Page 450 - Fundamentals of Enhanced Oil and Gas Recovery

438 Afshin Tatar

Table 10.5 MEOR Screening Criteria Suggested by Sheng [24] Based on the
Literature Information [392,768]
Parameter Suitable Range

Formation temperature ,98 C, preferably , 80 C

Pressure 10.5 20 MPa
Formation depth ,2400 3500 m
Porosity .0.15
Permeability .50 mD
Formation water TDS NaCl , 10% 15%
pH 4 9
Oil density ,0.966 g/cm 3
Oil viscosity 5 50 cP
Residual oil saturation .0.25
Elements Arsenic, mercury , 15 mg/L
Well spacing 40 ac

TDS, total dissolved solids.

to take the desired action. Sheehy [803] specified that a main reason for failure of
MEOR field trials is insufficient consideration of the reservoir properties and the
physiology of the microorganisms, which thrive in that condition. The reservoir phys-
ical and chemical parameters such as temperature, pressure, salinity, pH, redox poten-
tial, etc. affect the microbial activities such as microorganisms’ growth, proliferation,
survival, metabolism, and the ability to produce the desired volume of the biochem-
icals [84]. Proper prior planning is mandatory for success of an MEOR field trial. It
should be mentioned that criteria proposed by different researchers might be slightly
different.
Scrutinizing 407 field trials reported in literature, Maudgalya et al. [23] stated that

a minimum reservoir permeability of 75 mD and temperatures less than 93 Chave
been the most suitable conditions for MEOR. More recently, Sheng [24] proposed
the MEOR screening criteria as it is listed in Table 10.5. More details about the
MEOR and screening criteria are debated in the following.

10.12.1 Reservoir Engineering Considerations

The first step in planning an MEOR project is acquiring a clear understanding about
the factor limiting the oil production and is aimed to be solved [17,22]. After the
problem was clearly identified, it can be decided which microbial processes or micro-
organism would be the best solution. This makes it essential to consider the problem
in engineering point of view by the reservoir engineers [66,407]. For example, in case
of mobilizing the trapped oil from the porous media, microorganisms such as
biosurfactant-producing species should be utilized. On the other hand, to remediate
the water channeling by the thief zones, in situ biopolymer generation may be the