A method for correcting hydrogen sulfide gas alarm concentration based on the influence of wind speed and direction

Abstract

The present invention discloses a method for correcting the alarm concentration of hydrogen sulfide gas affected by wind speed and wind direction. A spatial coordinate system OXYZ is established on the FPSO wellhead, an anemometer and a hydrogen sulfide gas probe are arranged, and the initial alarm concentration ρ0 of the probe is determined. A three-dimensional numerical simulation model is established in FLACS. The wind direction and wind speed are detected in real time by the anemometer, and a judgment is made according to the wind direction. If there is no wind or the wind approaches the probe through the wellhead, no correction is required. If the wind passes through the wellhead and moves away from the probe, correction is required, that is, the theoretical alarm concentration is obtained by simulating different wind speeds and wind directions in FLACS. Then, the actual concentration ρ1 detected by the probe is compared with the alarm concentration to determine whether to give an alarm. The alarm concentration of each hydrogen sulfide gas probe is corrected and adjusted in real time according to different wind speeds and wind directions, thereby realizing the timely alarm of hydrogen sulfide gas leakage, reducing the number of probes and saving costs, and meeting the requirements for ensuring the personal safety of employees.

Description

Technical Field

[0001] The invention relates to a method for detecting H2S gas concentration, and in particular to a method for correcting the detection of H2S gas alarm concentration at an offshore platform wellhead under the influence of wind speed and direction. Background Art

[0002] Due to space limitations on offshore oil and gas production platforms, the impact of hydrogen sulfide gas leakage is more serious. The detection of hydrogen sulfide gas on offshore oil production platforms where there is a risk of hydrogen sulfide gas leakage is crucial. At present, the method of hydrogen sulfide gas detection on offshore platforms is to arrange multiple probes in the detection area for joint detection. By increasing the number of probes, the risk of missed reports during hydrogen sulfide gas detection is avoided, which will increase costs due to too many probes; in addition, this method cannot guarantee the accuracy of detection in the complex external environment of the offshore platform. For example, the probe cannot guarantee timely detection of hydrogen sulfide gas leakage under the continuous changes in external wind direction and wind speed, which will endanger personal safety in serious cases. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide a method for correcting the H2S gas alarm concentration based on the influence of wind speed and wind direction. Under the premise of ensuring that the detection accuracy is met, this method realizes real-time correction and adjustment of the alarm concentration of each hydrogen sulfide gas probe according to the wind speed and wind direction, thereby timely alarming, reducing the number of probes to save costs, and ensuring the personal safety of employees.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for correcting hydrogen sulfide gas alarm concentration based on the influence of wind speed and wind direction of the present invention comprises the following steps:

[0006] Step 1, establish a spatial coordinate system OXYZ on the horizontal plane of the FPSO wellhead, the center point O of the spatial coordinate system OXYZ is located at the geometric center point of the horizontal plane of the wellhead, select any side direction of the wellhead on the horizontal plane of the wellhead as the positive direction of the X-axis, select a direction perpendicular to the X-axis on the horizontal plane of the wellhead as the positive direction of the Y-axis, and the Z-axis is perpendicular to the X-axis and the Y-axis and perpendicular to the horizontal plane of the wellhead and upward as the positive direction;

[0007] An anemometer is arranged in the wellhead area of ​​the offshore oil and gas production platform to detect the wind direction and wind speed in the area in real time. The anemometer is connected to a computer installed in the FPSO main control room through a wireless network, and the computer reads the wind speed and wind direction in the wellhead area in real time;

[0008] Step 2: Install a hydrogen sulfide gas probe near any side of the FPSO wellhead, and determine the coordinates of the center point A of the detection hole of the hydrogen sulfide gas probe in the spatial coordinate system OXYZ, recorded as A(X1, Y1, Z1), and then store the coordinate information of the center point A of the detection hole in the computer;

[0009] Step 3: Use FLACS preprocessor CASD software to establish a three-dimensional numerical simulation model of the FPSO wellhead;

[0010] Step 4: determine the initial alarm concentration of the hydrogen sulfide gas probe, denoted as ρ0;

[0011] Step 5: Start the anemometer and hydrogen sulfide gas probe. The hydrogen sulfide gas probe detects the concentration of hydrogen sulfide gas once at a fixed time. The actual concentration of hydrogen sulfide gas at the spatial position point A (X1, Y1, Z1) in the scene is detected by the hydrogen sulfide gas probe, recorded as ρ1, and transmitted to the computer in the FPSO general control room through the wireless network; at the same time, the anemometer transmits the wind speed and wind direction information to the computer, and the computer makes the following judgments based on the wind direction at this time:

