Coal bed gas negative pressure extraction equipment

Abstract

The invention discloses coal bed gas negative pressure extraction equipment which comprises a motor, a main machine screw pump and an oil-gas separator which are sequentially communicated through a gas main pipeline. The oil-gas separator, the oil cooling fan, the oil filter and the oil cut-off valve are sequentially communicated through an oil pipeline; one end of the air inlet water-air separator is connected with the air inlet, and the other end of the air inlet water-air separator is communicated to the host screw pump through an air The method is suitable for the technical field of coal bed gas development, a well group is connected into a set of negative pressure extraction equipment, when the casing pressure of an extraction well is higher than the system pressure, the size of a pressure balance manifold stop valve and a bypass stop valve are adjusted, the gas flow is controlled to effectively enter a gathering and transportation pipe network, and when the casing pressure of the extraction well is lower than the system pressure, the gas flow is controlled to effectively enter the gathering and transportation pipe network. The gas can still effectively enter a gathering and transportation pipe network, and balanced production, long-term continuous production and stable production of the whole well group are achieved. The device has the advantages of being small in occupied area, high in working stability, free of installation foundation, capable of achieving continuous pumping drainage, low in operation and maintenance cost and easy to operate and maintain.

Description

Technical Field

[0001] The invention belongs to the technical field of coalbed methane development, and in particular relates to coalbed methane negative pressure extraction equipment. Background Art

[0002] Coalbed methane is mainly present in coal pores in an adsorbed state, a small amount exists in cleats and other cracks or pores in a free state, and a very small amount exists in groundwater in the coal seam in a dissolved state. The reservoir pressure is reduced by drainage, so that methane molecules are desorbed from the surface of the coal matrix. When the pressure gradually decreases and reaches the critical desorption pressure, methane molecules are desorbed from the surface of the coal matrix and diffuse from the micropores in the matrix to the cleats under the action of the concentration difference. This process is an important step for the conversion of coalbed methane from an adsorbed state to a free state, allowing methane to migrate in the formation. With the continuous drainage and pressure reduction, the gas production gradually increases and stabilizes, a gas production peak occurs, and the water production gradually decreases.

[0003] As the coalbed methane well enters the middle and late stages of drainage, the dynamic liquid level drops to the coal seam, and methane desorption tends to balance. When the casing pressure of the drainage well is lower than the system pressure, the well still produces gas, but it cannot enter the pipeline network for external transmission. Conventional drainage equipment alone can no longer meet the needs of drainage production, and installing negative pressure extraction equipment on the ground to assist production has become a realistic option. If negative pressure extraction equipment is installed on each single well in the well group, the cost is high, the area occupied is large, and the operation and management are difficult. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a coalbed methane negative pressure extraction device.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A coalbed methane negative pressure extraction device, comprising:

[0007] A motor, a main engine screw pump and an oil-gas separator are connected in sequence through a gas main line;

[0008] An oil-gas separator, an oil cooling fan, an oil filter and an oil cut-off valve which are sequentially connected through an oil pipeline; and

[0009] An air inlet water-gas separator, one end of which is connected to the air inlet, and the other end is connected to the main engine screw pump through an air inlet valve;

[0010] in:

[0011] The oil cut-off valve is further connected to the main engine screw pump to form a loop;

[0012] An oil separator core is built into the top of the oil-gas separator, and the oil separator core, the air cooling fan and the water-gas separator at the air outlet are connected to the air outlet through a gas main line.

[0013] Preferably, after the motor is started, the motor drives the main engine screw pump to operate, and the low-pressure gas is compressed into the oil-gas separator through the air inlet on the air inlet valve, the air inlet water-gas separator, the air inlet valve, and the main engine screw pump; the oil in the oil-gas separator flows in a mist state driven by the air flow, and the oil-gas mixture compressed by the main engine screw pump flows to the oil-gas separator to establish an initial pressure;

[0014] Under the action of the initial pressure, the oil in the lower part of the oil-gas separator passes through the oil cooling fan, the oil filter and the oil cut-off valve in turn to circulate to the main engine screw pump position to complete the oil circulation; the high-pressure gas passes through the oil separation core, the air cooling fan and the outlet water-gas separator and is transported to the system pipe network;

[0015] Wherein, the initial pressure is 0.2-0.3Mpa.

