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50387schD01R1 11/29/01 5:23 AM Page 44 Global Warming and the E&P Industry The question as to what extent man-made emissions of greenhouse gases may be causing climate change has stirred intense debate around the world. Continued shifts in the Earth’s temperatures, predicted by many scientists, could dramatically affect the way we live and do business. This article examines the evidence and the arguments, and describes some of the mitigating actions being taken by the exploration and production (E&P) industry. Melvin Cannell Centre for Ecology and Hydrology Edinburgh, Scotland Jim Filas Rosharon, Texas, USA John Harries Imperial College of Science, Technology and Medicine London, England Geoff Jenkins Hadley Centre for Climate Prediction and Research Berkshire, England Martin Parry University of East Anglia Norwich, England Paul Rutter BP Sunbury on Thames, England Lars Sonneland Stavanger, Norway Jeremy Walker Houston, Texas 44 Scientists use language cautiously. They tend to err on the side of understatement. During the mid-1990s, in the Second Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), leading scientists from around the world expressed a consensus view that “the balance of evidence suggests a discernible human influence on global climate.” In July 2001, for the IPCC Third Assessment Report, experts took this conclusion a step further. Considering new evidence, and taking into account remaining uncertainties, the panel stated “most of the observed warming over the last 50 years is likely to have been due to the increase in greenhouse-gas concentrations.”1 The word ‘likely’ is defined by the IPCC as a 66 to 90% probability that the claim is true. An important and influential segment of the global scientific community firmly believes that human activity has contributed to a rise in the Earth’s average surface temperature and a resulting worldwide climate change. They contend that such activity may be enhancing the so-called ‘greenhouse effect.’ Other distinguished scientists disagree, some dismissing the IPCC view as simplistic. The Greenhouse and Enhanced Greenhouse Effects The greenhouse effect is the name given to the insulating mechanism by which the atmosphere keeps the Earth’s surface substantially warmer than it would otherwise be. The effect can be illustrated by comparing the effects of solar radiation on the earth and the moon. Both are roughly equidistant from the sun, which supplies the radiation that warms them, and both receive about the same amount of heat energy per square meter of their surfaces. Yet, the earth is much warmer—a global average temperature of 15°C [59°F] compared with that of the moon, -18°C [-0.4°F]. The difference is largely due to the fact that the moon has almost no atmosphere while the Earth’s dense atmosphere effectively traps heat that would otherwise escape into space. Climatologists use a physical greenhouse analogy to explain how warming occurs. Energy from the sun, transmitted as visible light, passes through the glass of a greenhouse without hindrance, is first absorbed by the floor and contents, and then reemitted as infrared radiation. For help in preparation of this article, thanks to David Harrison, Houston, Texas, USA; Dwight Peters, Sugar Land, Texas; and Thomas Wilson, Caracas, Venezuela. Special thanks to the Hadley Centre for Climate Prediction and Research for supplying graphics that were used as a basis for some of the figures appearing in this article. 1. Climate Change 2001: The Scientific Basis: The Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. New York, New York, USA: Cambridge University Press (2000): 10. Oilfield Review 50387schD01R1 11/29/01 5:24 AM Page 45 50387schD01R1 11/29/01 5:24 AM Page 46 Because infrared radiation cannot pass through the glass as readily as sunlight, some of it is trapped, and the temperature inside the greenhouse rises, providing an artificially warm environment to stimulate plant growth (right). In the natural greenhouse effect, the Earth’s atmosphere behaves like panes of glass. Energy coming from the sun as visible short-wavelength radiation passes through the atmosphere, just as it does through greenhouse glass, and is absorbed by the surface of the earth, which then reemits it as long-wavelength infrared radiation. Infrared radiation is absorbed by naturally occurring gases in the atmosphere—water vapor, carbon dioxide [CO2], methane, nitrous oxide, ozone and others—and reradiated. While some energy goes into outer space, most is reradiated back to earth, heating its surface.2 An enhanced greenhouse effect occurs when human activities increase the levels of certain naturally occurring gases. If the atmosphere is pictured as a translucent blanket that insulates the earth, adding to the concentration of these greenhouse gases is analogous to increasing the thickness of the blanket, improving its insulating qualities (below). Some reemitted infrared radiation is reflected by the glass and trapped inside. Visible energy from the sun passes through the glass, heating the ground. > The greenhouse analogy. A greenhouse effectively traps a portion of the sun’s energy impinging on it, raising the interior temperature and creating an artificially warm growing environment. Natural Greenhouse Effect Enhanced Greenhouse Effect Enhanced absorption by greenhouse gases Absorption of outgoing radiation by indigenous atmospheric gases Reradiation into space Outgoing long-wavelength radiation Incoming short-wavelength radiation Reradiation to earth Reradiation into space Outgoing long-wavelength radiation Incoming short-wavelength radiation Reradiation to earth > Natural and enhanced greenhouse effects. In the natural greenhouse effect (left), indigenous atmospheric gases contribute to heating of the Earth’s surface by absorbing and reradiating back some of the infrared energy coming from the surface. In the enhanced greenhouse effect (right), increased gas concentrations, resulting from human activity, improve the atmosphere’s insulating qualities. 46 Oilfield Review 50387schD01R1 11/29/01 5:24 AM Page 47 Atmospheric constituent Source Lifetime Carbon dioxide Combustion of fossil fuels and woods Land-use changes 100 years Methane Production and transport of fossil fuels Decomposing waste Agriculture Dissociation of gas hydrates 10 years Combustion of fossil fuels Combustion of waste 150 years Chlorofluorocarbons Production 100 years Ground-level ozone Transport Industrial emissions 3 months Aerosols Power generation Transport 2 weeks Nitrous oxide Nitrous oxide 10% Autumn 2001 Carbon dioxide 63% Others 3% > Man-made emission sources and lifetimes for greenhouse gases. Various gases and aerosols are emitted daily in commercial, industrial and residential activities. Carbon dioxide is the most important, because of its abundance and effective lifetime in the atmosphere of about 100 years. Man-made emissions of greenhouse gases occur in a number of ways. For example, carbon dioxide is released to the atmosphere when solid waste, wood and fossil fuels—oil, natural gas and coal—are burned. Methane is emitted by decomposing organic wastes in landfill sites, during production and transportation of fossil fuels, by agricultural activity and by dissociation of gas hydrates. Nitrous oxide is vented during the combustion of solid wastes and fossil fuels (above left). Carbon dioxide is the most important, due principally to the fact that it has an effective lifetime in the atmosphere of about 100 years, and is the most abundant. Every year, more than 20 billion tons are emitted when fossil fuels are burned in commercial, residential, transportation and power-station applications. Another 5.5 billion tons are released during land-use changes, such as