25 3 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery (MEOR)

Transcription

1 25 3 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery (MEOR) H. Volk*. K. Liu CSIRO, Wealth from Oceans Flagship, North Ryde, Australia *Herbert.Volk@csiro.au 1 Introduction History of MEOR Field Trials Examples of MEOR Field Application Bebee Field, Oklahoma, USA Dagang Oilfield, China Jilin Oilfield, China Daqing Oilfields, China Beatrice Oilfield, North Sea Talara Offshore Oilfields, Northwest Peru The Role of MEOR in the EOR Portfolio Current Trends and Future Projection Economics Challenges and Potential Research Needs K. N. Timmis (ed.), Handbook of Hydrocarbon and Lipid Microbiology, DOI / _203, # Springer-Verlag Berlin Heidelberg, 2010

2 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery Abstract: Decades of laboratory research and field trials of MEOR for a range of reservoirs worldwide have shown some encouraging results. With more effective bacteria and inexpensive nutrients, MEOR has the potential to become an economically feasible and technically viable mainstream component of the EOR portfolio. MEOR potentially offers an environmentally sustainable and cost effective technology that can reduce or eliminate the need to use harsh chemicals and energy intensive EOR methods in recovering the vast amounts of oil that remain trapped in aging fields. Integrated research programs and rapidly advancing insights into the diversity of microbial life and biochemical cycles have the potential to deliver breakthrough knowledge for understanding the effects of microbes that thrive in petroleum reservoirs in production time scales. At present, MEOR is yet to be able to provide the reliable benefits that the petroleum industry requires from EOR techniques. However, due to the relatively low costs and low environmental impact of this tertiary recovery method, the potential reward for developing and implementing MEOR based on new fundamental understandings in microbiotechnology and reservoir engineering may be enormous. 1 Introduction The concept of Microbially Enhanced Oil Recovery (MEOR) is amongst the oldest of EOR strategies, but it is not yet an accepted or routine procedure in the petroleum industry. One key reason may be inadequate scientific understandings of the fundamentals and different approaches of MEOR including the processes and mechanisms, which were discussed in > Chapter 24, Vol. 4, Part 4. However, any EOR strategy will need to be measured against practical experiences of the oil industry, and a careful evaluation of the risks, costs and benefits is required. The literature reports many successful MEOR field trials (> Fig. 1), yet there is a high degree of scepticism in the industry as to the validity of some of the claims in the literature. To a large degree, this scepticism is caused by the lack of detailed accounts of the published case studies. In addition, conditions may vary greatly from reservoir to reservoir. There have been suggestions of reservoir-specific customization of MEOR processes, but this has the potential to undermine the economic viability of MEOR. Although the outcomes of MEOR are more difficult to predict than those of some of the conventional EOR methods (e.g., thermal EOR, gas injection or chemical EOR using surfactants or polymers), the economic potential of MEOR could be huge considering that logistical costs of implementation may only approach the costs of conventional water flooding, especially for microbial stimulations using residual oil as the carbon source (Bryant and Lockhart, 2002). Moreover, unlike conventional EOR methods, the MEOR approach targets more than one process simultaneously (> Table 1), including (1) viscosity reduction and density modification by solvents, gases and acids, (2) removal of paraffin wax by solvents and acids to enhance permeability, (3) removal of trace metal rims from pore throats by acids, solvents, alcohols and bio-surfactants to increase permeability, and (4) oil-water and oil-rock interfacial tension reduction by bio-surfactants, solvents and acids to improve oil flow. This chapter provides a brief history of MEOR field trials, presents results from selected field applications of MEOR from the literature, and discusses the role of MEOR in the overall EOR portfolio. Special attention is given to the economics, potential contributions and challenges of MEOR.