[0016] Preferably, it also includes: an air intake valve and a vent valve;

[0017] in:

[0018] When the gas outlet pressure is higher than the preset gas outlet value, the inlet valve is closed and the vent valve is opened, so that the pressure of the oil-gas separator is kept in a safe state;

[0019] When the air inlet pressure is lower than the preset air inlet value, the air inlet valve is closed and the vent valve is opened to ensure the safety of the well site pipeline process.

[0020] Preferably, the pressure of the oil-gas separator is maintained at 0.4 MPa, that is, it is in a safe state.

[0021] Preferably, a host temperature sensor and a check valve are further provided between the host screw pump and the oil-gas separator, wherein the host temperature sensor is used to measure the temperature of the host and convert the measured host temperature information into an electrical signal for subsequent processing and control, and the operating range of the host temperature is set to 70-85°C. When the host temperature is detected to be lower than 70°C, the oil cooling fan stops heat dissipation, and when the temperature is higher than 85°C, the oil cooling fan starts forced heat dissipation;

[0022] The check valve is used to prevent oil and gas from flowing back to the separation tank.

[0023] Preferably, the air inlet water-gas separator is further connected to an inlet flame arrester, the inlet flame arrester is connected to a gas filter, and the gas filter is connected to the air inlet valve.

[0024] Preferably, the air outlet water-gas separator is further connected to the outlet flame arrester, and an exhaust temperature sensor is provided between the air outlet water-gas separator and the outlet flame arrester for detecting the air outlet temperature.

[0025] Preferably, an oil return filter is provided above the oil separation core, and the oil return filter is connected to the intake valve through an oil pipeline.

[0026] Preferably, a minimum pressure valve is provided between the oil separator core and the air-cooling fan, and a pressure sensor is provided between the air-cooling fan and the air outlet water-gas separator, and the pressure sensor is used to detect the air outlet pressure.

[0027] Preferably, the bottom of the oil-gas separator is connected to a drain outlet via a ball valve.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] In the present invention, a set of negative pressure extraction equipment is connected to the well group. When the casing pressure of the drainage well is higher than the system pressure, the gas volume can be effectively controlled to enter the gathering and transportation network by adjusting the size of the pressure balance manifold stop valve and adjusting the bypass stop valve. When the casing pressure of the drainage well is lower than the system pressure, the gas volume can still effectively enter the gathering and transportation network, so as to achieve balanced production of the entire well group, long-term continuous production, and stable production. The advantages of the present invention are small footprint, high working stability, no need for installation foundation, continuous extraction, low operation and maintenance costs, and simple operation and maintenance.

[0030] In the present invention, by connecting the manifold of the negative pressure extraction device, the total gas production of the later drainage well group can be increased by adjusting the size of the stop valve of the pressure balance manifold, and the single well of the well group can be controlled to achieve balanced production increase. The bypass of the negative pressure extraction equipment can play a diversion role by adjusting the stop valve to avoid the well group from increasing production too quickly and causing adverse effects on the well.

[0031] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A working principle diagram of a coalbed methane negative pressure extraction device according to an embodiment of the present invention;

[0033] Figure 2 A schematic diagram of a coalbed methane negative pressure extraction device according to an embodiment of the present invention;

[0034] Figures 3a to 3e This is a diagram showing the production increase effect of a single well in the XX-1 well group after the coalbed methane negative pressure extraction equipment according to an embodiment of the present invention is installed;

[0035] Figure 4 This is a diagram showing the overall production increase effect of the XX-1 well group after the coalbed methane negative pressure extraction equipment according to an embodiment of the present invention is installed;

[0036] Figure 5It is a curve diagram of the change of air intake pressure of the coalbed methane negative pressure extraction equipment according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The specific embodiments of the present invention are described in detail below.

