfactant.

In some embodiments of the second aspect, the concentration of the surfactant is from 50 to 300 g/L.

In some embodiments of the second aspect, the effective viable count of the Bacillus in the microbial foam drainage agent is 5X 10 or more⁷cfu/mL。

In some embodiments of the second aspect, the concentration of the surfactant in the microbial foam drainage agent is from 10 to 75 g/L.

In some embodiments of the second aspect, wherein the bacillus culture and the surfactant are each in parts by volume, based on the volume of the microbial foam drainage agent:

1-10 of the Bacillus culture

1-10 parts of surfactant.

In a third aspect, a method of draining or assisting in draining a gas well, comprises:

injecting into a gas well from 0.1% to 10% (w/w) of the daily water production of the gas well the microbial foam drainage agent of the first aspect or the microbial foam drainage agent prepared by the method of the second aspect.

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 3 to 20 days 0.1% to 10% (w/w) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent prepared by the method of the second aspect.

In a fourth aspect, the present application provides use of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent prepared by the method of the second aspect in natural gas extraction or assisted natural gas extraction.

Detailed Description

The following definitions and methods are provided to better define the present application and to guide those of ordinary skill in the art in the practice of the present application. Unless otherwise indicated, terms are to be understood in accordance with their ordinary usage by those of ordinary skill in the relevant art. All patent documents, academic papers, and other publications cited herein are incorporated by reference in their entirety.

Definition of

The term "natural gas" as used herein refers to a mixture of hydrocarbon and non-hydrocarbon gases that are naturally resident in a subterranean formation. In petrogeology, oil field gas and gas field gas are commonly referred to, and their composition is predominantly hydrocarbon and contains non-hydrocarbon gases. In some embodiments of the present application, the natural gas includes conventional natural gas and unconventional natural gas (e.g., shale gas). In some embodiments of the present application, shale gas refers to natural gas that is rich in organic matter, mature dark or high carbon shale, which has stored and maintained some commercially valuable biogenic, pyrogenic, and mixed biogenic sources due to organic adsorption or the presence of cracks and matrix pores in the rock.

The term "gas well" as used herein refers to a well drilled from the surface to a gas formation for the production of natural gas. In some embodiments of the present application, the gas wells include conventional natural gas wells and unconventional natural gas wells (e.g., shale gas wells).

The term "microbial foam drainage agent" as used herein refers to a product of a biological foam drainage system comprising an effective microbial species as an active ingredient, which may additionally comprise a carrier or excipient formulation, and may also comprise other substances that facilitate the growth metabolism or maintain activity of the strain, e.g., culture media, trace elements, vitamins, amino acids, broths, and the like. In some embodiments, the microbial foam drainage agent further comprises a surfactant.

The term "culture" as used herein refers to a microbial preparation formed by fermentation of a microbial species on a specific medium under the control of specific process conditions, which mainly comprises the cell population of the microbial species, extracellular metabolites of the microbial species and the medium after fermentation.

The term "surfactant" as used herein refers to a substance that is capable of causing a significant reduction in the surface tension of a target solution. Has fixed hydrophilic and lipophilic groups and can be directionally arranged on the surface of the solution.

The term "biosurfactant" as used herein refers to a metabolite secreted by a microorganism during metabolism under certain conditions and having a certain surface activity. Biosurfactants include many different classes. They can be classified into glycolipids, lipopeptides, fatty acids and phospholipids, neutral lipids, and polymeric surfactants according to their structural characteristics and microbial origin. Biosurfactants not only have the common properties of surfactants such as solubilization, emulsification, wetting, foaming, dispersion, surface tension reduction and the like, but also have the advantages of no toxicity, biodegradability, ecological safety, high surface activity and the like compared with other surfactants produced by chemical synthesis or petroleum refining methods. The biosurfactant as a biosurfactant has low toxicity, good compatibility with human bodies and the environment, good characteristics of emulsification, dispersion, solubilization and the like, and has research and development values in many fields. In some embodiments of the present application, the biosurfactant is selected from the group consisting of: lipopeptides, fatty acids, algal glycolipids and gramicidin.

The term "lipopeptide" as used herein refers to a class of biosurfactants of microbial origin that have good potential for use in a variety of fields. Lipopeptide substances are usually mixtures, and chemical mechanisms of the lipopeptide substances comprise nonpolar hydrophobic groups and polar hydrophilic groups which are connected by chemical bonds, so that the lipopeptide substances are asymmetric in structure, have strong polarity profile water-oil amphipathy and can greatly reduce surface tension and interfacial tension.