3 3 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery Figure 1 Worldwide MEOR implementation. Dots sizes are meant to approximate number of field applications.. Table 1 Types of microbial processes for oil recovery (modified after Mokhatab and Giangiacomo, 2006) Process Production problem Type of activity or product needed Production well stimulation to improve oil drainage into wellbores Injection well stimulation to improve water injection rates Injection well profile modification to improve injection efficiency and reduce high water production due to permeability variations Increase oil recovery to unlock oil bound by water/rock Reduce oil viscosity to allow oil to flow with less energy input Improve mobility ratio and sweep efficiency to allow more efficient displacement of oil by water Sweeten produced fluids (reduce hydrogen sulfide) Emulsion and paraffin, asphaltene and scale deposits Build-up of residual oil; scale deposits Water channelling into flushed high permeability zones; bypassing lower permeability oil-bearing zones High surface tension between oil and water; oil wet rock Slow flow rates Thickened water issue Corrosion; iron sulfide scale; safety concerns Demulsifiers, biosurfactants, solvents, acids, hydrocarbon degradation Biosurfactants, solvents, acids, hydrocarbon degradation Biomass and polymers Solvents and biosurfactants Solvents, gases, biocracking Biopolymers Stimulate deniftrifying bacteria population

4 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery 2 History of MEOR Field Trials Pioneering MEOR field studies were carried out in the USA in the 1930s and 1940s by Claude ZoBell with the group at the Scripps Institute of Oceanography in La Jolla, California (e.g., ZoBell, 1946). A thorough review of early case studies is given in by Premuzic and Woodhead (1993) who outlined details and references for hundreds of field trials. In the 1960s and 1970s, many Eastern European countries such as Czechoslovakia, Hungary, and Poland carried out field MEOR trials, which were based on the injection of mixed anaerobic or facultative anaerobic bacteria selected on their ability to generate high quantities of gases, acids, solvents, polymers, surfactants, and cell-biomass (Lazar et al., 2007). From the mid- 1980s to the mid 1990s there were many studies and field applications of MEOR, and a plethora of independent companies utilized various proprietary mixes of microbes and nutrients for wellbore injection. MEOR was demonstrated to work in the majority of reported cases, but it has also been shown to be ineffective in some other cases. Van Hamme et al. (2003) estimated that more than 400 MEOR field tests had been conducted in the USA alone, most of which were as single-well stimulation treatments on low-productivity wells onshore. Low oil prices in the late 1990s led to diminishing research in MEOR, especially for largescale field studies designed to rigorously test performance. Several extensive trials of MEOR in Chinese oilfields (e.g., Daqing, Jilin, Xinjiang, Liaohe, Shengli and Dagang) were reported by Song et al. (2004). For example, application of Pseudomonas aeuginosa and its metabolic products in the Daqing oilfield is reported to have enhanced oil recovery by 11% by Li et al. (2002). Higher oil prices, more stringent environmental regulations for oil production and advances in biotechnology have now spurred renewed interest in MEOR, and the application of biotechnology in the oil industry has great potential, although it is still regarded as a frontier endeavor (Kotlar et al., 2004). 3 Examples of MEOR Field Application Although hundreds of MEOR field trails have been carried out world-wide, reliable data are sparse, as most of the applications are for single well stimulations for low productivity wells using unpublished proprietary mixtures of microbes and nutrients. The examples presented here were chosen to represent a variety of MEOR processes for addressing various reservoir engineering problems (> Table 2). The full spectrum of MEOR processes are covered, ranging from biodegradation, viscosity and interfacial tension (IFT) reduction to bio-plugging using a variety of implementation mechanisms including single production well stimulation ( huffand-puff ), single well water injection and multi-well injection and production. 3.1 Bebee Field, Oklahoma, USA In a study supported by the US Department of Energy, Youssef et al. (2007) tested whether two halotolerant bacillus strains (RS-1 and Bacillus subtilis subsp. spizizenii strain NRRL B-23049) both of which produce lipopeptide biosurfactants, can metabolize and produce biosurfactants in the Bebee Field (Pontotoc County, Oklahoma) in sufficient quantity to stimulate MEOR. They applied huff-puff tests on five production wells that produce from the Ordovician Viola Limestone. Two wells received inoculums of the Bacillus strains and nutrients comprising

