Yield increasing method for prolonging self-spraying period of gas-containing oil well

Abstract

The invention relates to a yield increasing method for prolonging the flowing period of a gas-containing oil well, and belongs to the technical field of oil exploitation. The gas supply process is used for providing a source for the oil-water mixed transportation process; the oil-water mixed transportation process is used for separating oil, water and natural gas; the pressurization process is used for compressing the natural gas; and the gas assisting and lifting process is used for injecting the compressed natural gas into an annular space between an oil pipe and a sleeve in the oil well Christmas tree station entering production process. By utilizing the gas source advantage of a gas-producing reservoir, the self-produced gas of a gas-containing oil well and other incoming gas resources in a well group, a low-yield gas-containing ultra-deep oil well or a cluster oil well group which adopts a compressor to continuously inject natural gas and adopts gas lift to assist discharge stop is provided, the optimal gas injection-production ratio is realized, the gas-liquid ratio of fluid in a shaft is increased, the density is reduced, and the self-spraying period of the oil well is prolonged; the underground production pressure difference in the stratum is reduced, the pressure loss is reduced, and the edge and bottom water coning speed is inhibited.

Description

Technical Field

[0001] The invention relates to a production increasing method for extending the self-flowing period of a gas-containing oil well, belonging to the technical field of oil exploitation. Background Art

[0002] Oil well self-flowing production is the most economical and ideal mining method, and waterless self-flowing oil production should be extended as much as possible. When the energy of the oil layer decreases with mining and the bottom hole pressure is lower than the crude oil saturation pressure, the dissolved natural gas in the crude oil begins to separate. For the self-flowing wells in the solution gas drive reservoir, the bottom hole flow pressure is very low, and the oil well self-flowing is mainly maintained by the elastic potential energy of gas expansion. When the oil layer pressure continues to drop, the gas expansion potential energy cannot overcome the gravity of the gas-liquid mixture and the slippage and friction losses, the fluid state in the pipe string will change from bubble flow to segment flow, and the amount of liquid accumulated in the wellbore will gradually accumulate, resulting in a decrease in the gas overflow capacity of the oil layer, and the cycle will start again, eventually leading to the shutdown of the self-flowing oil well.

[0003] At present, the domestic reservoir energy replenishment methods have developed gas injection, water injection, carbon dioxide injection and other driven development methods. For single wells, artificial lifting methods are adopted, including: pumping units, electric submersible pumps, jet pumps, gas lift and other measures.

[0004] During the production process of gas-bearing oil wells, gas lock seriously affects pump efficiency. Currently, gas lift production has become an important lifting method for high gas-oil ratio oil wells, especially deep wells and cluster wells that flow freely to extend the high production period. For wells that still have high oil layer pressure and are affected by the wellbore liquid column and stop flowing, in order to avoid early pumping, oil fields generally use nitrogen to induce flow and gas lift to extend the flow period of oil wells.

[0005] However, the construction cost of nitrogen gas lift is high, and the conventional electric drive displacement is 1200Nm 3 / h nitrogen truck costs include nitrogen gas source fees and electricity costs. For example, the daily cost of continuous injection can reach 15,000 yuan / day. The long-term impact of nitrogen construction cannot be ignored, including the following aspects:

[0006] (1) Seriously affects the purity of natural gas at the oil well production end. Due to the large amount of nitrogen injection, the nitrogen content of the produced gas increases. The nitrogen produced by the nitrogen gas lift well directly enters the mixed pipeline, and enters the natural gas transmission pipeline after gas-liquid separation, affecting the purity of the exported natural gas. According to the test, the peak nitrogen content of the output gas of the nitrogen gas lift well is as high as 66%, which seriously affects the purity of the natural gas produced by the oil well and its subsequent sales;

[0007] (2) Due to the low purity of gas lift nitrogen production equipment, the oxygen content of the output gas increases, the risk of pipe corrosion is high, and there is even a risk of explosion. Oxygen in the high temperature and high pressure environment of the underground and station process is prone to oxidative corrosion of metal pipes, tools and equipment, and is also prone to explosion, posing a serious safety risk to production;

[0008] (3) Nitrogen has poor solubility in crude oil and is free after being injected into the wellbore, which is a rigid gas lift. During the nitrogen gas lift process, nitrogen slugs are easily formed in the wellbore and the gathering and transportation pipeline network, which have weak liquid carrying capacity and are easy to induce formation agitation and cause bottom water coning.

