Method for improving efficiency of mechanical recovery system of high-wax high gas-liquid ratio reservoir and application thereof

Abstract

The application discloses a method for improving the efficiency of a mechanical mining system of a high-wax-content and high-gas-liquid-ratio oil reservoir, and discloses the application of the method in a high-wax-content and high-gas-liquid-ratio oil field.The method comprises the following steps: step 1, selecting a high-wax-content and high-gas-liquid-ratio oil field to be mined; step 2, using a single strain to carry out microbial single-well huff and puff on the reservoir stratum of the oil field to be mined, so as to remove the wax pollution near the wellbore; step 3, designing corresponding combined gas lift processes according to different gas-liquid ratios of single wells and combining operation running tools; and step 4, using a hollow rod electric heating rod string to heat crude oil in a tubing in the mining process, so as to increase the fluidity of the crude oil and prevent the rod and the tubing string from being waxed.The method provided by the application can solve the problem of low crude oil recovery rate caused by serious waxing in a wellbore.

Description

Technical Field

[0001] This invention belongs to the field of oil production technology, and relates to a method for improving the efficiency of mechanical oil production systems in reservoirs with high wax content and high gas-liquid ratio, as well as the application of the above-mentioned method for improving the efficiency of mechanical oil production systems in reservoirs with high wax content and high gas-liquid ratio. Background Technology

[0002] When using conventional oil recovery techniques, crude oil lifting is difficult, pumping unit loads are high, sucker rod loads are heavy, downhole resistance is high, and the downhole pump casing fill factor is low. Pump efficiency and mechanical oil recovery system efficiency are far lower than in conventional oilfields. Therefore, how to efficiently extract "double-high" oilfields with high wax content and high oil-gas ratios has become a current focus. Mechanical oil extraction is the foundation of oilfield extraction technology. When the reservoir energy is insufficient to sustain natural flow, mechanical energy is artificially supplemented from the surface to extract oil. Rod pump extraction primarily uses surface power equipment to drive the pumping unit, which in turn drives the deep well pump via the sucker rod. By rationally selecting and applying mechanical oil recovery technologies, crude oil can be extracted from the reservoir more effectively, improving the oilfield's recovery rate.

[0003] Meanwhile, the level of oil production technology and management directly affects the level of oilfield development. Pump efficiency, pump inspection cycle and system efficiency are important indicators that reflect the overall management level and energy consumption of a single well or block, and are a comprehensive reflection of the level of oil production engineering.

[0004] Crude oil with a wax content exceeding 10% and a gas-liquid ratio greater than 200 m 3 / m 3 The oilfield can be classified as a "high-wax-content, high-gas-liquid-ratio" reservoir, characterized by severe wax buildup in the wellbore. For mechanically pumped wells, this increases pump load, reduces pump efficiency, decreases production, and can even lead to wax blockage and production shutdowns. For flowing wells, it causes well stoppage, and if not addressed promptly, can result in wellbore and pump blockage, severely restricting normal production. Some mechanically pumped wells have experienced production declines and pump blockages within a short period, making overall production and development difficult, well maintenance challenging, and development costs high. Therefore, it is necessary to develop corresponding mechanical oil production technologies to address the conditions and well status of "high-wax-content" reservoirs, enabling effective oil production operations in various complex downhole environments and improving the overall efficiency of the oilfield's mechanical oil production system.

[0005] Currently, the conventional methods to improve the efficiency of the hoisting system of mechanical wells are as follows: (1) Optimize the surface equipment: For motors with low load rates, select the rated power reasonably according to the power of the polished rod and perform "large adjustment to small"; (2) Optimize the pumping unit: Select high-efficiency and energy-saving pumping units, such as heterogeneous crank balance pumping units, front-mounted pumping units, etc.; adjust the balance of the pumping unit in a timely manner, and keep the balance rate at 85% to 100%; (3) Reasonably select the pump type and pump diameter: Select the appropriate pump type according to the oil well's production, fluid properties, and supply capacity, such as sand control pumps. , thick oil pumps, etc.; for oil wells with sufficient fluid supply, the pump diameter can be appropriately increased; for oil wells with insufficient fluid supply, a small pump diameter should be selected; (4) Optimize rod and tubing combination: according to the oil well depth, well inclination, etc., the material and specifications of sucker rod and tubing should be reasonably selected, and high-strength, low-friction sucker rod and tubing should be used; tubing anchoring technology should be applied to reduce stroke loss; (5) Apply chemical viscosity reduction and wax prevention: for heavy oil wells and wells prone to waxing, chemical viscosity reducers should be used to reduce crude oil viscosity and reduce oil pumping resistance; wax prevention treatment should be carried out regularly to prevent wax blockage from affecting pump efficiency and system efficiency.