Drawings

Fig. 1 shows a foam state after being left for 10 minutes using the microbial foam drainage agent of the present application.

Fig. 2 shows a foam state after standing for 2 hours using the chemical foaming drainage agent.

Detailed Description

In a first aspect, the present application provides a microbial foam drainage agent comprising a bacillus; optionally, the microbial foam drainage agent further comprises a surfactant.

In some embodiments of the first aspect, the microbial foam drainage agent comprises a culture of the bacillus.

In a second aspect, the present application provides a method of preparing a microbial foam drainage agent, comprising:

culturing bacillus to obtain a culture of the bacillus; optionally, the method further comprises mixing the culture of bacillus with a surfactant to obtain the microbial foam drainage agent.

In some embodiments of the second aspect, the culture is a liquid culture or a semi-solid culture.

In some embodiments of the second aspect, the culturing is liquid culturing.

In some embodiments of the second aspect, the bacillus is mixed with the surfactant at a volumetric ratio at 40 ℃.

In a third aspect, a method of draining or assisting in draining a gas well, comprises:

injecting into a gas well a microbial foam drainage agent of the first aspect or prepared by the method of the second aspect with a daily water production of the gas well of 0.1% to 10% (w/w) (e.g., 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% (w/w), or a range consisting of any two of the foregoing values).

In some embodiments of the third aspect, the microbial foam drainage agent of the first aspect or the microbial foam drainage agent prepared by the method of the second aspect is injected into a gas well at a water production per day of the gas well of 0.5% to 5% (w/w) (e.g., 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5% (w/w), or a range consisting of any two of the above values).

In some embodiments of the third aspect, the microbial foam drainage agent of the first aspect or the microbial foam drainage agent prepared by the method of the second aspect is injected into a gas well at a daily water production of the gas well of 0.5%, 1%, 2%, 3%, 4%, or 5% (w/w) of water.

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 3 to 20 days (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 days, or a range of any two values thereof) a daily water production of the gas well of 0.1% to 10% (w/w) (e.g., 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% (w/w), or a range of any two values thereof) of the microfoam drainage agent of the first aspect or the microfoam drainage agent produced by the method of the second aspect.

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 5 to 15 days (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 days, or a range of any two values thereof) a daily water production of the gas well of 0.1% to 10% (w/w) (e.g., 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% (w/w), or a range of any two values thereof) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent produced by the method of the second aspect.

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 5, 7, 10, or 15 days, from 0.1% to 10% (w/w) (e.g., 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% (w/w), or a range consisting of any two of the above) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent produced by the method of the second aspect.

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 3 to 20 days (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 days, or a range of any two values thereof) a daily water production of the gas well of 0.5% to 5% (w/w) (e.g., 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5% (w/w), or a range of any two values thereof) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent produced by the method of the second aspect.

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 5 to 15 days (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 days, or a range of any two values thereof) a daily water production of the gas well of 0.5% to 5% (w/w) (e.g., 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5% (w/w), or a range of any two values thereof) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent produced by the method of the second aspect.

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 5, 7, 10, or 15 days an amount of water produced by the gas well daily (e.g., 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5% (w/w), or a range consisting of any two of the foregoing) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent produced by the method of the second aspect.

In some embodiments of the third aspect, the method further comprises injecting into the gas well 0.5%, 1%, 2%, 3%, 4%, or 5% (w/w) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent produced by the method of the second aspect every 3 to 20 days (e.g., 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 days, or a range consisting of any two of the above values).

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 5 to 15 days (e.g., 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 days, or a range consisting of any two of the above values) 0.5%, 1%, 2%, 3%, 4%, or 5% (w/w) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent produced by the method of the second aspect.

In some embodiments of the third aspect, the method further comprises injecting into the gas well every 5, 7, 10, or 15 days with 0.5%, 1%, 2%, 3%, 4%, or 5% (w/w) of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent produced by the method of the second aspect.

In some embodiments of the third aspect, the amount of microbial foam drainage agent subsequently injected into the gas well may be the same as the amount of microbial foam drainage agent first injected.

In some embodiments of the third aspect, the amount of microbial foam drainage agent subsequently injected into the gas well may be different than the amount of microbial foam drainage agent first injected.

