MEOR — Microbial Enhanced Oil Recovery
The MEOR process developed and tested by MicroPro GmbH over a period of 20 years is a highly effective tertiary oil production process on a microbiological basis. This technology by reduction of water-cut leads to a revitalization of oil production in depleting reservoirs. It enables an enhanced production of oil through the injection of molasses and trillions of selected and adapted bacteria. The injected microorganisms grow on molasses, proliferate and synthesize various products (gases, acids, alcohols, surfactants) deep inside the reservoir.
For case-specific treatments at high temperature and salinity MicroPro GmbH provides a comprehensive culture collection of MEOR-bacteria.
The MEOR process includes a number oft production enhancing effects:
- Bacterial gases increase reservoir pressure up to 20 bar and lead to a higher energy potential deep in the oil field
- Organic acids build up new flow channels for oil by dissolving carbonate rock
- Biolipids increase wettability and break up oil/water barriers
Due to the above processes fresh sections of the matrix which are not quite drained will be pulled into the oil extraction and increased pressure and permeability and therefore push significant amounts of trapped normally unrecoverable oil toward the production well. Per ton of molasses injected into the reservoir ~ 50 bbl MEOR-oil can be produced. Hence, on top of a water-flooding treatment an additional production of 10 – 15% of the Original Oil in Place (OOIP) has been recorded.
MEOR results are:
- Reduction of water-cut by 15 – 30 %
- Increasing production rate of stimulated producers by up to 50 %
- Enhanced oil production by up to 150 %
The costs for treatment amount, according to case-specific complexity, to a few USD per bbl additional oil.
Technology
MEOR – Technology
For MEOR treatment of oil reservoirs previously selected bacteria are bred in fermenters on site and injected into the underground formation together with a molasses media. MEOR can be applied as a cyclic (“huff and puff”) or as a continuous flooding process. Together with injection water selected microorganisms are injected deep into the reservoir, where they multiply and ferment the introduced nutrients (molasses).
Deep inside the reservoir trillions of microorganisms generate a number of production increasing substances, which lead to reduction of water cut and a significantly increased crude oil production rate.
Bacterial products and their impact on oil production:
Bacterial gases
| Microbial products | effects | Oil field parameters |
| CO2 (80 %), H2 (20 %) up to 380 mL per gram oft molasses | Increase of pressure up to 20 bar in model experience | Increase of energy potential in the oil field |
| CH4 as final product from organic acids, alcohol’s and hydrogen | Increase of oil volume factor and therefore decrease of oil viscosity | Increase of oil mobilization |
| Change of pressure potential in fissures and pores | Increase of oil production rate |
Organic acids
| Microbial products | effects | Oil field parameters |
| Essig‑, Propion‑, Butter- und Valerian-Säure | Decrease of pH down to 4.8 | Increase of rock permeability |
| Dissolving of carbonatic rock by ~0.2 ton per ton molasses | Extension of oil production to fresh not yet drained rock | |
| Build up of new flow channels |
Alcohols, biolipids
| Microbial products | effects | Oil field parameters |
| Methanol, ethanol, propanol, butanol | Decrease of inter-factional tension (for example against heptane down to 12 — 46,5 mNm-1) | Force imbibition of injected, fermented molasses media into pore canals and fissures to give more oil from the rock |
| biolipids | Alteration of rock wettability | Break up of oil/water barriers and creating emulsions, Improve of flow rate |
Effects of the MEOR-technology have been proven in numerous studies and applications:
- Increase of energy potential inside the reservoir
- Improvement of pressure potential in fissures and pores
- Decrease of oil viscosity
- Reduction of oil/water surface tension
- Improvement of capillary adsorption of liquids
- Increase of permeability by rock dissolution
In numerous tests and field application the oil production could be enhanced by more than 100 %.
Minimizing the risks
For a successful application of the MEOR technology we strongly recommend field-specific preliminary investigations. This involves the evaluation of reservoir parameters and analysis of formation waters. More detailed preparations are carried only in case the reservoir is in principle suited for MEOR treatment.
A simulation of the MEOR process in model experiments on basis of original samples enables a reliable prognosis of anticipated oil extraction rate and enhanced oil production. This reduces the economic risk level significantly before a field application.