[0006] However, for the aforementioned "double-high" oil reservoirs with high wax content and high gas-liquid ratio, the wax buildup inside the wellbore is severe, and the above measures are not very effective and cannot meet the current needs of exploiting "double-high" oil fields. Summary of the Invention

[0007] The first objective of this invention is to provide a method for improving the efficiency of mechanical oil recovery systems in reservoirs with high wax content and high gas-liquid ratio. It provides a three-in-one process method that combines microbial huff and puff, combined gas lift, and electric heating of hollow sucker rods, which solves the problem of low crude oil recovery caused by severe wax buildup in the wellbore.

[0008] The second objective of this invention is to provide an application of the above-mentioned method for improving the efficiency of mechanical oil extraction systems in reservoirs with high wax content and high gas-liquid ratio.

[0009] The first technical solution adopted in this invention is a method for improving the efficiency of mechanical oil recovery systems in reservoirs with high wax content and high gas-liquid ratio, as detailed below: Step 1: Select oil fields with high wax content and high gas-liquid ratio for potential production; Step 2: Use a single strain of microorganisms to carry out single-well infusion in the oil reservoir of the oilfield to remove wax contamination in the near-wellbore area; Step 3: Design corresponding combined gas lift processes and combine them with the operation and deployment tools according to different gas-liquid ratios of single wells; Step 4: During the extraction process, hollow rod electric heating rods are used to heat the crude oil in the tubing, increasing the fluidity of the liquid and preventing wax from forming on the rods and tubing.

[0010] The invention is further characterized by: The selection criteria for oilfields with high wax content and high gas-liquid ratio in step 1 are as follows: Screening criteria for high wax content: Wax content in crude oil exceeds 10%; Screening criteria for high gas-liquid ratio: gas-liquid ratio greater than 200 m 3 / m 3 .

[0011] The specific method for step 2 is as follows: Microbial culture solution was injected into the annulus space using the casing annulus injection method, with an injection volume of 5-20 m³. 3 The injection displacement is 0.2~0.3 m³. 3 The injection rate is 10-15 MPa per minute. After complete injection, the well is shut in and incubated for 5-7 days before production begins.

[0012] The microbial culture solution specifically consists of a mixture of Bacillus belye S1 and its fermentation products, with a pH of 6.6–7.5 and a bacterial count ≥10⁻⁶. 8 The bacterial concentration in the mixture is 10%-30%, the nutrient solution concentration is 5%-10%, and the pH of the nutrient solution is 7.9-8.1.

[0013] Bacillus velezensis S1 is deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 28915 and deposit date November 8, 2023.

[0014] The combined airlift in step 3 specifically refers to the combined application of five air-control and air-prevention processes: counterweight ball pump, inner-shroud air-prevention device, multi-stage progressive high-efficiency separator, airlift valve, and jacketed air valve, as detailed below: For oil wells with a gas-liquid ratio of less than 50, mechanical production parameters of small pump diameter, long stroke, and slow stroke frequency are adopted, and the combination of "casing gas valve + heavy ball pump" is applied to keep the casing pressure control and back pressure balanced. For oil wells with a gas-liquid ratio of 50 to 100, the casing pressure control range is 1.5 to 2 MPa. An internal gas-proof device or a multi-stage progressive high-efficiency separator should be used. For oil wells with a gas-liquid ratio of 100 to 180 and a casing pressure control range of 1.5 to 2 MPa, a combination of "heavy ball pump + inner cover gas-proof device" or "heavy ball pump + multi-stage progressive high-efficiency separator" should be used. For oil wells with a gas-liquid ratio greater than 180, use a combination of "heavy ball pump + inner cover gas prevention device + gas lift valve" or a combination of "heavy ball pump + multi-stage progressive high-efficiency separator + gas lift valve" to close the wellhead oil casing connection gate.

