rus
Issue #6/2022
F. G. Agaev, I. H. Asadov
On the Possibility of Satellite Spectrophotometric Estimation of the Volume of the Trace Gase Emission into the Atmosphere During the Hydrocarbon Gas Flaring
On the Possibility of Satellite Spectrophotometric Estimation of the Volume of the Trace Gase Emission into the Atmosphere During the Hydrocarbon Gas Flaring
DOI: 10.22184/1993-7296.FRos.2022.16.6.476.482
The article is devoted to the improvement of previously developed methods of satellite spectrophotometric control of volumes of hydrocarbon gases burned in flares by assessing and registering an increase in the content of trace gases in the atmosphere. A new method for determining the volumes of gases NO2 and SO2 emitted into the atmosphere during the combustion of associated hydrocarbon gas is proposed. To implement the proposed method, an on-board IR spectroradiometer VIIRS and an on-board spectroradiometer of the OMI type or other similar devices can be used. Before calculating the concentrations of gases NO2 and SO2 emitted into the atmosphere, the source of their occurrence is to be determined: whether the results of spectrophotometric measurements relate exclusively to the flaring of the associated hydrocarbon gas or to the operation of diesel engines. Using the detection criterion in the form of the ratio of the initially calculated values of the volumes NO2 and SO2, the source of the emission is determined: Based on belong of the sources to the associated hydrocarbon gas flaring or to the operation of diesel engines, the measurement results will contribute to the monitoring of oil and gas production zones where significant anomalies in the concentration of trace gases are observed.
The article is devoted to the improvement of previously developed methods of satellite spectrophotometric control of volumes of hydrocarbon gases burned in flares by assessing and registering an increase in the content of trace gases in the atmosphere. A new method for determining the volumes of gases NO2 and SO2 emitted into the atmosphere during the combustion of associated hydrocarbon gas is proposed. To implement the proposed method, an on-board IR spectroradiometer VIIRS and an on-board spectroradiometer of the OMI type or other similar devices can be used. Before calculating the concentrations of gases NO2 and SO2 emitted into the atmosphere, the source of their occurrence is to be determined: whether the results of spectrophotometric measurements relate exclusively to the flaring of the associated hydrocarbon gas or to the operation of diesel engines. Using the detection criterion in the form of the ratio of the initially calculated values of the volumes NO2 and SO2, the source of the emission is determined: Based on belong of the sources to the associated hydrocarbon gas flaring or to the operation of diesel engines, the measurement results will contribute to the monitoring of oil and gas production zones where significant anomalies in the concentration of trace gases are observed.
Теги: atmosphere gas flare satellite control spectroradiometer trace gases атмосфера газовый факел малые газы спектрорадиометр спутниковый контроль
On the Possibility of Satellite Spectrophotometric Estimation of the Volume of the Trace Gase Emission Into the Atmosphere During the Hydrocarbon Gas Flaring
F. G. Agaev, I. H. Asadov
National Aerospace Agency, Baku, Republic of Azerbaijan
The article is devoted to the improvement of previously developed methods of satellite spectrophotometric control of volumes of hydrocarbon gases burned in flares by assessing and registering an increase in the content of trace gases in the atmosphere. A new method for determining the volumes of gases NO2 and SO2 emitted into the atmosphere during the combustion of associated hydrocarbon gas is proposed. To implement the proposed method, an on-board IR spectroradiometer VIIRS and an on-board spectroradiometer of the OMI type or other similar devices can be used. Before calculating the concentrations of gases NO2 and SO2 emitted into the atmosphere, the source of their occurrence is to be determined: whether the results of spectrophotometric measurements relate exclusively to the flaring of the associated hydrocarbon gas or to the operation of diesel engines. Using the detection criterion in the form of the ratio of the initially calculated values of the volumes NO2 and SO2, the source of the emission is determined: Based on belong of the sources to the associated hydrocarbon gas flaring or to the operation of diesel engines, the measurement results will contribute to the monitoring of oil and gas production zones where significant anomalies in the concentration of trace gases are observed.
Key words: gas flare, spectroradiometer, satellite control, trace gases, atmosphere
The article is received on: 19.04.2022
The article is admitted to publication on:13.06.2022
It is well known that according to the Paris Agreement, in order to reduce carbon emissions into the atmosphere, measures should be taken to strictly control the volumes of hydrocarbon gas flared [1,2]. According to [3], such control can be carried out by organizing independent measurements of the concentrations in the atmosphere of trace gases emitted during the combustion of hydrocarbon natural gas. Measurements of the concentration of such trace gases as NO2, SO2, etc., in the atmosphere are currently carried out by both satellite [4, 5] and ground-based means [6].