deforestation.3 The concentration of CO2 in the atmosphere has increased by more than 30% since the start of the Industrial Revolution. Methane 24% > Relative warming projected from different greenhouse gases during this century. Of the various greenhouse gases, carbon dioxide is predicted to have the greatest capacity for causing additional global warming, followed by methane and nitrous oxide. Analysis of air trapped in antarctic ice caps shows that the level of carbon dioxide in the atmosphere in pre-industrial days was about 270 parts per million (ppm). Today, readings taken at the Mauna Loa Observatory in Hawaii, USA, place the concentration at about 370 ppm.4 Concentrations of methane and nitrous oxide, which have effective lifetimes of 10 and 150 years, respectively, also have increased— methane more than doubling and nitrous oxide rising by about 15% over the same time span. Both are at much lower levels than CO2— methane at 1.72 ppm and nitrous oxide at 0.3 ppm—but they exert a significant influence because of their effectiveness in trapping heat. Methane is 21 times more effective in this regard than CO2, while nitrous oxide is 310 times more effective, molecule for molecule.5 The global-warming potential of a gas is a measure of its capacity to cause global warming over the next 100 years. The warming effect of an additional 1-kg [2.2-lbm] emission of a greenhouse gas discharged today—relative to 1 kg of CO2—will depend on its effective lifetime, the amount of extra infrared radiation it will absorb, and its density. On this basis, experts calculate that, during this century, CO2 will be responsible for about two-thirds of predicted future warming, methane a quarter and nitrous oxide around a tenth (above right).6 2. The description above is a simplification. In fact, about 25% of solar radiation is reflected back into space before reaching the Earth’s surface by clouds, molecules and particles, and another 5% is reflected back by the Earth’s surface. A further 20% is absorbed before it reaches the earth by water vapor, dust and clouds. It is the remainder—just over half of the incoming solar radiation—that is absorbed by the Earth’s surface. The greenhouse analogy, although widely used, is also only partly accurate. Greenhouses work mainly by preventing the natural process of convection. 3. Jenkins G, Mitchell JFB and Folland CK: “The Greenhouse Effect and Climate Change: A Review,” The Royal Society (1999): 9-10. 4. Reference 1: 12. 5. “The Greenhouse Effect and Climate Change: A Briefing from the Hadley Centre,” Berkshire, England: Hadley Centre for Climate Prediction and Research (October 1999): 7. 6. Reference 5: 7. 47 50387schD01R1 11/29/01 5:24 AM Page 48 Observed behavior Comparison and validation Climate-system model Computer simulation Predicted behavior Update and refine model > Climate simulations. Scientists use sophisticated models and computer simulations of the Earth’s climate system to confirm historical, and predict future, temperature changes. Results are validated by comparison with actual temperature measurements. Such analyses form a basis for updating and refining the reliability of simulations. Temperature anomalies, C 1.0 1.0 Model Observations 0.5 0.5 0.0 0.0 –0.5 –1.0 1850 –0.5 Natural factors only 1900 1950 Temperature anomalies, C 1.0 Model Observations Human factors only –1.0 2000 1850 1900 1950 2000 Model Observations 0.5 0.0 –0.5 –1.0 1850 Human and natural factors 1900 1950 2000 > Observed and simulated global warming. Neither natural nor man-made effects alone account for the evolution of the Earth’s climate during the 20th century. By combining the two, however, the observed pattern is reproduced with reasonable accuracy. 48 Measuring and Modeling Climate Change IPCC scientists believe that we are already experiencing an enhanced greenhouse effect. According to their findings, the Earth’s global average surface temperature increased by about 0.6°C [1.1°F] during the last century. They maintain that this increase is greater than can be explained by natural climatic variations. The panel believes there is only a 1 to 10% probability that inherent variability alone accounts for this extent of warming. Most studies suggest that, over the past 50 years, the estimated rate and magnitude of warming due to increasing concentrations of greenhouse gases alone are comparable to, or larger than, the observed warming.7 To better understand the physical, chemical and biological processes involved, scientists investigating climate variations construct complex mathematical models of the Earth’s weather system. These models are then used to simulate past changes and predict future variations. The more closely that simulations match historical climate records built from direct observations, the more confident scientists become in their predictive capabilities (left). Greater emphasis on diagnosing and predicting the impact of global warming has resulted in increasingly sophisticated simulations. For example, a state-of-the-art, three-dimensional (3D) ocean-atmosphere model developed at the Hadley Centre for Climate Prediction and Research in Berkshire, England, appears to replicate—with reasonable precision—the evolution of global climate during the late 19th and 20th centuries. This simulation matches records that clearly show that the global mean surface air temperature has increased by 0.6°C ± 0.2°C [1.1°F ± 0.4°F] since 1860, but that the progression has not been steady. Most of the warming occurred in two distinct periods—from 1910 to 1945, and since 1976—with little change in the intervening three decades. When factors that impact the Earth’s climate vary—concentrations of greenhouse gases, but also heat output from the sun, for example— they exert a ‘forcing’ on climate (see “Increases in Greenhouse Forcing,” next page). A positive forcing causes warming, a negative one results in cooling. When researchers at the Hadley Centre and the Rutherford Appleton Laboratory, near Oxford, England, simulated the evolution of 20th century climate, they concluded that, by themselves, natural forcings—changes in volcanic aerosols, solar output and other phenomena—could not account for warming Oilfield Review 50387schD01R1 11/29/01 5:25 AM Page 49 Increases in Greenhouse Forcing Observed 90˚ N 45˚ N 45˚ S 90˚ S 180˚ W 90˚ W –1 –0.5 0˚ 0 0.5 90˚ E 1 1.5 180˚ E 2 Simulated 90˚ N 45˚ N 45˚ S 90˚ S 180˚ W 90˚ W –1 –0.5 0˚ 0 0.5 90˚ E 1 1.5 180˚ E 2 > Observed (top) and simulated (bottom) surface air temperature changes. Computer models closely resemble the global temperature signature produced by measurements of the change in air temperature. Values increase from negative to positive as the color scale moves from blue to red. in recent decades. They also concluded that anthropogenic, or man-made, forcings alone were insufficient to explain the warming from 1910 to 1945, but were necessary to reproduce the warming since 1976. However, by combining the two simulations, researchers were able to reproduce the pattern of temperature change with reasonable accuracy. Agreement between observed and simulated temperature variations supports the contention that 20th century warming resulted from a combination of natural and external factors (previous page, bottom).8 In addition to examining the global mean temperature, researchers at the Hadley Centre also Autumn 2001 compared geographic patterns of temperature change across the surface of the earth. They used models to simulate climate variations driven by changes in greenhouse-gas concentrations and compared the ‘fingerprint’ produced with patterns of change that emerge from observation. Striking similarities are evident between the fingerprint generated by a simulation of the last 100 years of temperature changes and the patterns actually