Multi-well injection method and device for natural gas

Abstract

The invention provides a natural gas multi-well injection method and device, multiple wells comprise a high-pressure gas flow well and a low-pressure gas flow well at the same time, and the device comprises a high-pressure adjusting valve, an ejector, a first gas flow adjusting valve and a second gas flow adjusting valve, an inlet of the low-pressure block valve is communicated with the low-pressure gas flow well, and an outlet of the low-pressure block valve is communicated with a second inlet of the ejector; the ejector comprises an outlet communicated with the inlet of the medium-pressure cut-off valve; a medium pressure intercept valve including an outlet in communication with the medium pressure outlet; one high-pressure regulating valve, one low-pressure cut-off valve, one ejector and one medium-pressure cut-off valve are marked as a group of regulating structures; the multiple sets of adjusting structures are connected in parallel, inlets of the multiple high-pressure adjusting valves communicate with the high-pressure gas flow well, and outlets of the multiple medium-pressure cut-off valves communicate with the medium-pressure outlet. According to the technical scheme, natural gas wellhead pressure energy can be fully utilized, and the method is particularly suitable for development of unconventional natural gas such as shale gas and tight gas.

Description

Technical Field

[0001] The present invention relates to, but is not limited to, the field of oil and gas gathering and transportation technology, and in particular to, but is not limited to, a method and device for injecting natural gas into multiple wells. Background Art

[0002] Domestic natural gas maintains a rapid development momentum, among which unconventional natural gas represented by shale gas and tight gas accounts for an increasing proportion of domestic natural gas. Compared with conventional natural gas, shale gas well production has the characteristics of large single well production and high pressure in the early stage, but extremely rapid decline, low production in the middle and late stages, but long stable production time. Generally, the time to maintain the wellhead pressure above the gathering and transportation system pressure (5.0MPa to 7.5MPa) is basically 1.5 to 2 years.

[0003] Shale gas is developed in a succession production mode to adapt to the decline in single well production, which leads to large differences in platform pressure at different development periods and complex operation and management. In order to adapt to the changing characteristics of shale gas wellhead pressure and the pressure level requirements of the gathering and transportation network, the current production mode has problems such as large equipment area, high energy consumption, and mutual interference between high and low pressure wells in the gathering and transportation system. There are two prominent contradictions in the production process of shale gas. One is the loss of high pressure energy caused by throttling and pressure regulation at the wellhead of the newly commissioned platform. The other is that the pressure at the wellhead of the old platform cannot enter the gathering and transportation network after the attenuation. It is necessary to set up a node compressor on the platform, and the pressure energy of the high-pressure gas flow cannot be effectively utilized.

[0004] Shale gas is developed by successive production to adapt to the decline in single well production, which leads to large differences in platform pressure at different development periods and complex operation and management. In order to adapt to the changing characteristics of shale gas wellhead pressure and the pressure level requirements of the gathering and transportation pipeline network, the current production method mainly adopts the method of throttling and reducing pressure on high-pressure platforms and single-point pressurization on low-pressure platforms, which has problems such as large equipment footprint, high energy consumption, and mutual interference between high-pressure and low-pressure wells in the gathering and transportation system.

[0005] For platforms that are close to each other, a branched pipeline network is usually used to connect the platforms in series, and the produced natural gas is transported to the downstream together. At the same time, shale gas production currently mainly adopts a pressure-controlled production method, that is, it is necessary to shut down the wellheads with excessively fast pressure decay at any time to maintain production capacity. Therefore, the inspection and maintenance between platforms are affected by various factors such as equipment failure or fluctuations in gas well status, and there is no regularity to follow. For the same series of branched pipelines, the upstream gas volume usually changes greatly due to the closure of individual upstream platforms.