5 3 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery Table 2 Selected MEOR Field application examples Country Field Description Argentina La Ventana, Viscosity and IFT reduction Tupungato-Refugio Australia Alton Single well stimulation; gas production; Interfacial tension (IFT) reduction China Daqing, Dagang, Jilin (Fuyu), Xinjiang, Liaohe Hydrocarbon degradation In situ stimulation, de-waxing, degradation, emulsion, IFT reduction, gas generation Single well stimulation (huff-and-puff) and microbial injection; selective plugging of highly permeable zones Viscosity and IFT reduction Microbial injection; hydrocarbon degradation India Four fields by ONGC Single well stimulation, water cut reduction Indonesia Ledok (offshore) Single well stimulation using indigenous microbes Malaysia Bokor (offshore) Single well stimulation; profile control, demulsification and plugging Peru Talara (offshore) Multi-well injection; bio-cracking UK Beatrice, North Sea Elimination of H 2 S USA Alaska, North Slope N Springfield, Indiana Oklahoma, Utah, Various mature fields in Texas Water cut reduction Single well stimulation; production profile control Water injection; plugging highly permeable zones Single well stimulation; solvent production and de-waxing Single well stimulation (huff-and-puff), viscosity and IFT reduction Venezuela Lake Maracaibo Multi-well injection and production, degradation and IFT and viscosity reduction glucose, sodium nitrate and trace metals. Two wells received only nutrients, whereas one received only formation water in order to provide a base case control. The experimental conditions and procedures are thoroughly described in Youssef et al. (2007), including baselines for the abundance of microbial metabolites prior to field testing. Particular attention was paid to the 3-hydroxy fatty acid composition of lipopeptides described in Youssef et al. (2005), who concluded that the average concentration of lipopeptide biosurfactant in the produced fluids of the inoculated wells was approximately nine times greater than the minimum concentration required to mobilize tertiary oil from a low-permeability Berea sandstone core. Some by-products such as carbon dioxide, acetate, lactate, ethanol, and 2,3-butanediol were also detected in the inoculated wells. In contrast, only carbon dioxide (CO 2 ) and ethanol were detected in the nutrients-only control wells, with no elevated concentrations of lipopeptide biosurfactant. Youssef et al. (2007) also presented microbiological and molecular data that showed recovery of the microorganisms injected into the formation, in the produced fluids of the inoculated wells. This indicates that exogenous microorganisms can be metabolically active in the presence of diverse, established populations of microorganisms that inhabited the

6 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery reservoir before the field trial, and thus demonstrates that biosurfactant-mediated oil recovery with a specific and selected microorganism is technically feasible. The volume of the soaked reservoir was small, and no significant increase in oil production was expected nor observed. Youssef et al. (2007) concluded that this process would be economical at oil prices >$65. More definitive results, from which cost-effectiveness of this approach could be obtained, will require up-scaling of injections and trials on different reservoir fluid combinations. 3.2 Dagang Oilfield, China MEOR has been applied in the Dagang Oilfield for over 10 years (Feng et al., 2006). The field trials were conducted in four reservoir intervals in two blocks with 24 injection wells and 55 production wells. Both in situ stimulation of indigenous microbial species and injection of exogenous microbial were employed. Feng et al. (2006) reported that the in situ stimulation of indigenous microbes at 60 C appeared to be more effective than injection of exogenous cultured microbes extracted from the formation fluids. A cumulative incremental oil production of 31,000 tons and 28,000 tons were achieved, respectively during the two microbial treatments. The in situ stimulation had reduced average water cut by 55%. The major MEOR processes involved were biosurfactant production, emulsion and gas generation. Nazina et al. (2007) studied the physicochemical conditions and microbiological characteristics of formation waters of the Kongdian reservoir of the Dagang Oilfield. Aerobic bacteria were detected mainly near the bottom of the injection wells, and these aerobic thermophilic bacteria were capable of oxidizing oil, with the formation of biomass and oxygenates such as volatile carboxylic acids and biosurfactants. They found that the reservoir is inhabited by microorganisms having great biotechnological potential. 3.3 Jilin Oilfield, China In collaboration with the Jilin Oilfield Company, the Japan Technology Research Centre (TRC) conducted a field trial in the Fuyu Oilfield (Nagases et al., 2002). The reservoir has been produced through water flooding for more than 20 years with water-cut reaching 80 90% before the MEOR trial. The microbial strain, TRC-322, Enterobacter together with other microbes that produce CO 2, acid and soluble polymers, were initially applied to the production wells. Microbes and nutrients were continuously injected in injector wells after a huff-and-puff test. Approximately 60% of the huff-and-puff test wells showed a reduction in water cut, but the effectiveness was limited. A different Enterobacter, CJF-002, which produces insoluble polymers, was injected into the oilfield using a huff-and-puff procedure at production wells and a microbial treatment at injection wells. Water cuts in the production wells were dramatically reduced shortly after microbial treatment at the injection wells. Oil production in the test area increased by more than 100% during the seven month field trial, and the effect of plugging high permeable zones with bio-polymer lasted for over half a year. During these treatments, in situ growth of the microbes and metabolic activities were monitored and evaluated to identify and understand mechanisms of the microbial process. The study concluded that microbe screening and adjusting to particular environments based on laboratory investigations are keys to the successful field applications of MEOR.

