Constant pressure adjusting device for gas drive injection and flow adjusting method

Abstract

The constant pressure adjusting device comprises an upstream flange, the upstream flange is sequentially connected with a filter, a flow meter and a downstream flange through gas injection pipelines, and a manual flow adjusting valve and a self-operated back pressure valve are sequentially arranged between the flow meter and the downstream flange through the gas injection pipelines; the invention further discloses a flow adjusting method for gas drive injection. The method specifically comprises the steps that the pressure value of the self-operated back pressure valve is determined; a compressor is started to conduct multi-well simultaneous injection, and it is guaranteed that injection is conducted on each injection well under the stable flow; when the injection well does not reach the single-day injection rate, the opening degree of the adjusting valve is adjusted to 100%, and when the pressure exceeds the set pressure value of the constant pressure valve, the bypass self-operated constant pressure valve is opened to ensure that the compressor does not stop, and meanwhile, an alarm is given out to remind an operator of normally stopping the compressor or adjusting the injection process to carry out the next round of injection. According to the constant pressure regulation protection control system and method, the workload of starting and stopping the compressor is reduced, the working efficiency is improved, and continuous operation and unattended operation are achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field surface engineering construction, relates to a constant pressure regulating device for gas drive injection, and also relates to a flow regulating method for gas drive injection. Background Art

[0002] As oilfield exploitation continues, the reservoir is dense and water injection development cannot establish an effective pressure displacement system, resulting in a gradual decline in crude oil production in the oil wells. In order to quickly replenish formation energy, establish an effective pressure displacement system, and improve the development level, gas phase flooding is carried out in the reservoir to inject associated gas or oxygen-reduced air to increase reservoir energy and thus increase the crude oil production of a single well.

[0003] At present, the gas phase injection method of oil fields is to install a compressor at the gas injection station to pressurize the injected gas phase medium. The pressurized gas is transported from the gas injection station to the downstream gas injection wells. The gas mains of each well field will then distribute the gas to each injection well. According to geological requirements, the injection volume needs to be controlled within a certain range, and continuous over-injection is not allowed; and due to the high pressure and small flow characteristics of the gas injection medium, each channel uses a flow meter and a flow control valve to form an automatic flow control device, and the metering accuracy and regulation accuracy are controlled by the automatic flow control device. Therefore, the manual flow control valves installed at the wellheads of each injection well are usually fixed and adjusted, and the opening is set according to manual experience to achieve balanced gas injection of each injection well in the injection well field. When all well fields have reached the daily injection volume, the compressor of the gas injection station stops working, and the gas injection of the block ends on that day.

[0004] However, the current gas injection control has the following defects: 1) The pressure of each gas well changes dynamically, and it is difficult to establish a fixed back pressure value behind the regulating valve. The flow regulation of each gas well is coupled and changes, making flow regulation difficult; 2) In the later stage of each round of gas injection, after the gas injection of other wells is completed, the pressure of the well with the lowest pressure or several lower wells has approached the compressor outlet pressure limit while not reaching the daily injection volume, resulting in the compressor being blocked or requiring manual emergency shutdown of the compressor. The restart procedure is cumbersome and time-consuming, which is not conducive to continuous operation and unmanned operation. Summary of the invention

[0005] The purpose of the present invention is to provide a constant pressure regulating device for gas drive injection, which solves the problems of coupled changes in flow regulation of gas wells and emergency stopping of compressors.

[0006] Another object of the present invention is to provide a method for regulating the flow rate of gas drive injection.

[0007] The technical solution adopted by the present invention is that the constant pressure regulating device for gas drive injection includes an upstream flange, the upstream flange is connected to a filter, a flow meter and a downstream flange in sequence through a gas injection pipeline, and a manual flow regulating valve and a self-operated back pressure valve are arranged in sequence between the flow meter and the downstream flange through the gas injection pipeline;

[0008] It also includes a self-operated constant pressure valve, which is connected in parallel with a manual flow regulating valve and a self-operated back pressure valve through an air injection pipeline.

[0009] Another technical solution adopted by the present invention is a flow rate regulation method for gas drive injection, using the above-mentioned constant pressure regulating device for gas drive injection, which is specifically implemented according to the following steps:

[0010] Step 1, connecting the upstream flange to the compressor, and connecting the downstream flange to the steam injection well;

[0011] Step 2, calculate the pressure of the self-operated back pressure valve and determine the range of the pressure setting value Pb;

[0012] Step 3, start the compressor to perform simultaneous injection in multiple wells, determine the opening of the manual flow control valve according to the range of the pressure setting value Pb in step 2 and the instantaneous value of the flow meter, and ensure that each injection well is injected at a stable flow rate;

[0013] Step 4, according to step 3: when the injection well reaches the daily injection volume, the gas injection is completed; when the injection well does not reach the daily injection volume, adjust the manual flow control valve and the self-operated constant pressure valve to ensure that the compressor is shut down normally or adjust the injection process for the next round of injection.