[0015] The hollow electric heating rod in step 4 is a combination of φ36 hollow electric heating rods and φ34 hollow electric heating rods, and its specific usage is as follows: When the pump depth is less than 1000m, a combination of φ36 hollow rod electric heating and φ34 hollow rod electric heating rods is used in a 2:3 ratio, and a φ19 solid rod is connected to the oil pump. When the pump depth is greater than 1000m, a 400-meter φ36 hollow rod and a 600-meter φ34 hollow rod electric heating rod are used, and a φ19 solid rod of the corresponding length is connected according to the pump depth.

[0016] The specific method for using a hollow rod electric heating rod column to heat the crude oil in the tubing throughout the entire process in step 4 is as follows: When the liquid volume is greater than 10 cubic meters, the gas volume is greater than 1000 cubic meters, and the heating position has a submersion, a cyclic heating method of "heating for 4 hours and stopping heating for 12 hours" is adopted. When the liquid volume is 5-10 cubic meters, the gas volume is less than 500 cubic meters, the heating position has a submersion degree, and the water content is greater than 90%, heating is not required. When the liquid volume is less than 5 cubic meters, the gas volume is 500~1000 cubic meters, and the heating position has a submersion, a cyclic heating method of "heating for 2 hours and stopping heating for 6 hours" is adopted. When the liquid volume is less than 5 cubic meters, the gas volume is less than 500 cubic meters, and there is no submersion at the heating position, a cyclic heating method of "heating for 3 hours and stopping heating for 6 hours" is adopted.

[0017] The second technical solution adopted in this invention is the application of a method for improving the efficiency of mechanical oil extraction systems in reservoirs with high wax content and high gas-liquid ratio, and the application of this method in oilfields with high wax content and high gas-liquid ratio.

[0018] The beneficial effects of this invention are: (1) The method of improving the efficiency of mechanical pumping system in oil reservoirs with high wax content and high gas-liquid ratio of the present invention is to use a three-in-one matching process method of microbial huff and puff, combined gas lift and hollow sucker rod electric heating, and further optimize the combined process. This integrated combined process technology is applied to oil fields with high wax content and high gas-liquid ratio, which significantly improves the overall pump efficiency and mechanical pumping system efficiency of the oil field, supports the further improvement of oil recovery rate, and the overall input-output ratio is greater than 1:6. (2) The method of improving the efficiency of the high wax content and high gas-liquid ratio reservoir mechanical production system of the present invention removes wax contamination in the near-wellbore area through microbial inhalation and exhalation, ensures the formation compatibility of the well medium, and solves the problem of formation waxing caused by degassing in the near-wellbore area; by adopting a combined gas lift process, the phenomenon of "gas lock" in the wellbore during oil well production is avoided; by using hollow rod electric heating rod string to heat the crude oil in the tubing, the viscosity of the crude oil is reduced, the fluidity of the liquid is increased, and waxing of the rod and tubing string is prevented, so as to achieve the purpose of increasing oil well production and efficiency. Attached Figure Description

[0019] Figure 1 This is a cell morphology diagram of strain S1 during large-scale fermentation in the method for improving the efficiency of the machine-harvested system of the present invention. Figure 2 This is a static wax dissolution experiment diagram of Yingdong wax sample in the method for improving the efficiency of the machine-collected system of the present invention; Figure 3 This is a temperature test diagram of an electrically heated well for improving the efficiency of the mechanical mining system according to the present invention. Figure 4 This is a diagram showing the relationship between oilfield formation temperature and well depth in the method for improving the efficiency of the mechanical extraction system of this invention. Detailed Implementation

[0020] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0021] The methods for improving the efficiency of mechanical oil recovery systems in reservoirs with high wax content and high gas-liquid ratio are as follows: Step 1: Select oilfields with high wax content and high gas-liquid ratio for potential production; the selection criteria for oilfields with high wax content and high gas-liquid ratio are as follows: Screening criteria for high wax content: Wax content in crude oil exceeds 10%; Screening criteria for high gas-liquid ratio: gas-liquid ratio greater than 200 m 3 / m 3 .