[0009] There have been reports in the prior art of using compressors to produce natural gas in oil wells, such as the pilot test of ultra-deep heavy oil injection natural gas lift to reduce the dilution of the oil published in the Daqing Petroleum Geology and Development Journal in February 2019 by Cao Chang, Luo Junlan, Liu Lei, etc. The article introduced that the heavy oil injection natural gas lift to reduce the dilution of the oil process technology is the first time to carry out field tests in China, and this pilot test is mainly aimed at the heavy oil gas lift auxiliary viscosity reduction and dilution reduction effect.

[0010] However, there are no reports on using unconventional methods to connect a single gas-bearing oil well to a separator, and using a compressor to continuously exhaust the self-produced gas for low-producing or shut-down gas-bearing deep wells and cluster well groups to extend the self-flowing cycle and resume flow. Summary of the invention

[0011] The present invention discloses a production increase method for extending the self-flowing period of gas-bearing oil wells, and aims to solve the problems in the existing technology for extending the self-flowing period of gas-bearing oil wells that the pump gas lock affects the pump efficiency, the nitrogen gas lift construction cost is high, and the later gathering and transportation, oil well production and environmental protection have a great impact. By utilizing the gas source advantage of the gas-producing oil reservoir itself, utilizing the self-produced gas of the gas-bearing oil well and other gas resources in the well group, a method is provided that uses a compressor to continuously inject natural gas, and through reasonable control of the equipment displacement, gas lift assists in drainage and stop, low-yield gas-bearing ultra-deep oil wells or cluster oil well groups, the optimal gas injection-production ratio is achieved, so as to increase the gas-liquid ratio of the fluid in the wellbore, reduce the density, and extend the self-flowing period of the oil well; reduce the downhole production pressure difference in the formation, reduce the pressure loss, and inhibit the cone advance speed of the edge and bottom water. The process method has the characteristics of economy, environmental protection, mildness, and continuity, and has a wide application prospect in the same type of oil reservoirs with mature gas source conditions.

[0012] The technical solution adopted by the present invention is a production increase method for extending the self-flowing period of a gas-bearing oil well, which specifically includes a gas supply process, an air-assisted gas lifting process, an oil-water mixed transmission process, and a pressurization process;

[0013] Gas supply process, used to provide a source for the oil-water mixed transportation process;

[0014] Oil-water mixed transportation process, used to separate oil, water and natural gas;

[0015] The boosting process is used to compress natural gas;

[0016] The assisted exhaust lift process is used to inject compressed natural gas into the annular space between the tubing and casing during the Christmas tree inlet production process of the oil well.

[0017] Furthermore, the gas supply process is specifically that all the production processes of the Christmas trees of all oil wells in the well site are merged into a main gas supply process through pipelines, the lead-out pipeline at the rear end of the gathering and transportation separator is connected to the main gas supply process, the gas supply source is adjusted by the stop valve B, the stop valve C of the oil well is used to turn on and off the gas supply of the corresponding oil well branch, the throttle valve of the oil well is used to adjust the gas supply volume of the corresponding oil well branch, and the main gas supply process is connected to the oil-water mixed transportation process.

[0018] Furthermore, the oil-water mixed transportation process is specifically divided into oil, water and natural gas by a three-phase separator; the oil-water process is connected to the Christmas tree inlet production process at the rear end of the stop valve C through a pipeline, and is pressed into the Christmas tree inlet production process through a pressure difference; the natural gas is separated and purified by a three-phase separator and then transported to the boosting process.

