Potential research of carbon ( iv ) oxide enhanced oil recovery ( CO 2-EOR ) in Middle East

Anthropological carbon (iv) oxide ( CO 2) emissions to the atmosphere are identified as a major driver for the global warming effect. Major CO 2 emissions sources are located within power and industrial sectors where fossil fuels are consumed to generate energy. With the anticipated escalation of global energy demand, CO 2 emissions are also expected to grow. Therefore, reducing CO 2 emissions to atmosphere is a fatal issue worldwide. Capturing CO 2 from emissions sources and injected into safe geological places for storage shows a practical mitigation strategy through CO 2 capture and storage (CCS) practices. In CCS projects, several options are available for CO 2 storage such as subsurface aquifers, coalbed bed methane formations, or depleted oil and gas reservoirs. Alternatively to these storage places, CO 2 can be utilized to enhance oil production from mature oil reservoirs. Utilization of CO 2 in enhanced oil recovery techniques (EOR) is a well known practice in oil industry. Therefore, synchronizing between the objectives of storing CO 2 and enhancing oil production to meet global demand can be achieved through CO 2 -EOR projects. The giant oil reservoirs in the Middle East represent potential places for CO 2 -EOR projects. In this paper, oil reservoirs located in the Middle East are selected to evaluate the potential of CO 2 -EOR projects in the region. These reservoirs were subjected to CO 2 -EOR screening where the fluid and rock properties are compared with a well known criteria. Furthermore, an analytical model is used to predict the performance of CO 2 -EOR in these reservoirs. The results showed that implementing CO 2 -EOR practices would enhance the oil recovery while storing a considerable amount of CO 2 in these reservoirs.


INTRODUCTION
The challenges facing offshore CO 2 enhanced oil recovery (EOR) and carbon capture and storage (CCS) projects are presented in this paper along with potential solutions based on the oil and gas (O&G) industry's CO 2 EOR and CCS experience and technology as applied in a few offshore locations.Prospects for future offshore projects are also discussed based on the O&G industry's experience, technology, and best practices.These achievements are the result of a safe and successful 58year history of well construction and operations in landbased, commercial CO 2 EOR projects.
Achieving CCS by injecting CO 2 into saline formations E-mail: meshalalgharaib@yahoo.comor for EOR in mature oil reservoirs is a safe and effective method to reduce GHG (greenhouse gas) emissions.The Intergovernmental Panel on Climate Change (IPCC) has defined enhanced oil and gas recovery via CO 2 injection as a recognized form of CCS.Using existing industry experience and technology developed over the past 58 years, CO 2 injection into oil reservoirs for EOR has been safely and effectively applied in 18,077 active wells worldwide (17,112 in USA) according to the latest EOR survey (O&GJ, 2010).Production from natural gas reservoirs has also benefitted from CO 2 injection in enhanced gas recovery (EGR) applications.
Records of earth surface temperature show an increasing trend in the recent years.Figure 1 shows a history of the annual average of the earth surface temperature during 1880 to 2008 (Goddard Institute for Space Studies).During the last century, the annual average of earth surface temperature increased by 0.74°C.Many researchers define this growing trend as Global Warming Effect which is a result of an increase in the concentrations of some gasses.These gases, which are known as Green House Gases (GHG), include mainly Carbon (iv) oxide (CO 2 ), Methane (CH 4 ), and Nitrous Oxide (N 2 O).According to the global warming theory, GHG allow sunlight to enter the atmosphere freely; however, they absorb the heat from the reflected sunlight.The annual average of earth surface temperature would be about (-19°C) rather than the present average of 14°C without GHG effect (Treut et al., 2007).However, increasing GHG concentrations in the atmosphere allows for more heat absorption and ultimately a rise in earth surface temperature.
Table 1 shows the concentrations of the main GHG in the atmosphere (Carbon Dioxide Information Analysis Center) with CO 2 representing more than 99%.The role of each gas in the global warming phenomenon is based on gas heat retention capacity, therefore; the contributions of GHG to the global warming effect is defined by the Global Warming Potentials (GWP) which represent the ratio of heat retention capacity of a specific GHG to that of CO 2 ( United State Greenhouse Gas Inventory Program).Table 1 shows the concentrations and contributions of each GHG.CO 2 contributes to more than 73% of the global warming effect followed by N 2 O (18.96%) and CH 4 (7.09%).