[0038] The "range" disclosed in the present invention is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10 to 50 is listed for a specific parameter, it is understood that the range of 10 to 40 and 20 to 50 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following ranges can all be expected: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4 and 2 to 5. In this application, unless otherwise specified, the range of values ​​"a to b" represents an abbreviation of any real number combination between a and b, where a and b are both real numbers. For example, the range of values ​​"0 to 5" means that all real numbers between "0 to 5" have been fully listed in this article, and "0 to 5" is only an abbreviation of these numerical combinations.

[0039] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0040] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0041] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0042] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0043] Unless otherwise specified, the reaction is carried out at room temperature and pressure.

[0044] Unless otherwise specified, all parts or percentages are by weight.

[0045] In the present invention, all substances used are known substances and can be purchased or synthesized by known methods.

[0046] In the present invention, the devices or equipment used are all conventional devices or equipment known in the art and are commercially available.

[0047] The specific implementation of the coalbed methane negative pressure extraction device of the present invention is further described below in conjunction with the embodiments. The coalbed methane negative pressure extraction device of the present invention is not limited to the description of the following embodiments.

[0048] An embodiment of the present invention proposes a coalbed methane negative pressure extraction device, which belongs to the coalbed methane well group negative pressure extraction technology. The present invention connects the coalbed methane well group to a set of negative pressure extraction equipment, and the negative pressure extraction equipment controls the balanced production, long-term continuous production, and stable production of the entire well group.

[0049] like Figure 1 As shown, the coalbed methane negative pressure extraction equipment of an embodiment of the present invention includes: a motor, a main screw pump, an oil-gas separator, an oil-cooling fan, an oil filter, an oil shut-off valve, an air intake valve, a vent valve, an oil separator core, an air-cooling fan, an air inlet water-gas separator and an air outlet water-gas separator.

[0050] Specifically, the main engine screw pump is built into the main engine. The motor, the main engine screw pump and the oil-gas separator are connected in sequence through the gas main line, and the oil-gas separator, the oil cooling fan, the oil filter and the oil shut-off valve are connected in sequence through the oil pipeline, and the oil shut-off valve is further connected to the main engine screw pump to form a loop. A main engine temperature sensor and a check valve are further arranged between the main engine screw pump and the oil-gas separator. Among them, the main engine temperature sensor is used to measure the temperature of the main engine and convert the measured temperature information of the main engine into an electrical signal for further processing and control. The operating range of the main engine temperature is set to 70-85°C. When the main engine temperature is detected to be lower than 70°C, the oil cooling fan stops dissipating heat. When the temperature is higher than 85°C, the oil cooling fan starts to dissipate heat forcibly. The check valve is used to prevent oil and gas from flowing back to the separation tank.

[0051] One end of the air inlet water-gas separator is connected to the air inlet, and the other end is connected to the main screw pump through the air inlet valve. The air inlet water-gas separator is further connected to the inlet flame arrester, the inlet flame arrester is connected to the gas filter, and the gas filter is connected to the air inlet valve.

[0052] The bottom of the oil-gas separator is connected to the drain port through a ball valve. An oil separator core is built into the top of the oil-gas separator, and the oil separator core, the air-cooling fan and the water-gas separator at the air outlet are connected to the air outlet through the main gas line. The water-gas separator at the air outlet is further connected to the outlet flame arrester, and an exhaust temperature sensor is provided between the water-gas separator at the air outlet and the outlet flame arrester to detect the air outlet temperature. An oil return filter is provided above the oil separator core, and the oil return filter is connected to the air inlet valve through an oil pipeline. A minimum pressure valve is provided between the oil separator core and the air-cooling fan, and a pressure sensor is provided between the air-cooling fan and the water-gas separator at the air outlet, and the pressure sensor is used to detect the air outlet pressure.