[0019] Furthermore, the boosting process is specifically that the natural gas separated and purified by the three-phase separator is connected to the booster through an oil pipe for primary boosting; and the booster is connected to the compressor for secondary boosting.

[0020] Furthermore, the assisted air-lift process is specifically that the casing valves in the production process of the Christmas trees of all oil wells in the well group are connected to the electric regulating gas volume valve through short-circuit and tee, and the electric regulating gas volume valve is connected to the boosting process through a pipeline.

[0021] Furthermore, the main gas supply process is connected to the three-phase separator of the oil-water mixed transmission process.

[0022] Furthermore, the electric air volume regulating valve is connected to a compressor of a pipeline pressurization process.

[0023] Furthermore, the natural gas is separated and purified by a three-phase separator and then transported to a supercharger in the supercharging process.

[0024] After connecting the pipelines through the above process, the continuous gas lift of oil and gas wells using natural gas is realized. Through the good gas-assisted gas lift performance of natural gas, the purpose of draining and extending the self-flowing cycle of gas-containing low-yield oil and gas wells can be achieved.

[0025] The present invention discloses a production increasing method for extending the spontaneous blowing period of a gas-containing oil well, and its beneficial effects include:

[0026] (1) Using natural gas as the starting gas source to achieve recycling, there is no need to purchase and produce gas lift gas sources, reducing gas lift costs and greatly reducing production costs; at the same time, timely adjustment of displacement can also save electricity costs.

[0027] (2) Natural gas is native to the formation and does not affect the purity of natural gas produced by the target oil well, which is conducive to high-quality sales in the later stage. The nitrogen and oxygen content is reduced, and the safety production coefficient is improved. The oxygen and nitrogen content at the output outlet of the oil well is greatly reduced, which greatly reduces the safety risk and reduces the corrosion of tools such as the pipe string and ground process.

[0028] (3) The natural gas compression equipment has a wide displacement adjustment range. It can adjust the injection pressure and gas injection volume according to the flow pressure change law and pressure gradient change of the oil well, reduce the pressure excitement caused to the formation during the gas lift process, and achieve gentle gas lift and reservoir protection. At the same time, multiple wells can be gas-lifted simultaneously through the electric adjustment of the gas volume valve.

[0029] (4) The use of natural gas lift is a mild and continuous gas lift, which can remove water from the wellbore, assist in suppressing the water cone, reduce the water content of the oil well, reduce the fluid density of the wellbore, and restore the self-flowing ability of the oil well; it can avoid the slugging and agitation caused by the fixed displacement of the nitrogen production equipment during nitrogen lift. Gentle gas lift with natural gas is not easy to induce bottom water cone. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 Shown is a schematic diagram of the process in Example 1;

[0032] Figure 2 The figure shows the principle diagram of the underground "U"-shaped pipe lifting in Example 1;

[0033] Figure 3 Shown is a schematic diagram of suppressing bottom water coning in Example 1.

[0034] As shown in the figure:

[0035] 1. Oil well; 2. Electric regulating gas volume valve; 3. Shut-off valve C; 4. Throttle valve; 5. Shut-off valve B; 6. Gathering and transportation separator; 7. Three-phase separator; 8. Booster; 9. Compressor. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] In order to further understand the content of the present invention, the present invention is further described below in conjunction with specific implementation methods.

[0038] Embodiment 1:

[0039] like Figure 1 As shown, this embodiment provides a method for increasing production for extending the spontaneous flow period of a gas-bearing oil well, which specifically includes a gas supply process, an air-assisted gas lifting process, an oil-water mixed transmission process, and a pressurization process;

[0040] The gas supply process is specifically that each oil well 1 is equipped with a stop valve C3 and a throttle valve 4 in the production process of the Christmas tree entering the station of all oil wells in the well site, and the main gas supply process is formed through various pipelines. The pipeline leading out of the rear end of the gathering and transportation separator 6 is connected with the main gas supply process, and the gas supply source is adjusted by the stop valve B5. The stop valve C3 of each oil well 1 is used to switch the gas supply of the corresponding oil well 1 branch, and the throttle valve 4 of the oil well 1 is used to adjust the gas supply volume of the corresponding oil well 1 branch. The main gas supply process is connected with the three-phase separator 7 of the oil-water mixed transportation process. In other words, the gas supply process is a process of collecting the natural gas produced by a single well to provide a gas source for the compressor 9.