SOURCES OF CARBON (IV) OXIDE (CO 2 ) EMISSIONS
Carbon (iv) oxide (CO 2 ) emissions sources are classified as natural or anthropological sources.The natural sources include animal and plant respiration, oceanatmosphere exchange, and volcanic eruptions; whereas, the anthropological sources include burning of fossil fuels to generate energy and as products of some industrial processes United Nation Environment Programme (UNEP) estimated that emissions of CO 2 from natural sources are 20 times greater than those from anthropological sources (United Nations Environmental Programme).However over a long period of time, the natural emissions sources are closely balanced by natural CO 2 sinks.As a result of this balance, CO 2 concentrations remained between 260 and 280 ppm for the last 10,000 years ( Denman et al., 2007).Human activity increased CO 2 emissions to the atmosphere starting from year 1750, when the industrial era started (IPCC, 2001), and continue to increase strongly in the current years.Figure 2 shows the development of CO 2 concentration in the atmosphere for the period 1980 to 2008 (Environmental Protection Agency).CO 2 concentration ascended from 338 ppm in 1980 to 385 ppm at the beginning of 2008.This represents an annual increase rate of 1.6 ppm, and accordingly if this rate is persisted, CO 2 concentration might reach 400 ppm in the next decade.This increase is driven by the growth of anthropological CO 2 emissions to the atmosphere.Figure 3 shows the global CO 2 emissions from petroleum, natural gas and coal consumption for the period 1980 to 2005 (Energy Information Administration).Annual CO 2 emissions rose rapidly from 18 billion tones in 1980 to 28 billion tones in 2005.This represents an annual rate of increase of 400 million tones.The main rationale behind this trend is due to the development in global energy demand.
The development of Arab World share to the worldwide CO 2 emissions is shown in Figure 4.In 1980, the Arab world contributed 2.8% to the global CO 2 emissions which rose to 4.7% in 2005 representing 1316.8 million tones.Figure 5 shows the CO 2 emissions for the Arab world countries at the end of 2005 where Saudi Arabia, Egypt, and UAE accounted for more than 50%.

CARBON (IV) OXIDE (CO 2 ) CAPTURE AND STORAGE (CCS)
The first patent for CO 2 EOR was granted in 1952 (Whorton).The Texas Railroad Commission (TRRC report) proposed CCS rule states that "the first three projects   emissions of CO 2 will grow in the future.Figure 6 shows the future energy demand as predicted by EIA (Rajesh et al., 2004).Energy consumption in industrial and transportation sectors represent over 80% of the future energy demand.These sectors are anticipated to emit large quantities of CO 2 .In order to minimize the global warming effect; efforts are currently focused on ways and techniques to capture CO 2 from large emissions sources and store them in safe geological formations.Recently, CO 2 Capture and Storage (CCS) practice shows a practical mitigation strategy in order to reduce CO 2 emissions to the atmosphere.In CCS projects, CO 2 is captured from emissions sources and injected into safe places for storage.The possible geological venues to store CO 2 are: depleted oil or gas reservoirs (10) , saline aquifers, coal bed methane formations (Wong et al., 2000), and in mature hydrocarbon reservoirs to enhance oil production (Picha, 2007;Feng,, 2010;IPCC, 2005).Currently, there are a number of CCS projects around the world in which CO 2 is being captured and stored into geological formations.Table 2 shows a listing of some CCS projects with their corresponding CO 2 storage venues ( Zhao et al., 2011;Herzoq, 1999) Most of these projects utilize CO 2 in EOR activities or