[0006] There are two prominent contradictions in the production process of shale gas. One is the loss of high-pressure pressure energy caused by throttling and pressure regulation at the wellhead of the newly commissioned platform. The other is that the pressure at the wellhead of the old platform cannot enter the gathering and transportation pipeline network after the pressure attenuation. It is necessary to set up a node compressor on the platform, and the pressure energy of the high-pressure gas flow cannot be effectively utilized. The ejector can use the high-speed jet formed when the high-pressure fluid flows through the nozzle to suck another low-pressure fluid and exchange energy in the device to reach the intermediate pressure value. Therefore, in unconventional gas fields represented by shale gas fields, the application of ejectors can solve the above contradictions to a certain extent, and can meet the pressure energy recovery needs between platforms of unconventional natural gas gathering and transportation systems such as shale gas or tight gas. However, the static ejector is a customized design product. Limited by the structural size, a single ejector is highly sensitive to flow. Once the high-pressure well gas flow changes greatly, the ejection effect may be significantly deteriorated. The operating range that a single ejector can adapt to is very narrow, generally about ±15% at most, and has poor adaptability to fluctuations in the volume of high-pressure gas, and cannot adapt to the attenuation changes in the early and middle and late stages of shale gas. When the gas flow fluctuates greatly, the ejection results will deteriorate significantly or even fail to form effective ejection. Considering the characteristics of the large-scale changes in the upstream gas volume in the aforementioned shale gas gathering and transportation system, a single ejector cannot meet the needs of shale gas production.

[0007] In unconventional natural gas production systems such as shale gas or tight gas, for the same string of branched pipelines, the upstream gas volume usually varies widely due to the shutdown of wells on individual upstream platforms. Summary of the invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] The present disclosure proposes a method and device for natural gas injection, which combines static injectors of different design sizes according to the number of wells on the platform and the production of a single well. By switching the combination, it can adapt to the injection conditions of gas of different sizes, and can improve the adaptability of a single static injector to the high-pressure gas flow rate. The present disclosure combines two or more adjustable injectors of different specifications for use in natural gas fields, especially in the gathering and transportation systems of unconventional gas fields such as shale gas or tight gas, and uses the pressure energy of the fluid produced by the high-pressure gas well to inject and pressurize the fluid produced by the low-pressure well, thereby achieving adaptability to large-scale changes in flow caused by differences in the timing of drilling, completion and commissioning of unconventional natural gas platforms, and can improve the utilization rate of gas well pressure energy, while increasing the pressure of low-pressure gas wells, and reducing the production energy consumption and cost of the entire gathering and transportation system.

[0010] The present disclosure provides a natural gas multi-well injection device, wherein the multi-wells include both high-pressure gas wells and low-pressure gas wells, and the device includes:

[0011] A high-pressure regulating valve, the inlet of which is connected to the high-pressure gas volume well, and the outlet of which is connected to the first inlet of the ejector;

[0012] A low-pressure cut-off valve, the inlet of which is connected to the low-pressure gas volume well, and the outlet of which is connected to the second inlet of the ejector;

[0013] An ejector including an outlet communicating with an inlet of the medium-pressure section valve;

[0014] A medium pressure cut-off valve including an outlet communicating with a medium pressure outlet;

[0015] One high-pressure regulating valve, one low-pressure shut-off valve, one ejector and one medium-pressure shut-off valve are recorded as a group of regulating structures; multiple groups of regulating structures are connected in parallel, the inlets of multiple high-pressure regulating valves are connected to the high-pressure gas volume well, and the outlets of multiple medium-pressure shut-off valves are connected to the medium-pressure outlet.

[0016] In some embodiments provided in the present disclosure, the high-pressure regulating valve may be a device for regulating the flow rate or disconnection of a fluid medium in a pipeline with a working pressure of 6 MPa to 10 MPa.

[0017] In some embodiments provided in the present disclosure, the low-pressure cut-off valve may be a device having a working pressure of 1 MPa to 5 MPa and controlling the connection or disconnection of a fluid medium in a pipeline.

[0018] In some embodiments provided in the present disclosure, the medium-pressure cut-off valve may be a device having a working pressure of 4 MPa to 6 MPa and controlling the connection or disconnection of a fluid medium in a pipeline.

[0019] In some embodiments provided in the present disclosure, the ejector may be: a device that utilizes a flow channel structure to allow momentum exchange to occur when a high-pressure fluid is mixed with a low-pressure fluid, and transfers the pressure energy of the high-pressure fluid to the low-pressure fluid, thereby obtaining an intermediate pressure fluid between high pressure and low pressure.