The relevance of studying the content of these trace gases in the atmosphere lies in the fact that NO2 and SO2 are the main reactive trace gases, as well as the main sources of secondary aerosols and tropospheric ozone [7]. According to the results of the experimental studies, significant anomalies in the concentration of these trace gases are observed in oil and gas production zones [8]. As noted in [7], basically, NO2 and SO2 are emitted both during the combustion of associated hydrocarbon gas, and during the operation of diesel engines. The sulfur content in these two sources differs significantly. Therefore, for the correct detection of the sources of the studied gases, a criterion is used in the form of the ratio of the volumes of emitted NO2 and SO2, i. e. NO2 / SO2.
The measurement results were obtained using a VIIRS (Visible Infrared Imaging Radiometer Suite) scanning radiometer manufactured by Raytheon Company, operating in the visible and infrared ranges, and an on-board OMI (Ozone Monitoring Instrument) spectrometer. VIIRS is designed to monitor and study the changes in vegetation properties, land use, hydrological cycle and energy balance of the Earth and is installed on Suomi NPP and NOAA‑206 satellites. The OMI onboard spectrometer is a wide-field scanning device operating in the range of 264–504 nm, installed on the Aura satellite (NASA).
The authors of this article consider the possibility of determining the volumes of SO2 and NO2 emissions into the atmosphere by comparing the results of calculations of the associated gas volume burned in flares performed by various methods. It was shown in [7] that the values of the volumes of the burned gas calculated on the basis of the results obtained by the VIIRS spectroradiometer, as well as the data of SO2 and NO2 emissions obtained from the OMI spectrometer, have a good match.
In Fig. 1, the blue and red continuous lines connecting the results of observations from 2004 to 2018 correspond to the volumes of SO2 and NO2 emissions into the atmosphere in these years. The green dotted line corresponds to the radiation heat recorded using the VIIRS installed on the satellite, the blue dotted line corresponds to the uncorrected data concerning NO2 volumes. VIIRS data are indicated starting from 2012 [7].
In the same years, the volumes of the associated hydrocarbon gas produced and the oil produced have changed (Fig.2).
The proposed method
Let’s consider the possibility of determining the volumes of the associated hydrocarbon gas burned in flares through IR thermal measurements using onboard IR cameras (radiometers) installed on the satellites. As noted in [7], at the first stage of the satellite gas flares observations, such work was carried out using the ATSR scanning radiometer installed on board the ERS‑1; ERS‑2; ENVISAT satellites, as well as the DMPS program satellites. In the future, the MODIS spectroradiometer was used, as well as the VIIRS broadband radiometer installed on the JRSS satellite. The VIIRS measurement method takes into account that temperatures in the range of 800–1 200 K are specific to biomass burning, and 1 700–1 800 K to gas burning. According to the VIIRS method, the volume of the gas burned (V) was determined by the formula.
V = 0.0281 · RH (1)
where: RH is the radiative heat emission, Watts. At the same time, V is measured in billions of cubic meters. The correlation between V and RH is shown in Fig. 3.
The RH indicator is determined by the formula:
RH = J · SD, (2)
where: D is the indicator of nonlinear correction; J is the radiative heat flux of the surface unit (J is determined by the Stefan-Boltzmann equation: J = σεT4); ε is the integral emissivity of the flame; σ is the Stefan–Boltzmann constant; S is the surface area of the flame.
The flame surface area is determined by the formula:
, (3)
where: h0 is the maximum value on the Planck curve corresponding to the flame (flare) radiation spectral density; hd is the maximum mark on the detector scale, which corresponds to the value of h0; M is the area of the image of the flare on the sensitive element of the detector.
As for the temperature of the flare T, the formula T = b / λmax is used, where: b is the constant Wien displacement; b = 2897.8 K · µm; is the wavelength corresponding to the wavelength of the maximum radiation emission.
Let’s consider the possibility of determining the volume of the associated hydrocarbon gas burned in flares by estimating the volumes of SO2 and NO2 emitted into the atmosphere.