observed over that period (above). Despite many advances, climate modeling remains an inexact science. There is concern that, at present, simulations may not adequately represent certain feedback mechanisms, especially those involving clouds. Researchers, like Early this year, scientists at the Imperial College of Science, Technology and Medicine in London, England, provided the first experimental observation of a change in the greenhouse effect. Previous studies had been largely limited to theoretical simulations.1 Changes in the Earth’s greenhouse effect can be detected from variations in the spectrum of outgoing longwavelength radiation, a measure of how the earth gives off heat into space that also carries an imprint of the gases responsible for the greenhouse effect. From October 1996 until July 1997, an instrument on board the Japanese ADEOS satellite measured the spectra of long-wavelength radiation leaving the earth. The Imperial College group compared the ADEOS data with data obtained 27 years earlier by a similar instrument aboard the National Aeronautics and Space Administration (NASA) Nimbus 4 meteorological satellite. The comparison of the two sets of clear-sky infrared spectra provided direct evidence of a significant increase in the atmospheric levels of methane, carbon dioxide, ozone and chlorofluorocarbons since 1970. Simulations show that these increases are responsible for the observed spectra. 1. Harries JE, Brindley HE, Sagoo PJ and Bantges RJ: “Increases in Greenhouse Forcing Inferred from the Outgoing Longwave Radiation Spectra of the Earth in 1970 and 1997,” Nature 410, no. 6832 (March 15, 2001): 355-357. those at Hadley, do not claim that close agreement between observed and simulated temperature changes implies a perfect climatic model, but if today’s sophisticated simulations of climate-change patterns continue to closely match observations, scientists will rely to a greater extent on their predictive capabilities. 7. Reference 1: 10. 8. Stott PA, Tett SFB, Jones GS, Allen MR, Mitchell JFB and Jenkins GJ: “External Control of 20th Century Temperature by Natural and Anthropogenic Forcings,” Science 290, no. 5499 (December 15, 2000): 2133-2137. 49 50387schD01R1 11/29/01 Radiation into space 5:19 AM Page 50 Radiation into space Soot Coalesced state Aerosol Radiation from Earth's surface Radiation from Earth's surface Separate soot and aerosol constituents (external mixing) Coalesced soot and aerosol constituents (internal mixing) > Impact of aerosols and soot. Temperature simulations that take into account an internally mixed, or coalesced, accumulation of aerosols and soot (right) are more consistent with observations than separate, or externally mixed, accumulations (left). Global-average surface temperature change (1900 to 2000) + 0.6 C Results: 10% decrease in snow cover (since the late 1960s) 2-week shorter annual ice cover 0.1- to 0.2-m sea-level rise 0.5 to 1% increase in precipitation per decade (Northern Hemisphere) > Observed impact of global warming. The 0.6°C temperature rise observed during the last 100 years has been postulated as the cause of decreased snow and ice cover, higher sea levels and increased precipitation. 50 The Opposing View Not all scientists accept the IPCC findings. Many distinguished researchers argue that the panel’s approach is too simplistic. For instance, Dr Richard Lindzen, Alfred P. Sloan Professor of Meteorology at the Massachusetts Institute of Technology (MIT) in Cambridge, USA, suggests that clouds over the tropics act as an effective thermostat and that any future warming because of increased carbon dioxide concentration in the atmosphere could be significantly less than current models predict. Scientists have voiced strong objections that even sophisticated circulation models do not adequately describe the complexity of the mechanisms at work. A group of researchers at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, for example, claims there are too many unknowns and uncertainties in climate modeling to have confidence in the accuracy of today’s predictions. The group argues that even if society had complete control over how much CO2 was introduced into the atmosphere, other variables within the climate system are not sufficiently well-defined to produce reliable forecasts. The researchers are not trying to disprove a significant man-made contribution, but rather contend that scientists do not know enough about the complexity of climate systems, and should be careful in ascribing too much relevance to existing models.9 New scientific studies are shedding more light on the problem. For example, previous investigations have concluded that the Earth’s climate balance is upset not only by emissions of man-made greenhouse gases during processes such as the combustion of fossil fuels, but also by small particles called aerosols, such as those formed from sulfur dioxide, which cool the Earth’s surface by bouncing sunlight back into space. But, new findings suggest that things may not be that simple. A researcher at Stanford University, California, USA, states that black carbon, or soot, emissions from the burning of biomass and fossil fuels are interfering with the reflectivity of aerosols, darkening their color so that they absorb more radiation. This reduces the cooling effect, and could mean that black carbon is a major cause of global warming, along with carbon dioxide and other greenhouse gases. Atmospheric computer simulations usually assume that aerosols and soot particles are separate, or externally mixed. An internally mixed state—in which aerosols and soot coalesce— also exists, but no one has yet successfully determined the relative proportions of the two states. The Stanford researcher ran a simulation in which black carbon was substantially coalesced with aerosols. His results were more consistent with observations than simulations that assumed mainly external mixing. Although this could mean that black carbon is a significant contributor to warming, there is a bright side to the discovery. Unlike the extended lifetime of carbon dioxide, black carbon disappears much more rapidly. If such emissions were stopped, the atmosphere would be clear of black carbon in only a matter of weeks (left).10 9. Soon W, Baliunas S, Idso SB, Kondratyev KY and Postmentier ES: “Modelling Climatic Effects of Anthropogenic Carbon Dioxide Emissions: Unknowns and Uncertainties.” A Center for Astrophysics preprint. Cambridge, Massachusetts, USA: Harvard-Smithsonian Center for Astrophysics (January 10, 2001): to appear as a review paper in Climate Research. 10. Jacobson M: “Strong Radiative Heating due to the Mixing State of Black Carbon in Atmospheric Aerosol,” Nature 409, no. 6821 (2001): 695-697. 11. Reference 1: 2-4. 12. Reference 1: 12-13. 