In exemplary embodiments, a method of draining or assisting in draining a gas well includes one or more of the following steps:

1) injecting into the gas well a microbial foam drainage agent having a gas well water production daily of 0.1-10% (w/w) (e.g., 0.5%, 1%, 2%, 3%, 4%, or 5% (w/w));

2) injecting 0.1% -10% (w/w) (e.g., 0.5%, 1%, 2%, 3%, 4%, or 5% (w/w)) of a microbial foam drainage agent into the gas well every 3-20 days (e.g., 5, 7, 10, or 15 days);

3) daily natural gas production was monitored.

In a fourth aspect, the present application provides use of the microbial foam drainage agent of the first aspect or the microbial foam drainage agent prepared by the method of the second aspect in natural gas extraction or assisted natural gas extraction.

In some embodiments of any of the aspects above, the Bacillus is Bacillus subtilis.

In some embodiments of any of the above aspects, the bacillus subtilis used herein may be obtained by conventional screening, commercial means, or other means.

In some embodiments of any of the above aspects, the Bacillus subtilis described herein is commercially available, alternatively, the above strain is available from Shaanxi Ridge Microbiol technologies, Inc. (address: 1502, International City, Chao, Hay, Gao, Hay, province, Shanxi province, Chao, Japan, code: 710065).

In some embodiments of any of the above aspects, the bacillus culture consists of the bacillus and a culture medium.

In some embodiments of any of the above aspects, the method of preparing the bacillus culture comprises:

inoculating Bacillus into sterilized fermentation medium, culturing at 28-37 deg.C (such as 35 deg.C) under aeration for 48-72 hr (such as 48 hr), and microscopic examination to obtain fermentation liquid with effective viable count of Bacillus being 1 × 10 or more⁸cfu/mL。

In some embodiments of any of the above aspects, the bacillus liquid culture comprises a population of bacillus cells, a bacillus metabolite (e.g., a lipopeptide, a protease, a lipase, a cellulase, an alpha-amylase, lactic acid, gramicidin, etc.), and a liquid culture medium after fermentation.

In some embodiments of any of the above aspects, the lipopeptide can act as a biosurfactant with foaming properties.

In some embodiments of any of the above aspects, the effective viable count of the Bacillus in the Bacillus culture is ≥ 5 × 10⁷cfu/mL。

In some embodiments of any of the above aspects, the effective viable count of the Bacillus in the Bacillus culture is ≧ 1X 10⁸cfu/mL。

In some embodiments of any of the above aspects, the effective viable count of the Bacillus in the Bacillus culture is ≧ 1X 10⁹cfu/mL。

In some embodiments of any of the above aspects, the medium in which the bacillus is cultured is a liquid medium or a semi-solid medium.

In some embodiments of any of the aspects above, the medium in which the bacillus is cultured is a liquid medium.

In some embodiments of any of the above aspects, the composition of the liquid medium is as follows: 1% (w/v) yeast extract, 1.5% (w/v) fish peptone, 2% (w/v) corn steep liquor, 0.5% (w/v) monopotassium phosphate, 0.02% (w/v) magnesium sulfate and 0.5% (w/v) sodium chloride, and the pH of the liquid medium was 7.2.

In some embodiments of any of the above aspects, the effective viable count of the Bacillus in the microbial foam drainage agent is 5X 10 or more⁷cfu/mL。

In some embodiments of any of the above aspects, the effective viable count of the Bacillus in the microbial foam drainage agent is ≥ 1 × 10⁸cfu/mL。

In some embodiments of any of the above aspects, the effective viable count of the Bacillus in the microbial foam drainage agent is ≥ 1 × 10⁹cfu/mL。

In some embodiments of any of the above aspects, the microbial foam drainage agent consists of the bacillus culture.

In some embodiments of any of the above aspects, the microbial foam drainage agent consists of a bacillus subtilis culture.

In some embodiments of any of the aspects above, the surfactant is a biosurfactant.

In some embodiments of any of the above aspects, the surfactant is selected from: lipopeptides, fatty acids, algal glycolipids and gramicidin.

In some embodiments of any of the aspects above, the surfactant is a lipopeptide.

In some embodiments of any of the foregoing aspects, the surfactant concentration is 50-300g/L (e.g., 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300g/L, or a range consisting of any two of the foregoing values).

In some embodiments of any of the foregoing aspects, the surfactant concentration is 75-200g/L (e.g., 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200g/L, or a range consisting of any two of the above values).