[0053] After the motor is started, the main engine screw pump is driven by the motor to operate, and the low-pressure gas is compressed into the oil-gas separator through the air inlet on the air inlet valve, the air inlet water-gas separator, the air inlet valve, and the main engine screw pump; the oil in the oil-gas separator flows in a mist state driven by the air flow, and the oil-gas mixture compressed by the main engine screw pump flows to the oil-gas separator to establish the initial pressure. In the embodiment of the present invention, the initial pressure is 0.2-0.3Mpa.

[0054] Then, under the action of the initial pressure, the oil in the lower part of the oil-gas separator circulates to the main engine screw pump position through the oil cooling fan, oil filter and oil cut-off valve in turn, completing the oil circulation.

[0055] The high-pressure gas is transported to the system pipeline through the oil separator core, air-cooling fan and air-water separator at the air outlet.

[0056] When the outlet pressure is too high (i.e., the outlet pressure is higher than the preset outlet pressure), the inlet valve is closed and the vent valve is opened to keep the pressure of the oil-gas separator in a safe state to maintain safe operation of the system. The preset outlet pressure is, for example, 0.4 MPa.

[0057] In the embodiment of the present invention, the pressure of the oil-gas separator is maintained at 0.4 MPa, that is, in a safe state.

[0058] When the air inlet pressure is lower than the preset air inlet value, the air inlet valve is closed and the vent valve is opened to ensure the safety of the well site pipeline process. The preset air inlet value is, for example, minus 10KPa.

[0059] Combine the following Figure 1 The working principle of the coalbed methane negative pressure extraction equipment of the present invention is described as follows:

[0060] When the main motor is in the stopped state, the intake valve BV101 is closed and the vent valve BV102 is opened. The main motor starts in star shape when there is no load, and at the same time, the oil cut-off solenoid valve BV103 is energized, the oil cut-off valve is opened, and it turns into triangle operation after 6 to 10 seconds. The low-pressure gas passes through the air inlet A on the intake valve → water-gas separator FF101 → flame arrester ZH101 → gas filter → intake valve BV101 → main engine screw compressor AE and is compressed into the oil-gas separator (the oil in the oil-gas separator flows in a mist under the drive of a strong airflow, and the oil-gas mixture compressed by the main engine screw pump flows to the oil-gas separator, establishing an initial system pressure of about 0.2 to 0.3Mpa) → the oil in the lower part of the oil-gas separator under the initial pressure → oil cooling fan HE101 → oil filter FF102 → oil cut-off valve BV103, through the oil filter of the cooling fan, and through the oil cut-off valve, circulates to the main engine screw pump position, completing the oil circulation. Among them, the oil plays the role of lowering the temperature of the main engine, sealing and lubricating.

[0061] The high-pressure gas passes through the oil separator core → air-cooling fan HE101 → water-gas separator FF103 → outlet B → and is transported to the system pipeline network.

[0062] When the pressure sensor detects that the outlet pressure is too high, the air inlet valve BV101 is closed and the vent valve BV102 is opened to keep the oil-gas separator pressure at 0.4MPa to maintain safe operation of the system.

[0063] When the intake pressure is lower than the set value, the intake valve BV101 is closed and the vent valve BV102 is opened to ensure the safety of the pipeline process.

[0064] The present invention connects the coalbed methane well group to the negative pressure extraction equipment, and the negative pressure extraction equipment controls the balanced production of the entire well group, long-term continuous production, and stable production. The specific steps are as follows:

[0065] Step 1: Select negative pressure extraction equipment based on the total daily gas production of the coalbed methane well group and the expected production increase space.

[0066] Step 2: Negative pressure extraction equipment works.

[0067] When the negative pressure extraction equipment is powered on, the starting motor drives the screw pump to operate. The oil-gas mixture compressed by the main screw pump flows to the oil-gas separator, establishing an initial system pressure of about 0.2-0.3Mpa. The initial system pressure causes the oil to circulate through the oil cooling fan, the oil filter, and the oil shut-off valve to the main screw pump position, completing the oil circulation.

