Air emissions

Recently, global climate change and air quality have become increasingly important environmental concerns. 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. 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. Industry surveys noted discrepancies that led to a thorough review of information that led to the improvement of estimation methods and emission factors associated with natural gas system activities. This has manifested itself in the engineering estimations that are used for compiling the U.S. Greenhouse Gas Inventory and in the methods used by companies for reporting under the U.S. Environmental Protection Agency's mandatory Greenhouse Gas Reporting Program.

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Carbon dioxide emissions

Carbon dioxide (CO₂) emissions from the burning of fossil fuels has been on the increase 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. 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. 

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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. 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 and/or 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 two-week spot campaign, and the implementation of a gap analysis based on reference limits mainly provided by the Tunisian normative framework and by a company standard. Because of experience gained during the project implementation in Tunisia, it is now 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.  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 rented or bought etc.) and benefits (consistent evaluation of air quality, satisfaction of legislative and local authorities, stakeholders, etc.).

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Reducing air emissions

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

Wet hydrocarbon recovery

Wet hydrocarbon recovery eliminates the continuous use of burn pit for wet HC from the blow down system and re-injects it back into the HC crude lines. The modification also allows for compliance with environmental regulations by eliminating the continuous flaring of wet HC, reserving the lifetime of the burn pits and protect the groundwater aquifer from contaminants.</u>

Reducing SO₂

One process used for sulfur oxide reduction is Claus, a catalytic chemical process that converts gaseous hydrogen sulfide (H2S) into elemental sulfur (S). Claus is commonly referred to as a sulfur recovery unit (SRU) and is widely used to produce sulfur from the hydrogen sulfide found in raw natural gas and from the by-product sour gases containing hydrogen sulfide derived from refining petroleum crude oil and other industrial facilities.

Several hundred Claus recovery units in operation worldwide. In fact, the vast majority of the 68,000,000 metric tons of sulfur produced worldwide in 2010 was by-product sulfur from petroleum refining and natural gas processing plants.

Upgrading sulfur units from the Claus process to SUPERCLAUS process achieves 98.7 % of sulfur recovery and reduce SO₂ emissions by installing new condensers with coalser oil skimmers and changing the converter 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 system is to avoid visible smoke and flames from flaring systems and to 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 CO2. Carbon 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. It is not a new technology and has been used by petroleum, chemical, and power industries for decades. In fact, carbon capture was first used in Texas in 1972 as a method to enhance oil recovery.

Purpose

CO₂ emissions from the burning of fossil fuels has been on the increase 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. 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. 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. 

Fig. 1—Three types of CO₂ sequestration.

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References

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Noteworthy papers in OnePetro

Agarwal, A., Singh, A.K. 2011. Evaluation of Fugitive Methane Emission factor for Oil and Gas in India. Presented at the SPE Annual Technical Conference and Exhibition Denver, Colorado, USA, 30 October-2 November. SPE-144628-MS. http://dx.doi.org/10.2118/144628-MS.

Barcelo, L. and Kline, J. 2012. The Cement Industry Roadmap to Reduce Carbon Emissions. Presented at the Carbon Management Technology Conference, Orlando, Florida, USA, 7-9 February. CMTC-152259-MS. http://dx.doi.org/10.7122/152259-MS.

Bradley, D.D. and Ontko, R. 2013. The Great Emissions Roundup: Strategies for Permitting Maintenance, Startup, and Shutdown (MSS) Emissions at Upstream Oil and Gas Facilities. Presented at the SPE Americas E&P Health, Safety, Security and Environmental Conference, Galveston, Texas, USA, 18-20 March. SPE-163762-MS. http://dx.doi.org/10.2118/163762-MS. 

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.

Djoko, S. 2002. Reducing Hydrocarbon Emission : Case Study At Plumpang Terminal Indonesia. Presented at the SPE International Conference on Health, Safety and Environment in Oil and Gas Exploration and Production, Kuala Lumpur, 20-22 March. SPE-74109-MS. http://dx.doi.org/10.2118/74109-MS.

Freund, P. 2002. Technology for Avoiding CO2 Emissions. WPC-32402. Presented at the 17th World Petroleum Congress, Rio de Janeiro, 1-5 September. https://www.onepetro.org/conference-paper/WPC-32402.

Hatamian, H. 1997. Air Emissions in the Up-stream Petroleum Operations. Presented at the SPE/UKOOA European Environment Conference, Aberdeen, United Kingdom, 15-16 April. SPE-37834-MS. http://dx.doi.org/10.2118/37834-MS.

Huglen, O. and Vik, R. 2001. Reducing VOC Emissions from Large Crude Carriers. Presented at the Offshore Technology Conference, Houston, 30 April-3. OTC-13241-MS. http://dx.doi.org/10.4043/13241-MS.

Mian, M.A. 2012. Air Emissions Reduction and Zero Flaring and Venting. Presented at the Abu Dhabi International Petroleum Conference and Exhibition, Abu Dhabi, 11-14 November. SPE-161558-MS. http://dx.doi.org/10.2118/161558-MS.

Schievelbein, V.H. 1997. Reducing Methane Emissions from Glycol Dehydrators. Presented at the SPE/EPA Exploration and Production Environmental Conference, Dallas, 3-5 March.SPE-37929-MS. http://dx.doi.org/10.2118/37929-MS.

Trout, L., Johnstone and J.E. 2003. Changes In Texas Air Emission Grandfathering Rules. Presented at the SPE/EPA/DOE Exploration and Production Environmental Conference, San Antonio, Texas, USA, 10-12 March. SPE-80601-MS. http://dx.doi.org/10.2118/80601-MS.

Vlasenko, V.S., Slesarenko, V.V., and Gulkov, A.N. 2014. Recuperation Vapors of Crude for Reducing Polluting Emissions. Presented at the The Twenty-fourth International Ocean and Polar Engineering Conference, Busan, Korea, 15-20 June. ISOPE-I-14-129. https://www.onepetro.org/conference-paper/ISOPE-I-14-129.

Zamzam, M.M., Reddy, V.B., Al Bisher, K.I., et al. 2012. Reducing Energy and Emissions through Predictive Performance Monitoring System. Presented at the Abu Dhabi International Petroleum Conference and Exhibition, Abu Dhabi, 11-14 November. SPE-161410-MS. http://dx.doi.org/10.2118/161410-MS.

External links

Eni. 2010. The environment and natural resources. From Annual Report 2010. http://2010ita.eni.com/annual-report/commitment-to-sustainable-development/the-environment-and-natural-resources.aspx?sc_lang=en.

Environmental Protection Agency. Air Pollution Monitoring. http://www.epa.gov/airquality/montring.html.

Environmental Protection Agency. Natural Gas Star Program. http://www.epa.gov/gasstar/. 

See also

CO2 sequestration

Glossary:Carbon_dioxide

Glossary:Methane