[0014] Another technical solution of the present invention is also characterized in that:

[0015] Step 2 is as follows:

[0016] Step 2.1, calculate the pressure loss △P between the compressor outlet and the wellhead self-operated back pressure valve;

[0017] Step 2.2: Calculate the pressure of the self-operated back pressure valve according to step 2.1: P1-△P, where P1 is the compressor outlet pressure value;

[0018] Step 2.3: Determine the range of the pressure setting value Pb of the self-operated back pressure valve according to step 2.2 as follows: (P1-△P)>Pb>P2, where P2 is the maximum wellhead pressure value.

[0019] The pressure loss ΔP in step 2.1 is the sum of the pressure loss of the gas injection pipeline, the pressure loss of the filter and the pressure loss of the flow meter.

[0020] Adjust the opening of the manual flow control valve in step 3:

[0021] When the instantaneous value of the flow meter is greater than the range of the pressure setting value Pb of the self-operated back pressure valve, reduce the opening of the manual flow control valve;

[0022] When the instantaneous value of the flow meter is less than the range of the pressure setting value Pb of the self-operated back pressure valve, increase the opening of the manual flow control valve.

[0023] In step 4, the manual flow regulating valve and the self-operated constant pressure valve are adjusted as follows: the opening of the manual flow regulating valve is adjusted to 100%, and when the pressure exceeds the pressure setting value Pd of the self-operated constant pressure valve, the bypass self-operated constant pressure valve is opened.

[0024] The range of the pressure setting value Pd of the self-operated constant pressure valve is: P1>Pd>Pb, where P1 is the compressor outlet pressure value and Pb is the pressure setting value of the self-operated back pressure valve.

[0025] The beneficial effects of the present invention are:

[0026] (1) The flow rate regulation of each gas well under constant pressure difference conditions of the present invention improves the accuracy and operability of regulation, and the on-site setting is more convenient and easy.

[0027] (2) The present invention prevents the compressor from being blocked or requiring emergency manual shutdown of the compressor, thereby improving on-site work efficiency, reducing the workload of starting and stopping the compressor, and achieving continuous operation and unattended operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a constant pressure regulating device for gas drive injection of the present invention;

[0029] Figure 2 It is a schematic flow chart of the flow rate regulation method of single well gas drive injection of the present invention.

[0030] In the figure, 1. upstream flange, 2. filter, 3. flow meter, 4. manual flow control valve, 5. self-operated back pressure valve, 6. self-operated constant pressure valve, 7. downstream flange. DETAILED DESCRIPTION

[0031] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Example 1

[0033] The constant pressure regulating device for gas drive injection of the present invention is as follows: Figure 1As shown, it includes an upstream flange 1, which is used to connect the upstream gas pipeline. The upstream flange 1 is connected to the filter 2, the flow meter 3 and the downstream flange 7 in sequence through the gas injection pipeline. The filter 2 is used to filter particles and impurities in the gas injection medium and to protect the flow meter 3 and the manual flow control valve 4 from being damaged and stuck. The purpose of the filtration is determined according to the actual process requirements; the flow meter 3 is used to measure the gas injection flow, the instantaneous value is used for production monitoring, and the cumulative value is used for gas injection volume adjustment; the downstream flange 7 is used to connect the downstream injection wellhead pipeline; the manual flow control valve 4 and the self-operated back pressure valve 5 are sequentially arranged between the flow meter 3 and the downstream flange 7 through the gas injection pipeline, and the opening of the manual flow control valve 4 is manually adjusted according to the data of the flow meter 3; the self-operated back pressure valve 5 sets the back pressure value to ensure that the quantitative adjustment of the flow meter 3 and the manual flow control valve 4 can be carried out under a stable differential pressure, thereby improving the adjustment accuracy.

[0034] It also includes a self-operated constant pressure valve 6, which is connected in parallel with the manual flow regulating valve 4 and the self-operated back pressure valve 5 through the gas injection pipeline. The self-operated constant pressure valve 6 automatically opens the bypass and injects at a constant pressure when the compressor is over-pressured by setting the opening and closing valve pressures, ensuring that the compressor does not stop in the short term, and sends an alarm to the control system through pressure detection to remind the operator to stop the compressor normally or adjust the injection process for the next round of injection.

