By Mahinaz El Baz
Hydrocarbons will likely remain the major component of the global energy mix, especially as energy demand is expected to increase by 50%, according to a paper published in the Journal of Applied Polymer Science by Miller et al. The contribution of renewable energy sources could prove insignificant in the face of growing demand. While global production could drop by 40 million barrels per day (b/d) by 2020, the world will need an additional 25 million b/d for supply to keep up with consumption, according to a study by Zitha et al. that was published by the Society of Petroleum Engineers.
With energy demand increasing and supply declining, discovering new fields and maximizing production from existing fields is extremely important. At present, most oil is recovered via water flooding in the primary and secondary phases. This process recovers approximately 35% of the oil, leaving approximately 65% in place. This gap in recovery represents a substantial opportunity, according to a report about Hydrocarbon Recovery Optimization by Shell. In the current business environment, affordable technologies will play a pivotal role in meeting demand. Experts think that many current and future field development projects will involve complex improved oil recovery (IOR) and enhanced oil recovery (EOR).
Scales of Reservoir
As discovering new oilfields becomes more difficult, the majority of international oil companies (IOCs) are currently focused on maximizing the recovery factor (RF) from their oilfields and maintaining a commercial rate. Studying the static properties and dynamic behavior of the hydrocarbon system on various scales is essential for IOCs to be able to maximize hydrocarbon RF. The average RF from mature oilfields around the world is between 20-40%. This contrasts with the typical RF from natural gas fields of between 80-90%, according to a paper published in Philosophical Transactions of the Royal Society by Muggeridge et al. Improving the oil recovery rate to that typical at natural gas fields could more than double global supply of recoverable oil. This would provide more time for companies to develop alternative and unconventional energy technologies, Muggeridge et al. write.
“Oil recovery processes involve the interplay of flow, transport, rock/fluid interactions, and thermodynamic processes on the meso-scale,” Zitha et al. argues. Physical and numerical modeling is the main tool to observe these processes. Advances in information technology (IT) methods and increased computational power should improve numerical simulations. “A full appreciation of the new tools will lead to the development of a novel generation of numerical simulators that can capture the physics of the oil recovery processes better and thus can better predict the behavior of reservoir systems. Such simulators should be based on improved mechanistic modeling of [the] physical-chemical processes underlying enhanced oil recovery. As a first step, the derived mechanistic models will be up-scaled to the core scale and validated by dedicated laboratory experiments. Finally, the models thus developed will be up-scaled to the field scale,” Zitha et al. argues.
Oil Recovery Phases
The lifecycle of an oilfield is divided into three major stages: production buildup, plateau production, and declining production, according to the Society of Petroleum Engineers. Sustaining production levels over the duration of the lifecycle requires the ability to control the recovery mechanisms involved. Scientists explain that a regular oil field has three main recovery phases—primary, secondary, and tertiary (known as EOR)—which are intended to progressively improve total recovery.
Wells are drilled during development phase, which is gen¬erally associated with the primary phase. During this phase, oil is produced using its own pressure. Oil and rock expand as reservoir pressure declines. “For primary recovery, the lifecycle is generally short and the recovery factor does not exceed 20% in most cases,” noted Zitha et al. The secondary phase starts after natural pressure falls to an insufficient level to push the oil out, a report by the US Geological Society authored by Verma notes. In the secondary phase, to increase reservoir pressure, water or gas is injected into the reservoir to force the oil out. Water and gas injections only boost RF if the reservoir has “good horizontal and vertical permeability,” permitting “gravity to keep the fluids segregated,” according to Verma. “For secondary recovery, relying on either natural or artificial water or gas injection, the incremental recovery ranges from 15-25%. Globally, the overall recovery factors for combined primary and secondary recovery range between 35-45%,” stated Zitha et al. This phase ends as profits fall.
This is when EOR techniques are applied. EOR refers to unconventional methods to recover hydrocarbons from oilfields, such as re-pressurizing the reservoir with miscible-gas or soluble-chemical injections, according to Corex. Interest in EOR techniques is growing around the world as most mature oilfields cannot maintain their production rates without EOR. Similarly, some oil reserves known as un-easy reserves require EOR from the beginning to produce an economically viable amount of oil. Some experts argue that EOR can not only optimize oil extraction but can also significantly extend global oil reserves if oil prices rise to the point where it becomes an economically feasible option, Muggeridge et al. note. EOR could unlock as much as 300 billion barrels of oil worldwide, according to the International Energy Agency.
IOR, while sometimes confused with EOR, refers to improvements in oil recovery achieved through the identification of oil that had been previously bypassed. Seismic surveys are used to locate these oil deposits and then new wells are drilled to extract the oil, according to Sneider et al. in a paper for the American Association of Petroleum Geologists. “Using combinations of traditional EOR and IOR technologies it has been possible to achieve RFs of between 50-70% for some fields but this is still less than the typical RF for a gas field,” the Society of Petroleum Engineers notes.
In recent years, progress has been made in the ‘modeling of the earth’ system. However, there is an ongoing need to improve up-scaling techniques to permit the complex modeling necessary for IOR and EOR. IOCs are seeking to develop expertise in these technologies. A broader use of visualization techniques, such as high-resolution and x-ray computed tomography and nuclear magnetic resonance, could lead to new insights into the recovery mechanisms, argue Muggeridge et al. “Recently, new technologies using the electromagnetic waves and using enzymes have been developed to improve oil recovery. These technologies are still under research and [are in the] development stage,” Dr. Mahmoud Abu El Ela, Professor of Petroleum Engineering at Cairo University, notes.