7 3 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery Daqing Oilfields, China The Daqing Oilfield in the Songliao Basin is the biggest oilfield in China and has produced oil since However, rapidly decreasing production rates have spawned many EOR field trials including MEOR. Nazina et al. (2003) claimed that the oilfield is inhabited by aerobic saprotrophic (including hydrocarbon-oxidizing) bacteria that are able to produce oil-releasing metabolites (e.g., surfactants and exopolysaccharides) during growth on a wide range of substrates including hydrocarbons, lower alcohols, volatile fatty acids, and sugars. Zhang et al. (1999) reported incremental MEOR in 17 of the 25 treated wells, with a cumulative incremental production of over 3,000 tons. It was also suggested that an increasing number of live microbes in the produced waters show the potential to change the course of MEOR. However, there are some concerns about microbial viability after injection in the field. The concentration of live microbes before and after MEOR for five treatments on 4 wells using 5-tube dilution for the Most Probable Number (MPN) method were studied, indicating a 1,000 fold increase in the abundance of microbes compared with the background concentration during MEOR stimulations. Zhang et al. (1999) reported that the main MEOR process occurring in the Daqing Oilfields is degradation of long-chain alkanes and reduction of viscosity. 3.5 Beatrice Oilfield, North Sea The Beatrice Oilfield is located in the in the UK sector of the North Sea. The Titan Process (previously termed BOS for Biological Oil Stimulation ) was applied to the field in early In total, eleven cycles of treatment were preformed over a three and a half year period. The field was on a well-established decline rate and was scheduled for abandonment in The field continues to produce to Some overlapping changes in production were implemented, which have complicated evaluation of MEOR such that quantifying its success is difficult; in addition, information on details on MEOR other than microbiology is scarce. The Titan website ( has considered the trial to be successful, with a 10% increase in oil production coupled with elimination of hydrogen sulphide (H 2 S) for two wells treated using single well stimulation procedures. 3.6 Talara Offshore Oilfields, Northwest Peru Maure et al. (2005) reported an MEOR field application on seven producing wells in the Providencia and Lobitos fields of Block Z-2 in the Talara Basin, Northwest Peru. The oils are predominantly paraffinic and therefore were targeted as promising candidates for biotreatment. This MEOR application suggests that biocracking can lead to systematically altered n-alkane profiles of the oils. Maure et al. (2005) presented information on applying enzyme biochemistry to accelerate redox reactions involving linear hydrocarbons, without providing biochemical detail. They claimed that by alternating aerobic/facultative hemicycles with strictly anaerobic cycles, the time-coordinated action of selected groups of microorganisms in oxidant and reductive environments results in substantial changes in oil composition.

