Method for reducing oxygen produced by fireflood production well and related working system

Abstract

The invention discloses a method for reducing oxygen produced by a fireflooding production well and a related working system. The method comprises the following steps: mixing a nutritional agent containing clear water, glucose, ammonium chloride, corn steep liquor dry powder and sodium dihydrogen phosphate with an aerobic microorganism bacterial solution to prepare a working solution; slowly injecting the prepared working fluid into a well through a pump truck; and closing the well until the preset duration is reached, and recovering the production of the oil field. According to the method, the aerobic microorganisms can be effectively activated by injecting the aerobic microorganism solution and the matched nutritional agent into the stratum in a biological oxygen consumption mode, so that the aerobic microorganisms can be effectively propagated and quickly consume the oxygen in the stratum; the oxygen content of stratums, wellbores and immediate vicinity of wellbores is reduced to a safe range in a short time, so that normal production of oil wells is guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil production engineering, in particular to a method for reducing oxygen output of a fire flooding production well and a related working system. BACKGROUND

[0002] Fire flooding technology is an important thermal recovery method for heavy oil, which realizes in-situ combustion by continuously injecting air into the formation through an air injection well and igniting the oil layer, so as to push the formation crude oil to the production well. Since fire flooding is a thermal recovery technology that generates heat by injecting oxygen and fuel into the formation, there is a risk of explosion of oxygen mixture in each link of the air injection process, which is mainly because the injected air contains oxygen, and the oxygen reacts with the crude oil in the reservoir to consume part of the oxygen. However, in the case of incomplete oxidation reaction, the light hydrocarbon components in the formation will form a mixed explosive gas with oxygen, which will explode under certain conditions when the concentration of the mixed gas reaches the explosion range. Therefore, gas monitoring and analysis must be performed on the production well during fire flooding production, and the components of the produced gas should at least include oxygen, methane and carbon dioxide. When the oxygen content is too high, only measures such as stopping injection and shutting in the well can be taken, which greatly affects the normal production of the well. SUMMARY

[0003] In view of the above problems, the present application is proposed to provide a method for reducing oxygen output of a fire flooding production well and a related working system to overcome the above problems or at least partially solve the above problems.

[0004] In a first aspect, an embodiment of the present application provides a method for reducing oxygen output of a fire flooding production well, comprising:

[0005] Mixing a nutrient agent containing clean water, glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate with an aerobic microbial bacteria solution to prepare a working solution;

[0006] Slowly injecting the prepared working solution into the well through a pump truck;

[0007] Shutting in the well until the production of the oilfield is resumed after a predetermined time period.

[0008] In one embodiment, the concentrations of glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate in the nutrient agent are: glucose 0.3-0.4%, ammonium chloride 0.3-0.4%, corn syrup dry powder 0.1-0.2%, and sodium dihydrogen phosphate 0.1-0.2%.

[0009] In one embodiment, the aerobic microbial bacteria solution is a hydrocarbon-oxidizing bacteria solution, wherein the concentration of the hydrocarbon-oxidizing bacteria is 2-5%.

[0010] In one embodiment, the nutrient agent comprising clean water, glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate is prepared by the following way:

[0011] Add the required mass of glucose into the clean water pool and stir;

[0012] Continue to add clean water and sequentially add ammonium chloride, corn syrup dry powder, sodium dihydrogen phosphate and continue to stir until the glucose, ammonium chloride, sodium dihydrogen phosphate are fully dissolved and mixed evenly with the corn syrup.

[0013] In one embodiment, before the step of slowly injecting the prepared working fluid into the well through the pump truck, further comprising:

[0014] Opening the casing and tubing valves, testing the casing ground surface pipeline, and starting the working fluid injection step after the testing is qualified.

[0015] In one embodiment, slowly injecting the prepared working fluid into the well through the pump truck, comprising:

[0016] Opening the casing and tubing valves, using the pump truck to slowly inject the working fluid into the wellbore, and the injection displacement is controlled according to the pressure;

[0017] After the working fluid fills the entire wellbore, closing the tubing valve;

[0018] Continuing to slowly inject the remaining working fluid into the formation with the pump truck, and the injection displacement is controlled according to the pressure.

[0019] In one embodiment, shutting in until a preset time length is reached, comprising:

[0020] Shutting in by closing the casing valve and waiting for 48 hours.