In some embodiments of any of the foregoing aspects, the surfactant concentration is from 75 to 250g/L (e.g., 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250g/L, or a range consisting of any two of the above values).

In some embodiments of any of the foregoing aspects, the concentration of the surfactant in the microbial foam drainage agent is from 10 to 75g/L (e.g., 10, 15, 16, 17, 18, 18.05, 18.10, 18.15, 18.20, 18.25, 18.30, 18.35, 18.40, 18.45, 18.50, 18.55, 18.60, 18.65, 18.70, 18.75, 18.80, 18.85, 18.90, 18.95, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75g/L, or a range consisting of any two values thereof).

In some embodiments of any of the foregoing aspects, the concentration of the surfactant in the microbial foam drainage agent is 15-50g/L (e.g., 15, 16, 17, 18, 18.05, 18.10, 18.15, 18.20, 18.25, 18.30, 18.35, 18.40, 18.45, 18.50, 18.55, 18.60, 18.65, 18.70, 18.75, 18.80, 18.85, 18.90, 18.95, 19, 20, 25, 30, 35, 40, 45, 50g/L, or a range consisting of any two of the foregoing values).

In some embodiments of any of the foregoing aspects, the concentration of the surfactant in the microbial foam drainage agent is from 18.75 to 50g/L (e.g., 18.75, 18.80, 18.85, 18.90, 18.95, 19, 20, 25, 30, 35, 40, 45, 50g/L, or a range consisting of any two of the foregoing values).

In some embodiments of any of the above aspects, wherein the bacillus culture and the surfactant are each in parts by volume, based on the volume of the microbial foam drainage agent:

1-10 of the Bacillus culture

1-10 parts of surfactant.

In some embodiments of any of the above aspects, the bacillus culture and the surfactant are in a volumetric ratio of 1:1 to 1:10 (e.g., 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, or a range consisting of any two of the foregoing values).

In some embodiments of any of the above aspects, the bacillus culture and the surfactant are in a 1:1, 1:2, 1:3, 1:4, 1:5, or 1:10 volume ratio.

In some embodiments of any of the above aspects, the bacillus culture and the surfactant are in a 1:3 or 1:4 volume ratio.

In some embodiments of any of the above aspects, the microbial foam drainage agent consists of the bacillus culture and the surfactant.

In some embodiments of any of the above aspects, the microbial foam drainage agent consists of a bacillus subtilis culture and a biosurfactant.

In some embodiments of any of the above aspects, the microbial foam drainage agent consists of a bacillus subtilis culture and a lipopeptide.

In some embodiments, the microbial foam drainage agent for natural gas production or assisted natural gas production provided herein achieves at least one of the following effects:

1) the selected microbial foam water discharging agent can reduce the surface tension of liquid, and the microbial foam water discharging agent is fully mixed with bottom accumulated liquid by stirring natural gas to generate a large amount of low-density water-containing foam, and the bottom accumulated liquid can be taken out.

2) The microbial foam drainage agent has the following characteristics: (1) can be completely biodegraded; (2) has the characteristics of high temperature resistance, high salt content and high condensate oil content; (3) a large amount of foam can be generated in the drainage and gas production process, and the foam can be quickly and thoroughly eliminated after reaching the ground without using any defoaming agent; (4) after the produced fluid reaches the ground and is kept stand, the generated emulsion is automatically demulsified, and a plurality of problems of post-treatment are reduced.

3) The microbial foam drainage agent can obviously improve the productivity of a natural gas well.

4) The microbial foam drainage agent has good compatibility with stratum, cannot generate denaturation phenomenon, and cannot cause stratum blockage in the near wellbore area.

The following examples are for the purpose of illustration only and are not intended to limit the scope of the present application.

Examples

Example 1 Effect of microbial species on surface tension of formation Water

The experimental samples were produced water and condensate in Su Li Ge block of Changqing oil field.

The formula of the culture medium for culturing the bacillus subtilis comprises the following components: 1% (w/v) yeast extract powder, 1.5% (w/v) fish peptone, 2% (w/v) corn steep liquor, 0.5% (w/v) potassium dihydrogen phosphate, 0.02% (w/v) magnesium sulfate and 0.5% (w/v) sodium chloride, and the pH was 7.2.