[0020] In some embodiments provided in the present disclosure, a buffer separator is further provided between the high-pressure gas volume well and the inlet of the high-pressure regulating valve, and the buffer separator is configured to separate and discharge liquid and solid phase substances in the high-pressure gas volume well.

[0021] In some embodiments provided by the present disclosure, the natural gas multi-well injection device further includes a control module;

[0022] The pipeline between the high-pressure gas volume well and the buffer separator is also provided with a high-pressure flow meter and a high-pressure pressure gauge;

[0023] The control module is configured to collect data from the high-pressure flow meter and the high-pressure pressure meter, and control the high-pressure regulating valve, the low-pressure shut-off valve, and the medium-pressure shut-off valve.

[0024] In some embodiments provided by the present disclosure, the number of the high-pressure gas volume wells is one or more than two, and the number of the low-pressure gas volume wells is one or more than two;

[0025] The two or more high-pressure gas volume wells are connected in parallel and communicated with the inlet of the high-pressure regulating valve;

[0026] The two or more low-pressure gas volume wells are connected in parallel and communicated with the inlet of the low-pressure cut-off valve.

[0027] In some embodiments provided in the present disclosure, the pressure of the high-pressure gas well is about 6 MPa to 10 MPa, and the pressure of the low-pressure gas well is about 1 MPa to 5 MPa.

[0028] In the present disclosure, “about”, “approximately”, or “close to” refers to ±30%, ±20%, ±10%, or ±5% of the number.

[0029] In some embodiments provided in the present disclosure, the high-pressure gas volume of the high-pressure gas well is about 50,000 cubic meters / day to 1,000,000 cubic meters / day, and the low-pressure gas volume is about 40% to 100% of the high-pressure gas volume.

[0030] In another aspect, the present disclosure provides a method for multi-well natural gas injection, using the above-mentioned injection device, the method comprising:

[0031] Determine the number n of parallel regulation structures according to formula (1):

[0032]

[0033] In formula (1), Q min is the minimum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max is the maximum high-pressure gas volume, unit: ten thousand cubic meters / day; round function is the function for rounding the numbers within the symbol;

[0034] Determine the design high pressure gas volume Q of the ejector in the i-th regulating structure (1≤i≤n) according to formula (2): i :

[0035]

[0036] In formula (2), Q min is the minimum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max is the maximum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max The maximum is about 5 million cubic meters per day, Q min The minimum is not less than about 50,000 cubic meters per day.

[0037] In some embodiments provided in the present disclosure, in the multi-well ejection method, the sum of the designed ejection volumes of the plurality of ejectors is not less than the high-pressure gas volume.

[0038] In some embodiments provided by the present disclosure, when the high-pressure gas volume is about 80,000 cubic meters / day to 400,000 cubic meters / day, the number of ejectors is 4. The designed high-pressure gas volume of each ejector is about 80,000 cubic meters / day, about 105,000 cubic meters / day, about 130,000 cubic meters / day, and about 165,000 cubic meters / day, respectively.

[0039] In some embodiments provided by the present disclosure, when the high-pressure gas volume is about 50,000 cubic meters / day to 1 million cubic meters / day, the number of ejectors is 8, and the designed high-pressure gas volume of each ejector is about 50,000 cubic meters / day, about 75,000 cubic meters / day, about 100,000 cubic meters / day, about 125,000 cubic meters / day, about 150,000 cubic meters / day, about 175,000 cubic meters / day, about 200,000 cubic meters / day, and about 175,000 cubic meters / day, respectively.

[0040] In some embodiments provided in the present disclosure, the natural gas is selected from any one or more of shale gas and tight gas.

[0041] In another aspect, the present disclosure provides the use of the above-mentioned natural gas multi-well injection device in unconventional natural gas injection;

[0042] In some embodiments provided in the present disclosure, the unconventional natural gas is selected from any one or more of shale gas and tight gas.

[0043] The beneficial effects of the present disclosure include at least:

[0044] (1) The technical solution provided by the present disclosure can fully utilize the natural gas wellhead pressure energy, and is particularly suitable for the development of unconventional natural gas such as shale gas and tight gas.

[0045] (2) A single ejector cannot adapt to the large-scale changes in the gas volume in the shale gas or tight gas gathering and transportation pipeline. The present invention combines the ejector units and reasonably sets the flow increment of each ejector unit. The device can adapt to the large-scale fluctuations in the high-pressure natural gas volume from the upstream of shale gas or tight gas, and the gathering and transportation system can form an effective ejector.