THE FUTURE OF CO 2 -EOR PROJECTS IN THE ARAB WORLD
The current utilizations of CO 2 in the Arab World are  (Wright, 2007).This is the only known CCS practice in the Arab World; however, great efforts are now initiated regionally to improve the contribution of Arab World in reducing CO 2 emissions.Saudi Arabia, for instance, has recently contributed $300 million to research and development programs related to climate change activities (The Guardian, 2007).Moreover, Kuwait, Qatar and UAE pledged an additional $150 million each for similar purposes.
The promised utilization of CO 2 in the Arab World is in the field of Enhanced Oil Recovery (EOR).Abu Dhabi, for example, announced the initiation of a strategic project to capture CO 2 from major existing and future emission sources and delivers it to oil fields for enhanced oil recovery purposes (Abu Dhabi Future Energy Company).The estimated $2 billion project would limit greenhouse gas emissions by capturing around 90% of the CO 2 generated, and permanently storing up to 1.7 million tones of CO 2 per year into geological formations.This is believed to be equivalent to decarbonizing Abu Dhabi's entire domestic transport sector.The project is planned for commercial operation in 2012.
The employment of CO 2 in EOR is a well known practice in the oil industry, in which CO 2 is injected into hydrocarbon strata to reduce oil viscosity and expands oil volume.Generally, it takes about 6 to15 thousand cubic feet of CO 2 to produce one barrel of oil (Pariani et al., 1992;Masoner et al., 1996).Currently, more than 38% of the daily EOR oil production in USA is due to CO 2 -EOR techniques (Moritis, 2008).Figure 7 shows the development of oil production due to CO 2 -EOR in USA for the period 1986-2008.The daily oil production rate exhibits a continuous growth with time.Figure 8, on the other side, shows the number of active CO 2 -EOR projects in USA for the same period.Currently, there are more than 100 CO 2 -EOR active projects which represent more than 57% of the total EOR projects in the USA.
Recently, many oil reservoirs in the Middle East approach their technical limit of primary oil production which necessitates the introduction of new energy to further exploit these reservoirs.Algharaib  reservoirs to evaluate the applicability of CO 2 -EOR projects (Algharaib, 2008).The reservoirs' properties were subjected to CO 2 -EOR screening where suitability of these reservoirs to CO 2 -EOR applications was checked against a well known criteria.Since these criteria are based on a worldwide experience, CO 2 -EOR screening task is expected to highlight the anticipated challenges for field applications.Table 3 shows the geographical distribution of the selected reservoirs and the results of the screening test.The results show that 64 reservoirs, out of 107, passed the screening criteria for CO 2 -EOR applications and are recommended as potential places for CO 2 -EOR projects.Furthermore, Table 4 shows the recommended ranges reservoir fluid and rock properties to pass the screening criteria (Li et al., 2012)    pressure criteria, while, failing to meet the minimum miscibility pressure and the presence of gas cap criteria represent more than 75% of the screening failures.
The reservoirs passing the EOR screening test were subjected to further investigations to determine the expected performance of CO 2 -EOR applications.An analytical predictive tool, which is developed by DOE and known as "CO 2 Miscible Flood Predictive Model", was used for this purpose (Department of Energy, 1986).During the performance prediction task, the incremental oil produced due to CO 2 -EOR, the amount of CO 2 stored, and CO 2 effectiveness ratio were determined.The performance predictions runs were based on implementing a CO 2 -EOR project on a 40-acres spacing with a five-spot well arrangement.The overall assessment of CO 2 -EOR applications shows promising results.
The Figure 9 show the incremental oil produced due to CO 2 -EOR applications.Incremental oil produced ranges from 2,700 to 42,800 barrel of oil per acre-foot.(Algharaib and Abu, 2007).The individual components of CO 2 -EOR projects are well developed, but they need to be integrated into a full scale project for further economical and technical assessments (International Energy Agency).For example, implementation of a full scale CO 2 -EOR project where CO 2 is captured from a power station and injected into a hydrocarbon reservoir would increase the   knowledge and experience needed for commercial evaluation.If the geological formation is properly chosen, CO 2 can be retained for very long periods.During CO 2 -EOR projects, the risk of CO 2 leakages is higher during the injection period, when reservoir pressure is high.Therefore, CO 2 leakages are more likely to happen during the early time of CO 2 -EOR project.The total amount of CO 2 stored and emitted during CO 2 -EOR projects is then can be estimated at the end of the project.However, there is still a need to provide site monitoring and proper remediation, in case any leaks occur.Currently, there is a commercial demonstration of CCS project where CO 2 is being captured from an industrial facility and injected back in a hydrocarbon reservoir to enhance oil production.Such demonstration is expected to provide more data and information about the storageability of geological formation (Malik and Islam, 2000).

CONCLUSIONS
In light of the previous discussions, the following conclusions are drawn: 1. Tremendous amount of CO 2 can be stored in the Arab world as indicated by performance prediction phase.Therefore, CO 2 capturing researches and technologies should be promoted especially in the power sector. 2. Inclusion of CCS projects in CDM is very beneficial for Arab World.3. Despite the current small contribution of Arab World countries to the global CO 2 emissions, the role of Arab World shows a continuous increase with time.Therefore, environmental policies of the Arab World countries should be evaluated in order to ease this trend.4. CO 2 -EOR screening shows a potential for utilizing a number of oil reservoirs in the Arab World in CCS projects.Hence, the Arab World countries are encouraged to invest in full scale CCS projects in order to gain the required experience and knowledge.5. Analytically, the performances of CCS projects in Arab World show encouraging results.Therefore, these results should be supported by numerical simulations and laboratory experiments.

Figure 1 .
Figure 1.Development of the annual average of the earth surface temperature (1880-2008).

Figure 5 .
Figure 5. CO 2 emissions from Arab World countries in 2005.

Figure 8 .
Figure 8. Development in the Number of CO 2 -EOR Projects

Figure 9 .
Figure 9. Cumulative oil produced per acre foot due to CO 2 -EOR.

Figure 10 .
Figure 10.Cumulative CO 2 Stored per acre foot at the End of CO 2 -EOR.

Figure 11 .
Figure 11.CO 2 effectiveness ratio at the end of CO 2 -EOR.

Table 1 .
Recent GHG concentrations in the atmosphere.

Table 3 .
Geographical distribution of the selected reservoirs.