[0022] Step 2: Use a single strain of microbial strain to carry out single-well infusion in the oil reservoir of the oilfield to be developed, and remove wax contamination in the near-wellbore area. The specific method is as follows: like Figure 1 As shown, during large-scale fermentation, the cell morphology of strain S1 was relatively uniform, exhibiting a discrete state. Individual cell outlines appeared as small, irregularly shaped, blue units in the field of view; for example... Figure 2 As shown, the static oil washing test results for tubing wax showed that the addition of microorganisms resulted in a faster wax removal rate and better wax removal effect than formation water, with a 5°C reduction in wax melting temperature. Based on the experimental results, the casing annulus injection method was used in the field to inject microbial solution into the casing annulus space at a volume of 5-20 m³. 3 The injection displacement is 0.2~0.3 m³. 3 The injection rate is 10-15 MPa per minute. After complete injection, the well is shut in and incubated for 5-7 days before production begins.

[0023] Furthermore, the microbial culture is specifically a mixture of Bacillus belye S1 and its fermentation products, with a pH of 6.6–7.5 and a bacterial count ≥10⁻⁶. 8The bacterial concentration in the mixture is 10%-30%, the nutrient solution concentration is 5%-10%, and the pH of the nutrient solution is 7.9-8.1.

[0024] Bacillus belye S1 is deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 28915.

[0025] Because degassing in the near-wellbore zone leads to wax deposition in the formation, in order to ensure the compatibility of the injected medium with the formation, a single strain of Bacillus belye S1 was screened and isolated from fresh oil and water samples from the oilfield. The strain's cell morphology distribution was relatively uniform. Microbial single-well huff and puff was carried out to remove wax contamination in the near-wellbore zone, which has a significant effect on improving the efficiency of mechanical production.

[0026] Step 3: Design corresponding combined gas lift processes based on different gas-liquid ratios for single wells and combine them with the operation and deployment tools to avoid "gas lock" in the wellbore during oil well production.

[0027] Specifically, the combined air lift refers to the combined application of five air control and prevention processes: counterweight ball pump, inner-shroud air-proof device, multi-stage progressive high-efficiency separator, air lift valve, and sleeve air valve, as detailed below: For oil wells with a gas-liquid ratio of less than 50, mechanical production parameters of small pump diameter, long stroke, and slow stroke frequency are adopted, and the combination of "casing gas valve + heavy ball pump" is applied to keep the casing pressure control and back pressure balanced. For oil wells with a gas-liquid ratio of 50 to 100, the casing pressure control range is 1.5 to 2 MPa. An internal gas-proof device or a multi-stage progressive high-efficiency separator should be used. For oil wells with a gas-liquid ratio of 100 to 180 and a casing pressure control range of 1.5 to 2 MPa, a combination of "heavy ball pump + inner cover gas-proof device" or "heavy ball pump + multi-stage progressive high-efficiency separator" should be used. For oil wells with a gas-liquid ratio greater than 180, use a combination of "heavy ball pump + inner cover gas prevention device + gas lift valve" or a combination of "heavy ball pump + multi-stage progressive high-efficiency separator + gas lift valve" to close the wellhead oil casing connection gate.

[0028] Step 4: During the extraction process, hollow rod electric heating rods are used to heat the crude oil in the tubing, such as... Figure 3 As shown, electric heating can effectively increase wellbore temperature, reduce crude oil viscosity, delay oil well wax deposition, increase fluid flow, and prevent rod and tubing from depositing wax, thereby achieving the goal of increasing oil well production and efficiency.

[0029] The hollow rod electric heating rod column is a combination of φ36 hollow rods and φ34 hollow rods, and its specific usage is as follows: Formation temperature is directly proportional to well depth, such as Figure 4 As shown, the formation temperature below 1000m has dropped to below 40℃, and wax deposition is likely to occur in oil wells. Therefore, when the pump depth is less than 1000m, a combination of φ36 hollow rods and φ34 hollow rods with electric heating is used in a 2:3 ratio, and a φ19 solid rod is connected to the pump. When the pump depth is greater than 1000m, a 400-meter φ36 hollow rod and a 600-meter φ34 hollow rod with electric heating are used, and a φ19 solid rod of the corresponding length is connected according to the pump depth.