Culturing Bacillus subtilis in the above culture medium at 35 deg.C for 48 hr to obtain Bacillus subtilis culture with effective viable count of 1 × 10 or more⁸cfu/mL。

A sample for determining the effect of microbial strains on the surface tension of formation water consists of 97% (w/w) formation water and 2% (w/w) condensate oil, and is sterilized, inoculated with 1% (w/w) Bacillus subtilis culture, and cultured at 60 ℃ for 48 h. The surface tension of the treated sample was measured using a liquid surface tensiometer (Dataphysics, Germany). The control group was prepared by adding 1% (w/w) of the medium instead of 1% (w/w) of the Bacillus subtilis culture.

The liquid surface tension test results of the experimental group and the control group are shown in table 1, and the results show that: compared with the control group, the surface tension of the formation water can be obviously reduced after the bacillus subtilis is used for treatment, and foam drainage of a gas well is facilitated.

TABLE 1 influence of microbial strains on surface tension of formation water

Example 2 comparative experiment of microbial foam drainage agent and chemical foam drainage agent

The experimental samples were produced water and condensate in Su Li Ge block of Changqing oil field.

The formulation of the medium and the cultivation method for cultivating Bacillus subtilis were the same as in example 1. The effective viable count of the bacillus subtilis in the cultured bacillus subtilis culture is more than or equal to 5 multiplied by 10⁹cfu/mL。

Selecting liquid lipopeptide, wherein the concentration of the lipopeptide is 75-200 g/L.

Uniformly mixing the bacillus subtilis culture and the lipopeptide according to the proportion of 1:3(v/v) to prepare the microbial foam drainage agent. In the microbial foam drainage agent, the effective viable count of the bacillus subtilis culture is more than or equal to 1 multiplied by 10⁹cfu/mL, the concentration of lipopeptide is 18.75-50 g/L.

The chemical foam water-discharging agent is a solid foam water-discharging agent sulfonate composite surfactant (UT-6, Chengdifuji science and technology, Inc.) for gas production currently used in three fields of gas production in Changqing oil fields, and is directly added from an oil sleeve annulus according to the weight ratio of the required daily water yield when in use.

The formation water was used in an amount of 1000mL (pH6.61, salinity 140PPT), and both the microbial foam drainage agent and the chemical foam drainage agent were added in amounts of 0.5% (w/w) and 1% (w/w) of the formation water, and then a gas pipe was inserted into the bottom of the measuring cylinder to stabilize the gas supply, and the results are shown in Table 2 and show that: the microbial foam drainage agent and the chemical foam drainage agent have the best drainage effect at 70 ℃, and both of the microbial foam drainage agent and the chemical foam drainage agent can drain water completely at the addition of 1% (w/w), but the use time of the microbial foam drainage agent is shorter.

TABLE 2 comparison of the results of the experiments with the microbial foam drainage agent and the chemical foam drainage agent

At 70 ℃ and at an addition amount of 1% (w/w), after drainage using the microbial foam drainage agent and the chemical foam drainage agent is finished, the microbial foam drainage agent group has little foam remaining after standing for 10min without using a defoaming agent and can naturally defoam under a ground temperature condition (fig. 1); while the chemical foam drainage agent group foam stably existed and did not change substantially after standing for 2h (fig. 2). Example 3 in-situ experiment of the microbial foam drainage agent for gas wells in certain operation area of a Suliger gas field

The formulation of the medium and the cultivation method for cultivating Bacillus subtilis were the same as in example 1. The effective viable count of the bacillus subtilis in the cultured bacillus subtilis culture is more than or equal to 5 multiplied by 10⁸cfu/mL。

Selecting liquid lipopeptide biosurfactant, wherein the concentration of the lipopeptide is 75-250 g/L.

Uniformly mixing the bacillus subtilis culture and the lipopeptide according to the proportion of 1:4(v/v) to prepare the microbial foam drainage agent. In the microbial foam drainage agent, the effective viable count of the bacillus subtilis culture is more than or equal to 1 multiplied by 10⁸cfu/mL, the concentration of lipopeptide is 15-50 g/L.

The basic conditions of the selected gas wells are shown in table 3. The field experiments were performed with different injection ratios and intervals, and the experimental results are shown in table 4.

TABLE 3 basic conditions of the experimental gas well in the field of the microbial foam drainage agent

TABLE 4 field experiment results of gas well microbial foam drainage agent

The results in table 4 show that: the microbial foam drainage agent has the advantages of being remarkable in drainage effect of a gas well, capable of remarkably improving the productivity of a natural gas well, good in using effect and high in economic benefit, and suitable for being popularized and applied in a gas field in a large range.

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.