[0035] Example 2

[0036] The flow rate regulation method of gas drive injection of the present invention is specifically implemented according to the following steps:

[0037] Step 1, connecting the upstream flange 1 of the above-mentioned constant pressure regulating device to the compressor outlet, and connecting the downstream flange 7 to the steam injection well;

[0038] Step 2, calculating the pressure of the self-operated back pressure valve 5, and determining the range of the pressure setting value Pb of the self-operated back pressure valve 5;

[0039] Step 2 is as follows:

[0040] Step 2.1, calculate the pressure loss △P between the compressor outlet and the wellhead self-operated back pressure valve 5;

[0041] The pressure loss ΔP in step 2.1 is the sum of the pressure loss of the gas injection pipeline, the pressure loss of the filter 2 and the pressure loss of the flow meter 3;

[0042] Step 2.2: According to step 2.1, the pressure of the self-operated back pressure valve 5 is calculated as: P1-△P, where P1 is the compressor outlet pressure value;

[0043] Step 2.3, according to step 2.2, the range of the pressure setting value Pb of the self-operated back pressure valve 5 is determined as follows: (P1-△P)>Pb>P2, where P2 is the highest wellhead pressure value;

[0044] Step 3, start the compressor to perform simultaneous injection in multiple wells, determine the opening of the manual flow control valve 4 according to the range of the pressure setting value Pb of the self-operated back pressure valve 5 in step 2 and the instantaneous value of the flow meter 3, and ensure that each injection well is injected at a stable flow rate;

[0045] Step 4, according to step 3: when the injection well reaches the daily injection volume, the gas injection is completed; when the injection well does not reach the daily injection volume, adjust the opening of the manual flow control valve 4 to 100%, and when the pressure exceeds the pressure setting value Pd of the self-operated constant pressure valve 6, the bypass self-operated constant pressure valve 6 is opened to ensure that the compressor does not stop, and at the same time, an alarm is issued to remind the operator to stop the compressor normally or adjust the injection process for the next round of injection.

[0046] Example 3

[0047] The flow rate regulation method of gas drive injection of the present invention is specifically implemented according to the following steps:

[0048] Step 1, connecting the upstream flange 1 of the above-mentioned constant pressure regulating device to the compressor outlet, and connecting the downstream flange 7 to the steam injection well;

[0049] Step 2, calculating the pressure of the self-operated back pressure valve 5, and determining the range of the pressure setting value Pb of the self-operated back pressure valve 5;

[0050] Step 2 is as follows:

[0051] Step 2.1, calculate the pressure loss △P between the compressor outlet and the wellhead self-operated back pressure valve 5;

[0052] The pressure loss ΔP in step 2.1 is the sum of the pressure loss of the gas injection pipeline, the pressure loss of the filter 2 and the pressure loss of the flow meter 3;

[0053] Step 2.2: According to step 2.1, the pressure of the self-operated back pressure valve 5 is calculated as: P1-△P, where P1 is the compressor outlet pressure value;

[0054] Step 2.3, according to step 2.2, the range of the pressure setting value Pb of the self-operated back pressure valve 5 is determined as follows: (P1-△P)>Pb>P2, where P2 is the highest wellhead pressure value;

[0055] Step 3, start the compressor to perform simultaneous injection in multiple wells, determine the opening of the manual flow control valve 4 according to the range of the pressure setting value Pb of the self-operated back pressure valve 5 in step 2 and the instantaneous value of the flow meter 3, and ensure that each injection well is injected at a stable flow rate;

[0056] Adjust the opening of the manual flow control valve 4 in step 3:

[0057] When the instantaneous value of the flow meter 3 is greater than the range of the pressure setting value Pb of the self-operated back pressure valve 5, the opening of the manual flow regulating valve 4 is reduced;

[0058] When the instantaneous value of the flow meter 3 is less than the range of the pressure setting value Pb of the self-operated back pressure valve 5, the opening of the manual flow control valve 4 is increased;

[0059] Step 4, according to step 3: when the injection well reaches the daily injection volume, the gas injection is completed; when the injection well does not reach the daily injection volume, the opening of the manual flow regulating valve 4 is adjusted to 100%, and when the pressure exceeds the pressure setting value Pd of the self-operated constant pressure valve 6, the bypass self-operated constant pressure valve 6 is opened to ensure that the compressor does not stop, and an alarm is issued at the same time to remind the operator to stop the compressor normally or adjust the injection process for the next round of injection;

[0060] The range of the pressure setting value Pd of the self-operated constant pressure valve 6 in step 4 is: P1>Pd>Pb, where P1 is the compressor outlet pressure value, and Pb is the pressure setting value of the self-operated back pressure valve 5.

[0061] Example 4

[0062] The flow rate regulation method of single well gas drive injection of the present invention is as follows: Figure 2 As shown, taking three injection wells as an example, well 1# is the last well to complete injection, and the remaining wells are completed by gas injection.

