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Air emissions

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Recently, global climate change and air quality have become increasingly important environmental concerns.[1] Consequently, there has been a rise in collaborative international efforts to reduce the concentration of greenhouse gases and criteria pollutants. Greenhouse gases include carbon dioxide (CO2)methane (CH4) and nitrous oxide (N2O), occuring naturally and as the result of human activity. Criteria pollutants include emissions of nitrogen oxide, sulfur dioxide, carbon monoxide, and total unburned hydrocarbons. International and national governments are implementing more regulations on air emissions. Drilling contractors can play an important role in environmental stewardship by reporting carbon emissions from drilling operations, eliminating redundant emission measurements, and leading the industry in efforts to reduce these emissions.

Methane emissions

Rapid worldwide expansion of natural gas developments and use in recent years is drawing attention to the need to improve understanding of methane emissions associated with natural gas.[2] New production technologies and practices, including those involving hydraulic fracturing, necessitate a thorough review of existing quantification methods for fugitive methane emissions from venting, flaring, and equipment leaks associated with natural gas systems and operations.

In the past few years, a broad variety of estimates have emerged regarding methane emissions from the United States natural gas industry sector. Some discrepancies noted by industry surveys have led to a thorough review of newly available information that is leading to the improvement of estimation methods and emission factors associated with activities that comprise natural gas systems. This has manifested itself in the engineering estimations that are used for compiling the U.S. GHG Inventory and in the methods used by companies for reporting under the U.S. Environmental Protection Agency mandatory Greenhouse Gas Reporting Program.

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Carbon emissions

Carbon emissions from the burning of fossil fuels has been on the incline since the industrial era; and with more than 85% of the world’s energy coming from fossil fuels, it will remain an important energy source well into the future.[3] As the demand for fossil fuels is growing, so is the volume of CO2 emitted each year. This has led to concerns over the impact of COemissions on global climate change. 

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Measuring air emissions

Industry and regulatory agencies have spent a great deal of study and effort to estimate air emissions from oil and gas.[4] The EPA's "AP-42" emissions estimating guideline is the standard for estimating emissions from most fugitive and combustion sources. Additionally, the EPA's "Gas Star" program helped to identify fuel gas emissions sources and rates. In the mid 1990's, the EPA developed guidance documents for estimating emissions from gas plants. The Texas Commission on Environmental Quality (TCEQ; a.k.a. TNRCC) developed guidelines and rules for determining emissions from combustion devices. A joint industry and government initiative produced "Gly-Calc" to determine emissions from glycol dehydration units. The American Petroleum Institute developed recent guidelines for the calculation of greenhouse gas emissions. Because of the calculation routines, advances in database programs, and internet reporting capabilities British Petroleum can estimate emissions from over 280 properties in the Permian Basin.

BP was the first company to apply the jointly developed techniques in estimating emissions for a large number of properties. The emission system was developed to meet two goals: 1) To gather regulatory required data for reporting emissions to the TCEQ and 2) To provide data for an intra-company greenhouse gas reporting and reduction program. Additionally, the program resulted in greater operating efficiencies and a reduction of air emissions.

In 2010, eni e&p developed the Air Quality Monitoring Standard, a guide for eni e&p subsidiaries for the design, installation, and management of fixed Air Quality Monitoring Systems (AQMS). Although fixed AQMS are the most complete and precise monitoring tools, their installation is not always necessary in order to manage air quality issues. Therefore, before installing a monitoring station, a general structured assessment of air quality and emissions' should be carried out in order to eventually identify different/cheaper monitoring options.

eni e&p gained some important expertise regarding this issue in 2011 via a structured project implemented in two Tunisian oil centers, one located in the desert, the other in a coastal area. The project has foreseen the on-site detailed evaluation of emission sources, the monitoring of air quality through a 2 weeks spot campaign and the implementation of a gap analysis based on reference limits mainly provided by the Tunisian normative framework and by the Company Standard.

Thanks to the experience gained during the project implementation in Tunisia, now it is possible to complete the currently available Air Quality Monitoring Company Standard by adding a methodological tool for carrying out a structured Air Quality Monitoring and Emissions Assessment (AQMEA) which should support Subsidiaries identifying suitable air monitoring strategies based on local particular needs. The present paper is aimed to describe the new possible methodology to be proposed.

Due to the increasing attention on environmental issues of public opinion and Governments of Countries where eni e&p operates, the attentive evaluation of air quality inside and around industrial operative sites is nowadays considered as a very important activity.

For this reason, after some experience on the field, a structured approach to air quality issues focused on local needs can be defined, which could be crucial for supporting Subsidiaries evaluating their on-site air quality. Basically, a methodological tool can now be created, which should be able to identify monitoring strategies representing a trade-off between costs (man-hours, monitoring instruments to be rent or bought etc.) and benefits (consistent evaluation of air quality, satisfaction of legislative/local authorities'/stakeholders' requirements etc.).

