Chemical Enhanced Oil Recovery

Advances in Polymer Flooding and Nanotechnology

Patrizio Raffa, Pablo Druetta

• Publisher: De Gruyter
• Year: 2019
• ISBN:
  9783110640434
• Edition: 1
• Topic: Tecnología e ingeniería
• Subtopic: Ingeniería química y bioquímica

This book aims at presenting, describing, and summarizing the latest advances in polymer flooding regarding the chemical synthesis of the EOR agents and the numerical simulation of compositional models in porous media, including a description of the possible applications of nanotechnology acting as a booster of traditional chemical EOR processes.

A large part of the world economy depends nowadays on non-renewable energy sources, most of them of fossil origin. Though the search for and the development of newer, greener, and more sustainable sources have been going on for the last decades, humanity is still fossil-fuel dependent. Primary and secondary oil recovery techniques merely produce up to a half of the Original Oil In Place. Enhanced Oil Recovery (EOR) processes are aimed at further increasing this value. Among these, chemical EOR techniques (including polymer flooding) present a great potential in low- and medium-viscosity oilfields.

• Describes recent advances in chemical enhanced oil recovery.

• Contains detailed description of polymer flooding and nanotechnology as promising boosting tools for EOR.

• Includes both experimental and theoretical studies.

About the Authors

Patrizio Raffa

is Assistant Professor at the University of Groningen. He focuses on design and synthesis of new polymeric materials optimized for industrial applications such as EOR, coatings and smart materials. He (co)authored about 40 articles in peer reviewed journals.

Pablo Druetta

works as lecturer at the University of Groningen (RUG) and as engineering consultant. He received his Ph.D. from RUG in 2018 and has been teaching at a graduate level for 15 years. His research focus lies on computational fluid dynamics (CFD).

1 An introduction to chemical enhanced oil recovery

1.1 Current trends in oil recovery

One of the main challenges of the current society is to replace fossil fuels with more sustainable and green resources [1, 2, 3, 4, 5]. The reasons for this need are simple: fossil fuels are 1) polluting and 2) finite. These issues are becoming more and more critical, and many experts agree that we have to focus all our efforts on finding ways to become independent from fossil fuels as soon as possible. The agreement recently negotiated in Paris by the United Nations Framework Convention on Climate Change (UNFCCC) [6], aims at contrasting climate change by significantly reducing emissions of greenhouse gases (mainly CO2) generated by human activity worldwide in a relatively short time. In Europe, the energy‐focused scenarios recently developed by Shell [7], denominated respectively the Sky, Oceans, and Mountains scenario, aimed at responding to the challenges posed by the Paris agreement, and describe a technologically, industrially, and economically possible way forward, consistent with limiting the global average temperature rise to well below 2 ℃ from pre-industrial levels.

Fossil fuels are nowadays our main source of both energy and platform chemicals, thus the challenge is actually twofold: the use of fossil fuels for the production of energy should be increasingly replaced by renewable resources (solar, wind, hydroelectric, geothermal, biofuels, etc.); and, platform chemicals should be obtained by bio-based resources, according to the concept of bio-refineries, which has become a familiar term in recent times [5]. Some worrying questions comes naturally to mind when thinking about this resource problem: how far are we from becoming independent from fossil fuels? Do we have enough of them to keep going until we manage to do so? Are we already late?

Of course, the answers to these questions are not straightforward, but we can have a look at some recent data. Figure 1.1 shows the global primary energy consumption (in million tonnes oil equivalent) from 1991 to 2016, according to the BP (British Petroleum) statistical review of world energy 2017 [8].

Fig. 1.1: Global primary energy consumption between 1991 and 2016 (in million ton oil equivalent) [8].

The BP report shows that the total world primary energy consumption grew by 1.0% in 2016, well below the last 10-year average of 1.8% and the third consecutive year at or below 1%. All fuels except oil and nuclear power grew at below-average rates. Oil provided the largest increment to energy consumption at 77 million tonnes of oil equivalent (mtoe), followed by natural gas (57 mtoe) and renewable power (53 mtoe). On a very simple level, it appears very clearly that even though the trend is positive (Fig. 1.2), renewable sources are not gaining much ground on fossil fuels yet and a “fossil fuel free” world is still far off.

Fig. 1.2: Shares of global primary energy consumption (in %) between 1966 and 2016 [8].

Looking more specifically at the oil situation, Fig. 1.3 illustrates the world oil demand and supply over the last few years, as reported by the International Energy Agency (IEA) in 2017, including predictions for 2018 [9]. Of course, the overall scenario of demand and supply is extremely complicated, due to all the political and economic factors in play, but it is again clear to the non-expert eye, that both are increasing and are predicted to keep on doing so.

Fig. 1.3: Balance between world supply and demand of oil (in million barrel per day) until 2017, with predictions for 2018, according to [9].

Oil is obviously a limited resource and it will eventually become unavailable, when there will be no new reservoirs to be discovered and the existing one will be no longer exploitable. It is practically impossible to foresee such a moment, but several theories, the first rigorous one being proposed by geophysicist Hubbert (as early as in 1956), have predicted the existence of a “peak oil” [10, 11, 12, 13]. According to the theory, the current increase in oil production will reach a peak, followed by a steady decline until full depletion of economically exploitable oil resources. This follows the evolution of every oil reservoir, which generally experiences a rise, peak, decline and depletion. Several studies have tried to place the position of the peak in a specific year. This will depend on many factors, such as the global economy, the discovery of new reservoirs, the development of new technologies or improvement of existing ones, which are so complex they make such an estimate very impractical. The most recent estimates places the “oil peak” around 2020, and in any case it seems very unlikely that it will be reached after 2030 [13].

The current and prospective worldwide energy demand has led either to exploiting more difficult and costly unconventional oil reserves (oil shale, tar sands, etc.), or to maximizing the exploitation of conventional oil sources. The latter triggered and still drives the development of new techniques aimed at improving the efficiency and lifetime of mature oil fields. These techniques usually go under the collective term of enhanced oil recovery (EOR). Figure 1.4 gives an estimate of total conventional and unconventional oil made by BP and IEA [14].

Fig. 1.4: Conventional (top) and unconventional (bottom) oil resources expressed in Giga barrels [14].

1.2 Enhanced oil recovery

Oil recovery processes can be divided into three main stages: primary, secondary and tertiary recovery. The latter is also known as enhanced oil recovery, (EOR) [15].

Primary recovery uses natural forces to produce the oil, through three different mechanisms: the aquifer drive, the gas cap drive and the gravity flow. The aquifer drive, according to which the pressure that is exerted on the oil by the aquifer represents the driving force for extraction, is the most efficient mechanism. The production of oil leads to a decrease in pressure of the reservoir, and the aquifer moves towards the production well. The oil cut decreases as more and more water is produced along with the oil. The gas cap drives the oil in a similar fashion as the aquifer drive. Gas production (along with the oil) is not seen as a disadvantage, since it also can be used as an energy source. Finally, gravity is the important factor in the gravity flow, for which the well placement is obviously relevant. The use of this method is limited and is heavily dependent on the geology of the reservoir. The primary techniques recover, depen...