[0030] Wellbore temperature is directly proportional to the duration of electric heating. After 4 hours of continuous heating, the rate of temperature increase in the wellbore decreases significantly. Considering that electric heating can effectively increase wellbore temperature and delay wax deposition in the well section below 1000m, the specific method of using a hollow rod electric heating string to heat the crude oil in the tubing is as follows: When the liquid volume is greater than 10 cubic meters, the gas volume is greater than 1000 cubic meters, and the heating position has a submersion, a cyclic heating method of "heating for 4 hours and stopping heating for 12 hours" is adopted. When the liquid volume is 5-10 cubic meters, the gas volume is less than 500 cubic meters, the heating position is submerged, and the water content is high (greater than 90%), heating is not required. When the liquid volume is less than 5 cubic meters, the gas volume is 500~1000 cubic meters, and the heating position has a submersion, a cyclic heating method of "heating for 2 hours and stopping heating for 6 hours" is adopted. When the liquid volume is less than 5 cubic meters, the gas volume is less than 500 cubic meters, and there is no submersion at the heating position, a cyclic heating method of "heating for 3 hours and stopping heating for 6 hours" is adopted.

[0031] Wax buildup in wellbore can lead to increased load on mechanically operated wells and reduced pump efficiency and system efficiency. This invention uses a hollow sucker rod with electric heating to heat the crude oil in the tubing throughout the process, thereby improving oil production efficiency.

[0032] The present invention relates to the application of the method for improving the efficiency of mechanical oil extraction systems in oilfields with high wax content and high gas-liquid ratio in oil reservoirs.

[0033] Effect verification: A certain oilfield conducted full-sample analysis of crude oil from 15 wells, tested the well temperature of 5 wells, and evaluated the wax melting rate and amount. The results are as follows: Experimental results showed that the microbial single-well huff and puff efficiency reached 100%. Compared with before the operation, the average daily fluid production increased by 1.64 tons, the average daily oil production increased by 0.57 tons, and the average water cut decreased by 0.9%, demonstrating a significant oil displacement effect after the operation. In the field test of oil well wax removal and prevention, the treatment extended the well washing cycle by an average of 40 days, with a wax removal and prevention efficiency of 91%. Before the operation, the average difference between the maximum and minimum loads of the oil well was 18.03 kN, while after the operation, the average difference was 14.81 kN, indicating a significant reduction in the oil well load. Comparing the microbial huff and puff before and after the operation, the cumulative oil production increased by 1336.3 tons, with an average effective period of 91 days.

[0034] Field tests of different combinations of gas lift technology were carried out, with a total of 312 well tests of gas-proof technology. The average daily liquid production increased by 3.04 t / d before and after the technology was introduced, and the pump efficiency increased by 10.07% after the technology was introduced. This solved the problem of high gas-liquid ratio affecting pump efficiency in "high-oil-volume" oilfields and effectively prevented gas lock.

[0035] Well temperature tests were conducted on 5 wells. The daily fluid production of the Ying 32-3-A4 well exceeded 10 cubic meters, and the gas production exceeded 1000 cubic meters. The heating position had submersion. After 4 hours of electric heating, the temperature increase was not significant. After heating was stopped, the temperature returned to the original wellbore temperature after 12 hours. Using an electric heating current of 85-90A, the heating was cyclically carried out according to the method of "heating for 4 hours and stopping heating for 12 hours". This can effectively reduce the viscosity of crude oil, prevent wax formation in the tubing, and improve the fluidity of crude oil, thereby achieving the goal of increasing oil well production and efficiency. A total of 520 wells have applied the electric heating technology. The average daily fluid production increased by 5.12 t / d before and after the technology was introduced. The pump efficiency increased by 11.25% after the technology was introduced, and the system efficiency increased by 4.52%.