A pilot test on a representative section of the reservoir with injection and production wells can provide us with concrete information about profitability of the MEOR process within a short period of time.
MEOR – Step by step
Review of existing reservoir data
Evaluation of geologic and geophysical data
- Evaluation of geologic and geophysical data
- Reservoir rock type, structure, thickness, porosity, permeability
- Oil/water saturation
- Mineral facies/ chemical composition
- Fluid and gas characteristics
- Chemical composition of oil, gas, water
- Oil viscosity, density under reservoir conditions
- Gas- oil; gas-water ratio, water cut
- Deposit evaluation
- OOIP — prognosis of deposit and single wells of interest, decline rate
- Oil field configuration
- Number and positions of production and injection wells
- Injection rates
Chemical and microbiological investigations
- Existing bacterial population in oil field system:
- Chemical composition of reservoir water
- Specification of adaptation program of MEOR bacteria to specific field conditions
Customization of MEOR to specific field conditions
- Characterization and selection of MEOR microbes
- Adaption of selected microbes to field conditions
- Optimization of nutrient media
- Analysis of bio-products with original sample material
- Process engineering — scale up
Economic and technical evaluation of MEOR under simulated field conditions
- Core flooding tests under reservoir conditions to simulate the MEOR drainage
MILESTONE: Decision about application of MEOR process
Design and construction of MEOR station
MEOR treatment with continues process control
Case studies
MEOR – Case studies
Basically the MEOR process is applicable at all reservoir types, if the physical and chemical conditions for bacterial growth are met.
The MEOR process is particularly suitable for carbonate deposits, representing ~ 50 % of oil reservoirs worldwide. Here some EOR-technologies, usually applied in sands (e.g. polymer‑, surfactant- and alkaline-flooding) show low efficiency because of chemical reactions. The particular advantages of the MEOR technology with molasses in carbonate formations are:
- Injected bacteria spread wider and more quickly through fissures, fractures and pure canals
- Reactions of generated bio-products take place deep inside the reservoir
- Plugging of oil bearing strata by filtration, adsorption and on-growth of bacteria is minimized
- Carbonates neutralize generated organic acids, which intensifies the formation of microbial products
- New, not yet drained sections of reservoir rock are included in recovery as a result of microbial rock solution
The following case studies illustrate the diverse and positive effects of MEOR treatment.
MEOR — Publications
- Wagner, M., et.al. (1995) Development and Application of a New Biotechnology of Molasses in-situ Method — Detailed Evaluation for Selected Wells in Romaschkino Carbonate Reservoir
5th MEOR Conference, Dallas, Texas 9 - Wagner, M. et.al.: Verfahren und Anlage zur Herstellung von Impfgut für eine verbesserte Erdölförderung
P 4307334, 24.04.1995 - Wagner, M. (1994) Microbial Improved Oil Recovery
Oil and Gas Technology, 3 - Muslimov, R. et.al. Wagner, M. (1993) Microbial Improved Oil Recovery in Carbonate Reservoirs — Preparation of a Pilot Project in the Oil Field Romaschkino, Republic of Tartarstan
7th European IOR Symposium, Moskau - Wagner, M. et.al. (1993) Microbially Improved Oil Recovery from Carbonate Reservoirs
Proceedings International Biohydrometallurgy Symposium, Jackson Hole, Wyoming, USA - Wagner, M. et.al.: Verfahren zur Unterdrückung sulfatreduzierender Bakterien bei MIOR
DE 41 27 744 A1, 25.02.1993 - Wagner, M. (1991) Microbial Enhancement of Oil Recovery from Carbonate Reservoirs with Complex Formation Characteristics
Proceedings of the 1990 int. Conf. On Microbial Enhancement of Oil Recovery, Developments in Petroleum Science 31 Elsevier - Wagner, M. et.al.: Stimulierungs- und Intensivierungsverfahren zur Gewinnung von Kohlenwasserstoffen
DL PS 277 297, 28.03.1990 - Wagner, M. et.al.: Verfahren zur mikrobiellen Sekundärgewinnung von Erdölen
DL PS 2007 515, 08.06.1983