13. Climate Change 2001: Impacts, Adaptation and Vulnerability: Contribution of Working Group II to the Third Assessment Report of the Intergovernmental Panel on Climate Change. New York, New York, USA: Cambridge University Press (2001): 5. Oilfield Review 50387schD01R1 12/17/01 10:04 PM Page 51 Greater exposure to disease Increase in frequency and intensity of severe weather Decreased food supply Water shortages Increased flooding > Future impact of global warming. IPCC scientists predict a number of consequences if climate changes track the latest simulations, ranging from water shortages to flooding and decreased food supply. Predicting the Future Impact of Global Warming The IPCC has described the current state of scientific understanding of the global climate system, and has suggested how this system may evolve in the future. As discussed, the panel confirmed that the global-average surface temperature of the earth increased by about 0.6°C during the last 100 years. Analyses of proxy data from the Northern Hemisphere indicate that it is likely the increase was the largest of any century in the past millennium. Because of limited data, less is known about annual averages prior to the year 1000, and for conditions prevailing in most of the Southern Hemisphere prior to 1861. The IPCC report states that temperatures have risen during the past four decades in the lowest 8 km [5 miles] of the atmosphere; snow cover has decreased by 10% since the late 1960s; the annual period during which rivers and lakes are covered by ice is nearly two weeks Autumn 2001 shorter than at the start of the century; and average sea levels rose by 0.1 to 0.2 m [0.3 to 0.7 ft] during the 1900s. The report further states that, during the last century, precipitation increased by 0.5 to 1% per decade over most middle and high latitudes of Northern Hemisphere continents, and by 0.2 to 0.3% per decade over tropical land areas (previous page, bottom).11 While these changes may appear to be modest, predicted changes for this century are much larger. Simulations of future atmospheric levels of greenhouse gases and aerosols suggest that the concentration of CO2 could rise to between 540 and 970 ppm. For all scenarios considered by the IPCC, both global-average temperature and sea level will rise by the year 2100—temperature by 1.4°C to 5.8°C [2.5°F to 10.4°F] and sea level by 0.09 to 0.9 m [0.3 to 2.7 ft]. The predicted temperature rise is significantly greater than the 1°C to 3.5°C [1.8°F to 6.3°F] estimated by the IPCC five years ago. Precipitation is also forecasted to increase. Northern Hemisphere snow cover is expected to decrease further, and both glaciers and ice caps are expected to continue to retreat.12 If climate changes occur as predicted, serious consequences could result, both with respect to natural phenomena, such as hurricane frequency and severity, and to human-support systems. The IPCC Working Group II, which assessed impacts, adaptation and vulnerability, stated that if the world continues to warm, we could expect water shortages in heavily populated areas, particularly in subtropical regions; a widespread increase in the risk of flooding as a result of heavier rainfall and rising sea levels; greater threats to health from insect-borne diseases, such as malaria, and water-borne diseases, such as cholera; and decreased food supply as grain yields drop because of heat stress. Even minimal increases in temperature could cause problems in tropical locations where some crops are already near their maximum temperature tolerance (above).13 51 50387schD01R1 11/29/01 5:25 AM Page 52 Sea-level rises could threaten five parts of Africa that have large coastal population centers—the Gulf of Guinea, Senegal, Gambia, Egypt and the southeastern African coast. Even a somewhat conservative scenario of a 40-cm [15.8-in.] sea-level rise by the 2080s would add 75 to 200 million people to the number currently at risk of being flooded by coastal storm surges, with associated tens of billions of dollars in property loss per country.14 Africa, Latin America and the developing countries of Asia may have a two-fold problem, being both more susceptible to the adverse effects of climate change and lacking the infrastructure to adjust to the potential social and economic impacts. The IPCC Working Group II has ‘high confidence’ that: • Increases in droughts, floods and other extreme events in Africa would add to stresses on water resources, food-supply security, human health and infrastructures, and constrain further development. • Sea-level rise and an increase in the intensity of tropical cyclones in temperate and tropical Asia would displace tens of millions of people in low-lying coastal areas, while increased rainfall intensity would heighten flood risks. • Floods and droughts would become more frequent in Latin America, and flooding would increase sediment loads and degrade water quality. The Working Group has ‘medium confidence’ that: • Reductions in average annual rainfall, runoff and soil moisture would increase the creation of deserts in Africa, especially in southern, northern and western Africa. • Decreases in agricultural productivity and aquaculture due to thermal and water stress, sea-level rise, floods, droughts and tropical cyclones would diminish the stability of food supplies in many countries in the arid, tropical and temperate parts of Asia. • Exposure to diseases such as malaria, dengue fever and cholera would increase in Latin America.15 Not all impacts would be negative, however. Among projected beneficial effects are higher crop yields in some mid-latitude regions; an increase in global timber supply; increased water availability for people in some regions, like parts of Southeast Asia, which currently experience water shortages; and lower winter death rates in mid- to high-latitude countries.16 52 Retreating glaciers Thawing of permafrost Melting of sea ice Floods Increased rainfall Intense cyclones Decreased food supply Rising sea levels Higher heat index Hotter summers Reduced water supply Increase in forest fires Deteriorating air quality Floods Droughts Degraded water quality Droughts Floods Decreased food supply Expanding deserts Sea-level rise > Impact of global warming by region. All continents will be affected significantly if global warming continues. The type and severity of specific impacts will vary, as will each continent’s or country’s capacity to use infrastructure and technology to cope with change. Other studies—such as the US Global Research Program’s report “Climate Change Impacts on the United States,” and the European Community-funded ACACIA (A Consortium for the Application of Climate Impact Assessments) Project report—are consistent with future IPCC forecasts, and provide a more detailed picture for particular regions. According to the US study, assuming there are no major interventions to reduce continued growth of world greenhouse-gas emissions, temperatures in the USA can be expected to rise by about 3°C to 5°C [5.4°F to 9°F] over the next 100 years, compared with the worldwide range of 1.4°C to 5.8°C [2.5°F to 10.4°F] suggested by the IPCC.17 Assuming there are no major interventions, other predictions include the following: • Rising sea levels could put coastal areas at greater risk of storm surges, particularly in the southeast USA. • Large increases in the heat index, the combination of temperature and humidity, and in the frequency of heat waves could occur, particularly in major metropolitan cities. • Continued thawing of permafrost and melting of sea ice in Alaska could further damage forests, buildings, roads and coastlines. In Europe, negative climate changes are expected to impact the south more than the north. Sectors such as agriculture and forestry will be affected to a greater extent than sectors such as manufacturing and retailing, and marginal and poorer regions will suffer more adverse effects than wealthy ones. The ACACIA report, which provided the basis for the IPCC findings on impacts in Europe, makes the following predictions for southern Europe: • Longer, hotter summers will double in frequency by 2020, with a five-fold increase in southern Spain, increasing the demand for air conditioning. • Available water volumes will decrease by 25%, reducing agricultural potential. Careful planning will be essential to satisfy future urban water needs. • Desertification and forest fires will increase. • Deteriorating air quality in cities and excessive temperatures at beaches could reduce recreational use and associated tourist income. Predictions for northern Europe include the following: • Cold winters will be half as frequent by 2020. • Northern tundra will retreat and there could be a loss of up to 90% of alpine glaciers by the end of the century. • Conversely, climate