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The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that for low injectivity reservoirs, small thickness of the oil-bearing zone, and reservoir heterogeneity limits the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. We present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (radio and microwave frequency).We show the applicability of electromagnetic heating in two example reservoirs. The first reservoir model has thin sand zones separated by impermeable shale layers, and very viscous oil. We model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir model has very low permeability and moderately viscous oil. In this case we use a high frequency microwave antenna located near the producing well as the heat source. Simulation results presented in this paper show that in some cases, electromagnetic heating may be a good alternative to steam injection or maybe used in combination with steam to improve heavy oil production. We identify the parameters which are critical in electromagnetic heating. We also discuss past field applications of electromagnetic heating including technical challenges and limitations.

An in situ microbial filter technology is being tested and developed for remediating migrating subsurface plumes contaminated with low concentrations of trichloroethylene (TCE). The current focus is the establishment of a replenishable bioactive zone (catalytic filter) along expanding plume boundaries by the injection of a representative methanotrophic bacterium, Methylosinus trichosporium OB3b. This microbial filter strategy has been successfully demonstrated using emplaced, attached resting cells (no methane additions) in a 1.1 m flow-through test bed loaded with water-saturated sand. Two separate 24 h pulses of TCE (109 ppb and 85 ppb), one week apart, were pumped through the system at a flow velocity of 15 mm h" 1 ; no TCE ( < 0.5 ppb) was detected on the downstream side of the microbial filter. Subsequent excavation of the wet sand confirmed the existence of a TCE-bioactive zone 21 days after it had been created. An enhanced longevity of the cellular, soluble-form methane monooxygenase produced by this methanotroph is a result of the laboratory bioreactor culturing conditions. Additional experiments with cells in sealed vials and emplaced in the 1.1 m test bed yielded a high resting-cell finite TCE biotransformation capacity of about 0.25 mg per mg of bacteria; this is suitable for a planned sand-filled trench field demonstration at a Lawrence Livermore National Laboratory site.

A field test has demonstrated that an in situ biofilter using resting-state cells effectively remediated groundwater with about 425 ppb of trichloroethene (TCE) as the sole contaminant species. About 5.4 kg (dry weight equivalent) of a strain of methanotrophic bacteria (Methylosinus trichosporium OB3b) was suspended in 1800 L of groundwater (5.4 × 10 9 cells/ mL) and injected into an aquifer through a single well at a depth of 27 m, several meters below the water table. The injected groundwater was devoid of TCE and growth substrates but was amended with a phosphate solution (10 mM) to buffer the pH and phenol red (20 µm) to act as a tracer. Approximately 50% of the injected bacteria attached to the sediments, forming an in situ, fixed-bed bioreactor of unknown geometry. Contaminated groundwater was subsequently withdrawn through the biofilter region by extracting at 3.8 L/min for 30 h and then at 2.0 L/min for the remaining 39 days of the field experiment. TCE concentrations in the extracted groundwater decreased from 425 to less than 10 ppb during the first 50 h of withdrawal, which is equivalent to a 98% reduction. TCE concentration extracted through the biofilter gradually increased to background values at 40 days when the experiment was terminated.