[0068] Step 3: Negative pressure extraction equipment controls the production of coalbed methane well groups, based on Figure 2 Negative pressure extraction equipment air inlet connection Figure 1 The air inlet is located at A, and the exhaust port is connected Figure 1At the outlet B position; install the pressure balancing manifold and the shut-off valve 2 bypass line.

[0069] The negative pressure extraction equipment controls the production of coalbed methane well groups and consists of the following four parts: wellhead process part, pressure balance manifold, control valve and negative pressure extraction equipment.

[0070] 1. Wellhead process part, including: gate valve, needle valve, vortex flowmeter.

[0071] Function of gate valve: During the production period of coalbed methane wells, the gate is raised and lowered to control the flow of the pipeline and cut off the fluid.

[0072] Function of needle valve: The flow control characteristic curve of needle valve is linear, and it can accurately control the flow of liquid or gas.

[0073] Function of vortex flowmeter: vortex flowmeter can accurately measure fluid. It is a velocity flowmeter with high measurement accuracy, good stability and strong anti-interference ability.

[0074] 2. Pressure balancing manifold, including: stop valve and pressure gauge.

[0075] Function of the pressure balance manifold: Balancing the intake pressure of each well can realize the different well conditions of each well in the well group, accurately control the production increase and stable production effect of the single well, and extend the recovery rate of the single well.

[0076] 3. Control valves, including: stop valve 1 (vent valve), stop valve 2 (bypass valve), stop valve 3 and stop valve 4.

[0077] Function of control valve: The frequency modulation range of negative pressure extraction equipment is narrow (the lowest frequency is 25HZ, the highest frequency is 50HZ), and the bypass pipe can realize quantitative gas diversion through stop valve 2. Function of stop valve 3 and stop valve 4: When the negative pressure extraction equipment is overhauled and maintained, the stop valve 3 and stop valve 4 are closed, and the bypass valve 2 is opened without affecting the production and causing pressure build-up in the well group.

[0078] 4. Negative pressure extraction equipment

[0079] The function of negative pressure extraction equipment is to reduce the system pipeline pressure and realize the smooth production of gas from the well group.

[0080] From the above, we can conclude that:

[0081] (1) Adjust the stop valve, pressure gauge, and single-well vortex flowmeter of the pressure balance manifold to accurately control the gas flow of each single well in the entire well group to achieve balanced production increase of the well group.

[0082] (2) Bypass stop valve 2 can solve the problem that the main screw pump of the negative pressure extraction equipment runs at the minimum frequency, but the gas volume still increases too fast. The bypass stop valve diverts the gas flow to avoid the well group from increasing production too quickly, which will cause adverse effects on the well.

[0083] (3) By adopting Figure 2 The connection can enable wells with different well conditions in the later well group to achieve uniform and balanced production increase.

[0084] Step 4: Adjust the switch status of the manifold valve and cut into the system pipe network.

[0085] Step 5: Fully open the stop valve of the pressure balance manifold, close the vent stop valve 1, fully open the stop valves 2, 3, and 4, and start debugging the equipment.

[0086] Step 6: Set the equipment intake and exhaust protection parameters according to the casing pressure and pipe pressure range before the well assembly machine.

[0087] Step 7: Before starting the equipment, first record the gas production pressure (MPa), casing pressure (MPa), daily gas production (m 3 / d), water production (m 3 / d), cumulative gas production of well groups (m 3 ) parameters to start the equipment trial run at the lowest frequency.

[0088] Step 8: Operate the negative pressure production equipment to achieve single well incremental balance.

[0089] According to the switch status of the manifold in step 5, all gas flow goes through bypass, and bypass stop valve 2 is slowly slightly closed until the cumulative gas production before the observation well assembly machine rises to the planned increased gas production, indicating that part of the gas production of the well group goes through bypass and the other part goes through negative pressure extraction equipment. At the same time, check the instantaneous gas production of the flow meter of the single well, adjust the stop valve of the pressure balance manifold to control the instantaneous gas production increment. For wells with too large production increment, reduce the gas production of the corresponding wells by reducing the pressure balance manifold. For wells with too small production increment, increase the gas production of the corresponding wells by increasing the pressure balance manifold to balance the increment of the single well.