As reported in [7], there are two independent methods for determining the volume of gas burned in flares by assessing the emissions of trace gases into the atmosphere as combustion products: a method based on the assessment of NO2 emissions and a method based on the assessment of SO2 emissions.
The principle of the NO2 emission-based estimation method is that high-temperature combustion of gas produces NO from N2 present in the atmosphere. Within a few minutes, NO, interacting with the O3 present in the air, creates NO2. At the same time, the emission coefficient weakly depends on the burner diameter, the gas flow rate, and the composition of the gas. There are various estimates of the coefficient of NO2 emission, which are in the range of 1,35 < < 1,75 (g / m3). If we take the average value of the emission coefficient of this gas = 1.56 ± 0,2 g / m3, then according to [7], the volumes of the burned gas Vf can be calculated by the formula
, (4)
where: is the volume of NO2 emission.
The method based on the assessment of SO2 emissions relies on the phenomenon that during the combustion of hydrocarbon natural gas, sulfurous gas is mainly emitted in the form of H2S. After the oxidation of this product, SO2 occurs. Thus, knowing the volume of SO2 emissions, the amount of combustible gas can be determined by the formula:
, (5)
where : is the molecular weight (64 g / mol);
is the molar volume at STP STP (0,022 m3 / mol);
is the mixing ratio of into the associated gas.
The value of varies within the range of 1.2% to 2.6%. The accuracy of the estimates according to the formulas (1), (2) can reach ± 40% [10].
Taking into account (4) and (5), we determine the criterion of the ratio of the measured values and to the flaring of the associated hydrocarbon gas. From (4) we get:
. (6)
From (5) we get:
. (7)
Then the indicator γ0, which can be used as the fitting criterion of the measured values and to the emission of gases released during the flaring of the associated hydrocarbon gas, will take the form of:
. (9)
Taking into account the above, we propose the following algorithm for measuring NO2 and SO2 and determining the source of their emission.
Determination by means of a pyrometer installed on board the satellite, of the volume of the burned gas Vf.
Calculation of and using formulas (6) and (7), respectively.
Determination of (OMI) and (OMI) using the OMI spectroradiometer installed on the satellite.
Checking the ratio (OMI) / (OMI) = γ to fulfill the criterion γ = γ0.
If γ = γ0, then the calculated values of and are confirmed as the volumes of emissions of gases released during the associated hydrocarbon gas flaring.
If γ ≠ γ0, then the difference between Δ and Δ is calculated, to be determined as:
, (10)
. (11)
These values show that diesel engines have become the source of emissions.
Conclusion
A method for determining the volume of emissions of gases NO2 and SO2 into the atmosphere during the combustion of the associated hydrocarbon gas is proposed. To implement the proposed method, an on-board IR spectroradiometer and an on-board OMI-type spectroradiometer or any other similar device can be used. The initial values of the emitted volumes of NO2 and SO2 are determined using the known results of calculations of the volumes of associated hydrocarbon gas burned. The satisfiability of the fitting criterion of the measured values and to the emission of gases released during the flaring of the associated hydrocarbon is preliminarily determined. Based on belonging of the sources of emitted volumes of NO2 and SO2 to the associated petroleum gas flaring or to the operation of diesel engines, the results of measurements of the NO2 and SO2 volumes will give a contribution to the monitoring of the oil-and-gas production zones, where there are significant anomalies in the concentration of the trace gases.
THE AUTHORS
Agaev F. G., Doctor of Technical Sciences, Professor, National Aerospace Agency, Baku, Republic of Azerbaijan.
ORCID: 0000-0002-9826-0868
Asadov I. H., postgraduate student, National Aerospace Agency, Baku, Republic of Azerbaijan.
ORCHID: 0000-0003-2535-3534
F. G. Agaev, I. H. Asadov
National Aerospace Agency, Baku, Republic of Azerbaijan
The article is devoted to the improvement of previously developed methods of satellite spectrophotometric control of volumes of hydrocarbon gases burned in flares by assessing and registering an increase in the content of trace gases in the atmosphere. A new method for determining the volumes of gases NO2 and SO2 emitted into the atmosphere during the combustion of associated hydrocarbon gas is proposed. To implement the proposed method, an on-board IR spectroradiometer VIIRS and an on-board spectroradiometer of the OMI type or other similar devices can be used. Before calculating the concentrations of gases NO2 and SO2 emitted into the atmosphere, the source of their occurrence is to be determined: whether the results of spectrophotometric measurements relate exclusively to the flaring of the associated hydrocarbon gas or to the operation of diesel engines. Using the detection criterion in the form of the ratio of the initially calculated values of the volumes NO2 and SO2, the source of the emission is determined: Based on belong of the sources to the associated hydrocarbon gas flaring or to the operation of diesel engines, the measurement results will contribute to the monitoring of oil and gas production zones where significant anomalies in the concentration of trace gases are observed.