[0041] The oil-water mixed transportation process is specifically divided into oil, water and natural gas by the three-phase separator 7; the oil-water process is connected to the Christmas tree inlet production process at the rear end of the stop valve C3 through a pipeline, and is pressed into the Christmas tree inlet production process through a pressure difference; the natural gas is separated and purified by the three-phase separator 7 and then transported to the boosting process.

[0042] The boosting process is specifically that the natural gas separated and purified by the three-phase separator 7 is transported to the booster 8 of the boosting process through an oil pipeline for primary boosting; the booster 8 is connected to the compressor 9 for secondary boosting.

[0043] The exhaust-assisted lifting process is specifically that the casing valves in the production process of the Christmas trees entering the station of all oil wells in the well group are connected to the electric regulating gas volume valve 2 through short circuits and three-way connections, and the electric regulating gas volume valve 2 is connected through the compressor 9 of the pipeline boosting process.

[0044] After connecting the pipelines through the above process, the continuous gas lift of oil and gas wells using natural gas is realized. Through the good gas-assisted gas lift performance of natural gas, the purpose of draining and extending the self-flowing cycle of gas-containing low-yield oil and gas wells can be achieved.

[0045] The process principle of the present invention is:

[0046] 1. Increase the gas-liquid ratio in the wellbore, reduce the fluid density, and realize the self-flowing production of the oil well.

[0047] like Figure 2As shown in the figure, this process is mainly based on the "U"-tube principle. After the external or self-produced oil well natural gas is purified by the separator, it is pressurized by the natural gas compressor and injected into the oil casing annulus (reverse lift) to mix it with the wellbore fluid, reduce the density of the gas-liquid mixture in the production string, improve the liquid carrying capacity, lift and drain the accumulated liquid, and realize self-flowing production.

[0048] 2. Reduce downhole production pressure difference, reduce reservoir pressure loss, and inhibit bottom water cone advancement speed.

[0049] like Figure 3 As shown in the figure, this process is mainly based on the principle of gravity differentiation. When high-pressure gas is injected into the annulus and reaches the pipe shoe (or gas lift valve), it will generate a certain back pressure on the lower part while entering the upper tubing string. This auxiliary pressure (Pf) is transmitted from the heel end to the toe end of the horizontal well, thereby increasing the bottom hole flow pressure (Pw) and reducing the downhole production pressure difference (Pr). When the oil layer has sufficient energy, due to the difference in oil and water density, gravity differentiation occurs, and the oil-water interface at the cone entry position is suppressed and falls back (or tends to be stable), thereby achieving the purpose of water control and cone elimination.

[0050] During the specific construction, wells with serious liquid accumulation are selected as gas lift auxiliary drainage wells, and other wells in the well group or natural gas from the gathering and transportation separation trunk line are used as gas supply sources. When the casing pressure of the gas lift well gradually rises and the liquid is returned after lifting, the displacement is reduced to avoid gas channeling affecting the gathering and transportation system. If the initial gas lift pressure exceeds the rated pressure of the equipment, the oil-casing channeling process can be used to positively inject gas to suppress the liquid accumulation in the tubing, artificially lower the liquid level in the tubing, and reduce the gas lift starting pressure.

[0051] ① Initial wellbore gas lift drainage stage: open the production valve of the low-yield gas-producing oil well, or the production valve of other gas-producing oil wells in the well group, and mix the oil and gas to the three-phase separator to separate the dry gas as the natural gas lift source of the measure well. Use the first-stage booster and the second-stage booster of the compressor. When the compressor outlet pressure is equal to the casing pressure of the measure well, open the casing valve of the injection end gas lift well, and keep the injection pressure near the starting pressure of the first-stage gas lift valve at the top of the measure well tubing. According to the designed gas injection displacement, the casing pressure rising rate per hour should be less than 3.0MPa. Observe the changes in the casing pressure and the output of the tubing. After the ground observes the step-by-step pressure relief of the downhole gas lift valve, when the injection end pressure is stable for 15 minutes or has reached the starting pressure of the deepest gas lift valve, adjust the ground gas supply to 2 / 3 of the designed gas injection volume to avoid excessive wellhead production oil pressure and reduce the pressure shock to the oil output system.