[0090] Step 9: According to the daily production increase system, gradually close the bypass valve to allow all the gas to pass through the negative pressure extraction equipment.

[0091] The minimum frequency of the screw pump of the negative pressure extraction equipment is 25Hz. Slightly close the bypass stop valve until it is completely closed, so that the instantaneous gas volume slowly increases to the planned gas increase volume. At this time, the gas production of the well group is completely introduced from the original bypass gas volume diversion state to the full-load production of the negative pressure extraction equipment. Among them, the bypass of the stop valve 2 can play a diversion role to avoid the well group from increasing production too quickly, causing adverse effects on the well. Repeat step 5 to control the single well production increase of the well group in a balanced state while maintaining the total production increase of the well group.

[0092] The present invention adopts Figure 2The negative pressure extraction device manifold connection shown in the figure can achieve the increase of total gas production of the later drainage well group by adjusting the size of the pressure balance manifold stop valve, and at the same time can control the single well of the well group to achieve balanced production increase. The bypass of the negative pressure extraction equipment can play a diversion role by adjusting the stop valve 2 to avoid the well group from increasing production too quickly and causing adverse effects on the well.

[0093] The present invention is described below by taking the coalbed methane XX well group in the Yushe-Wuxiang block of the Qinshui Coalfield in Shanxi Province as an example in conjunction with the attached drawings. The well group consists of 5 wells, of which: the XX well group includes 1 vertical well (XX-1), 4 directional wells (XX-1-1, XX-1-2, XX-1-3, XX-1-4), the production has reached the middle and late stages, the liquid level has reached the lowest, the casing pressure is lower than the pipe pressure, if the normal drainage system is followed, the methane desorption tends to balance, and the gas production effect of the well group begins to decrease. The casing pressure of the five wells is basically the same as the system pressure and cannot be input into the system pipe network, so the balanced production increase of the 5 wells in the well group includes the following steps:

[0094] S1: Well group negative pressure extraction equipment, such as Figure 2 Connect the pipeline as shown.

[0095] S2: Adjust the switch status of the manifold valve and cut into the system pipeline network.

[0096] S3: Fully open the stop valve of the pressure balance manifold, close the vent stop valve 1, fully open the stop valves 2, 3, and 4, and start debugging the equipment.

[0097] S4: Set the equipment air intake and exhaust protection parameters according to the casing pressure and pipe pressure range before the well assembly machine.

[0098] Before installation, the casing pressure of the five wells in the well group ranges from 84KPa to 110KPa, and the pipe pressure ranges from about 80KPa. During the debugging phase, when the equipment performance is not fully understood, the suction pressure should be set to 100Kpa based on the original pipeline network, and the exhaust pressure should be set to 0.4MPa.

[0099] S5: Before starting the equipment, first record the gas production pressure (MPa), casing pressure (MPa), daily gas production (m 3 / d), water production (m 3 / d), cumulative gas production of well groups (m 3 ) parameters to start the equipment trial run at the lowest frequency.

[0100] Well XX-1 has a flowing pressure of 0.411MPa, a casing pressure of 0.086MPa, and a daily gas production of 1798m 3 / d, water output 2.12m 3 / d;

[0101] Well XX-1-1 has a flowing pressure of 0.191MPa, a casing pressure of 0.110MPa, and a daily gas production of 1737m 3 / d, water output 0.31m3 / d;

[0102] XX-1-2 well has a flowing pressure of 0.333MPa, a casing pressure of 0.087MPa, and a daily gas production of 1348m 3 / d, water output 0.09m 3 / d;

[0103] XX-1-3 well has a flowing pressure of 0.087MPa, a casing pressure of 0.087MPa, and a daily gas production of 1034m 3 / d, water output 0.05m 3 / d;

[0104] Well XX-1-4 has a flowing pressure of 0.232MPa, a casing pressure of 0.084MPa, and a daily gas production of 428m 3 / d, water output 0.01m 3 / d;

[0105] S6: Operate negative pressure production equipment to achieve single well incremental balance.