changes could increase agricultural and forest productivity and water availability, although the risk of flooding could increase (above).18 Oilfield Review 50387schD01R1 11/29/01 5:20 AM Page 53 The Sociopolitical Debate and Its Impact on Process and Technology On balance, the potential dangers and adverse effects of global warming far outweigh any possible benefits. Both legislative and technical options are being explored to mitigate the impacts of future climate change. With its 100-year effective lifetime, CO2 concentration in the atmosphere is slow to respond to any cut in emissions. If nothing is done to reduce emissions, the concentration would more than double over the next century. If emissions are lowered to 1990 levels, the concentration would still rise, probably to more than 500 ppm. Even if emissions were slashed to half that level and held there for 100 years, there would still be a slow rise in concentration. Best estimates suggest it would take a reduction of 60 to 70% of the 1990 emission levels to stabilize the concentration of CO2 at the 1990 levels.19 Against this backdrop, there have been political attempts to grapple with the problem for nearly a decade. These have achieved, at best, modest results. Although an in-depth discussion of global-warming politics is beyond the scope of this technically focused article, conferences held to date and their resulting protocols illustrate the challenges that will be faced by new-generation oilfield processes and technologies, and by business and industry in general (above). The political movement toward global consensus began in 1992 at the United Nations Conference on Environment and Development held in Rio de Janeiro, Brazil. This conference resulted in the United Nations Framework Convention on Climate Change (UNFCCC), a statement of intent on the control of greenhousegas emissions, signed by an overwhelming majority of world leaders. Article II of the convention, which came into force in 1994, said the signatories had agreed to “achieve stabilization of greenhouse-gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system…within a time frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened, and to enable economic development to proceed in a sustainable manner.” The developed nations taking part also committed themselves to reduce their emissions of greenhouse gases in the year 2000 to 1990 levels. A more ambitious target was set in 1997 in the Kyoto Protocol, an agreement designed to Autumn 2001 Conference _____ Outcome 1992 1997 2000 2001 Rio de Janeiro, Brazil _________ Kyoto, Japan _________ The Hague, The Netherlands _________ Bonn, Germany _________ Statement of intent on control of greenhouse gases Protocol on reduction levels for specific commitment period Collapse of implementation plan for Kyoto Protocol Broad agreement on rulebook for implementing Kyoto protocol (except USA) > Major international global warming conferences. A concerted effort at addressing the sociopolitical implications of global warming in a forum of nations began in 1992 in Rio de Janeiro, Brazil. The most recent conference, held in July 2001 in Bonn, Germany, was the latest attempt to reach some type of formalized agreement on reducing greenhouse-gas emissions. commit the world’s 38 richest nations to reduce their greenhouse-gas emissions by an average of at least 5% below 1990 levels in the period from 2008 to 2012.20 The Kyoto Protocol put most of the burden on developed countries, which, as a group, had been responsible for the majority of greenhouse gases in the atmosphere. It excluded more than 130 developing countries, even though many poorer nations were adding to the problem in their rush to catch up with the developed world. European Union (EU) countries agreed to a reduction of 8%, and the USA promised a 7% cutback, based on 1990 levels. To take effect, it was agreed that the Protocol must be ratified by at least 55 countries, including those responsible for at least 55% of 1990 CO2 emissions from developed countries. The targets set in Kyoto are more rigorous than they might first appear since many developed economies have, until very recently, been growing rapidly and are emitting greater volumes of greenhouse gases. In 1998, for example, the US Department of Energy forecasted that US emissions in the year 2010 would exceed the Kyoto target by 43%. The November 2000 talks in The Hague on implementing the Kyoto Protocol collapsed when the EU rejected a request that the estimated 310 million tons of CO2 soaked up by forests in the USA be set against its 7% commitment. The EU suggested instead that the USA be allocated a 7.5-million ton offset. In July 2001, 180 members of the UNFCCC finally reached broad agreement on an operational rulebook for the Kyoto Protocol at a meeting in Bonn, Germany. The USA rejected the agreement. If the Protocol is to go forward, the next step would be for developed-country governments to ratify it so that measures could be brought into force as soon as possible, possibly by 2002. One issue resolved at the Bonn meeting was how much credit developed countries could receive towards their Kyoto targets through the use of ‘sinks’ that absorb carbon from the atmosphere. There was agreement that activities that could be included under this heading included revegetation and management of forests, croplands and grazing lands. Individual country quotas were set so that, in practice, sinks will account only for a fraction of the emission reductions that can be counted towards the target levels. Similarly, storage options exist for carbon dioxide that offer attractive alternatives to sinks under certain conditions (see “Mitigating the Impact of Carbon Dioxide: Sinks and Storage,” page 54). The conference also adopted rules governing the so-called Clean Development Mechanism (CDM) through which developed countries can invest in climate-friendly projects in developing countries and receive credit for emissions thereby avoided. (continued on page 56) 14. Reference 13: 13-14. 15. Reference 13: 14-15. 16. Reference 13: 6. 17. Climate Change Impacts on the United States, The Potential Consequences of Climate Variability and Change: Foundation Report, US Global Change Research Program Staff. New York, New York, USA: Cambridge University Press (2001): 6-10. 18. Parry ML (ed): Assessment of Potential Effects and Adaptations for Climate Change in Europe. Norwich, England: Jackson Environment Institute, University of East Anglia, 2000. 19. Jenkins et al, reference 3: 10. 20. Kyoto Protocol, Article 31, available at Web site: http://www.unfccc.de/resource/docs/convkp/kpeng.html 53 50387schD01R1 11/29/01 5:21 AM Page 54 Mitigating the Impact of Carbon Dioxide: Sinks and Storage In the short to medium term, the world will continue to depend upon fossil fuels as cheap energy sources, so there is growing interest in methods to control carbon dioxide emissions— for example, the creation of carbon sinks and storage in natural reservoirs underground or in the oceans.1 Carbon sinks—Carbon sinks are newly planted forests where trees take CO2 from the atmosphere as they grow and store it in their branches, trunks and roots. If too much CO2 is being pumped into the atmosphere by burning fossil fuels, discharge levels can be compensated for, to some extent, by planting new trees that soak up and store CO2. In 1995, the IPCC estimated that some 345 million hectares [852 million acres] of new forests could be planted between 1995 and 2050 that would sequester nearly 38 gigatons of carbon. These actions would offset about 7.5% of fossil-fuel emissions. The IPCC added that other measures, like slowing tropical deforestation, could sequester another 20 to 50 gigatons. Taken together, new forests, agroforestry, regeneration and slower deforestation might offset 12 to 15% of fossil-fuel emissions by the year 2050. An attractive feature of this approach is that, if implemented globally, it buys time during which longer term solutions can be sought to meet world energy needs without endangering the climate system. There are, however, other factors that must be considered, such as how to quantify the amount of carbon being sequestered, how to verify sequestration claims and how to deal with ‘leakage.’ Leakage occurs when actions to increase carbon storage in one place promote activities elsewhere that cause either a decrease in carbon storage (negative leak) or an increase in carbon storage (positive leak). Preserving a forest for carbon storage may, for instance, produce deforestation elsewhere (negative leakage) or stimulate tree planting elsewhere to provide timber (positive leakage). The carbon-sink process is reversible. At some future date, some forests could become unsustainable, leading to a rise in CO2 levels. Carbon storage—Carbon dioxide is produced as a by-product in many industrial processes, 54 Sleipner West Sleipner East Statfjord Gullfaks NORWAY Frigg Heimdal Stavanger Sleipner Ula Ekofisk NORTH SEA DENMARK UNITED KINGDOM GERMANY > Sleipner field location. usually in combination with other gases. If the CO2 can be separated from the other gases—at present, an expensive process—it can be stored rather than released to the atmosphere. Storage could be provided in the oceans, deep saline aquifers, depleted oil and gas reservoirs, or on land as a solid. Oceans probably have the greatest potential storage capacity. While there are no real engineering obstacles to overcome, the environmental implications are not adequately understood. For years, carbon dioxide has been injected into operating oil fields to enhance recovery, and normally remains in the formation. The use of depleted oil or gas reservoirs for CO2 storage, however, has a further advantage in that the geology is well-known, so disposal takes place in areas where formation seals can contain the gas. The first commercial-scale storage of CO2 in an aquifer began in 1996 in the Sleipner natural gas field belonging to the Norwegian oil company Statoil. The project is named SACS (Saline Aquifer CO2 Storage) and is sponsored by the EU research program Thermie. A million tons, a year of CO2 production, are removed from the natural gas stream using a solvent-absorption process and then reinjected into the Utsira reservoir, 900 m [2950 ft] below the floor of the North Sea (above). According to a report by the Norwegian Ministry of Petroleum and Energy, the Utsira formation is widespread and about 200 m [660 ft] thick, so it can theoretically accommodate 800 billion tons of CO2—equivalent to the emissions from all northern European power stations and major industrial establishments for centuries to come (next page, bottom). Oilfield Review 50387schD01R1 11/29/01 5:21 AM Page 55 To monitor the CO2-injection area, Schlumberger is conducting four-dimensional (4D), or time-lapse, seismic studies that compare seismic surveys performed before and during injection. A survey acquired in 1994, two years before injection began, served as the baseline for comparison with a 1999 survey acquired after about 2 million tons of CO2 had been injected. Higher seismic amplitudes in the 1999 survey show the location where gas has displaced brine in the Utsira formation. Another 4D survey is scheduled for late 2001 (right). The Sleipner CO2 sequestration project already has inspired other oil and gas companies to consider or plan similar efforts in southeast Asia, Australia and Alaska. Sleipner CO2 injection siesmic monitoring E-W section preliminary raw stack 1. Cannell M: Outlook on Agriculture 28, no. 3: 171-177. > Seismic responses due to carbon dioxide injection. A 1994 seismic survey (left) served as a baseline for a 1999 survey (right) that showed the pattern of brine displacement by carbon dioxide following injection of 2 million tons of the gas. 1994 1999 after injecting 2 millIon tons of CO2 since 1996 no change above this level Top Utsira formation –250 m Injection point 500 m Velocity push-down beneath CO2 cloud Depth, m Sleipner T Sleipner A 0 500 CO2 injection well 1000 CO2 Utsira formation 1500 Sleipner East production and injection wells 2000 2500 0 500 1000 1500 m 0 1640 3280 4920 ft Heimdal formation > Carbon dioxide injection well in Utsira. The Utsira formation is about 200 m [660 ft] thick and can hold the equivalent of all carbon dioxide emissions from all northern European power stations and industrial facilities for centuries to come. Autumn 2001 55 11/29/01 5:25 AM Page 56 BP Emissions-Reduction Program _________ Capture and reuse emissions. Stop deliberate venting of carbon dioxide and methane. Improve energy efficiency. Eliminate routine flaring. Develop technologies to separate carbon dioxide from gas mixtures. > Cutting emission levels. BP has undertaken an aggressive, multifaceted program to reduce emissions, ranging from improved energy efficiency to elimination of routine gas flaring. The Kyoto Protocol includes a compliance mechanism. For every ton of gas that a country emits over its target, it will be required to reduce an additional 1.3 tons during the Protocol’s second commitment period, which starts in 2013. Some reports contend that concessions made at the conference reduced emissions cuts required by the Protocol from 5.2% to between 0 and 3% in 2010. The UNFCCC is more cautious in its statements. As of August of this year, its secretariat had not calculated how the Bonn agreements might affect developed-country emission reductions under the Kyoto Protocol, and indicated that this would not be known with any precision until the 2008-2012 target period. E&P Company Initiatives Today, many oil and gas companies are taking global warming seriously, convinced that it is sensible to adopt a precautionary approach. Others have taken a more conservative stance: they agree that climate change may pose a legitimate long-term risk, but argue that there is still insufficient scientific understanding to make reasonable predictions and informed decisions, or to justify drastic measures. All agree that a combination of process changes and advanced technologies will be required within the industry to meet the types of emission standards being proposed. BP and Shell have implemented strategies based on a judgment that while the science of climate change is not yet fully proven, it is prudent to behave as though it was. Both companies have established ambitious internal targets for reduction of their own emissions. The Kyoto Protocol calls for an overall reduction of greenhouse-gas emissions of at least 5% by 2008 to 2012, compared with 1990. BP has undertaken to 56 reduce its greenhouse-gas emissions by 10% by the year 2010, against the 1990 baseline. Shell intends to reduce emissions by 10%, against the same baseline, by 2002. Companies are choosing to cut emissions in several different ways. The BP emissions reduction program, for instance, includes ambitious commitments: • Ensure that nothing escapes into the environment that can be captured and, ideally, used elsewhere. BP intends to stop the deliberate venting of methane and carbon dioxide wherever possible. This may involve redesigning or replacing equipment, and identifying and eliminating leaks. • Improve energy efficiency. Engineers are examining all energy-generating equipment to ensure that the company is making the best possible use of hydrocarbon fuels and the heat that is a by-product of energy generation. • Eliminate routine flaring. It is better to flare gas than vent it directly to the atmosphere, but it is still a waste of hydrocarbons—although some flaring may still be necessary