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Reducing air emissions

Because complying with environmental regulations is a challenge to the industry fields, companies like UGP have taken the initiative to been committed to comply with the government and industry environmental standards by implementing programs to enhance air quality.

Wet hydrocarbon recovery

The first idea is Wet Hydrocarbon Recovery System which eliminates the continuous use of burn pit for Wet HC from eth blow down system and re-injects back into the HC crude lines. Beside this modification will allow UGP to comply with environmental regulations by eliminating the continuous flaring of Wet HC, it will reserve the life time of the burn pits and protect the ground water aquifer from contaminations.

Reducing SO2

The second idea is upgrading the Sulfur units from CLAUS process to SUPERCLAUS process to achieve 98.7 % of sulfur recovery and reduce SO2 emissions by installing new condenser with coalser and changing the type of converters' catalysts. All of these modifications resulted in decreasing the SO2 emissions by 25 %. The third idea is Flare Gas Recovery System which the system will recover the flare gases from the flare headers and then compressed the gas to 260 psig for feeding the plant low pressure sour gas header. The ultimate goal of this idea is to avoid visible smoke and flame from flaring system and comply with environmental regulations. The system is very attractive not only reducing flares' emissions but also it would recover the valuable gases being wasted to the flare stack. 

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CO2 sequestration

Sequestration is one option that is gaining interest to stabilize and reduce the concentration of CO2Carbon capture and storage technology involves the process of trapping and separating the CO2, transporting it to a storage location, and then storing it long-term so that it does not enter into the atmosphere.[5] It is not a new technology and has been used by petroleum, chemical, and power industries for decades.[6] In fact, carbon capture was first used in Texas in 1972 as a method to enhance oil recovery.[7]

Purpose

CO2 emissions from the burning of fossil fuels has been on the incline since the industrial era; and with more than 85% of the world’s energy coming from fossil fuels, it will remain an important energy source well into the future.[8] As the demand for fossil fuels is growing, so is the volume of CO2 emitted each year. This has led to concerns over the impact of CO2 emissions on global climate change. CO2 sequestration is an option that is gaining interest to stabilize and reduce the concentration of CO2.

Types

After CO2 is captured at the source, it must be safely sequestered or stored away.[9] There are three types of CO2 sequestration: terrestrial, geologic, and mineralization (Fig. 1). More than 150 CO2 sequestration projects are in progress in North America alone. 

Types of CO2 sequestration.png

Fig. 1—Three types of CO2 sequestration.[9]

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References

  1. Cadigan, M.F., Peyton, K. 2005. Baselining and Reducing Air Emissions from an Offshore Drilling Contractor's Perspective. Presented at the SPE/EPA/DOE Exploration and Production Environmental Conference, Galveston, Texas, USA, 7-9 March. SPE-94432-MS. http://dx.doi.org/10.2118/94432-MS.
  2. Ritter, K., Shires, T.M., and Lev-On, M. 2014. Methane Emissions From Natural Gas Systems: A Comparative Assessment for Select Industry Segments. Presented at the SPE International Conference on Health, Safety, and Environment, Long Beach, California, USA, 17-19 March. SPE-168379-MS. http://dx.doi.org/10.2118/168379-MS.
  3. Ramharack, R.M., Aminian, K., and Ameri, S. 2010. Impact of Carbon Dioxide Sequestration in Gas/Condensate Reservoirs. Presented at the SPE Eastern Regional Meeting, Morgantown, West Virginia, USA, 13–15 October. SPE-139083-MS. http://dx.doi.org/10.2118/139083-MS.
  4. Johnstone, J.E., Stobbe, A. 2003. Estimating Air Emissions for Permian Basin Oil and Gas Properties. Presented at the SPE/EPA/DOE Exploration and Production Environmental Conference, San Antonio, Texas, USA, 10-12 March. SPE-80574-MS. http://dx.doi.org/10.2118/80574-MS.
  5. Ronca, D. 2014. How Carbon Capture Works, http://science.howstuffworks.com/environmental/green-science/carbon-capture1.htm (accessed 25 September 2014).
  6. Carbon Sequestration Leadership Forum. 2011. CO2 Capture—Does It Work? inFocus http://www.cslforum.org/publications/documents/CSLF_inFocus_CO2Capture_DoesItWork.pdf.
  7. Richey, S. 2013. Carbon Sequestration: Myth or Hope?, http://www.steverichey.com/writing-samples/climate-change/carbon-sequestration-myth-or-hope/ (accessed 23 September 2014).
  8. Ramharack, R.M., Aminian, K., and Ameri, S. 2010. Impact of Carbon Dioxide Sequestration in Gas/Condensate Reservoirs. Presented at the SPE Eastern Regional Meeting, Morgantown, West Virginia, USA, 13–15 October. SPE-139083-MS. http://dx.doi.org/10.2118/139083-MS.
  9. 9.0 9.1 The University of Utah, Department of Civil and Environmental Engineering. 2011. Carbon Capture and Sequestration, http://co2.egi.utah.edu/ (accessed 4 September 2014).

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Noteworthy papers in OnePetro

External links

See also

Category