[0106] According to the operation steps, the switch status of S2 manifold is adopted, and the gas flow rate is all bypassed. Slowly slightly close the bypass stop valve 2 until the cumulative gas production of the observation well group reaches 6345m before installation. 3 / d adjusted to 6600m 3 / d, indicating that part of the gas production of the well group goes through the bypass, and the other part goes through the negative pressure extraction equipment; at the same time, check the instantaneous gas production of the flow meter of the single well, adjust the stop valve of the pressure balance manifold to control the instantaneous gas production increment, and for wells with too large production increment, reduce the gas production of the corresponding wells by closing the pressure balance manifold; for wells with too small production increment, increase the gas production of the corresponding wells by opening the pressure balance manifold to balance the increment of the single well.

[0107] S7: According to the daily production increase system, gradually close the bypass valve to allow all the gas to pass through the negative pressure extraction equipment.

[0108] The minimum frequency of the screw pump of the negative pressure extraction equipment is 25HZ. The bypass stop valve is slightly closed until it is completely closed, so that the instantaneous gas volume is 6345m 3 / d slowly increases to 8200m 3 / d, at this time, the gas production of the well group is completely introduced into the negative pressure extraction equipment for full-load production from the original bypass gas volume diversion state (the bypass of the shut-off valve 2 can play a diversion role to avoid the well group from increasing production too quickly and causing adverse effects on the well). Repeat the operation method S5, and control the single well production increase of the well group to be in a balanced state while keeping the total production of the well group unchanged.

[0109] Figure 3 to Figure 3e This is the production increase effect diagram of a single well in the XX-1 well group after the negative pressure extraction equipment was installed. Figure 4This is the overall increase in production effect of the XX-1 well group after the negative pressure extraction equipment was installed. Table 1 is the basic data of the XX-1 well group in the later period.

[0110] Table 1

[0111]

[0112] By adjusting the size of the stop valve of the pressure balance manifold, the negative pressure extraction equipment is operated for 45 days. Figure 4 and Figure 5 As shown, the gas production of the well group is from 6345m 3 / d increased to 8900m 3 / d, the production increase effect is significant, the air inlet pressure of the negative pressure extraction equipment slowly decreases from 80Kpa and stabilizes at 50Kpa. Properly reducing and stabilizing the air inlet pressure is of great significance to improving the recovery rate of the later coalbed methane well group.

[0113] The coalbed methane negative pressure extraction equipment of the embodiment of the present invention has the following beneficial effects:

[0114] The present invention connects the well group to a set of negative pressure extraction equipment. When the casing pressure of the drainage well is higher than the system pressure, the gas volume can be effectively controlled to enter the gathering and transportation network by adjusting the size of the pressure balance manifold stop valve and adjusting the bypass stop valve. When the casing pressure of the drainage well is lower than the system pressure, the gas volume can still effectively enter the gathering and transportation network, realizing balanced production of the entire well group, long-term continuous production, and stable production. The advantages of the present invention are small footprint, high working stability, no need for installation foundation, continuous extraction, low operation and maintenance costs, and simple operation and maintenance.

[0115] The present invention is connected to the manifold of the negative pressure extraction device, and can achieve the increase of the total gas production of the later drainage well group by adjusting the size of the stop valve of the pressure balance manifold, and can also control the single well of the well group to achieve balanced production increase. The bypass of the negative pressure extraction equipment can play a diversion role by adjusting the stop valve to avoid the well group from increasing production too quickly, which will cause adverse effects on the well.

