Page 439 - Fundamentals of Enhanced Oil and Gas Recovery

Microbial Enhanced Oil Recovery: Microbiology and Fundamentals 427

Table 10.4 Important Biopolymers With the Producing Microorganism
Biopolymer Producing Microorganisms References
Xanthan Xanthomonas comprestris sp., [652 655]
gum
Curdlan Agrobacterium sp., Paenibacillus sp., Pseudomonas sp. QL212, [656 663]
Alcaligenes faecalis
Levan Lactobacillus reuteri, Zymomonas mobilis., streptococcus [664 669]
salivarius, Serratia sp., Bacillus subtilis
Pullulan Aureobasidium pullulans, Pullularia pullulans [670 672]
Dextran Leuconostoc mesenteroides, cariogenic streptococcus, Pediococcus [673 677]
pentosaceus, Weissella cibaria
Scleroglucan Sclerotium rolfsii [678 680]
Poly-β- Azotobacter vinelandii, Bacillus spp., Alcaligenes eutrophus [651,681,682]
hydroxybutyrate
(PHB)
Polyglutamic acid Bacillus licheniformis., Bacillus subtilis [651,683,684]
(PGA)

PHB, poly-β-hydroxybutyrate; PGA, polyglutamic acid.
This table is limited to the biopolymers can be used in MEOR processes.

about the using biopolymers in MEOR can be found in literature
[16 19,21,24,617,619 622,624,634,640,643,644].
In addition to the microorganisms listed in Table 10.4, distinguished bacteria to
produce the biopolymers include Xanthomonous, Aureobasidium, Bacillus, Alcaligeness,
Leuconostoc, Sclerotium, Brevibacterium, and Enterobacter [15,24].

10.10.3 Bioacids

The produced acids by microbial metabolisms dissolve the carbonate rocks (and also
sandstones cemented by carbonate minerals [66]) and subsequently increase the poros-
ity and permeability, which leads to improve the oil migration [566,685]. Dissolution
of iron scales in media containing magnetite and goethite is also reported due to acid
production by bacteria [686]. In addition, acids can generate gases, which improve the
oil displacement by reducing the viscosity along with several other fruitful effects such
as oil swelling. Moreover, acids can reduce the permeability due to the clay movement
[24]. The other role of bioacids is aiding emulsification [24]. In case of bioacid pro-
duction in large volumes via in-situ microbial fermentation, it would have the poten-
tial to be an alternative for the conventional acid treatments [686]. Members of the
genera Bacillus and Clostridium are the most commonly used microorganisms to pro-
duce bioacids, biogases, and biosolvents [6,22,24,88,114,397,408,567,685,687].
Clostridium spp. can produce acetate and butyrate acids, while Bacillus spp. produce
acids of acetate, formate, lactate, etc. [6]. Moreover, lactic acid bacteria (LAB) can