[0046] (3) The device has a compact structure, does not contain moving equipment, and can be installed on a skid, making it easy to disassemble and reuse between different gas wells. Other features and advantages of the present disclosure will be described in the subsequent description, and part of them will become obvious from the description, or can be understood by practicing the present disclosure. Other advantages of the present disclosure can be invented and obtained by the schemes described in the description. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The accompanying drawings are used to provide an understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation on the technical solution of the present disclosure.

[0048] Figure 1 It is a process principle flow chart of the present disclosure.

[0049] Figure numerals: 1. high-pressure flowmeter; 2. high-pressure pressure gauge; 3. buffer separator; 4. high-pressure regulating valve group; 5. low-pressure shut-off valve group; 6. ejector group; 7. medium-pressure shut-off valve group; 8. medium-pressure pressure gauge; 9. control module; 41. first high-pressure regulating valve; 42. second high-pressure regulating valve; 43. third high-pressure regulating valve; 44. fourth high-pressure regulating valve; 51. first low-pressure shut-off valve; 52. second low-pressure shut-off valve; 53. third low-pressure shut-off valve; 54. fourth low-pressure shut-off valve; 61. first ejector; 62. second ejector; 63. third ejector 64. fourth ejector; 71. first medium-pressure shut-off valve; 72. second medium-pressure shut-off valve; 73. third medium-pressure shut-off valve; 74. fourth medium-pressure shut-off valve.

[0050] Figure 2 The pressure data are recorded during continuous operation for 24 hours in working condition 1 of the embodiment (the recording period is 20 minutes).

[0051] Figure 3 The gas flow data is recorded for 24 hours of continuous operation in working condition 1 of the embodiment (the recording period is 20 minutes).

[0052] Figure 4 The pressure data are recorded during continuous operation for 24 hours in working condition 1 of the embodiment (the recording period is 20 minutes).

[0053] Figure 5 The gas flow data is recorded for 24 hours of continuous operation in working condition 1 of the embodiment (the recording period is 20 minutes). DETAILED DESCRIPTION

[0054] To make the purpose, technical solution and advantages of the present disclosure more clear, the embodiments of the present disclosure are described in detail below. It should be noted that the embodiments and features in the embodiments of the present disclosure can be combined with each other arbitrarily without conflict.

[0055] In the embodiments of the present disclosure, some natural gas multi-well injection devices are provided, wherein the multi-wells include both high-pressure gas wells and low-pressure gas wells, and the devices include:

[0056] A high-pressure regulating valve, the inlet of which is connected to the high-pressure gas volume well, and the outlet of which is connected to the first inlet of the ejector;

[0057] A low-pressure cut-off valve, the inlet of which is connected to the low-pressure gas volume well, and the outlet of which is connected to the second inlet of the ejector;

[0058] An ejector including an outlet communicating with an inlet of the medium-pressure section valve;

[0059] A medium pressure cut-off valve including an outlet communicating with a medium pressure outlet;

[0060] One high-pressure regulating valve, one low-pressure shut-off valve, one ejector and one medium-pressure shut-off valve are recorded as a group of regulating structures; multiple groups of regulating structures are connected in parallel, the inlets of multiple high-pressure regulating valves are connected to the high-pressure gas volume well, and the outlets of multiple medium-pressure shut-off valves are connected to the medium-pressure outlet.

[0061] Exemplarily, the high-pressure regulating valve may be a device with a working pressure of 6 MPa to 10 MPa, which is used to adjust the flow rate of the fluid medium in the pipeline or to disconnect it.

[0062] Exemplarily, the low-pressure cut-off valve may be a device having a working pressure of 1 MPa to 5 MPa and controlling the connection or disconnection of a fluid medium in a pipeline.

[0063] Exemplarily, the medium-pressure cut-off valve may be a device having a working pressure of 4 MPa to 6 MPa and controlling the connection or disconnection of a fluid medium in a pipeline.