[0012] In the first step, if there is no wind or the wind approaches the hydrogen sulfide gas probe through the wellhead, the initial alarm concentration of the hydrogen sulfide gas probe will not be corrected, and the actual alarm concentration ρ2 of the hydrogen sulfide gas probe will be maintained at the initial alarm concentration ρ0, and then step six will be executed:

[0013] ρ2=ρ0=14.2mg / m 3

[0014] If the wind passes through the wellhead and is far away from the hydrogen sulfide gas probe, the initial alarm concentration of the hydrogen sulfide gas probe is corrected and the second step is executed;

[0015] In the second step, the computer executes the following steps to obtain the theoretical alarm concentration at the spatial position point A (X1, Y1, Z1) in step 2, recorded as ρ3, and then executes step 7:

[0016] Step 501, calling the basic control equation of gas diffusion, continuity equation, momentum conservation equation, energy conservation equation, component mass conservation equation and k-ω turbulence model function in the FLACS software on the computer, and setting the calculation parameters in the parameter setting interface of the FLACS software according to the parameter setting requirements of the FLACS software, wherein the calculation parameters include the pressure of hydrogen sulfide gas in the wellhead of the FPSO offshore platform, the leakage rate of hydrogen sulfide gas, and the wind speed and direction information at the wellhead of the FPSO offshore platform measured by the wind speed and direction meter;

[0017] Step 502, simulating the diffusion of hydrogen sulfide gas leakage at the wellhead of the FPSO offshore platform according to the wind speed and wind direction information read by the computer, and obtaining the alarm concentration of the spatial position point A (X1, Y1, Z1);

[0018] Step 6: When there is no wind or the wind is approaching the hydrogen sulfide gas probe through the wellhead, compare the actual detection concentration ρ1 measured by the hydrogen sulfide gas probe with the actual alarm concentration ρ2. If ρ2 ≥ ρ1, it indicates that hydrogen sulfide gas is leaking and an alarm is issued; otherwise, proceed to step 8;

[0019] Step 7: When the wind passes through the wellhead and is far away from the hydrogen sulfide gas probe, compare the actual detection concentration ρ1 measured by the hydrogen sulfide gas probe with the theoretical alarm concentration ρ3. If ρ3 ≥ ρ1, it indicates that hydrogen sulfide gas is leaking and an alarm is issued; otherwise, proceed to step 8;

[0020] Step 8. Repeat steps 5, 6, and 7 to enter the next round of detection.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention realizes the detection of H2S gas based on the influence of wind speed and wind direction. Under the guidance of gas diffusion analysis theory, it realizes real-time correction and adjustment of the alarm concentration of each hydrogen sulfide gas probe according to the wind speed and wind direction, thereby giving an alarm in time, reducing the number of probes, saving costs, and ensuring the personal safety of employees. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The present invention provides a method for correcting the concentration of hydrogen sulfide gas alarm based on the influence of wind speed and wind direction;

[0024] Figure 2 It is a schematic diagram of the coordinate system and probe position coordinates of the present invention;

[0025] Figure 3 It is a schematic diagram of no wind or wind approaching or moving away from the wellhead according to the present invention;

[0026] Figure 4 It is a schematic diagram of simulation results in a certain scenario of the present invention. DETAILED DESCRIPTION

[0027] The present invention is described in detail below in conjunction with specific implementations.

[0028] As shown in the attached drawings, a method for correcting the concentration of hydrogen sulfide gas alarm based on the influence of wind speed and wind direction is provided, comprising the following steps:

[0029] Step 1: Establish a spatial coordinate system OXYZ on the horizontal plane of the FPSO wellhead. The center point O of the spatial coordinate system OXYZ is located at the geometric center point of the horizontal plane of the wellhead. Select any side direction of the wellhead on the horizontal plane of the wellhead as the positive direction of the X-axis. Select a direction perpendicular to the X-axis on the horizontal plane of the wellhead as the positive direction of the Y-axis. The Z-axis is perpendicular to the X-axis and the Y-axis and is perpendicular to the horizontal plane of the wellhead and upward as the positive direction.

