to hydrodesulfurization. The biodesulfurization process is carried out at low pressure
and mild temperature. In biodesulfurization, DBT and other sulfur compounds are
transformed in harmless compounds by microbes. For increasing the efficiency of
biodesulfurization process, genetic engineering technology has also been applied
(Ma 2010).
Rhodococcus erythropolis has a high ability to remove sulfur from crude oil. This
species is aerobic, chemoorganotrophic, gram negative, non-motile, and
non-endospore forming. It also has a variety of catabolic enzymes, more than one
plasmid. Thus, all these properties give greater biotransformation capability across a
wide range of compounds. It utilizes the DBT as a source of sulfur, rather than a
source of carbon and uses 4S pathway for DBT desulfurization. Other than
Rhodococcus,
Agrobacterium,
Mycobacterium,
Gordonia,
Nocardia,
Sphingomonas, Stenotrophomonas, Sphingobacterium, Klebsiella, Pseudomonas,
Arthrobacter, and Bacillus species have shown capabilities for desulfurization of
crude oil and oil products (Alkhalili et al. 2017).
Other than the desulfurization of produced crude oil, heavy oil to light oil
conversion is also a bio-upgradation process for crude oil. This is now been
developed as a new focus area by oil industries and petroleum microbiologist.
Heavy crude (bitumen) is majorly produced by unconventional oil reservoir (e.g.,
Venezuela oil sands, Athabasca oil sands). This heavy oil is very viscous in nature
and contains a high concentration of asphaltene, resins, nitrogen, and sulfur
containing hetero-aromatics and several metals (nickel and vanadium). This heavy
oil has a high production cost, difficult in transportation, and requires a conventional
refining process (Leon and Kumar 2005). For transportation of heavy oil, solvent
addition is needed for easier flowing in pipelines. The cost of solvent and vast heavy
oil production require another method for decreasing its viscosity.
The upgradation of heavy oil is generally done by thermal cracking or by catalytic
hydro conversion. But both processes have some common concern like been energy
and cost intensive, less selective and environment reactive. Biological conversion
could be an alternative process for the upgradation of heavy crude oil. Biological
process is less severe and highly selective for specific reactions. This biological
upgradation can be done by the microbial and enzymatic transformation process.
6.7
Intervention of Biotechnology in Unconventional Oil
and Gas Production (Oil Sands and Shale Gas Fields)
Oil sands are heavy oil deposits that have a composition of sand, clay, and petroleum. These unconventional oil reserves are present in the Orinoco Oil Belt
(Venezuela), Athabasca (Alberta, Canada), Olenik (Siberia, Russia), and Maya
(Mexico) heavy oil sands. These reserves contain oil with high levels of bitumen.
For the recovery of oil from such oil sands, very few biotechnological approaches
are proposed. Therefore, biotechnological intervention can be applied on tailing
ponds management. Oil sands tailing ponds are engineered dam and dyke, contain
the waste by-product such as water, sand, slit, clay, and residual bitumen produced
6 Application of Biotechnology in Oil and Gas Industries
127
and mild temperature. In biodesulfurization, DBT and other sulfur compounds are
transformed in harmless compounds by microbes. For increasing the efficiency of
biodesulfurization process, genetic engineering technology has also been applied
(Ma 2010).
Rhodococcus erythropolis has a high ability to remove sulfur from crude oil. This
species is aerobic, chemoorganotrophic, gram negative, non-motile, and
non-endospore forming. It also has a variety of catabolic enzymes, more than one
plasmid. Thus, all these properties give greater biotransformation capability across a
wide range of compounds. It utilizes the DBT as a source of sulfur, rather than a
source of carbon and uses 4S pathway for DBT desulfurization. Other than
Rhodococcus,
Agrobacterium,
Mycobacterium,
Gordonia,
Nocardia,
Sphingomonas, Stenotrophomonas, Sphingobacterium, Klebsiella, Pseudomonas,
Arthrobacter, and Bacillus species have shown capabilities for desulfurization of
crude oil and oil products (Alkhalili et al. 2017).
Other than the desulfurization of produced crude oil, heavy oil to light oil
conversion is also a bio-upgradation process for crude oil. This is now been
developed as a new focus area by oil industries and petroleum microbiologist.
Heavy crude (bitumen) is majorly produced by unconventional oil reservoir (e.g.,
Venezuela oil sands, Athabasca oil sands). This heavy oil is very viscous in nature
and contains a high concentration of asphaltene, resins, nitrogen, and sulfur
containing hetero-aromatics and several metals (nickel and vanadium). This heavy
oil has a high production cost, difficult in transportation, and requires a conventional
refining process (Leon and Kumar 2005). For transportation of heavy oil, solvent
addition is needed for easier flowing in pipelines. The cost of solvent and vast heavy
oil production require another method for decreasing its viscosity.
The upgradation of heavy oil is generally done by thermal cracking or by catalytic
hydro conversion. But both processes have some common concern like been energy
and cost intensive, less selective and environment reactive. Biological conversion
could be an alternative process for the upgradation of heavy crude oil. Biological
process is less severe and highly selective for specific reactions. This biological
upgradation can be done by the microbial and enzymatic transformation process.
6.7
Intervention of Biotechnology in Unconventional Oil
and Gas Production (Oil Sands and Shale Gas Fields)
Oil sands are heavy oil deposits that have a composition of sand, clay, and petroleum. These unconventional oil reserves are present in the Orinoco Oil Belt
(Venezuela), Athabasca (Alberta, Canada), Olenik (Siberia, Russia), and Maya
(Mexico) heavy oil sands. These reserves contain oil with high levels of bitumen.
For the recovery of oil from such oil sands, very few biotechnological approaches
are proposed. Therefore, biotechnological intervention can be applied on tailing
ponds management. Oil sands tailing ponds are engineered dam and dyke, contain
the waste by-product such as water, sand, slit, clay, and residual bitumen produced
6 Application of Biotechnology in Oil and Gas Industries
127