[0064] Exemplarily, the ejector may be a device that utilizes a flow channel structure to allow momentum exchange to occur when a high-pressure fluid is mixed with a low-pressure fluid, thereby transferring the pressure energy of the high-pressure fluid to the low-pressure fluid, thereby obtaining an intermediate pressure fluid between high pressure and low pressure.

[0065] Exemplarily, a buffer separator is further provided between the high-pressure gas volume well and the inlet of the high-pressure regulating valve, and the buffer separator is configured to separate and discharge liquid and solid phase substances in the high-pressure gas volume well.

[0066] Exemplarily, the unconventional natural gas multi-well injection device further includes a control module;

[0067] The pipeline between the high-pressure gas volume well and the buffer separator is also provided with a high-pressure flow meter and a high-pressure pressure gauge;

[0068] The control module is configured to collect data from the high-pressure flow meter and the high-pressure pressure meter, and control the high-pressure regulating valve, the low-pressure shut-off valve, and the medium-pressure shut-off valve.

[0069] Exemplarily, the number of the high-pressure gas volume wells is one or more than two, and the number of the low-pressure gas volume wells is one or more than two;

[0070] The two or more high-pressure gas volume wells are connected in parallel and communicated with the inlet of the high-pressure regulating valve;

[0071] The two or more low-pressure gas volume wells are connected in parallel and communicated with the inlet of the low-pressure cut-off valve.

[0072] Exemplarily, the pressure of the high-pressure gas well is about 6 MPa to 10 MPa, and the pressure of the low-pressure gas well is about 1 MPa to 5 MPa.

[0073] Exemplarily, the high-pressure gas volume of the high-pressure gas well is about 50,000 cubic meters per day to 1,000,000 cubic meters per day, and the low-pressure gas volume is about 40% to 100% of the high-pressure gas volume.

[0074] The embodiments of the present disclosure also provide some natural gas multi-well injection methods, using the above-mentioned injection device, the method comprising:

[0075] Determine the number n of parallel regulation structures according to formula (1):

[0076]

[0077] In formula (1), Q min is the minimum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max is the maximum high-pressure gas volume, unit: ten thousand cubic meters / day; round function is the function for rounding the numbers within the symbol;

[0078] Determine the design high pressure gas volume Q of the ejector in the i-th regulating structure (1≤i≤n) according to formula (2): i :

[0079]

[0080] In formula (2), Q min is the minimum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max is the maximum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max The maximum is about 10 million cubic meters per day, Q min Minimum not less than 50,000 cubic meters per day;

[0081] After high-pressure gas enters from the inlet of the high-pressure regulating valve, the high-pressure gas enters the ejector through the high-pressure regulating valve. The ejector uses the ejection effect to draw low-pressure gas from the low-pressure inlet through the low-pressure regulating valve and into the ejector. The ejector outputs medium-pressure gas that passes through the medium-pressure cut-off valve and is output from the medium-pressure outlet.

[0082] Exemplarily, in the multi-well injection method, the sum of the designed injection volumes of the plurality of injectors is not less than the high-pressure gas volume.

[0083] For example, when the high-pressure gas volume is about 80,000 cubic meters per day to 400,000 cubic meters per day, the number of ejectors is 4. The designed high-pressure gas volume of each ejector is about 80,000 cubic meters per day, about 105,000 cubic meters per day, about 130,000 cubic meters per day, and about 165,000 cubic meters per day, respectively.

[0084] Exemplarily, when the high-pressure gas volume is about 50,000 cubic meters / day to 1 million cubic meters / day, the number of ejectors is 8, and the designed high-pressure gas volume of each ejector is about 50,000 cubic meters / day, about 75,000 cubic meters / day, about 100,000 cubic meters / day, about 125,000 cubic meters / day, about 150,000 cubic meters / day, about 175,000 cubic meters / day, about 200,000 cubic meters / day, and about 175,000 cubic meters / day.

[0085] Exemplarily, the pressures of both high-pressure gas and low-pressure gas will fluctuate slightly, the high-pressure gas volume will vary within a certain range, and the ejected low-pressure gas volume will automatically change according to the high-pressure gas volume, that is, the ejected low-pressure gas volume will be automatically determined based on the energy that the upstream high-pressure gas can provide.

[0086] Exemplarily, the unconventional natural gas is selected from any one or more of shale gas and tight gas.

