Enhanced Oil Recovery: Techniques And Challenges

Oil recovery problems nowadays

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Production of oil is divided into three phases such as primary, secondary and tertiary. Enhanced oil recovery refers to symbolize oil recovery beyond primary and secondary oil production. Primary oil recovery is restricted to hydrocarbons, which naturally gets up to the surface, or those that exercise artificial lift devices such as pump jacks. Secondary recovery also produces oil through water flooding. This method employs water and gas injection, which let the oil to be displaced and risen to the surface. US Department of Energy found that these two methods are only capable to remove 25% oil from the oil (Lake et al., 2014). It is only tertiary recovery method which remove 75% oil from the well. Enhanced oil recovery is an initiation, which targets to improve oil production up to 75% from the well.

The energy of the oil reservoir required to produce oil is not enough because of the distribution of permeability in the reservoir that has been uncertain at certain stages. The statistical approaches are based on limited numbers of assumptions related to the heterogeneity of the reservoir. The recovery of oil from the gas drive reservoirs is quite low that ranges in between 5 to 30 percent. The oil reservoir is not much effective to produce oil because the pressure has dropped significantly. Due to this, the expansion of gases that are dissolved in the water and oil has taken up most of the drive energy present in the reservoir. The demands have increased though the supply is not sufficient to cater the needs and requirements of people (Yousef, Al-Saleh & Al-Jawfi, 2012).

When an inappropriate pattern is formed between the unstable interface between the two fluids such as oil or water, it causes problem such as viscosity fingering. It is a major problem because a lesser thick fluid is injected that displaces a more thick fluid, occurred due to gravitational force. The patterns formed tend to create fingers by splitting the tips simultaneously causing less flow or production of oil. This instable flow of fluids in the porous media is further affected by mobility or density ratios, creating problems such as production of fluids consisting of contaminants. The reservoirs that have low viscosity , i.e., less than 5 mPa.s can be flowed evenly though with the increase in oil recovery level, the flow of water reduces and the efficiency difference deteriorates within the reservoir. The reservoirs that have medium-high viscosity oil allow the water to be injected during the water flooding process in a streamline, which prevents the coverage to be swept. With the increase in oil recovery, the streamline starts to get thin and the coverage becomes void of, furthermore the effectiveness of the top and bottom surface of the reservoirs decrease. Due to this, the increased velocity of the water is reduced and the oil production rate further decreases and thus it becomes not suitable for the medium to high viscosity reservoirs. Therefore, these are the major differences experienced during the recovery of oil.

Use of Enhanced oil Recovery

The production of crude Oil production can be categorized into various phases including the primary, secondary and tertiary and is referred to as the Enhanced Oil Recovery (EOR). One example could be of ADNOC, which had utilized various technologies to manage the wells in the onshore and offshore areas. The people have used carbon dioxide and gas injection EOR not only to enhance the lifespan of the wells for producing oil but also has increased the production level largely. The gas injection techniques are also considered as effective for enhancing the oil recovery process with ease and effectiveness. The energy present at the reservoir is used to move the oil and gas to the wellbore and has increased the effectiveness of drive mechanisms. It has allowed the people to recover hydrocarbons and maintained steady data and fluid production ratios (Pereira et al., 2013). The people mostly used the drive mechanisms that included solution gas drive, water drive and gas cap drive. The energy source of solution gas drive is evolved solution gas expansion and it has a recovery rate of nearly 30 percent.

The solution gas drive, gas cap drive and water drive are the three most effective methods used for recovery and production of oil. The rate of recovery of oil though differs for these various methods and techniques along with the sources of energy. The solution gas drive allows the oil bearing rock to get surrounded by impermeable barriers. With the decrease in pressure during the production, the oil and dissolved gas expands to provide enough drive energy for the reservoir, which facilitates the production of oil at a faster rate. The gas cap drive, on the other hand, generates energy from the initial gas cap, which tends to increase with the decrease in reservoir pressure (Farajzadeh et al., 2012). With the solution gas expansion, additional energy is generated. The water drive is preferred more effective because the oil zone is linked with an aquifer that has produced the most amount of energy required for oil recovery and production. The water present in the aquifer increases and goes inside the reservoir, which produces the oil to get displaced.