There is also ongoing academic research to develop new nanotechnologies for the oil and gas industry. “Fruition of such research could bring about considerable changes on way oil exploration and production is done. For instance, swarms of nanodevices transported by flood water could aid real-time mapping of reservoir fluids, resulting in unprecedented accuracy. Nano-devices are also being contemplated as carriers of chemicals that can be delivered directly to the oil/water interface to modify the microscopic displacement pattern,” Zitha et al. write.
“The latest trends involve applications of smart fluids and nanofluids, in addition to modification of biopolymers like xanthan gum, cellulose, and starch. Moreover, some recent academic research tend to microbial EOR by injection of some bacterial species capable of oil degradation in the reservoir, but this is on academic scale only not on industrial scale,” Dr. Abdelaziz El Hoshoudy, a Researcher at the Egyptian Petroleum Research Institute, stated.
Furthermore, George Basta, and Waleed Tarek Kortam, Reservoir Engineers at Scimitar Production Egypt Ltd., believe that the latest trend is for environmental friendly and low-cost methods, such as solar EOR and solvent EOR (VAPEX). There is another global trend that aims to reduce water usage and CO2 emissions in the oil recovery process while cutting back on energy consumption to reduce operating costs, they added.
Egypt’s Oil Recovery Status
At present, oil in Egypt is mainly recovered in the primary and secondary phases. El Hoshoudy noted that “EOR techniques involve water-flooding by polymer in Agiba sessions on a narrow scale and steam flooding in Scimitar Petroleum Company. Concerning miscible flooding by CO2, it is widely applied in US, but not in Egypt.” In the same context, Abu El Ela noted that, “currently, the oil reservoirs in Egypt are mainly producing under the primary and secondary recovery mechanisms-water-flooding projects-with limited applications of EOR techniques including steam stimulation technique thermal-EOR method-and polymer flooding known as chemical EOR method.”
Referring to case studies, Basta and Kortam stated that “primary recovery production with the aid of artificial lift, then pressure maintenance recovery production like water flooding is already implemented in fields: Karama Field, Morgan Field, Ramadan Field, and October Field. While EOR techniques are implemented in Issaran field since 2004 through [the use of] thermal EOR. Currently, there is a new thermal EOR project starting in Lagia Field.”
Highlighting the benefits of implementing more EOR in Egypt, El Hoshoudy mentioned that the amount of residual oil remaining in reservoirs after primary and secondary techniques is estimated to be one billion barrels. “If 50% of this amount were recovered by different EOR technologies it will provide the national income [with] hundreds of millions of dollars,” he stated.
Experts argue that implementing EOR techniques will benefit Egypt’s hydrocarbon industry. “The increasing energy demand in Egypt needs to be met with an increase in energy supply. Conventional oil resources will become depleted [with] time, and new methods and strategies are needed to extract unconventional resources. This will be achieved by EOR implementation. It is critical to start implementing EOR as soon as possible so that by time and by gaining experience, EOR applications become more economic. EOR can be a great tool to increase the economic resources in Egypt. Moreover, Egypt can benefit from implementing EOR by gaining experience and knowhow. If implemented correctly, we can then look forward to becoming pioneers of EOR methods in the future. According to international reports, unconventional resources make up around 75% of global oil in place, and so becoming experts in EOR implementation is a great opportunity that could benefit Egyptian engineers and companies,” Basta and Kortam write.
Challenges of Using EOR in Egypt
There are many financial challenges and technical concerns that could prevent the wide application of EOR technologies in Egypt. “The main challenge is related to oil prices, as EOR application is a costly process, so countries and companies resort to it in case of high oil prices. Other challenges are related to petroleum companies’ policies in which studies and applications of EOR studies are restricted to the foreign partner, which is mainly focused on exploration and drilling, not interested in EOR,” noted El Hoshoudy.
Affirming El Hoshoudy’s opinion, Basta and Kortam believe that there are financial challenges facing the application of EOR in Egypt, such as the pilot test price, the modeling costs, the capital cost to modify the surface and down-hole systems, and the operating costs. “Other challenges are mainly technical, as the [main purpose of] EOR implementation is usually the unconventional oil reservoirs. The challenges faced also include finding accurate tools to support the studies, which increases the risk of studying, but with the help of universities, companies can find solutions,” Basta and Kortam argue.
Abu El Ela believes that “most of the current oil production in Egypt comes from mature fields. The rate of replacement of the produced reserves by new discoveries has been declining steadily in the last decades. In addition, operators are focusing on redeveloping and improving oil recovery from existing oil reservoirs because of increased exploration costs for new oil fields and the limited opportunity for discovering major high-quality oil reserves. Therefore, the increase of the recovery factors from mature fields by applying the EOR technologies will play a key role to meet the growing energy demand in the coming years. However, there are several challenges before applying such technologies—technical challenges and the associated costs—to the Egyptian oil fields.” On the other hand, “to improve the performance of the existing fields, most of the development plans recommend several solutions such as drilling of infill wells, using of artificial lift technologies such as gas lift, ESP, sucker rod pumping, and PCP or carrying out stimulation operations,” he argues.
Recovering hydrocarbons is becoming more difficult at a time when oil fields are declining; hence effective techniques are essential to extract more oil from mature fields. Each step to improve recovery, however, comes with increased costs due to the complexity of the fields. Operational excellence in the primary and secondary phases is a prerequisite for successful implementation of EOR technologies. Excellent and cost-effective reservoir monitoring, for instance, is essential to make well-informed field-development decisions, mitigate project risks, and meet production targets.