8 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery. Figure 2 Types of non-thermal EOR methods currently used by the petroleum industry. They also emphasized the importance of evaluating propensities of oils to act as carbon sources for nourishing microbial communities. 4 The Role of MEOR in the EOR Portfolio 4.1 Current Trends and Future Projection At present, MEOR only forms a minute component of the overall EOR portfolio (Thomas, 2008) which also includes (1) thermal processes, (2) gas injection (both miscible and immiscible), (3) chemical flooding such as polymer, surfactant, alkaline, or a combination (e.g., alkaline-surfactant-polymer/asp, emulsion and micellar treatment) and (4) foam flooding (> Fig. 2). As an emerging alternative method, MEOR is currently largely confined to laboratory investigations and small-scale field applications, although single well stimulations and borehole clean-ups have been carried out widely in the petroleum industry, in particular for onshore US and Chinese wells. Khire and Khan (1994a, b) reported that MEOR has been applied to over 400 wells in the US. Over 1,000 wells in a dozen oilfields in China (Chinese Ministry of Land and Resources; were also treated. Most major oil companies, including Shell, BP, Chevron, PetroChina, PETROBRAS and PETRONAS are currently including MEOR as an option in their overall EOR portfolio. Much of the nearly 2,000 billion barrels of conventional oil and about 5,000 billion barrels of heavy oil that have remained in reservoirs worldwide after conventional recovery, may be recovered by EOR, including MEOR (Thomas, 2008). The estimated worldwide EOR production in 2007 was about 2.5 million barrels per day (Thomas, 2008), of which MEOR accounted

9 3 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery Figure 3 Estimated world-wide EOR production barrels per day in 2006 with a total EOR production of 2.5 MMBL/D (modified from Thomas, 2008). for a negligible amount. However, a recent study by the Chinese Ministry of Land and Resources ( indicates that about 50 billion barrels of oil in onshore Chinese oilfields may be suitable for MEOR. Currently the most EOR is carried out in USA, Mexico, Venezuela, Canada, Indonesia and China (> Fig. 3), and these countries account for at least 99% of the world s EOR production. Among the EOR portfolio, thermal EOR accounts for the highest percentage (> Fig. 4), followed by gas injection and chemical flooding, which is primarily used in some Chinese oil fields amounting for 200,000 barrels per day in 2006 (Thomas, 2008). 4.2 Economics While EOR allows the production of residual oil in place that otherwise could not be recovered, and can help maintain production rates in mature fields, the main issues of conventional methods are cost-effectiveness and environment impact. EOR (tertiary recovery) is much more costly than primary and secondary recovery. In the 1990s, when the oil price was about US$ 20 per barrel (> Fig. 5), the cost for various EOR processes varied from $10 per barrel to over $50 per barrel (> Fig. 6; Lake et al., 1992). Among the EOR methods, surfactant flooding is by far the most expensive ($20-$52 per incremental barrel in 1990), although it is the most effective, attaining recoveries of up to 75% of original oil in place (OOIP; > Fig. 6). CO 2 injection can also be expensive, depending on the CO 2 availability and locations of

10 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery. Figure 4 US EOR application by type (modified after Thomas, 2008).. Figure 5 World crude oil price from (source from US Department of Energy). injection. Thermal EOR also can be costly and extremely energy intensive; it requires costly surface facilities and incremental production increases costed $10-$25 per barrel in 1990 (> Fig. 6). Polymer flooding is one of the more cost effective options among conventional EOR methods. Apart from the high cost of conventional EOR methods, environmental impact should also be considered in economic terms. For example, chemical flooding such as ASP can cause