One of the major problems with the water drive reservoir could be the inappropriate size of the aquifer, lack of its permeability and lesser production rate of the reservoir.  The water control effects were quite different as well, which could deteriorate the water influx control and furthermore reduce the oil recovery and production rate. The water accumulation in the reservoir might sometimes create rust and reduce the purity level of water. It should be important to keep the water drive reservoir clean to maintain proper functioning of the enhanced oil recovery process (Ogolo, Olafuyi & Onyekonwu, 2012).

Use of water, gas and Water alternating gas injection methods of oil recovery

Steam foam drive method is considered as an effective method for enhanced oil recovery where the oil is recovered from a petroleum reservoir through the improvement of steam sweep effectiveness. A particular foaming agent is used to change the direction of the steam towards the areas where steam is not produced. The steam is passed through the reservoir and the production well, which allows for inserting the amount of liquid water in the injection well in a separate way. This helps in recovering the oil from the production well, furthermore allowed for steady production of oil. The insertion of surfactants to the steam has created a better steam flood flow. It has influenced the steam to push the hydrocarbons from the portions that were less depleted directly to the production well, finally producing oil in good amounts (Muggeridge et al., 2014).

One of the most popular oil refineries ADNOC has used the EOR and ERD to ensure that the values of resources are maximized and the needs and requirements of the people are met. The company aims to develop hydrocarbon resources because the energy was not effective enough to recover oil. By partnership working with other companies, ADNOC made sure that the recovery of oil is enhanced from the reserves. The wells have been drilled horizontally and then carbon dioxide is used to inject gas and improve the longevity of the oil fields. The company has aimed to increase productivity by 400000 bpd in the next two years. The extended reach drilling has allowed the company to drill the offshore oil fields, produce the maximum amount of oil to ensure contributing to the economic growth of Abu Dhabi, and furthermore remain competitive within the business environment. To do so, ADNOC has delivered the best quality resources and made sure to explore more areas where offshore oil fields can be found (Lake et al., 2014). The company has even established partnership working with the Abu Dhabi Marine Operating Company and Zakum Development Company to bring out better benefits in the form of financial profit and higher oil production too. This has allowed the organization to respond to the changing demands in the markets and furthermore positioned itself by using the strategies scopes and become successful in the future (Pereira et al., 2013).

References

Lake, L. W., Johns, R. T., Rossen, W. R., & Pope, G. A. (2014). Fundamentals of enhanced oil recovery.

Pereira, J. F., Gudiña, E. J., Costa, R., Vitorino, R., Teixeira, J. A., Coutinho, J. A., & Rodrigues, L. R. (2013). Optimization and characterization of biosurfactant production by Bacillus subtilis isolates towards microbial enhanced oil recovery applications. Fuel, 111, 259-268.

Farajzadeh, R., Andrianov, A., Krastev, R., Hirasaki, G. J., & Rossen, W. R. (2012). Foam–oil interaction in porous media: implications for foam assisted enhanced oil recovery. Advances in colloid and interface science, 183, 1-13.

Muggeridge, A., Cockin, A., Webb, K., Frampton, H., Collins, I., Moulds, T., & Salino, P. (2014). Recovery rates, enhanced oil recovery and technological limits. Phil. Trans. R. Soc. A, 372(2006), 20120320.

Yousef, A. A., Al-Saleh, S., & Al-Jawfi, M. S. (2012, January). Improved/enhanced oil recovery from carbonate reservoirs by tuning injection water salinity and ionic content. In SPE Improved Oil Recovery Symposium. Society of Petroleum Engineers.

Ogolo, N. A., Olafuyi, O. A., & Onyekonwu, M. O. (2012, January). Enhanced oil recovery using nanoparticles. In SPE Saudi Arabia section technical symposium and exhibition. Society of Petroleum Engineers.