for safety reasons. • Develop technology to separate carbon dioxide from gas mixtures, then reuse it for enhanced oil recovery or store it in oil and gas reservoirs that are no longer in use, or in saline formations (above). Integrated oil companies also are trying to help customers reduce greenhouse-gas emissions by increasing the availability of fuels with lower carbon content and offering renewable energy alternatives, like solar and wind-driven power. Some companies, including BP and Shell, have introduced internal greenhouse-gas emissions trading systems. The attraction of emissions trading is that it allows reductions to be achieved at the lowest cost; companies for whom emissions reductions are cheap can lower their emissions and sell emission rights to firms that would have to pay more to decrease emissions. The BP emissions trading system is based on a cap-and-trade concept, and was primarily designed to provide BP with practical experience dealing with an emissions trading market and to learn about its complexities. At its simplest level, a cap is set each year to steer the group toward the most efficient use of capital to meet its 2010 target of 10%. Say, for example, increased production is planned from an offshore platform, thereby causing emissions above its allocated allowance. If the platform’s on-site abatement costs are higher than the market price of CO2, the company may decide to purchase CO2 allowances for that unit. Similarly, if a downstream unit has upgraded its refinery and emits less CO2 than its allowances cover, it is economically desirable to both companies if the latter sells its allowances to the former (below). The operation of these systems will be closely followed not only by other oil and gas companies but also by governments, since the principles behind emissions trading are broadly the same whether trading takes place within a single company, among companies within a single country, among companies internationally or between nations. Oilfield Technology Development and Application Working with oil and gas companies, major oilfield service suppliers have been at the forefront in addressing a range of health, safety and environmental issues—from reducing personnel exposure to risks at the wellsite, to application of ‘green’ chemicals that provide equal or enhanced performance while decreasing ecological impact, and to methods for cutting or eliminating emissions resulting from processes such as burning oil and flaring gas during well-testing operations. Emission limit after trading Units bought Carbon dioxide emissions 50387schD01R1 –10 Units sold 40 Each company initially is allocated 50 permits to emit 50 tons Company A +10 Emission limit before trading 50 Company B > Emissions trading system. This process strives to reduce emissions at the lowest cost by permitting the buying and selling of emissions rights between various units within a given company or between companies. Oilfield Review 50387schD01R1 11/29/01 5:26 AM Page 57 Gas Flaring Series of pumps Produced fluid Oil Pipeline Water and oil emulsion Disposal Stage 1 Separator Flaring Gas Produced fluid Gas and oil Neutralizer and emulsion breaker Series of pumps Separator Stage 2 Oil Broken emulsion Skimmer Oil Pipeline Surge tank Clean water Produced fluid Gas and oil Neutralizer and emulsion breaker Disposal Gas and oil Multiphase flowmeter Multiphase pump Stage 3 Pipeline Broken emulsion Skimmer Oil Surge tank Clean water Disposal > Three-stage program to eliminate flaring. A Schlumberger team in the Middle East committed to first reduce and then fully eliminate flaring of gas and burning of oil and, at the same time, generate greater revenue for the operator by increasing pipeline throughput. Solutions to eliminate flaring—Burning oil and flaring natural gas during testing operations not only are costly due to lost revenue, but also produce large quantities of carbon dioxide. Small amounts of toxic gases, soot and unburned hydrocarbons are also released. Eliminating oil burning and, ultimately, gas flaring not only creates a safer working environment, but also helps reduce the key constituent, carbon dioxide, thought to be associated with global warming. Recently, a Schlumberger team in the Middle East, working closely with a major operator in the region, addressed the flaring problem for production testing where an existing export pipeline was available. Considering the nature of the testing program, there were several key challenges that had to be overcome. Wells are typically highly deviated or horizontal, and penetrate massive carbonate formations. Large quantities of acid are used to treat the zones, giving rise to long cleanup periods and an erratic initial flow of mixtures of spent acid, emulsions, oil and gas. Autumn 2001 Traditionally, the wells were flowed until sufficient oil was produced at sufficient pressure to go directly into the production pipeline, requiring burning of oil in the interim. Care had to be taken that the fluid’s pH was high enough so as not to cause corrosion problems. A three-stage program to eliminate flaring and simultaneously solve associated well-testing problems was undertaken. In the first stage, beginning in 1998, the goal was to pump separated oil into the pipeline from the outset, instead of burning it. This required the design of specialized, dual-packing centrifugal pumps that were run in series to achieve the required pressure for oil injection into the pipeline. Natural gas was still flared, and separated water discarded. Residual oil and water emulsions remained a problem, since a single separator was insufficient to break them. In the second stage of the project, a neutralizer and breaker system was designed for treatment of the emulsion phase prior to entering the main separator. Remaining gas and oil were then flowed through the separator. A skimmer and chemical injection system were employed to reduce the oil content in the water underflow stream from 3000 ppm to less than 80 ppm, allowing safe disposal of all residual water. Oil produced through emulsion breaking was pumped into a surge tank and then into the production pipeline, saving additional oil that would have otherwise been discarded. In the third stage, currently under way, the goal is for complete elimination of flaring by using advanced multiphase pumping technology with multiphase metering. When the wellhead pressure is insufficient to route gas back through the line after the multiphase meter, a variabledrive multiphase pump—that can handle a variety of flow rates and pressures—would be introduced so that both oil and gas can be injected into the production pipeline (above). 