11 3 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery Figure 6 Comparison of the cost of MEOR with other EOR techniques (modified from Lake et al., 1992). extensive scaling on drill pipes and damages to the production facility, which are often irreversible (Cao et al., 2007). Chemical flooding may also contaminate formation waters as well as surface environments. Thermal EOR is extremely energy intensive and can lead to considerable greenhouse gas emissions, which may have significant economic ramifications, especially in countries engaging in carbon trading schemes. MEOR may offer a viable EOR alternative both in terms of costs and environmental considerations. Giangiacomo (1997) evaluated the economics of conventional chemical and microbial treatments for paraffin based on an oil price of US$ 15/bbl. He showed that the ratio of the benefit to cost was approximately 1.03 for chemical flooding, but 1.48 for microbial treatment for every EOR dollar. The adoption of indigenous microbial flooding is likely to be the most economically viable MEOR method, because it does not require facilities for culturing microbes. However, identification of extant microbial biomes and selection of appropriate nutrients and injection techniques to stimulate microbes are critical for these techniques. In the selected field application examples mentioned above and listed in > Table 2, increases for recovery in most cases were reported to be from 6 8% (Dagang Field, China; Feng et al., 2006) to 66% (La Ventana Field, Argentina; Maure et al., 2001) and in some cases over 100% (e.g., Fuyu Field, China; Nagases et al., 2002). In addition to the increased oil production, decreased water production, increased gas to oil ratios and improved injectivity applied for some cases. In some onshore US oil fields a single-well stimulation treatment could double the production rate for most wells and this could be sustained for 2 6 months without additional treatments (Khire and Khan, 1994a, b). For a recent application in Peru, the MEOR cost per barrel ranged from $1.30 to $7.92 (Maure et al., 2005). The investment:return ratio for MEOR has been up to 1:9 at an oil price of US$40 per bbl for field trials in the Daqing, Dagang and Shengli oilfields (Chinese Ministry of Land and Resources, With the post-2007 high oil prices (> Fig. 5), the potential return on investment from MEOR is much more attractive.

12 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery Microbial activity can also be used for treating oil spills in onshore and marine environments around drilling rigs and have been routinely used in borehole cleaning and bioremediation. Some microbes are able to repair reservoir formations damaged by conventional EOR (e.g., polymer injection) processes (Feng et al., 2006). 4.3 Challenges and Potential Despite numerous MEOR tests, considerable uncertainty remains, in particular regarding process performance. The major risk of MEOR at present is its reliability and reproducibility. While most reported cases indicate improvement in oil recovery, there are some cases where MEOR was reported to be ineffective. The biggest challenge in MEOR field application is in increasing its robustness with predictable outcomes. Unlike other EOR methods, MEOR is may be limited by environment specific factors of the reservoirs such as the reservoir type, reservoir temperature, formation water salinity and prevailing indigenous microbial communities. The most serious challenge, however, is in ascertaining if the formation of microbial metabolite and biomass is sufficient to cause EOR effects in reasonable time frames. Although at present, MEOR is still perceived by the majority of oil producers as a low cost but unreliable EOR strategy, it has huge potential in offering an environmentally low impact, cost effective and energy efficient approach in the future. 5 Research Needs To enable a technically robust MEOR application with predictable outcomes, the areas that require further investigation are, 1. Identification and development of microbial strains that can thrive in the hostile environments of petroleum reservoirs (e.g., at elevated temperatures or high salinities or both), 2. Determining the rates of biochemical processes to ensure sufficient production of microbial biomass and metabolites, 3. Establishment of common baselines prior to successful MEOR strategies, 4. Development of rapid and innovative microbial screening methods, including sequencing and gene mapping techniques, leading to a gene collection database, and 5. Development of more advanced and robust MEOR simulation and prediction models by combining laboratory experiments, field trials and numerical models. MEOR will therefore provide a rich field for fundamental and applied research for many years to come. References Bryant SL, Lockhart TP (2002) Reservoir engineering analysis of microbial enhanced oil recovery. SPE Reservoir Eval Eng 5: Cao G, Liu H, Shi G, Wang G, Xiu Z, Ren H, Zhang Y (2007) Technical breakthrough in PCPs scaling issue of the ASP flooding in Daqing Oilfield. Society of Petroleum Engineers, Paper Feng Q, Ni F, Qin B, Ma X, Ji C, Wang X (2006) Review of MEOR technology application in Dagang oilfield for