[0063] The upstream flange 1 of the above-mentioned constant pressure regulating device is connected to the compressor outlet, and the downstream flange 7 is connected to the steam injection well; when the compressor outlet pressure is 22Mpa, the sum of the pressure loss of the gas injection pipeline, the pressure loss of the filter 2 and the pressure loss of the flowmeter 3 is 2Mpa, and the pressure of the self-operated back-pressure valve 5 is 20MPa; start the compressor to inject gas into 3 wells at the same time, ensuring that the 3 injection wells are injected at a stable flow rate; the remaining two wells reach the single-day injection volume, and the gas injection is completed; the injection volume of well 1# continues to decrease, and the opening of the manual flow regulating valve 4 is adjusted to 100%, but the pressure is still out of control at 20Mpa, and the outlet pressure of the upstream compressor will exceed 22Mpa. According to the actual operating conditions, the opening pressure of the self-operated constant pressure valve 6 is set to 21Mpa, and the bypass self-operated constant pressure valve 6 is opened to ensure that the compressor does not stop, and an alarm is issued at the same time to remind the operator to stop the compressor normally or adjust the injection process for the next round of injection.

[0064] The flow regulation of each gas well under constant pressure difference conditions in the present application improves the accuracy and operability of the regulation; without stopping the compressor, the bypass is opened for protection, and then manual measures are taken to avoid automatically stopping the compressor, which improves on-site work efficiency, reduces the workload of starting and stopping the compressor, and realizes continuous operation and unattended operation.

Claims

1. A constant pressure regulating device for gas drive injection, characterized in that: The invention comprises an upstream flange (1), wherein the upstream flange (1) is connected to a filter (2), a flow meter (3) and a downstream flange (7) in sequence through a gas injection pipeline, and a manual flow regulating valve (4) and a self-operated back pressure valve (5) are arranged in sequence between the flow meter (3) and the downstream flange (7) through the gas injection pipeline; It also comprises a self-operated constant pressure valve (6), which is connected in parallel with the manual flow regulating valve (4) and the self-operated back pressure valve (5) via a gas injection pipeline.

2. A flow rate regulation method for gas drive injection, characterized in that: The constant pressure regulating device for gas drive injection as claimed in claim 1 is implemented specifically according to the following steps: Step 1, connecting the upstream flange (1) to the compressor, and connecting the downstream flange (7) to the steam injection well; Step 2, calculating the pressure of the self-operated back pressure valve (5) and determining the range of the pressure setting value Pb; Step 3, start the compressor to perform simultaneous injection into multiple wells, determine the opening of the manual flow control valve (4) according to the range of the pressure setting value Pb in step 2 and the instantaneous value of the flow meter (3), and ensure that each injection well is injected at a stable flow rate; Step 4, according to step 3: when the injection well reaches the daily injection volume, the gas injection is completed; when the injection well does not reach the daily injection volume, the manual flow control valve (4) and the self-operated constant pressure valve (6) are adjusted to ensure that the compressor is shut down normally or the injection process is adjusted for the next round of injection.

3. The flow rate regulation method for gas drive injection according to claim 2, characterized in that: The step 2 is specifically as follows: Step 2.1, calculate the pressure loss ΔP between the compressor outlet and the wellhead self-operated back pressure valve (5); Step 2.2, according to step 2.1, the pressure of the self-operated back pressure valve (5) is calculated as: P1-△P, where P1 is the compressor outlet pressure value; Step 2.3: Determine the range of the pressure setting value Pb of the self-operated back pressure valve (5) as follows: (P1-△P)>Pb>P2, where P2 is the highest wellhead pressure value.

4. The flow rate regulation method for gas drive injection according to claim 3, characterized in that: The pressure loss ΔP in step 2.1 is the sum of the pressure loss of the gas injection pipeline, the pressure loss of the filter (2) and the pressure loss of the flow meter (3).

5. The flow rate regulation method for gas drive injection according to claim 2, characterized in that: The opening adjustment of the manual flow control valve (4) in step 3: When the instantaneous value of the flow meter (3) is greater than the range of the pressure setting value Pb of the self-operated back pressure valve (5), the opening of the manual flow regulating valve (4) is reduced; When the instantaneous value of the flow meter (3) is less than the range of the pressure setting value Pb of the self-operated back pressure valve (5), the opening of the manual flow regulating valve (4) is increased.

6. The flow rate regulation method for gas drive injection according to claim 2, characterized in that: The adjustment of the manual flow regulating valve (4) and the self-operated constant pressure valve (6) in step 4 is specifically as follows: the opening of the manual flow regulating valve (4) is adjusted to 100%, and when the pressure exceeds the pressure setting value Pd of the self-operated constant pressure valve (6), the bypass self-operated constant pressure valve (6) is opened.

7. The flow rate regulation method for gas drive injection according to claim 6, characterized in that: The range of the pressure setting value Pd of the self-operated constant pressure valve (6) is: P1>Pd>Pb, wherein P1 is the compressor outlet pressure value, and Pb is the pressure setting value of the self-operated back pressure valve (5).

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