Overview of Available Techniques for Recovery in Oil Production

Introduction

Recovery in oil production is the procedure of increasing the quantity of recoverable oil from reservoirs. Enhanced Oil Recovery (EOR) techniques are applicable in achieving recovery which involves injecting substances into an oil reservoir to reduce oil viscosity and increase pressure. Tunio, Haque, Ghirano, and Adawy (2011, p. 143) while describing EOR techniques cite that they are proven approaches to boosting production of oil globally. According to Tunio, Haque, Ghirano, and Adawy (2011, p. 144), the sole reason for the discovery of EOR methods is large quantities of oil that remain in reservoirs after primary and secondary recovery. In Tunio, Haque, Ghirano, and Adawy's (2011, p. 143) literature review, many studies demonstrate that there is a possibility of boosting primary and secondary recovery by a value of between 60% and 65% when modern EOR methods are used. Such a boost increases productivity considering that ordinary drive mechanism could initially contribute 20-30% and 30-40% volumes in primary and secondary recovery respectively. Because of the positive attributes of EOR techniques, oil production companies should utilize a recent, technologically savvy, environmentally friendly and economical technique. Tunio, Haque, Ghirano, and Adawy (2011, p. 146) lists the present-day oil recovery techniques which include gas injection, carbon dioxide injection, thermal techniques, Immiscible Water Alternating Gas (IWAG) method, water alternating gas (WAG) approach and microbial enhanced recovery technique (MEOR). The working principle of EOR regardless of the approach is such that a method can either fall into the category that improves displacement efficiency or one which increases volumetric sweep. The listed EOR techniques in Tunio, Haque, Ghirano, and Adawy (2011, p. 145-148 ) article has numerous flaws. For instance, although carbon dioxide (CO2) injection is the most prevalent oil recovery technique, its effectiveness and viability are reliant on availabi1lity of natural CO2, a gas which is complex to collects on sufficient amounts enough to support industrial applications. Thermal methods, on the other hand, has the disadvantage of requiring more funds to buy and install special equipment and environmental implication such as the likelihood of damaging underground well structures posing safety risks. It is for that reason that the best new is microbial enhanced oil recovery (MEOR) technique which is rapidly gaining traction in the oil sector.

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Appropriate Technique: Microbial Enhanced Oil Recovery (MEOR)

The working principle of microbial enhanced oil recovery (MEOR) is that there is an injection of suitable bacteria and nutrients with the capability of growing in oil reservoirs anaerobically. As these microbial substances grow, they produce metabolic products such as enzymes, gases, solvents, acids, biopolymers, and biosurfactants. The microbes both enhance displacement efficiency of oil and increase volumetric sweep by modifying oil properties and its interaction with porous reservoir media and water which enhance oil mobility thus improving recovery and extending reservoirs' producing lives. According to Rashedi, Yazdian, and Naghizadeh (2012, p. 75), various mechanisms explain microbial actions in MEOR technique. They include changing the wettability due to the bacterial presence and surfactant production and reducing oil-water interfacial tension. These are the two main mechanisms that cause the greatest impact during the process of recovering oil. The third mechanism is acid production which dissolves rock minerals thus achieving consequential absolute rock permeability. Other MEOR mechanisms include selective plugging actions by metabolites of injected microorganism, reduction of oil viscosity after the production of gaseous products or when saturated long-chain hydrocarbons degrade. All the five mechanisms contribute to the production of compounds that mobilize oil in reservoirs. Clogging mechanism sums up all the MEOR approaches as it explains the general strategy in which microbial activities in reservoirs assist in enhancing oil recovery. According to Rashedi, Yazdian, and Naghizadeh (2012, p. 77), microorganisms introduced into oil reservoirs modify the flow of oil by changing the flow of fluid from reservoir zones with high permeability to those areas with low or moderate permeability. The shift in fluid flow improves sweep efficiency consequently directing injected water to flow through previous oil zones.

The choice of the technique follows the advantages set forth by the different study. Rashedi, Yazdian, and Naghizadeh (2012, p. 77) say that the preference of MEOR over other EOR techniques is due to five main reasons. The first one is the reduced cost of implementation because nutrients and bacteria are easy and inexpensive to get and apply in oil reserve fields. Secondly, processes associated with MEOR are economical making the method suitable for marginally producing oil reserves. Thirdly, there is less energy input required by the cell's factories in producing MEOR agents thus making the method to be one of the cheapest EOR techniques. Unlike other EOR strategies, MEOR demands less or no modification of the oil field characteristics for effective implementation thus increasing enhancing its cost-effective nature. The fourth advantage is in agreement with Tunio, Haque, Ghirano, and Adawy (2011, p.148) assertion that MEOR does not need any modification of oil recovery facilities as it is environmental friendly with minimum alteration of oil reserves' structure and functions. Lastly, injected fluids in MEOR are free from petrochemicals, the method is not only environmentally sustainable but also cheap as its costs are not reliant on the fluctuation of the prices of global crude.

MEOR and Economics

As a technique for increasing the production of oil, MEOR directly affects macroeconomic factors such as employment and business operations. Microbial enhanced oil recovery is the most cost-effective approach to recovering additional barrels of oil that could be wasted as the technique recover as much as 60% of oil in the field. Because nations invest billions of dollars in oil production, it is necessary to choose a technique that ensures maximum recovery to boost production with the lowest cost possible. Recovery of oil indirectly affects business by influencing the cost of oil. Recovery of more oil that would be waste means that oil will be present in surplus amount thus reducing the fuel prices and directly influencing the costs of manufacturing and production in all industries relying on oil. A good example is a direct relationship existing between the costs of gasoline and the prices of air transport. On the other hand, increased availability of oil due to effective recovery reduce fuel prices which consequently lowers costs of transportation thus promoting the movement of goods and services. The manufacturing sector which forms the backbone of Iran's economy benefits the most from reduced oil prices considering that almost 80% of industrial chemical originate from refined oil. Oil availability directly impacts prices of commodities and also drive investment and job creation. Therefore, it is economically viable to invest in an effective and environmentally friendly advanced recovery technique such as microbial enhanced oil recovery (MEOR) to capitalize on higher-cost shale oil reserves. Microbial enhanced oil recovery (MEOR) is appropriate for oil companies in Iran considering it is a nation contributing up to 16% of the global oil reserves.

References

Rashedi, H., Yazdian, F., & Naghizadeh, S. (2012). Chapter 3: Microbial Enhanced Oil Recovery. In Introduction to Enhanced Oil Recovery (EOR) Processes and Bioremediation of Oil-Contaminated Sites (pp. 71-83). Tehran: University of Tehran.

Tunio, S. Q., Haque, A., Ghirano, N. A., & Adawy, Z. M. (2011). Comparison of Different Enhanced Oil Recovery Techniques for Better Oil Productivity. International Journal of Applied Science and Technology, 1(5), 143-151.