13 3 Oil Recovery: Experiences and Economics of Microbially Enhanced Oil Recovery the last decade. Society of Petroleum Engineers, Paper Giangiacomo L (1997) Chemical and Microbial Paraffin Control Project. Rocky Mountain Oilfield Testing Centre, 17 Dec 1997, Open File Report FC9544/ 96PT12. Khire JM, Khan MI (1994a) Microbially enhanced oilrecovery (MEOR). Part 1: importance and mechanism of MEOR. Enzyme Microb Technol 16: Khire JM, Khan MI (1994b) Microbially enhanced oilrecovery (MEOR). Part 2: microbes and the subsurface environment for MEOR. Enzyme Microb Technol 16: Kotlar HK, Brakstad OG, Markussen S, Winnberg A (2004) Use of petroleum biotechnology throughout the value chain of an oil company: an integrated approach. Stud Surf Sci Catal 151: Lake LW, Schmidt RL, Venuto PB (1992) A niche for enhanced oil recovery in the 1990s. Schlumberger Oilfield Review, January, p Lazar I, Petrisor IG, Yen TE, (2007) Microbial enhanced oil recovery (MEOR). Stud Surf Sci Catal 25: Li Q, Kang C, Wang H, Liu C, Zhang C (2002) Application of microbial enhanced oil recovery technique to Daqing Oilfield. Biochem Eng J 11: Maure A, Dietrich F, Gómez U, Vallesi J, Irusta M (2001) Waterflooding optimization using biotechnology: 2-year field test, La Ventana Field, Argentina. Society of Petroleum Engineers, Paper Presented at the SPE Latin American and Caribbean Petroleum Engineering Conference, Buenos Aires, Argentina, March Maure A, Saldaña AA, Juarez AR (2005) Biotechnology application to EOR in Talara off-shore oil fields, North West Peru. Society of Petroleum Engineers, Paper 94934, Nagases K, Zhang ST, Asami H, Fujiwara K, Enomoto H, Hong CX, Liang CX (2002). A successful field test of microbial EOR process in Fuyu Oilfield, China. Society of Petroleum Engineers, Paper Presented at the SPE/DOE Improved Oil Recovery Symposium, Tulsa OK, USA, Apr Nazina TN, Grigor yan AA, Shestakova NM, Babich TL, Ivoilov VS, Feng Q, Ni F, Wang J, She Y, Xiang T, Luo Z, Belyaev SS, Ivanov MV (2007) Microbiological investigations of high-temperature horizons of the kongdian petroleum reservoir in connection with field trial of a biotechnology for enhancement of oil recovery. Microbiology 76: Premuzic E, Woodhead A (1993) Microbial enhancement of oil recovery-recent advances. In Proceedings of the 1992 Conference on Microbial Enhanced Oil Recovery, Elsevier, Amsterdam. Song S, Zhang Z, Li S (2004) Progress of microbial enhanced oil recovery in laboratory investigation. Petrol Sci 1 (4): Thomas S (2008) Enhanced oil recovery: an overview. Oil Gas Sci Technol Rev IFP 63: Van Hamme JD, Singh A, Ward OP (2003) Recent advances in petroleum microbiology. Microbiol Mol Biol Rev 67: Youssef NH, Duncan KE, McInerney MJ (2005) Importance of 3-hydroxy fatty acid composition of lipopeptides for biosurfactant activity. Appl Environ Microbiol 71: Youssef N, Simpson DR, Duncan KE, McInerney MJ, Folmsbee M, Fincher T, Knapp RM (2007) In situ biosurfactant production by Bacillus strains injected into a limestone petroleum reservoir. Appl Environ Microbiol 73: Zhang Y, Xu Z, Ji P, Hou W (1999) Microbial EOR Laboratory studies and application results in Daqing Oilfield. In Proceedings of the 1999 SPE Asia Pacific Oil and Gas Conference and Exhibition, Jakarta, Indonesia, April , pages 1 8. Society of Petroleum Engineers, Paper ZoBell C (1946) Bacteriological process for treatment of fluid-bearing earth formations, US Patent No

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