[0087] In another aspect, the embodiments of the present disclosure provide application of the above-mentioned natural gas multi-well injection device in unconventional natural gas injection;

[0088] Exemplarily, the unconventional natural gas is selected from any one or more of shale gas and tight gas.

[0089] Example 1

[0090] The design conditions of the integral ejector provided in this embodiment are shown in Table 1. The design working expansion ratio of the ejector is 3.41, and the compression ratio is 1.36.

[0091] Table 1 Design conditions of ejector

[0092] High voltage end Low voltage side Medium voltage end pressure About 7.5MPa About 2.2MPa About 3.0MPa temperature 20℃ 20℃ 20℃

[0093] The device provided by the present disclosure is used in a shale gas field to use the high-pressure natural gas in the gathering and transportation network to inject the natural gas from the low-pressure production platform to increase its pressure and output it stably. There is no limit on the number of wellheads of the high-pressure production platform and the low-pressure production platform, and they are combined into one airflow before entering the device provided by the present disclosure.

[0094] In order to achieve the adjustment of the overall device to cope with the change of high-pressure gas volume within the range of 80,000 cubic meters / day to 400,000 cubic meters / day, the number of ejectors is determined to be 4 according to formula (1) and formula (2); the design high-pressure gas volume of each ejector is about 80,000 cubic meters / day, about 105,000 cubic meters / day, about 130,000 cubic meters / day, and about 165,000 cubic meters / day respectively.

[0095] Design the ejection device according to the calculation, such as Figure 1 As shown, the device is composed of a high-pressure flow meter 1, a high-pressure pressure gauge 2, a buffer separator 3, a high-pressure regulating valve group 4, a low-pressure cut-off valve group 5, an ejector group 6, a medium-pressure cut-off valve group 7, and a medium-pressure pressure gauge 8 connected in sequence. Figure 1 As shown, the high-pressure regulating valve group 4, the low-pressure shut-off valve group 5, the ejector group 6, and the medium-pressure cut-off valve group 7 are each provided with 4 devices, which respectively form 4 different ejector groups. The rated high-pressure gas volume of each ejector group is different, and the rated high-pressure gas volume increment relationship of each ejector unit is calculated according to formula (2). The control module 9 is data-connected with the high-pressure flowmeter 1, the high-pressure pressure gauge 2, and the high-pressure regulating valve group 4.

[0096] By controlling the opening and closing of the high-pressure regulating valve group 4, the above-mentioned ejection units can work independently or two or more ejection units can work together. The control module 9 can calculate and determine the combination scheme based on the data of the high-pressure flow meter 1 and the high-pressure pressure meter 2 and formulas (1) and (2) and control the high-pressure regulating valve. The rated minimum high-pressure gas volume of the device is the rated high-pressure gas volume of the smallest ejection unit, and the maximum rated high-pressure gas volume of the device is the sum of the rated high-pressure gas volumes of the four ejection units.

[0097] like Figure 1 As shown, after the unconventional natural gas such as high-pressure shale gas or tight gas enters the device from the high-pressure gas inlet, the flow and pressure data are recorded by the high-pressure flowmeter 1 and the high-pressure pressure gauge 2, and then enters the buffer separator 3, in which free water and solid impurities are separated, and the high-pressure gas passes through the high-pressure regulating valve group 4 and enters the ejector group 6. The ejection effect of the ejector group 6 is used to draw the low-pressure gas from the low-pressure inlet through the low-pressure regulating valve group 5 and into the ejector group 6. The medium-pressure gas obtained at the outlet of the ejector group 6 flows out from the medium-pressure outlet through the medium-pressure section valve group 7 and the medium-pressure pressure gauge 8, and then enters the gathering and transportation pipeline.

[0098] The regulating flow increment of the device provided in this embodiment is about 25,000 cubic meters / day. The first high-pressure regulating valve 41, the second high-pressure regulating valve 42, the third high-pressure regulating valve 43, the fourth high-pressure regulating valve 44, the first low-pressure shut-off valve 51, the second low-pressure shut-off valve 52, the third low-pressure shut-off valve 53, the fourth low-pressure shut-off valve 54, the first medium-pressure shut-off valve 71, the second medium-pressure shut-off valve 72, the third medium-pressure shut-off valve 73, and the fourth medium-pressure shut-off valve 74 respectively control the closing and operating states of the four ejector groups in the skid, and are combined in parallel to form different ejection conditions. The combination method is shown in Table 2, using the operational flexibility of a single ejector itself to the high-pressure gas volume fluctuation of ±30,000 cubic meters / day.

