This set of Environmental Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Microbial Extraction of Petroleum”.
1. Which oil recovery mechanism yields the most oil andis the most efficient oil recovery mechanism?
a) Selective plugging by microorganisms and their metabolites
b) Oil viscosity reduction by gas production
c) Production of acids by dissolving minerals in the rock
d) Degradation of long-chain saturated hydrocarbons
View Answer
Explanation: Selective plugging or bacterial clogging is a mechanism of microbial oil recovery and is the most efficient. This is effective asmost of the bacteria grow indigenously and due to indigenous (that grows naturally) growth the labor requirement is less, and the activity keeps continuing, giving more result.
2. Which microbe is used as a solvent and applied in microbial oil recovery?
a) Leuconostoc
b) Xanthomonas
c) Brevibacterium
d) Klebsiella
View Answer
Explanation: Klebsiella is used as a solvent in the application of microbial oil recovery. It helps to dissolve rocks for greater permeability and also used in oil viscosity reduction.
3. Some strains of ______ bacteria can produce hydrogen, methane, acetate etc. by ________ of carbohydrates during initial growth phase.
a) obligate anaerobic; oxidation
b) facultative aerobic; reduction
c) obligate anaerobic; fermentation
d) facultative anaerobic; oxidation
View Answer
Explanation: The obligate anaerobic bacteria such as clostridia is applied as gas and solvents. At the initial growth phase, the carbohydrates are fermented and hydrogen, carbon dioxide, methane, acetate, and butyrateare produced.
4. The effects of bacterial activity decreases with time and distancefrom the injection well.
a) True
b) False
View Answer
Explanation: The activity of bacteria tends to improve as their growth increases in the reservoir. The temperature, pressure and if all the optimum conditions are maintained the growth and activity of bacteria keeps on increasing.
5. How the flow pattern in clogging mechanism is achieved?
a) By increasing the pressure
b) By increasing the viscosity
c) Bydecrease in microbial cell mass
d) By increasing the cell mass of microbes
View Answer
Explanation: The increase in the cell mass of microbes affects the flow pattern by shifting the fluid flow from high permeability zones to low permeability zones in the reservoir. This stimulates the growth of microorganisms which increases the mechanism of microbial plugging.
6. Clostridium is used as which metabolite in microbial oil recovery?
a) Solvents, Acid and Gases
b) Biomass, Surfactants and Polymers
c) Solvents, Polymers and Gases
d) Acids, Surfactants and Biomass
View Answer
Explanation: Clostridium is an obligate anaerobe. It is used as a solvent, acid as well as gas in microbial oil recovery. As solvent it is used to dissolve rocks for better permeability and reduction of oil viscosity, as acid it is used for emulsification and aslo to increase permeability, and as gas it is used to increase pressure and for oil swelling. Hence, Clostridium is used as solvents, acid and gases.
7. In which form of microbial product is Leuconostoc applied in microbial oil recovery?
a) Biomass
b) Surfactants
c) Polymers
d) Solvents
View Answer
Explanation: Leuconostoc is a gram-positive coccus shaped bacterium. It is used as biomass in microbial oil recovery and is used to modify viscosity and for selective plugging.
8. Which is the most used bacteria strain in microbial oil recovery?
a) Bacillus
b) Pseudomonas
c) Arthrobacterium
d) Micrococcus
View Answer
Explanation: Bacillus strains is the most utilized bacteria in Microbial Oil Recovery. It grows in a medium which has glucose salts and is used mostly in selective plugging.
9. Which of these is not a strategy for the application of biosurfactants in oil recovery?
a) Injection of biosurfactants into reservoir through well that produce microorganisms and multiply their growth in-situ
b) Production of biosurfactants ex-situ while the same is injected into the reservoir
c) Injecting selected nutrients into the reservoir
d) Injecting microorganisms along with nutrients producing biomass
View Answer
Explanation: Injecting microorganisms along with nutrients producing biomass is a mechanism of microbial plugging and not biosurfactants. The other three options are a strategy of biosurfactants. The injection of selected nutrients into the reservoir stimulates the growth of naturally occurring biosurfactants that produce microorganisms.
10. Less modification of the existing field characteristics are required to implement the recovery process by Microbial Oil Recovery technologies.
a) True
b) False
View Answer
Explanation: According to Lazar’s studies in 2007, it is true that less modifications is required to the already existing field characteristics for Microbial Oil Recovery technologies. This also makes it more cost effective and they are easily applicable.
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