Jurisdiccional Auxiliar
UNIDAD DE PROGRAMAS ESPECIALES (UPE)
It is apparent that when oilfield parameters are ignored and testing of treatments are conducted under standard lab conditions (Table 5.1), higher recoveries are seen (Banat, 1993; Makkar & Cameotra, 1997; Qazi et al., 2013). However, with testing conditions not mimicking those of the reservoir this as we know does not bode well for the accuracy of the microcosm simulations, and will in all likelihood lead to failures in the field as we have seen many times before (Maudgalya et al., 2007). However, of the studies that
do mimic reservoir parameters, the most commonly simulated parameters are that of temperature, crude oil density and gravity and FW brine composition, with only a limited number of trials replicating additional parameters such as substrate porosity and well pressure. Yet the model systems where all oilfield conditions were replicated (Pressure, Crude oil, Rock porosity, FW brine,
Temperature), yielded less oil recovery compared to the less exacting
laboratory studies (Dastgheib et al., 2008; Suthar et al., 2009).
Most of the in vitro studies conducted have used sand pack porous micromodels. Although the use of core floods provides a more accurate estimate of a microorganisms MEOR potential, the increased expense in time and money of core flood experiments, alongside the difficulty of core aquisition, make the use of core floods an impractical process for large scale MEOR screening projects, like the one described in this thesis. Furthermore, it is apparent from the literature that very little research has been conducted with regards to heavy or unconventional oil fields. Although heavy oil is in a large abundance on the planet, due to difficulties in its mobilisation and refinery, heavy oil has not been the focus of research initiatives. However, with rapidly decreasing amounts of conventional oils and no obvious renewable energy technology ready to replace the use of fossil fuels, it is plausible to conceive that heavy oil MEOR could be the defining process to stave off the impending energy crisis.
Table 5.1 Reservoir simulated conditions and additional oil recovery in porous micromodel systems by bacterial species.
Microorganism Reservoir simulated features Model system / inoculum Additional oil recovery (%)
Oil type Reference
Bacillus sp. AB-2 -
*
Sand pack column/ bacteria & nutrient 95 Light oil (Banat, 1993)B. subtilis MTCC
2423 -
Sand-packed column/ purified
biosurfactant 60 Light oil
(Makkar & Cameotra, 1997)
B. licheniformis
BNP29 -
Sandstone core/biomass & nutrient medium (selective
plugging)
15 Light oil (Yakimov et al., 1997)
B. brevis sp. N/A Sand packed column/consortia
in nutrient medium 16.5 Light oil
(Almeida et al., 2004)
B. mojavensis JF-2 - Berea sandstone core/crude
purified biosurfactant 10–40 Light oil
(Mcinerney et al., 2004)
B. subtilis sp. -
Glass etched flow micromodels/bacteria &
nutrient medium
30 Light oil (Soudmand-asli et
al., 2007)
P. aeruginosa sp. Porosity,
Temperature
Sand pack column/ crude
biosurfactant 30 N/A
(Bordoloi & Konwar, 2008)
B. licheniformis AC01
Pressure, Crude oil, Rock porosity, FW brine, Temperature
Sand packed column/ bacteria
& nutrient medium 22 Light oil
(Dastgheib et al., 2008)
B. licheniformis AC01
Pressure, Crude oil, Rock porosity, FW brine, Temperature
Sand packed column/
bioemulsifier < 1 Light oil
(Dastgheib et al., 2008)
B. licheniformis
TT42 FW brine, Pressure
Sand-packed column/crude
biosurfactant 35 Synthetic (Suthar et al., 2008)
B. licheniformis
K125 FW brine, Pressure
Sand-packed column/crude
bioemulsifier 43 Synthetic (Suthar et al., 2008)
B. mojavensis JF-2 FW brine, Pressure Sand-packed column/crude
bioemulsifier 29 Synthetic (Suthar et al., 2008)
B. subtilis 20B FW brine, Rock
porosity
Sand-packed column/crude
biosurfactant 25–33 Light oil (Joshi et al., 2008)
B. subtilis 20B Crude oil, FW brine,
Rock porosity
Glass packed column/crude
biosurfactant 30 Light oil (Joshi, et al., 2008)
B. licheniformis TT33
Pressure, Crude oil, FW brine, Temperature
Sand packed column/microbial biomass in nutrient medium
(selective plugging)
25–32 Heavy oil (Suthar et al., 2009)
Bacillus sp. Crude oil,
temperature Glass etched micromodels/ 13 (Gao, 2011)
E.
sakazakii/B.subtilis fusion
Pressure, FW brine, Temperature
Sand pack column & sandstone core/ engineered
bacteria & nutrient
17-25 N/A (Xu & Lu, 2011)
B. licheniformis sp. Temperature, Crude
oil
Sand pack column/ bacteria &
nutrient 6-25 Light oil
(Gudiña et al., 2013)
B. licheniformis sp. Temperature, Crude oiil Sand pack column/ bacteria & nutrient 15-17 Heavy oil (Gudiña et al., 2013)
B.licheniformis R1 FW brine, Rock
porosity
Sand pack column/ crude
biosurfactant 32 N/A (Joshi et al., 2013)
Fusarium sp. BS-8 FW brine Sand pack column/ crude
biosurfactant 46 Light oil (Qazi et al., 2013)
B. subtillis W19 Crude oil, FW brine,
Porosity
Berea sandstone core/ crude
biosurfactant 15 Light oil
(Souayeh et al., 2014)
C. albicans sp.
Crude oil, FW brine Sand pack column/ selective
plugging 9 Light oil
(El-Sheshtawy, et
al., 2016) B. subtilis
MTCC2422 N/A
Sand pack column/ bacteria &
nutrient 9 Synthetic
(Rajesh Kanna et
al., 2016) B. licheniformis
ATCC 14580 Crude oil, FW brine
Sand pack column/ crude
biosurfactant 17 Light oil
(El-Sheshtawy, et
al., 2016)
*
Signifies no petrophysical or geochemical characteristics were simulated in the model system.Table 5.1 Reservoir simulated conditions and additional oil recovery in porous micromodel systems by bacterial species.
5.1.4 Research hypothesis, aims and objectives
The primary aim of this chapter was to successfully create a reproducible microcosm model to simulate the reservoir characteristics of the Bentley Oilfield. Once created and optimized, these porous micromodels will be used to investigate the potential of reservoir isolates previously identified in Chapter 4 to drive additional oil recovery, in comparison to other known MEOR stimulating microorganisms. The potential of the reservoir isolates to drive MEOR in our simulated reservoirs will be done through analysis of bioreactor models and application of qPCR, establishing whether surfactant mediated IFT alteration is the predominant MEOR mechanism.
This chapter investigated two distinctive hypotheses. Firstly, it was hypothesised that any isolates from the heavy oilfield environment (Bentley Oilfield) that were capable of producing SACs would increase residual oil recovery. Secondly, the hypothesis that a dual mechanisms of action was taking place within the bioreactor was also tested.