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MICROBIALLY ENHANCED HYDROCARBON RECOVERY (MEHR)
Program PIs: Terry Hazen, Bruce Fouke, John Coates
Lead Campus: UC Berkeley
MEHR techniques involve the introduction of microorganisms, nutrients, and oxygen into the reservoir to produce metabolic events that lead, by a variety of mechanisms, to enhanced oil recovery. Several challenges prohibit the routine, cost-effective, and large-scale implementation of MEHR. To overcome these challenges, it is imperative to 1) develop an understanding of native reservoir bacteria and their potential to enhance oil recovery, through alteration of crude oil molecular structure or associated flowpaths; 2) engineer microbial strains to promote traits that facilitate recovery; 3) predict microbial growth and reactivity within petroleum reservoirs with enough accuracy to guide MEOR treatments; 4) develop in situ procedures to implement MEOR effectively and over large spatial scales; and 5) monitor treatments and associated products in real-time and over field-relevant scales.
MEHR takes advantage of various microbial metabolisms to increase hydrocarbon and energy yield by improving oil flow and flood water sweep in a reservoir during tertiary recovery. MEHR strategies can be one or a mixture of processes which alter the
lithology of the reservoir matrix, the hydrological flow of the flood waters, the viscosity of the flood waters, the viscosity of the oil in place, the chemical (molecular) characteristics of the oil in place, or the in-situ pressure driving the oil out of place. These effects are based on the ability of microorganisms to:
(i) directly weather (biotransform) rock minerals altering porosity through oxidative and reductive reactions;
(ii) to metabolize various substrates into endproducts such as acids, alkalis, or ligands that indirectly weather rock;
(iii) to produce gases,biosurfactants, or polymeric substances, which alter the viscosity and fluid characteristics of the flood waters and oil in place improving sweep efficiency;
(iv) to form biomass which alters the permeability of the rock strata to floodwaters and improves sweep volume;
(v) to biotransform the hydrocarbon components of crude oil into lighter molecular structures making the oil more inviscid and improving its fluidicity.
An additional important aspect of MEHR is control of biosouring (the production of H2S) in-situ or in the produced fluids. Underscoring all of this is our assumed knowledge of the predictability of the microbial response in oil reservoir. Although much is known of these individual metabolisms under benign environmental conditions, there is little knowledge of the microbiology involved in the hypersaline and hyperthermal environments that are typical of most active oil fields and of the community effects or environmental parameters that control the activities of the relevant species.
This program is designed to understand all biological, environmental and geological aspects of oil resources, including microbial community structure, function, and distribution, linked to the physical and chemical nature of the sedimentary rock reservoir in which they are housed. From this basic information, it is hoped that predictive models of MEHR applicability to various environments can be developed, as well as novel technologies to enhance hydrocarbon recovery for fuels.
Teams will focus on ecogenomics, flow rates and mechanisms, reservoir geology and geochemistry, and monitoring and modeling. Among the program’s “natural subsurface laboratories” will be a demonstration injection well and two monitoring wells in Decatur, IL, which are being drilled as part of a research program on carbon sequestration being funded by the U.S. Department of Energy and the Midwest Geological Sequestration Consortium (MGSC) headed by the Illinois State Geological Survey (ISGS; http://www.sequestration.org). EBI researchers will study the genetic makeup of microbial communities found in the formation water and rock samples extracted from the wells, and then quantitatively link their metabolic activity and distribution to the environmental and geological conditions of the subsurface.
The EBI teams will analyze the environmental and geological conditions of shallower Paleozoic hydrocarbon reservoirs in addition to the deeper Cambrian CO2 sequestration saline reservoir target. This includes water and rock geochemistry and hydrocarbon composition and will chart the geologic thermal burial history of each sample. Then they will determine the genetic spread and profiles of the subsurface microbes, including bacterial and viral communities, under various physical and chemical conditions. Their results will be gathered into a model framework that future EBI research can use for MEHR microbial engineering, on-site biology manipulation, and treatment and monitoring strategies.
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February 2010 |
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