[0021] In one embodiment, after the production of the oilfield is resumed, further comprising:

[0022] Periodically monitoring the concentration of hydrocarbon-oxidizing bacteria and the oxygen content in the produced liquid.

[0023] In one embodiment, the content of oxygen in the wellbore and the near-wellbore range is monitored, and if the oxygen content is not greater than 5%, it is determined that the production is safe.

[0024] In a second aspect, an embodiment of the present application provides a working system for reducing oxygen production in a fire flooding production well, characterized in that it comprises a tank truck, a liquid preparation pool and a pump truck.

[0025] The tank truck is used to transport clean water to the liquid preparation pool.

[0026] The liquid preparation tank is used for mixing the nutrient agent containing clean water, glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate with the bacterial liquid to prepare the working liquid, wherein the concentrations of the glucose, the ammonium chloride, the corn syrup dry powder and the sodium dihydrogen phosphate are respectively: 0.3%-0.4% of glucose, 0.3-0.4% of ammonium chloride, 0.1-0.2% of corn syrup dry powder and 0.1-0.2% of sodium dihydrogen phosphate;

[0027] The pump truck is used for slowly injecting the prepared working liquid into the well.

[0028] The beneficial effects of the above technical solutions provided by the embodiments of the present application at least include:

[0029] The embodiments of the present application utilize the oxygen consumption mode of the biological consumption, and by injecting the aerobic microbial solution and the matched nutrient agent into the formation, the aerobic microorganisms can be effectively activated, the aerobic microorganisms can be effectively multiplied and rapidly consume the oxygen in the formation, and the oxygen content in the formation, the wellbore and the near wellbore zone is reduced to the safety range in a short time, so as to ensure the normal production of the oil well.

[0030] Further, the embodiments of the present application utilize the hydrocarbon-oxidizing bacteria liquid and the matched nutrient agent as the working liquid, the hydrocarbon-oxidizing bacteria is a kind of microorganism which can utilize hydrocarbon as carbon source and energy material to grow, can be well activated and multiply in large quantities in the well, and under the aerobic condition, can perform aerobic respiration by taking oxygen as the electron acceptor to obtain energy by oxidizing the hydrocarbon material; can rapidly consume the oxygen in the formation, the wellbore and the near wellbore zone, and realize the effect of reducing the oxygen in a short time, and improve the efficiency of reducing the oxygen in the formation, the wellbore and the near wellbore zone.

[0031] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be achieved and obtained by means of the structures particularly pointed out in the written description, the claims, and the accompanying drawings.

[0032] The technical solutions of the present application will be further described in detail below by means of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0033] The accompanying drawings are used to provide further understanding of the present application, and constitute a part of the specification, and are used to explain the present application together with the embodiments of the present application, and do not constitute a limitation to the present application. In the drawings:

[0034] Figure 1 The flow chart of the method for reducing the oxygen output of the fire flooding production well in the embodiments of the present application;

[0035] Figure 2A structural block diagram of a working system for reducing oxygen production of a fire flooding production well in an embodiment of the present application. DETAILED DESCRIPTION

[0036] Exemplary embodiments of the present disclosure will be described in greater detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be accurately conveyed to those skilled in the art.

[0037] The inventors of the present application found that in the prior art, there can be multiple ways to process the fire flooding production gas of an oilfield, for example, the patent application with publication number CN113803049A, which mainly solves the problem of low recovery and utilization rate of the fire flooding production gas of an oilfield, and the produced gas is introduced into a gas-liquid separation device, and the separated produced gas is detected and analyzed, and the remaining gas after classification treatment is transported and injected back into the oil reservoir, but it does not involve a processing method for solving the problem of high oxygen content.

[0038] For example, the buffer oxygen removal device for the fire flooding oilfield associated gas combustion converter disclosed in the patent application with publication number CN109609222A can remove oxygen in the hot fluid formed by the combustion conversion of the fire flooding oilfield associated gas, and the buffer oxygen removal device for the fire flooding oilfield associated gas combustion converter includes a shell body, the shell body is filled with an oxygen removal filler unit capable of removing oxygen in the hot fluid, and the oxygen removal filler unit can move and remove the oxidation layer by friction. The filler in the device can effectively remove excess oxygen in the hot fluid formed by the combustion conversion of the fire flooding oilfield associated gas, and realizes safe and reliable continuous recovery and utilization of the hot fluid formed by the combustion conversion of the fire flooding oilfield associated gas, but the device cannot solve the problem of high oxygen content in the production well.

