Microbially Enhanced Oil Recovery: Past, Present, and Future

This chapter assesses the technical feasibility of microbial enhanced oil recovery (EOR) and improved oil production (IOP) processes by analyzing laboratory and field data to determine if microbial products or processes meet appropriate engineering design criteria. Although microbial products and activities are discussed independently, it is likely that microbial processes act synergistically to effect oil recovery. Microbially enhanced oil recovery (MEOR) processes can be grouped into four main categories, depending on the type of production problem and whether the process is localized to the well bore or is reservoir wide. They are well bore cleanup processes, well stimulation technologies, microbially enhanced waterflooding processes, fermentative microbially enhanced waterflooding processes, permeability profile modification or selective plugging, biosurfactant-enhanced waterflooding. Most of the microbial field trials can be classified as well bore cleanout or well stimulations where the purpose of the treatment is to increase the production of oil from an individual well. A number of factors are critical in the assessment of microbial treatments, including reaction rate kinetics, adsorption losses, flow rates, nutrient concentrations, source of nutrients, and finally whether the microbes are exogenous or indigenous. The risk for implementing MEOR is low in marginal fields, since the fields are close to the end of their economic life. The data needed to assess performance, e.g., oil production rates and operating costs, are relatively easy to obtain.