[0052] ②Continuous auxiliary production stage: After working continuously for 12 to 18 hours under the condition of maintaining the gas supply volume at 2 / 3 of the designed gas injection volume, adjust the casing natural gas injection displacement according to the gas-liquid ratio of the gas lift well to form a stable production stage of oil and gas output. According to historical construction experience, excessive displacement at this stage is prone to natural gas degassing and gas channeling, and too low displacement is prone to repeated liquid accumulation and stop of wellbore spraying. The displacement of the equipment in this process can refer to the critical flow predicted by Li Min's critical liquid carrying model. Considering the solubility and expansion properties of natural gas in crude oil, the critical liquid carrying displacement in construction is often 45% to 60% of the theoretical value for better results;

[0053] Gas lift well control parameters: Install the nozzle according to the production management system requirements of the oil well to ensure that the tubing pressure is controlled within 10MPa. If the tubing pressure exceeds 10MPa, the machine will be shut down and self-flowing will be adopted. When the tubing pressure drops to within 5MPa, the machine will be started for continuous gas lift operation. The casing gas injection natural gas pressure will be dynamically adjusted according to the actual production situation, and the maximum is not allowed to exceed 20MPa. If the casing pressure is higher than 20MPa, shutdown measures will be taken, the gate will be closed, and the shutdown and self-flowing production method will be adopted. When the tubing pressure is lower than 5MPa, the compressor will be started for gas lift operation.

[0054] When a single well reaches the designed normal level after gas lift measures, it is converted into a gas supply well. The total amount of natural gas injected by the compressor and the daily output of the oil well are counted, and the balance between gathering and transportation and self-produced gas is matched. Gas lift and liquid drainage construction is carried out one by one on the gas wells in the well site to achieve effective liquid drainage of the whole well group, record the liquid production cycle and liquid volume of the single well, and schedule the construction and replacement rounds;

[0055] When some wells cannot form a gas lift construction cycle due to the influence of downhole tools (failed packers, chokes) during gas lift construction, a circulation channel can be established by mechanically punching the tubing without moving the production tubing and without suppressing the well to pollute the reservoir.

[0056] In August 2019, natural gas compression gas lift-assisted drainage and production increase measures were carried out in XX well in a certain oil field. The well was put into production in October 2008, with a completed well depth of 4683m. The tubing in the well was a 6-level gas lift valve production tubing. It had been flowing since it was put into production until June 2018. The pressure coefficient in the wellbore dropped from the original 1.13 to 0.78 before construction. The well showed insufficient self-flowing production capacity and a rapid decline in production. Intermittent and continuous nitrogen gas lift production were carried out from September 2018 to August 2019.

[0057] Before the natural gas compression gas lift and drainage increase production measures were implemented on August 20, the well group was produced through nitrogen gas lift and induced blowdown measures, with a daily single well liquid production of 29t / d, a water content of 1%, and a gas production of 19000m 3 The average amount of nitrogen injected per day is 28,000 m 3As the nitrogen lift time increases, the impact of nitrogen injection on oil wells and production gradually becomes apparent, mainly manifested in: poor gas-oil solubility, prone to cross-layering in surrounding oil wells, oxygen in nitrogen constantly flushes oil pipes and packers, causing oil pipe corrosion; leading to unstable oil well pressure, and a gradual downward trend in liquid production; the nitrogen and oxygen content of the produced gas is much higher than the methane content, and the quality of the produced gas is poor.