[0039] The above-mentioned prior art still cannot solve the problem of high oxygen content in the production well.

[0040] Based on the problem of high oxygen content in the production well, especially in the formation, in the prior art, which may form a mixed explosive gas with the light hydrocarbon components in the formation, causing a safety hazard, an embodiment of the present application provides a method for reducing the production of oxygen in a fire flooding production well, as shown in Figure 1 The method comprises the following steps:

[0041] S1, mixing a nutrient agent containing clean water, glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate with an aerobic microbial solution to prepare a working solution;

[0042] S2, slowly injecting the prepared working solution into the well through a pump truck;

[0043] S3, shut-in and seal until a preset time length is reached, and then resume production of the oilfield.

[0044] The embodiment of the present application utilizes the way of biological oxygen consumption, and by injecting the aerobic microbial solution and the matching nutrient agent into the well to the formation, the aerobic microorganisms can be effectively activated, so that the aerobic microorganisms can be effectively multiplied and rapidly consume the oxygen in the formation, and the oxygen content in the formation, the wellbore and the near wellbore zone is reduced to the safe range in a short time, so as to ensure the normal production of the oil well.

[0045] The aerobic microorganism is a microorganism that can grow and multiply in an aerobic environment. In the energy metabolism process of oxidizing organic or inorganic matter, the aerobic microorganism takes molecular oxygen as the final electron acceptor and performs aerobic respiration. In the embodiment of the present application, the aerobic microbial solution can be a Pseudomonas aeruginosa hydrocarbon-oxidizing bacteria solution.

[0046] The reason for using hydrocarbon-oxidizing bacteria (HoB) is that the hydrocarbon-oxidizing bacteria is a kind of microorganism that can use hydrocarbons as carbon source and energy source to grow, and can be well activated and multiply in the well, and under aerobic conditions, the hydrocarbon-oxidizing bacteria takes oxygen as the electron acceptor to perform aerobic respiration and obtain energy by oxidizing hydrocarbons. The hydrocarbon-oxidizing bacteria can rapidly consume the oxygen in the formation, the wellbore and the near wellbore zone, and can also produce a series of hydrocarbon-degrading enzymes through its own metabolic action, and through cracking heavy hydrocarbons, the hydrocarbon-oxidizing bacteria can convert macromolecular substances in the hydrocarbons into small molecular substances. The biological degradation can also reduce the viscosity of crude oil and improve the flow performance of the crude oil.

[0047] In one embodiment, the concentration of the hydrocarbon-oxidizing bacteria in the aerobic microbial solution is 2-5% (mass ratio).

[0048] In one embodiment, the concentrations (mass percentage) of glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate in the nutrient agent are as follows: glucose 0.3%-0.4%, ammonium chloride 0.3-0.4%, corn syrup dry powder 0.1-0.2%, and sodium dihydrogen phosphate 0.1-0.2%.

[0049] Further, the nutrient agent can be prepared by the following method:

[0050] Add the required mass of glucose into the water pool and stir;

[0051] Continue to add water and sequentially add appropriate amounts of ammonium chloride, corn syrup dry powder, sodium dihydrogen phosphate, and continue to stir until the glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate are dissolved and uniformly mixed.

[0052] For example, add clean water in the pool, open the stirrer switch, start stirring, continue to add clean water and add other reagents in turn, such as appropriate amount of ammonium chloride, corn syrup dry powder, sodium dihydrogen phosphate, and continue to add appropriate clean water to meet the above concentration requirements after all reagents are added, stop adding water, and continue stirring until the glucose, ammonium chloride and sodium dihydrogen phosphate are fully dissolved and uniformly mixed with the corn syrup dry powder.

[0053] Before the step of slowly injecting the prepared working fluid into the well through the pump truck in the above step S2, the embodiment of the present application also needs to perform the following steps: opening the casing and tubing valves, testing the casing ground surface pipeline, and starting the working fluid injection after the test is qualified.

[0054] In one embodiment, the slow injection of the prepared working fluid into the well through the pump truck in the above step S2 can be achieved by the following method:

[0055] 1. Open the casing valve and the tubing valve, and use the pump truck to slowly inject the working fluid into the wellbore, and the injection displacement is controlled according to the pressure;

[0056] 2. After the working fluid fills the entire wellbore, close the tubing valve;

[0057] 3. Continue to slowly inject the remaining working fluid into the formation with the pump truck, and the injection displacement is controlled according to the pressure.