[0036] Example 1 The methods for improving the efficiency of mechanical oil recovery systems in reservoirs with high wax content and high gas-liquid ratio are as follows: Step 1: Select oilfields with high wax content and high gas-liquid ratio for potential production. The selection criteria for oilfields with high wax content and high gas-liquid ratio are as follows: Screening criteria for high wax content: Wax content in crude oil exceeds 10%; Screening criteria for high gas-liquid ratio: gas-liquid ratio greater than 200 m 3 / m 3 .

[0037] Step 2: Use a single strain of microorganisms to carry out single-well infusion in the oil reservoir of the oilfield to remove wax contamination in the near-wellbore area; Step 3: Design corresponding combined gas lift processes and combine them with the operation and deployment tools according to different gas-liquid ratios of single wells; Step 4: During the extraction process, hollow rod electric heating rods are used to heat the crude oil in the tubing, increasing the fluidity of the liquid and preventing wax from forming on the rods and tubing.

[0038] Example 2 Based on Example 1, the specific method for step 2 in this embodiment is as follows: Microbial culture solution was injected into the annulus space using the casing annulus injection method, with an injection volume of 5-20 m³. 3 The injection displacement is 0.2~0.3 m³. 3 The injection rate is 10-15 MPa per minute. After complete injection, the well is shut in and incubated for 5-7 days before production begins.

[0039] Furthermore, the microbial culture is specifically a mixture of Bacillus belye S1 and its fermentation products, with a pH of 6.6–7.5 and a bacterial count ≥10⁻⁶. 8 The bacterial concentration in the mixture is 10%-30%, the nutrient solution concentration is 5%-10%, and the pH of the nutrient solution is 7.9-8.1.

[0040] Bacillus belye S1 is deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 28915.

[0041] Example 3 Based on Example 1, the combined air lift in step 3 of this embodiment specifically refers to the combined application of five air control and prevention processes: counterweight ball pump, inner cover-type air-proof device, multi-stage progressive high-efficiency separator, air lift valve, and sleeve air valve, as detailed below: For oil wells with a gas-liquid ratio of less than 50, mechanical production parameters of small pump diameter, long stroke, and slow stroke frequency are adopted, and the combination of "casing gas valve + heavy ball pump" is applied to keep the casing pressure control and back pressure balanced. For oil wells with a gas-liquid ratio of 50 to 100, the casing pressure control range is 1.5 to 2 MPa. An internal gas-proof device or a multi-stage progressive high-efficiency separator should be used. For oil wells with a gas-liquid ratio of 100 to 180 and a casing pressure control range of 1.5 to 2 MPa, a combination of "heavy ball pump + inner cover gas-proof device" or "heavy ball pump + multi-stage progressive high-efficiency separator" should be used. For oil wells with a gas-liquid ratio greater than 180, use a combination of "heavy ball pump + inner cover gas prevention device + gas lift valve" or a combination of "heavy ball pump + multi-stage progressive high-efficiency separator + gas lift valve" to close the wellhead oil casing connection gate.

[0042] Example 4 Based on Example 1, this embodiment uses a combination of φ36 and φ34 hollow electric heating rods in step 4. The specific usage is as follows: When the pump depth is less than 1000m, a combination of φ36 hollow rod electric heating and φ34 hollow rod electric heating rods is used in a 2:3 ratio, and a φ19 solid rod is connected to the oil pump. When the pump depth is greater than 1000m, a 400-meter φ36 hollow rod and a 600-meter φ34 hollow rod electric heating rod are used, and a φ19 solid rod of the corresponding length is connected according to the pump depth.

[0043] Example 5 Based on Example 1, the specific method for heating the crude oil in the tubing throughout the entire process using a hollow rod electric heating rod column in step 4 of this embodiment is as follows: When the liquid volume is greater than 10 cubic meters, the gas volume is greater than 1000 cubic meters, and the heating position has a submersion, a cyclic heating method of "heating for 4 hours and stopping heating for 12 hours" is adopted. When the liquid volume is 5-10 cubic meters, the gas volume is less than 500 cubic meters, the heating position has a submersion degree, and the water content is greater than 90%, heating can be suspended according to the actual production situation. When the liquid volume is less than 5 cubic meters, the gas volume is 500~1000 cubic meters, and the heating position has a submersion, a cyclic heating method of "heating for 2 hours and stopping heating for 6 hours" is adopted. When the liquid volume is less than 5 cubic meters, the gas volume is less than 500 cubic meters, and there is no submersion at the heating position, a cyclic heating method of "heating for 3 hours and stopping heating for 6 hours" is adopted.