[0116] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0117] It is not difficult for those skilled in the art to understand that the present invention includes any combination of the invention content and specific implementation methods of the above specification and the various parts shown in the drawings. Due to the limited space and to make the specification concise, the various schemes composed of these combinations are not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0118] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A coalbed methane negative pressure extraction device, characterized in that: include: A motor, a main engine screw pump and an oil-gas separator are connected in sequence through a gas main line; An oil-gas separator, an oil cooling fan, an oil filter and an oil cut-off valve are sequentially connected through an oil pipeline; as well as An air inlet water-gas separator, one end of which is connected to the air inlet, and the other end of which is connected to the main engine screw pump through an air inlet valve; in: The oil cut-off valve is further connected to the main engine screw pump to form a loop; An oil separator core is built into the top of the oil-gas separator, and the oil separator core, the air cooling fan and the water-gas separator at the air outlet are connected to the air outlet through a gas main line.

2. A coalbed methane negative pressure extraction device according to claim 1, characterized in that: After the motor is started, the main engine screw pump is driven by the motor to operate, and the low-pressure gas is compressed into the oil-gas separator through the air inlet on the air inlet valve, the air inlet water-gas separator, the air inlet valve, and the main engine screw pump; the oil in the oil-gas separator flows in a mist state driven by the air flow, and the oil-gas mixture compressed by the main engine screw pump flows into the oil-gas separator to establish an initial pressure; Under the action of the initial pressure, the oil in the lower part of the oil-gas separator passes through the oil cooling fan, the oil filter and the oil cut-off valve in turn to circulate to the main engine screw pump position to complete the oil circulation; the high-pressure gas passes through the oil separation core, the air cooling fan and the outlet water-gas separator and is transported to the system pipe network; Wherein, the initial pressure is 0.2-0.3Mpa.

3. A coalbed methane negative pressure extraction device according to claim 1, characterized in that: Also includes: Inlet valve and exhaust valve; in: When the gas outlet pressure is higher than the preset gas outlet value, the inlet valve is closed and the vent valve is opened, so that the pressure of the oil-gas separator is kept in a safe state; When the air inlet pressure is lower than the preset air inlet value, the air inlet valve is closed and the vent valve is opened to ensure the safety of the well site pipeline process.

4. A coalbed methane negative pressure extraction device as claimed in claim 3, characterized in that: The pressure of the oil-gas separator is maintained at 0.4 MPa, which is in a safe state.

5. The coalbed methane negative pressure extraction equipment according to claim 1, characterized in that: A host temperature sensor and a check valve are further provided between the host screw pump and the oil-gas separator, wherein the host temperature sensor is used to measure the temperature of the host and convert the measured host temperature information into an electrical signal for subsequent processing and control, and the operating range of the host temperature is set to 70-85°C. When the host temperature is detected to be lower than 70°C, the oil cooling fan stops heat dissipation, and when the temperature is higher than 85°C, the oil cooling fan starts forced heat dissipation; The check valve is used to prevent oil and gas from flowing back to the separation tank.

6. The coalbed methane negative pressure extraction equipment according to claim 1, characterized in that: The air inlet water-gas separator is further connected to an inlet flame arrester, the inlet flame arrester is connected to a gas filter, and the gas filter is connected to the air inlet valve.

7. A coalbed methane negative pressure extraction device as claimed in claim 1, characterized in that: The air outlet water-gas separator is further connected to the outlet flame arrester, and an exhaust temperature sensor is provided between the air outlet water-gas separator and the outlet flame arrester for detecting the air outlet temperature.

8. The coalbed methane negative pressure extraction equipment according to claim 1, characterized in that: An oil return filter is arranged above the oil separation core, and the oil return filter is communicated with the air intake valve through an oil pipeline.

9. The coalbed methane negative pressure extraction equipment according to claim 1, characterized in that: A minimum pressure valve is provided between the oil separator core and the air-cooling fan, and a pressure sensor is provided between the air-cooling fan and the air outlet water-gas separator, wherein the pressure sensor is used to detect the air outlet pressure.

10. The coalbed methane negative pressure extraction equipment according to claim 1, characterized in that: The bottom of the oil-gas separator is connected to the drain outlet through a ball valve.

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