[0058] In one embodiment, the well can be closed by closing the casing valve, and the oilfield production can be resumed after waiting for 48 hours.

[0059] In one embodiment, after the oilfield production is resumed, the concentration of hydrocarbon-oxidizing bacteria and the oxygen content in the produced liquid need to be monitored regularly.

[0060] Example 1: A well A field test in an oilfield:

[0061] The concentration of each component in the nutrient agent: glucose 0.40%, ammonium chloride 0.3%, corn syrup dry powder 0.2%, and sodium dihydrogen phosphate 0.1%.

[0062] The bacteria solution is a hydrocarbon-oxidizing bacteria solution with a concentration of 2%.

[0063] On-site preparation and injection method of the working fluid:

[0064] 1. When the clean water added to the pool is 1 / 3, open the water switch and add the required amount of glucose (which can be knocked and added);

[0065] 2. When the clean water added to the pool is 1 / 2, open the stirrer switch and start stirring;

[0066] 3. While stirring, continue to add clean water and add other reagents in turn;

[0067] 4. After all the medicaments are added, stop adding water when the water is 20 cm from the top of the tank, and continue stirring;

[0068] 5. Open the casing and tubing valves, and slowly inject the working fluid into the well using the pump truck at low displacement. After the entire wellbore is filled, close the tubing valve, and control the injection displacement in time according to the injection pressure.

[0069] 6. Continue to slowly inject the remaining working fluid into the formation using the pump truck at low displacement, and control the injection displacement in time according to the injection pressure.

[0070] 7. After the construction is completed, close the casing valve, remove the construction equipment, and open the well 48 hours after shutting down to resume production.

[0071] The oxygen content of the well before the above measures were taken was 14.89%, and after injecting the microorganisms, the oxygen content in the wellbore was reduced to 0.16% when the well was opened, which shows that the microorganisms consumed all the oxygen in the wellbore within 48 hours, achieving the purpose of making the microorganisms work in a short time. The bacterial concentration of the produced liquid of the oil well was maintained at 10 7 individuals / ml, and the oxygen content of the produced gas was maintained at 5%, which shows that the effect of reducing the oxygen content is obvious.

[0072] Example Two: Field Test of Well B in a Certain Oilfield

[0073] The concentrations of the components in the nutrient agent are: glucose 0.40%, ammonium chloride 0.38%, corn syrup dry powder 0.1%, and sodium dihydrogen phosphate 0.17%.

[0074] The bacterial solution is a hydrocarbon-oxidizing bacterial solution with a concentration of 5%.

[0075] Preparation of the working fluid on site and injection method:

[0076] 1. Open the water adding switch, and when 1 / 3 of the water is added to the tank, add the required amount of glucose (knock and add);

[0077] 2. When the water is added to 1 / 2 of the tank, open the stirrer switch and start stirring;

[0078] 3. While stirring, continue to add water and sequentially add other medicaments;

[0079] 4. After all the medicaments are added, stop adding water when the water is 20 cm from the top of the tank, and continue stirring;

[0080] 5. Open the casing and tubing valves, and slowly inject the working fluid into the well using the pump truck at low displacement. After the entire wellbore is filled, close the tubing valve, and control the injection displacement in time according to the injection pressure.

[0081] 6. Continue to use a pump truck to slowly inject the remaining working fluid into the formation at a low displacement, and control the injection displacement in a timely manner according to the injection pressure.

[0082] 7. After the construction is completed, close the casing valve, dismantle the construction equipment, and close the well. Reopen the well to resume production 48 hours later.

[0083] Serial Number | Unit | Name | Amount (Yuan) | Remarks Before implementing the above measures, the oxygen content of this well was 9.83%. With the corresponding ignition well's gas injection rate remaining unchanged, after injecting microorganisms, the oxygen content in the wellbore dropped to 0.47% upon opening the well. This indicates that the microorganisms consumed all the oxygen in the wellbore within 48 hours, achieving the goal of enabling the microorganisms to function quickly. During 7 days of continuous oil production, the bacterial concentration in the produced fluid remained at 10... 7 The oxygen content of the produced gas is less than 5%, and the effect of reducing oxygen is obvious.