[0030] An anemometer is arranged in the wellhead area of ​​the offshore oil and gas production platform to detect the wind direction and wind speed in the area in real time. The anemometer is connected to a computer installed in the FPSO main control room through a wireless network, and the computer reads the wind speed and wind direction in the wellhead area in real time;

[0031] Step 2: Install a hydrogen sulfide gas probe near either side of the FPSO wellhead, and determine the coordinates of the center point A of the detection hole of the hydrogen sulfide gas probe in the spatial coordinate system OXYZ, recorded as A(X1, Y1, Z1), and then store the coordinate information of the center point A of the detection hole in the computer.

[0032] Step 3: Use the FLACS preprocessor CASD software to establish a three-dimensional numerical simulation model of the FPSO wellhead.

[0033] Step 4: Determine the initial alarm concentration of the hydrogen sulfide gas detector, denoted as ρ0; by consulting the data, it is known that the mass concentration of hydrogen sulfide gas that immediately endangers human health or life is 14.2 mg / m 3 The hydrogen sulfide gas detection alarm is generally set at 14.2 mg / m 3 , that is, ρ0 = 14.2 mg / m 3

[0034] Step 5: Start the anemometer and hydrogen sulfide gas probe. The hydrogen sulfide gas probe detects the concentration of hydrogen sulfide gas once at a fixed time. The actual concentration of hydrogen sulfide gas at the spatial position point A (X1, Y1, Z1) in the scene is detected by the hydrogen sulfide gas probe, recorded as ρ1, and transmitted to the computer in the FPSO general control room through the wireless network; at the same time, the anemometer transmits the wind speed and wind direction information to the computer, and the computer makes the following judgments based on the wind direction at this time:

[0035] In the first step, if there is no wind or the wind approaches the hydrogen sulfide gas probe through the wellhead, the initial alarm concentration of the hydrogen sulfide gas probe will not be corrected, and the actual alarm concentration ρ2 of the hydrogen sulfide gas probe will be maintained at the initial alarm concentration ρ0, and then step six will be executed:

[0036] ρ2=ρ0=14.2mg / m 3

[0037] There is no wind, that is, there is no influence of wind speed and direction, so no correction is needed. However, the wind passes through the wellhead and approaches the hydrogen sulfide gas probe. The influence caused by wind speed and direction is manifested as an increase in the concentration of hydrogen sulfide gas near the probe, which helps the probe to alarm in time, so no correction is needed;

[0038] If the wind passes through the wellhead and away from the hydrogen sulfide gas probe, the hydrogen sulfide gas concentration near the probe will decrease. If the hydrogen sulfide gas alarm concentration is not corrected, it will cause missed alarms and endanger the personal safety of the staff. If the wind passes through the wellhead and away from the hydrogen sulfide gas probe, the initial alarm concentration of the hydrogen sulfide gas probe should be corrected and the second step should be executed;

[0039] In the second step, the computer executes the following steps to obtain the theoretical alarm concentration at the spatial position point A (X1, Y1, Z1) in step 2, recorded as ρ3, and then executes step 7:

[0040] Step 501, calling the basic control equation of gas diffusion, continuity equation, momentum conservation equation, energy conservation equation, component mass conservation equation and k-ω turbulence model function in the FLACS software on the computer, and setting the calculation parameters in the parameter setting interface of the FLACS software according to the parameter setting requirements of the FLACS software, wherein the calculation parameters include the pressure of hydrogen sulfide gas in the wellhead of the FPSO offshore platform, the leakage rate of hydrogen sulfide gas, and the wind speed and direction information at the wellhead of the FPSO offshore platform measured by the wind speed and direction meter;

[0041] Step 502, simulating the diffusion of hydrogen sulfide gas leakage at the wellhead of the FPSO offshore platform under the influence of different wind speeds and wind directions, and obtaining the theoretical alarm concentration of the spatial position point A (X1, Y1, Z1).

[0042] Step 6. When there is no wind or when wind approaches the hydrogen sulfide gas probe through the wellhead, compare the actual detection concentration ρ1 measured by the hydrogen sulfide gas probe with the actual alarm concentration ρ2. If ρ2 ≥ ρ1, it indicates that hydrogen sulfide gas is leaking and an alarm is issued.

[0043] Otherwise, proceed to step eight;

[0044] Step 7: When the wind passes through the wellhead and is far away from the hydrogen sulfide gas probe, compare the actual detection concentration ρ1 measured by the hydrogen sulfide gas probe with the theoretical alarm concentration ρ3. If ρ3 ≥ ρ1, it indicates that hydrogen sulfide gas is leaking and an alarm is issued. Otherwise, proceed to step 8;

[0045] Step 8. Repeat steps 5, 6, and 7 to enter the next round of detection.