[0099] Table 2 Combination of ejectors under different high pressure gas volumes

[0100]

[0101] According to the arrangement and combination of multiple ejectors, according to the high-pressure ejection gas volume of the ejectors, the demand for high-pressure gas volume ranging from 80,000 cubic meters / day to 400,000 cubic meters / day can be covered. In this embodiment, the design high-pressure flow rate of the ejector (or the sum of the design high-pressure flow rates of multiple ejectors) is ±25,000 cubic meters / day, and the ejector combination mode under different upstream high-pressure gas volumes is designed.

[0102] In this embodiment, the high-pressure gas source is the gas from the upstream A gas gathering station, which can be multiple high-pressure gas wells connected in parallel and then entering the A gas gathering station. The low-pressure gas source is the gas produced at the wellhead of the B platform. The medium-pressure outlet gas of the device is transmitted to the downstream C platform after passing through the outlet valve group. The average wellhead pressure of the B platform is 2.16MPa, and the daily gas production is about 185,020 cubic meters / day; the inlet pressure of the gas from the upstream A gas gathering station is about 5.9MPa to 6.1MPa;.

[0103] The gas from the upstream A gas gathering station (shale gas production) will fluctuate constantly, so it is slightly different from the design working conditions of the ejector. This embodiment uses two working conditions to illustrate the combination of the two ejector groups in the equipment.

[0104] Example working condition 1: 8+105,000 cubic meters of ejector group ejection

[0105] When the high-pressure gas volume is about 190,000 cubic meters / day, the high-pressure pressure is about 6MPa, and the low-pressure pressure is 1.7MPa to 2.1MPa. The 80,000 cubic meters / day and 105,000 cubic meters / day ejection groups are selected for combined ejection. The equipment can form effective ejection. The specific ejection data is shown in Table 3. The data record of continuous operation for 24 hours is shown in the attached Figure 2 and attached Figure 3 The high-pressure gas pressure is close to 6MPa, the high-pressure gas volume is stable at 190,000 cubic meters, the injection rate (the ratio of low-pressure gas volume to high-pressure gas volume) is 55.2% to 101%, and the injection rate exceeds 50%, forming a stable injection boosting effect.

[0106] Table 3 Ejection effect of 8+105,000m3 ejection group

[0107]

[0108] Example working condition 2: 8+130,000 cubic meters of ejector group ejection

[0109] When the high-pressure gas volume is about 210,000 cubic meters / day, the high-pressure pressure is about 6MPa, and the low-pressure pressure is 1.7MPa to 2.1MPa. The 80,000 cubic meters / day and 130,000 cubic meters / day ejection groups are selected for combined ejection. The equipment can form effective ejection. The specific ejection data is shown in Table 4. The data record of continuous operation for 24 hours is shown in the attached Figure 4 and attached Figure 5The high-pressure gas pressure is close to 6MPa, the high-pressure gas volume is stable at 210,000 cubic meters, the injection rate (the ratio of low-pressure gas volume to high-pressure gas volume) is 57.6% to 74.3%, and the injection rate exceeds 50%, forming a stable injection boosting effect.

[0110] Table 4 Ejection effect of 8+130,000m3 ejection group

[0111]

[0112] In the above embodiments, after the device establishes a good injection and pressurization process, the high-pressure gas volume is basically maintained at 180,000 to 220,000 cubic meters per day, and the low-pressure gas volume (injection gas volume) is 100,000 to 160,000 cubic meters per day; the low pressure (injection pressure) is 1.7 MPa to 2.2 MPa, and the medium pressure for external transmission is 2.7 MPa to 3.0 MPa. It is explained that after the device provided in the present disclosure establishes a good injection and pressurization process, it can use high-pressure pressure to pump low-pressure wells, improve gas well production conditions, and at the same time increase the platform external transmission pressure, improve the pipeline flow of the downstream pressure system and the compressor pressurization operation condition.