[0084] This invention also provides a working system for reducing oxygen production in fire-driven production wells, as described in the following embodiments. Figure 2 As shown, it includes: tank trucks, liquid preparation tanks, and pump trucks; among which:

[0085] Tanker trucks are used to transport clean water to the mixing tank;

[0086] The solution preparation tank is used to mix the nutrient solution containing water, glucose, ammonium chloride, corn steep liquor powder, and sodium dihydrogen phosphate with the bacterial solution to prepare the working solution. The concentrations of glucose, ammonium chloride, corn steep liquor powder, and sodium dihydrogen phosphate are as follows: glucose 0.3%-0.4%, ammonium chloride 0.3%-0.4%, corn steep liquor powder 0.1%-0.2%, and sodium dihydrogen phosphate 0.1%-0.2%.

[0087] Pump trucks are used to slowly inject the prepared working fluid into the well.

[0088] Reference Figure 2 As shown, first open the casing and tubing valves, and the pump truck slowly injects the working fluid. After filling the entire wellbore, close the tubing valve. Then, the pump truck continues to inject the working fluid into the formation at a low rate until all the remaining working fluid has been injected. After the operation is completed, close the casing valve.

[0089] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method of reducing oxygen production from a fire flood production well, characterized by, The application relates to a method for improving oilfield production by using aerobic microorganisms. The method comprises the following steps: a nutrient agent containing clean water, glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate is mixed with an aerobic microorganism liquid to prepare a working liquid; the prepared working liquid is slowly injected into a well through a pump truck; 2. The method of claim 1, wherein, the well is closed until a preset time length is reached, and then the oilfield production is resumed.

3. The method of claim 1, wherein, In the nutrient agent, the concentrations of glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate are respectively 0.3%-0.4% of glucose, 0.3-0.4% of ammonium chloride, 0.1-0.2% of corn syrup dry powder and 0.1-0.2% of sodium dihydrogen phosphate.

4. The method of claim 1, wherein, The aerobic microorganism liquid is a hydrocarbon-oxidizing bacteria liquid, and the concentration of the hydrocarbon-oxidizing bacteria is 2-5%. The nutrient agent containing clean water, glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate is prepared by the following method: a required amount of glucose is added to a clean water pool and stirred; 5. The method of claim 1, wherein, clean water is continuously added, and ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate are sequentially added and continuously stirred until the glucose, ammonium chloride and sodium dihydrogen phosphate are fully dissolved and uniformly mixed with the corn syrup. Before the step of slowly injecting the prepared working liquid into the well through the pump truck, the method further comprises the following steps:

6. The method of claim 1, wherein, sleeve and tubing valves are opened, the sleeve is grounded to the ground pipeline, and the working liquid injection is started after the pressure test is qualified. The prepared working liquid is slowly injected into the well through the pump truck, which comprises the following steps: the sleeve valve and the tubing valve are opened, the working liquid is slowly injected into the well shaft by using the pump truck, and the injection displacement is controlled according to the pressure; after the working liquid fills the whole well shaft, the tubing valve is closed; 7. The method of claim 1, wherein, the remaining working liquid is slowly injected into the formation by using the pump truck, and the injection displacement is controlled according to the pressure. The well is closed until a preset time length is reached, which comprises the following steps:

8. The method according to any one of claims 1 to 7, wherein the well is closed by closing the sleeve valve, and the well is closed for 48 hours. After the oilfield production is resumed, the method further comprises the following steps:

9. The method of claim 8, wherein, the concentration of the hydrocarbon-oxidizing bacteria in the output liquid and the oxygen content are monitored regularly.

10. A working system for reducing oxygen production in a fire flood production well, characterized in that, The oxygen content in the well shaft and the near-well range is monitored, and if the oxygen content is not greater than 5%, it is determined that the production is safe. The application relates to a method for improving oilfield production by using aerobic microorganisms. The method comprises the following steps: a tank truck, a liquid preparation pool and a pump truck; the tank truck is used for transporting clean water to the liquid preparation pool; the liquid preparation pool is used for mixing a nutrient agent containing clean water, glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate with a liquid to prepare a working liquid, wherein the concentrations of glucose, ammonium chloride, corn syrup dry powder and sodium dihydrogen phosphate are respectively 0.3%-0.4% of glucose, 0.3-0.4% of ammonium chloride, 0.1-0.2% of corn syrup dry powder and 0.1-0.2% of sodium dihydrogen phosphate; the pump truck is used for slowly injecting the prepared working liquid into a well.

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