Claims

1. A method for correcting hydrogen sulfide gas alarm concentration based on the influence of wind speed and wind direction, comprising the following steps: Step 1, establish a spatial coordinate system OXYZ on the horizontal plane of the FPSO wellhead, the center point O of the spatial coordinate system OXYZ is located at the geometric center point of the horizontal plane of the wellhead, select any side direction of the wellhead on the horizontal plane of the wellhead as the positive direction of the X-axis, select a direction perpendicular to the X-axis on the horizontal plane of the wellhead as the positive direction of the Y-axis, and the Z-axis is perpendicular to the X-axis and the Y-axis and perpendicular to the horizontal plane of the wellhead and upward as the positive direction; An anemometer is arranged in the wellhead area of ​​the offshore oil and gas production platform to detect the wind direction and wind speed in the area in real time. The anemometer is connected to a computer installed in the FPSO main control room through a wireless network, and the computer reads the wind speed and wind direction in the wellhead area in real time; Step 2: Install a hydrogen sulfide gas probe near any side of the FPSO wellhead, and determine the coordinates of the center point A of the detection hole of the hydrogen sulfide gas probe in the spatial coordinate system OXYZ, recorded as A(X1, Y1, Z1), and then store the coordinate information of the center point A of the detection hole in the computer; Step 3: Use FLACS preprocessor CASD software to establish a three-dimensional numerical simulation model of the FPSO wellhead; Step 4: determine the initial alarm concentration of the hydrogen sulfide gas probe, denoted as ρ0; Step 5: Start the anemometer and hydrogen sulfide gas probe. The hydrogen sulfide gas probe detects the concentration of hydrogen sulfide gas once at a fixed time. The actual concentration of hydrogen sulfide gas at the spatial position point A (X1, Y1, Z1) in the scene is detected by the hydrogen sulfide gas probe, recorded as ρ1, and transmitted to the computer in the FPSO general control room through the wireless network; at the same time, the anemometer transmits the wind speed and wind direction information to the computer, and the computer makes the following judgments based on the wind direction at this time: In the first step, if there is no wind or the wind approaches the hydrogen sulfide gas probe through the wellhead, the initial alarm concentration of the hydrogen sulfide gas probe will not be corrected, and the actual alarm concentration ρ2 of the hydrogen sulfide gas probe will be maintained at the initial alarm concentration ρ0, and then step six will be executed: ρ2=ρ0=14.2mg / m 3 If the wind passes through the wellhead and is far away from the hydrogen sulfide gas probe, the initial alarm concentration of the hydrogen sulfide gas probe is corrected and the second step is executed; In the second step, the computer executes the following steps to obtain the theoretical alarm concentration at the spatial position point A (X1, Y1, Z1) in step 2, recorded as ρ3, and then executes step 7: Step 501, calling the basic control equation of gas diffusion, continuity equation, momentum conservation equation, energy conservation equation, component mass conservation equation and k-ω turbulence model function in the FLACS software on the computer, and setting the calculation parameters in the parameter setting interface of the FLACS software according to the parameter setting requirements of the FLACS software, wherein the calculation parameters include the pressure of hydrogen sulfide gas in the wellhead of the FPSO offshore platform, the leakage rate of hydrogen sulfide gas, and the wind speed and direction information at the wellhead of the FPSO offshore platform measured by the wind speed and direction meter; Step 502, simulating the diffusion of hydrogen sulfide gas leakage at the wellhead of the FPSO offshore platform according to the wind speed and wind direction information read by the computer, and obtaining the alarm concentration of the spatial position point A (X1, Y1, Z1); Step 6: When there is no wind or the wind is approaching the hydrogen sulfide gas probe through the wellhead, compare the actual detection concentration ρ1 measured by the hydrogen sulfide gas probe with the actual alarm concentration ρ2. If ρ2 ≥ ρ1, it indicates that hydrogen sulfide gas is leaking and an alarm is issued; otherwise, proceed to step 8; Step 7: When the wind passes through the wellhead and is far away from the hydrogen sulfide gas probe, compare the actual detection concentration ρ1 measured by the hydrogen sulfide gas probe with the theoretical alarm concentration ρ3. If ρ3 ≥ ρ1, it indicates that hydrogen sulfide gas is leaking and an alarm is issued; otherwise, proceed to step 8; Step 8. Repeat steps 5, 6, and 7 to enter the next round of detection.

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