[0044] Statistical validation of the results: The first batch: According to the well temperature test guidelines, when the liquid volume is greater than 10 cubic meters, the gas volume is greater than 1000 cubic meters, and the heating position has a submersion, the cyclic heating method of "heating for 4 hours and stopping heating for 12 hours" is adopted. The test tracked the effect for 330 days, saving 3600 kWh of electricity per day.

[0045] The second batch: According to the well temperature test guidelines, when the liquid volume is 5-10 cubic meters, the gas volume is less than 500 cubic meters, the heating position has submersion, and the water content is greater than 90%, 7 wells were tested without heating. The test results were tracked for 260 days, and production was normal, saving 3000 kWh of electricity per day.

[0046] The third batch: When the liquid volume is less than 5 cubic meters, the gas volume is 500~1000 cubic meters, and the heating position has a submersion, the cyclic heating method of "heating for 2 hours and stopping heating for 6 hours" is adopted. The test was conducted in 6 wells, and the test effect was tracked for 300 days. Production was normal in all cases, and the daily electricity saving was 1800 kWh.

[0047] The fourth batch: When the liquid volume is less than 5 cubic meters, the gas volume is less than 500 cubic meters, and there is no submersion at the heating position, a cyclic heating method of "heating for 3 hours and stopping heating for 6 hours" is adopted. The test was conducted in 14 wells, and the test effect was tracked for 70 days, saving 2400 kWh of electricity per day.

[0048] Example 6 Currently, Yingdong Oilfield has 592 wells in operation. After five years of promoting the integrated technology of hollow sucker rod electric heating, microbial huff and puff, and combined gas lift, and based on the differences in well conditions, the combined technology of two-in-one and three-in-one has been applied to 312 wells, with a coverage rate of 52.7%. The oilfield's pump efficiency and system efficiency indicators have been greatly improved, with pump efficiency increasing from 21% to 43.70% and system efficiency increasing from 15% to 25.20%. A total of 160,000 tons of oil has been added. Calculated at an oil settlement price of 3,000 yuan / ton, the cumulative economic benefits generated are 480 million yuan, with an input-output ratio of more than 1:6. This has helped the "high-yield and high-quality" Yingdong Oilfield complete the construction of a 500,000-ton oil and gas equivalent production capacity.

Claims

1. A method for improving the efficiency of mechanical oil recovery systems in reservoirs with high wax content and high gas-liquid ratio, characterized in that, Specifically as follows: Step 1: Select oil fields with high wax content and high gas-liquid ratio for potential production; Step 2: Use a single strain of microorganisms to carry out single-well infusion in the oil reservoir of the oilfield to remove wax contamination in the near-wellbore area; Step 3: Design corresponding combined gas lift processes and combine them with the operation and deployment tools according to different gas-liquid ratios of single wells; Step 4: During the extraction process, hollow rod electric heating rods are used to heat the crude oil in the tubing, increasing the fluidity of the liquid and preventing wax from forming on the rods and tubing.

2. The method for improving the efficiency of a high-wax-content, high-gas-liquid-ratio reservoir mechanical production system according to claim 1, characterized in that, The selection criteria for oilfields with high wax content and high gas-liquid ratio in step 1 are as follows: Screening criteria for high wax content: Wax content in crude oil exceeds 10%; Screening criteria for high gas-liquid ratio: gas-liquid ratio greater than 200 m 3 / m 3 .

3. The method for improving the efficiency of a high-wax-content, high-gas-liquid-ratio reservoir mechanical production system according to claim 1, characterized in that, The specific method for step 2 is as follows: Microbial culture solution was injected into the annulus space using the casing annulus injection method, with an injection volume of 5-20 m³. 3 The injection displacement is 0.2~0.3m³. 3 The injection rate is 10-15 MPa per minute. After complete injection, the well is shut in and incubated for 5-7 days before production begins.