[0058] During the test period, natural gas was used to replace nitrogen gas lift to extend the oil well crude oil flow period. The test results were good. As shown in Table 1-3, the daily liquid production of the platform well group reached 38.5t / d after assisted drainage, the water content dropped from 1% to 0.34%, the average oxygen content of the oil well output gas dropped from 3.9% to 0.9%, the nitrogen content dropped from 47.4% to 7.78%, the methane content increased from 47% to 78%, and the daily power consumption dropped from 7000kW·h to about 4000kW·h. Compared with nitrogen gas lift equipment, the average daily cost per well was reduced by 5482.4 yuan.

[0059] Table 1 Comparison of natural gas continuous gas lift and nitrogen gas lift operations

[0060]

[0061] Table 2 Comparison of gas and liquid components produced by natural gas continuous gas lift and nitrogen gas lift

[0062]

[0063] Table 3 Comparison of gas lift costs between two gases

[0064]

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for increasing the production of a gas-bearing oil well for extending the spontaneous flow period. It is characterized in that Specifically including gas supply process, air-assisted gas lifting process, oil-water mixed transmission process, and pressurization process; Gas supply process, used to provide a source for the oil-water mixed transportation process; Oil-water mixed transportation process, used to separate oil, water and natural gas; The boosting process is used to compress natural gas; The assisted exhaust lift process is used to inject compressed natural gas into the annular space between the tubing and casing during the Christmas tree inlet production process of the oil well.

2. A method for increasing production of a gas-bearing oil well for extending the spontaneous flow period according to claim 1, It is characterized in that The gas supply process is specifically that the production processes of the Christmas trees of all oil wells (1) in the well site are merged into a main gas supply process through pipelines, the pipeline leading out from the rear end of the gathering and transporting separator (6) is connected with the main gas supply process, and the gas supply source is adjusted by the stop valve B (5). The pipeline of the Christmas tree production process of each oil well (1) is installed with a stop valve C (3) and a throttle valve (4), wherein the stop valve C (3) of the oil well (1) is used to open and close the gas supply of the oil well (1) branch, and the throttle valve (4) of the oil well (1) is used to adjust the gas supply volume of the corresponding oil well (1) branch, and the main gas supply process is connected with the oil-water mixed transportation process.

3. A method for increasing production of a gas-bearing oil well for extending the spontaneous flow period according to claim 2, It is characterized in that The oil-water mixed transmission process is specifically divided into oil-water and natural gas by a three-phase separator (7); the oil-water process is connected to the Christmas tree inlet production process at the rear end of the stop valve C (3) through a pipeline, and is pressed into the Christmas tree inlet production process under pressure difference; the natural gas process is separated and purified by the three-phase separator (7) and then transported to the boosting process.

4. A method for increasing production of a gas-bearing oil well for extending the spontaneous flow period according to claim 3, It is characterized in that The specific process of the pressurization is that the natural gas separated and purified by the three-phase separator (7) is connected to the supercharger (8) through an oil pipe for primary pressurization; the supercharger (8) is connected to the compressor (9) for secondary pressurization.

5. A method for increasing production of a gas-bearing oil well for extending the spontaneous flow period according to claim 4, It is characterized in that The exhaust-assisted lifting process is specifically that the casing valves in the production process of the Christmas tree entering the station of all oil wells (1) in the well group are connected to the electric regulating gas volume valve (2) through short-circuiting and three-way, and the electric regulating gas volume valve (2) is connected to the pressurization process through a pipeline.

6. A method for increasing production of a gas-bearing oil well for extending the spontaneous flow period according to claim 3, It is characterized in that The main gas supply process is connected to the three-phase separator (7) of the oil-water mixed transmission process.

7. A method for increasing production for extending the spontaneous flow period of a gas-bearing oil well according to claim 5, It is characterized in that The electric gas volume regulating valve (2) is connected to the compressor (9) of the boosting process through a pipeline.

8. A method for increasing production of a gas-bearing oil well for extending the spontaneous flow period according to claim 4, It is characterized in that The natural gas is separated and purified by a three-phase separator (7) and then transported to a booster (8) in the boosting process.

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