Key words: gas flare, spectroradiometer, satellite control, trace gases, atmosphere
The article is received on: 19.04.2022
The article is admitted to publication on:13.06.2022
It is well known that according to the Paris Agreement, in order to reduce carbon emissions into the atmosphere, measures should be taken to strictly control the volumes of hydrocarbon gas flared [1,2]. According to [3], such control can be carried out by organizing independent measurements of the concentrations in the atmosphere of trace gases emitted during the combustion of hydrocarbon natural gas. Measurements of the concentration of such trace gases as NO2, SO2, etc., in the atmosphere are currently carried out by both satellite [4, 5] and ground-based means [6].
The relevance of studying the content of these trace gases in the atmosphere lies in the fact that NO2 and SO2 are the main reactive trace gases, as well as the main sources of secondary aerosols and tropospheric ozone [7]. According to the results of the experimental studies, significant anomalies in the concentration of these trace gases are observed in oil and gas production zones [8]. As noted in [7], basically, NO2 and SO2 are emitted both during the combustion of associated hydrocarbon gas, and during the operation of diesel engines. The sulfur content in these two sources differs significantly. Therefore, for the correct detection of the sources of the studied gases, a criterion is used in the form of the ratio of the volumes of emitted NO2 and SO2, i. e. NO2 / SO2.
The measurement results were obtained using a VIIRS (Visible Infrared Imaging Radiometer Suite) scanning radiometer manufactured by Raytheon Company, operating in the visible and infrared ranges, and an on-board OMI (Ozone Monitoring Instrument) spectrometer. VIIRS is designed to monitor and study the changes in vegetation properties, land use, hydrological cycle and energy balance of the Earth and is installed on Suomi NPP and NOAA‑206 satellites. The OMI onboard spectrometer is a wide-field scanning device operating in the range of 264–504 nm, installed on the Aura satellite (NASA).
The authors of this article consider the possibility of determining the volumes of SO2 and NO2 emissions into the atmosphere by comparing the results of calculations of the associated gas volume burned in flares performed by various methods. It was shown in [7] that the values of the volumes of the burned gas calculated on the basis of the results obtained by the VIIRS spectroradiometer, as well as the data of SO2 and NO2 emissions obtained from the OMI spectrometer, have a good match.
In Fig. 1, the blue and red continuous lines connecting the results of observations from 2004 to 2018 correspond to the volumes of SO2 and NO2 emissions into the atmosphere in these years. The green dotted line corresponds to the radiation heat recorded using the VIIRS installed on the satellite, the blue dotted line corresponds to the uncorrected data concerning NO2 volumes. VIIRS data are indicated starting from 2012 [7].
In the same years, the volumes of the associated hydrocarbon gas produced and the oil produced have changed (Fig.2).
The proposed method
Let’s consider the possibility of determining the volumes of the associated hydrocarbon gas burned in flares through IR thermal measurements using onboard IR cameras (radiometers) installed on the satellites. As noted in [7], at the first stage of the satellite gas flares observations, such work was carried out using the ATSR scanning radiometer installed on board the ERS‑1; ERS‑2; ENVISAT satellites, as well as the DMPS program satellites. In the future, the MODIS spectroradiometer was used, as well as the VIIRS broadband radiometer installed on the JRSS satellite. The VIIRS measurement method takes into account that temperatures in the range of 800–1 200 K are specific to biomass burning, and 1 700–1 800 K to gas burning. According to the VIIRS method, the volume of the gas burned (V) was determined by the formula.
V = 0.0281 · RH (1)
where: RH is the radiative heat emission, Watts. At the same time, V is measured in billions of cubic meters. The correlation between V and RH is shown in Fig. 3.
The RH indicator is determined by the formula:
RH = J · SD, (2)
where: D is the indicator of nonlinear correction; J is the radiative heat flux of the surface unit (J is determined by the Stefan-Boltzmann equation: J = σεT4); ε is the integral emissivity of the flame; σ is the Stefan–Boltzmann constant; S is the surface area of the flame.