4. The method for improving the efficiency of a high-wax-content, high-gas-liquid-ratio reservoir mechanical production system according to claim 3, characterized in that, The microbial culture is specifically a mixture of Bacillus belye S1 and its fermentation products, the pH of the mixture is 6.6-7.5, and the bacterial count in the mixture is ≥10. 8 The bacterial concentration in the mixture is 10%-30%, the nutrient solution concentration is 5%-10%, and the pH of the nutrient solution is 7.9-8.

1.

5. The method for improving the efficiency of a high-wax-content, high-gas-liquid-ratio reservoir mechanical production system according to claim 4, characterized in that, The Bacillus belyes S1 is deposited at the China General Microbiological Culture Collection Center (CGMCC), located at No. 3, Courtyard 1, Beichen West Road, Chaoyang District, Beijing, Institute of Microbiology, Chinese Academy of Sciences, with accession number CGMCC No. 28915.

6. The method for improving the efficiency of a high-wax-content, high-gas-liquid-ratio reservoir mechanical production system according to claim 1, characterized in that, The combined airlift in step 3 specifically refers to the combined application of five air-control and air-prevention processes: counterweight ball pump, inner-shroud air-prevention device, multi-stage progressive high-efficiency separator, airlift valve, and sleeve air valve, as detailed below: For oil wells with a gas-liquid ratio of less than 50, mechanical production parameters of small pump diameter, long stroke, and slow stroke frequency are adopted, and the combination of "casing gas valve + heavy ball pump" is applied to keep the casing pressure control and back pressure balanced. For oil wells with a gas-liquid ratio of 50 to 100, the casing pressure control range is 1.5 to 2 MPa. An internal gas-proof device or a multi-stage progressive high-efficiency separator should be used. For oil wells with a gas-liquid ratio of 100 to 180 and a casing pressure control range of 1.5 to 2 MPa, a combination of "heavy ball pump + inner cover gas prevention device" or "heavy ball pump + multi-stage progressive high-efficiency separator" should be used. For oil wells with a gas-liquid ratio greater than 180, use a combination of "heavy ball pump + inner cover gas prevention device + gas lift valve" or a combination of "heavy ball pump + multi-stage progressive high-efficiency separator + gas lift valve" to close the wellhead oil casing connection gate.

7. The method for improving the efficiency of a high-wax-content, high-gas-liquid-ratio reservoir mechanical production system according to claim 1, characterized in that, The hollow electric heating rod in step 4 is a combination of φ36 hollow electric heating rod and φ34 hollow electric heating rod, and its specific usage is as follows: When the pump depth is less than 1000m, a combination of φ36 hollow rod electric heating and φ34 hollow rod electric heating rods is used in a 2:3 ratio, and a φ19 solid rod is connected to the oil pump. When the pump depth is greater than 1000m, a 400-meter φ36 hollow rod and a 600-meter φ34 hollow rod electric heating rod are used, and a φ19 solid rod of the corresponding length is connected according to the pump depth.

8. The method for improving the efficiency of a high-wax-content, high-gas-liquid-ratio reservoir mechanical production system according to claim 7, characterized in that, The method for heating the crude oil in the tubing throughout the entire process using a hollow rod electric heating rod column in step 4 is as follows: When the liquid volume is greater than 10 cubic meters, the gas volume is greater than 1000 cubic meters, and the heating position has a submersion, a cyclic heating method of "heating for 4 hours and stopping heating for 12 hours" is adopted. When the liquid volume is 5-10 cubic meters, the gas volume is less than 500 cubic meters, the heating position has a submersion degree, and the water content is greater than 90%, heating is not required. When the liquid volume is less than 5 cubic meters, the gas volume is 500~1000 cubic meters, and the heating position has a submersion, a cyclic heating method of "heating for 2 hours and stopping heating for 6 hours" is adopted. When the liquid volume is less than 5 cubic meters, the gas volume is less than 500 cubic meters, and there is no submersion at the heating position, a cyclic heating method of "heating for 3 hours and stopping heating for 6 hours" is adopted.

9. The application of the method for improving the efficiency of mechanical oil recovery systems with high wax content and high gas-liquid ratio as described in any one of claims 1 to 8, characterized in that, Application of the method for improving the efficiency of mechanical oil extraction systems in oilfields with high wax content and high gas-liquid ratio.

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