Claims

1. A natural gas multi-well injection device, wherein the multi-wells include both high-pressure gas wells and low-pressure gas wells, characterized in that: The device comprises: A high-pressure regulating valve, the inlet of which is connected to the high-pressure gas volume well, and the outlet of which is connected to the first inlet of the ejector; A low-pressure cut-off valve, the inlet of which is connected to the low-pressure gas volume well, and the outlet of which is connected to the second inlet of the ejector; An ejector including an outlet communicating with an inlet of the medium-pressure section valve; A medium pressure cut-off valve including an outlet communicating with a medium pressure outlet; One high-pressure regulating valve, one low-pressure shut-off valve, one ejector and one medium-pressure shut-off valve are recorded as a group of regulating structures; multiple groups of regulating structures are connected in parallel, the inlets of multiple high-pressure regulating valves are connected to the high-pressure gas volume well, and the outlets of multiple medium-pressure shut-off valves are connected to the medium-pressure outlet.

2. The natural gas multi-well injection device according to claim 1, characterized in that: A buffer separator is also provided between the high-pressure gas volume well and the inlet of the high-pressure regulating valve, and the buffer separator is configured to separate and discharge liquid and solid phase substances in the high-pressure gas volume well.

3. The natural gas multi-well injection device according to claim 2, characterized in that: The natural gas multi-well injection device also includes a control module; The pipeline between the high-pressure gas volume well and the buffer separator is also provided with a high-pressure flow meter and a high-pressure pressure gauge; The control module is configured to collect data from the high-pressure flow meter and the high-pressure pressure meter, and control the high-pressure regulating valve, the low-pressure shut-off valve, and the medium-pressure shut-off valve.

4. The natural gas multi-well injection device according to any one of claims 1 to 3, characterized in that: The number of the high-pressure gas volume wells is one or more than two, and the number of the low-pressure gas volume wells is one or more than two; The two or more high-pressure gas volume wells are connected in parallel and communicated with the inlet of the high-pressure regulating valve; The two or more low-pressure gas volume wells are connected in parallel and communicated with the inlet of the low-pressure cut-off valve.

5. The natural gas multi-well injection device according to any one of claims 1 to 3, characterized in that: The pressure of the high-pressure gas well is 6MPa to 10MPa, and the pressure of the low-pressure gas well is 1MPa to 5MPa.

6. The natural gas multi-well injection device according to any one of claims 1 to 3, characterized in that: The high-pressure gas volume of the high-pressure gas well is 50,000 cubic meters per day to 1,000,000 cubic meters per day, and the low-pressure gas volume is 40% to 100% of the high-pressure gas volume.

7. A natural gas multi-well injection method, characterized in that: Using the ejection device according to any one of claims 1 to 6, the method comprises: Determine the number n of parallel regulation structures according to formula (1): In formula (1), Q min is the minimum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max is the maximum high-pressure gas volume, unit: ten thousand cubic meters / day; round function is the function for rounding the numbers within the symbol; Determine the design high pressure gas volume Q of the ejector in the i-th regulating structure (1≤i≤n) according to formula (2): i : In formula (2), Q min is the minimum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max is the maximum high-pressure gas volume, unit: ten thousand cubic meters / day; Q max The maximum capacity is 10 million cubic meters per day. min Minimum not less than 50,000 cubic meters per day; After high-pressure gas enters from the inlet of the high-pressure regulating valve, the high-pressure gas enters the ejector through the high-pressure regulating valve. The ejector uses the ejection effect to draw low-pressure gas from the low-pressure inlet through the low-pressure regulating valve and into the ejector. The ejector outputs medium-pressure gas that passes through the medium-pressure cut-off valve and is output from the medium-pressure outlet.

8. The natural gas multi-well injection method according to claim 7, characterized in that: In the multi-well ejection method, the sum of the designed ejection volumes of the plurality of ejectors is not less than the high-pressure gas volume.

9. The natural gas multi-well injection method according to claim 7 or 8, characterized in that: The natural gas is selected from any one or more of shale gas and tight gas.

10. Application of the natural gas multi-well injection device according to any one of claims 1 to 6 in natural gas injection; Optionally, the natural gas is selected from any one or more of shale gas and tight gas.

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