The flame surface area is determined by the formula:
, (3)
where: h0 is the maximum value on the Planck curve corresponding to the flame (flare) radiation spectral density; hd is the maximum mark on the detector scale, which corresponds to the value of h0; M is the area of the image of the flare on the sensitive element of the detector.
As for the temperature of the flare T, the formula T = b / λmax is used, where: b is the constant Wien displacement; b = 2897.8 K · µm; is the wavelength corresponding to the wavelength of the maximum radiation emission.
Let’s consider the possibility of determining the volume of the associated hydrocarbon gas burned in flares by estimating the volumes of SO2 and NO2 emitted into the atmosphere.
As reported in [7], there are two independent methods for determining the volume of gas burned in flares by assessing the emissions of trace gases into the atmosphere as combustion products: a method based on the assessment of NO2 emissions and a method based on the assessment of SO2 emissions.
The principle of the NO2 emission-based estimation method is that high-temperature combustion of gas produces NO from N2 present in the atmosphere. Within a few minutes, NO, interacting with the O3 present in the air, creates NO2. At the same time, the emission coefficient weakly depends on the burner diameter, the gas flow rate, and the composition of the gas. There are various estimates of the coefficient of NO2 emission, which are in the range of 1,35 < < 1,75 (g / m3). If we take the average value of the emission coefficient of this gas = 1.56 ± 0,2 g / m3, then according to [7], the volumes of the burned gas Vf can be calculated by the formula
, (4)
where: is the volume of NO2 emission.
The method based on the assessment of SO2 emissions relies on the phenomenon that during the combustion of hydrocarbon natural gas, sulfurous gas is mainly emitted in the form of H2S. After the oxidation of this product, SO2 occurs. Thus, knowing the volume of SO2 emissions, the amount of combustible gas can be determined by the formula:
, (5)
where : is the molecular weight (64 g / mol);
is the molar volume at STP STP (0,022 m3 / mol);
is the mixing ratio of into the associated gas.
The value of varies within the range of 1.2% to 2.6%. The accuracy of the estimates according to the formulas (1), (2) can reach ± 40% [10].
Taking into account (4) and (5), we determine the criterion of the ratio of the measured values and to the flaring of the associated hydrocarbon gas. From (4) we get:
. (6)
From (5) we get:
. (7)
Then the indicator γ0, which can be used as the fitting criterion of the measured values and to the emission of gases released during the flaring of the associated hydrocarbon gas, will take the form of:
. (9)
Taking into account the above, we propose the following algorithm for measuring NO2 and SO2 and determining the source of their emission.
Determination by means of a pyrometer installed on board the satellite, of the volume of the burned gas Vf.
Calculation of and using formulas (6) and (7), respectively.
Determination of (OMI) and (OMI) using the OMI spectroradiometer installed on the satellite.
Checking the ratio (OMI) / (OMI) = γ to fulfill the criterion γ = γ0.
If γ = γ0, then the calculated values of and are confirmed as the volumes of emissions of gases released during the associated hydrocarbon gas flaring.
If γ ≠ γ0, then the difference between Δ and Δ is calculated, to be determined as:
, (10)
. (11)
These values show that diesel engines have become the source of emissions.
Conclusion
A method for determining the volume of emissions of gases NO2 and SO2 into the atmosphere during the combustion of the associated hydrocarbon gas is proposed. To implement the proposed method, an on-board IR spectroradiometer and an on-board OMI-type spectroradiometer or any other similar device can be used. The initial values of the emitted volumes of NO2 and SO2 are determined using the known results of calculations of the volumes of associated hydrocarbon gas burned. The satisfiability of the fitting criterion of the measured values and to the emission of gases released during the flaring of the associated hydrocarbon is preliminarily determined. Based on belonging of the sources of emitted volumes of NO2 and SO2 to the associated petroleum gas flaring or to the operation of diesel engines, the results of measurements of the NO2 and SO2 volumes will give a contribution to the monitoring of the oil-and-gas production zones, where there are significant anomalies in the concentration of the trace gases.
THE AUTHORS
Agaev F. G., Doctor of Technical Sciences, Professor, National Aerospace Agency, Baku, Republic of Azerbaijan.
ORCID: 0000-0002-9826-0868
Asadov I. H., postgraduate student, National Aerospace Agency, Baku, Republic of Azerbaijan.
ORCHID: 0000-0003-2535-3534
Readers feedback