57 50387schD01R1 11/29/01 5:21 AM Page 58 In the first year of implementation of the initial stages of the project, the operator was able to sell an additional 375,000 barrels [59,600 m3] of oil that otherwise would have been burned, generating more than $11 million in increased revenues.21 Zero-emission testing—The next frontier is a generalized solution for zero-emission testing for exploration and appraisal wells where an export pipeline is not available. Here, the challenge is to take a quantum step beyond improved burner technology. The goal is elimination of all emissions by keeping produced hydrocarbons contained either below surface or the mudline, or in special offshore storage vessels. Through the use of advanced downhole measurements and tools, high-quality test data and samples could still be captured. There are several approaches to downhole containment. In particular, three options are currently undergoing intensive investigation. The first is closed-chamber testing. Here, test fluids flow from the formation into an enclosed portion of a tool or pipestring. A short flow period is achieved as the chamber fills and its original contents become compressed. Flow stops as the chamber reaches equilibrium, allowing analysis of the subsequent buildup. This method, applicable to both oil and gas wells, is simple, and the short test duration limits rig time compared with a conventional test. But, there are drawbacks. With only a small flowed volume due to capacity limitations of the test string or wellbore, only a limited radius of investigation near the wellbore can be evaluated. Lack of thorough cleanup after perforating can potentially affect the quality of collected samples. If the formation is not wellconsolidated, hole damage or collapse may occur because of high inflow rates (below left). Surface valve A second method is production from one zone and reinjection into the same zone, known as harmonic testing. Here, fluid is alternately withdrawn into a test string and then pumped back into the reservoir at a given periodic frequency. The reservoir signature is determined point-bypoint as a function of frequency by varying the frequency during testing. The advantage is that a 21. The team that spearheaded this project won the Performed by Schlumberger Chairman’s Award 2000, the top award in a company-wide program to strengthen the Schlumberger culture of excellence. Client team members included Abdullah Faddaq, Suishi Kikuchi, Mahmoud Hassan, Eyad Al-Assi, Jean Cabillic, Graham Beadie, Ameer El-Messiri and Simon Cossy. Schlumberger team members included Jean-Francois Pithon, Abdul Hameed Mohsen, Mansour Shaheen, Thomas F. Wilson, Nashat Mohammed, Aouni El Sadek, Karim Mohi El Din Malash, Akram Arawi, Jamal Al Najjar, Basem Al Ashab, Mohammed Eyad Allouch, Jacob Kurien, Alp Tengirsek, Mohamed Gamad and Thomas Koshy. Tubing Circulating valve Barrier valve Upper packer Circulating valve Ball valve Downhole pump assembly Gas-liquid interface Test valve Produced fluid and initial liquid cushion Packer Lower packer Pressure gauge Sand screen and gravel pack > Closed-chamber testing. Test fluids from the formation enter an enclosed space until the contents compress and reach equilibrium. This brief flow period is then followed by a second stage of pressure buildup. 58 Flow direction > Continuous production and reinjection. A specially designed tool allows produced fluid from one zone to be continuously injected into another using a downhole pump to provide a prolonged testing period. Samples can be retrieved, and flow and pressure data are measured downhole for subsequent analysis. Oilfield Review 50387schD01R1 11/29/01 5:26 AM Page 59 Drilling and production unit Storage modules and processing facilities Dynamically positioned storage or shuttle tanker Rigid production riser Export flowline BOP or subsea test tree > Offshore storage-module concept. A vessel for storing and offloading fluids collected in closed modules during testing operations might offer an approach to eliminate the need for flaring while generating increased revenues. separate zone for disposal of the produced fluid is not needed, but defining the pressure-response curve would require more time than for a conventional test and may not be cost-effective. Advanced signal processing may be able to reduce the time required, but still may not make the process economically viable. The third method is to continually produce from one zone and inject the produced fluid into another zone. Reservoir fluids are never brought to surface, but are reinjected using a downhole pump. Drawdown is achieved by pumping from the production zone into the disposal zone. Buildup is provided by simultaneously shutting in the production zone and stopping the downhole pump. If injectivity can be maintained, this continuous process emulates a full-scale well test. A larger radius of investigation is possible due to larger flow volumes, with the potential to investigate compartmentalization or even reservoir limits. A longer flow period improves cleanup prior to sampling. Flow and pressure are measured downhole and analyzed with conventional methods for radial flow. It is possible to capture small pressure-volume-temperature (PVT)-quality samples and larger dead-oil samples downhole. Drawbacks include a somewhat complex tool string, an inability to handle significant quantities of gas and no time-saving over a conventional well test. The key factor is having a suitable injection zone that provides sufficient isolation (previous page, bottom right). Two joint industry programs have been established to investigate each of the three methods in detail, with participation by BP, Chevron, Norsk Hydro and Schlumberger. The first, conducted by Schlumberger, is assessing downhole tool design Autumn 2001 and capability requirements. The second, a threeyear program at Imperial College in London, England, is defining the interpretation packages and procedures that would be required to capture the maximum amount of reliable information from the data. Once the selection of the preferred method is finalized, the next step will be a proof-of-concept field experiment that mirrors the requirements of a variety of well-test conditions. Currently, the continuous production-reinjection option looks most promising. Modules mounted on the deck or in the hold of a suitable floating vessel are being investigated for storing fluids collected offshore during testing. Fluid-processing facilities also would be provided onboard. Large discoveries, marginal fields and deepwater prospects are targeted applications. Equipment would be designed to handle a broad range of testing conditions and durations. The vessel would receive and store gas and liquids, and offload the contents at the end of the well test or at intervals during the test. This concept could completely eliminate the need for flaring, and generate revenues from sale of produced fluids that would otherwise be lost. The procedures for handling and storing liquids have already been successfully demonstrated in extended well tests in fields such as BP’s Machar—proving both the feasibility and financial viability of the approach. Gas handling and storage, however, pose additional challenges that would probably require compression and transfer facilities to create compressed natural gas. This is a costly proposition and may not be economically viable at current gas prices (above). With growing emphasis on eliminating all types of gas emissions, particularly carbon dioxide, these areas of investigation are expected to continue to receive close attention and significant industry funding. Future Challenges In the near future, governments around the world will receive the IPCC Synthesis Report which will attempt to answer, as clearly and simply as possible, 10 policy-relevant scientific questions. Perhaps the pivotal question, as stated by the IPCC, is: “How does the extent and timing of the introduction of a range of emissions-reduction actions determine and affect the rate, magnitude and impacts of climate change, and affect global and regional economies, taking into account historical and current emissions?” In another five years, the IPCC is expected to publish its Fourth Assessment Report. By then, climatologists may have resolved some of the uncertainties that limit today’s climate models. They should, for example, be able to provide a better description of the many feedback systems associated with climatic phenomena, particularly clouds. Greater understanding could lead to reduced uncertainty about a causal connection between increased greenhouse-gas concentrations and global warming. This would be a major step forward. In the interim, oil and gas companies, working closely with oilfield service companies, will continue to be proactive in developing technologies and operational procedures for reducing emissions. —MB/DEO 59