Technology Update: New Microbial Method Shows Promise in EOR

Abstract

Technology Update Tertiary oil recovery technologies can extend the economic life of maturing waterflooded reservoirs. This article describes the results from a biologically based enhanced oil recovery (EOR) technology that has improved waterflood efficiency by increasing oil production and decreasing the decline rates, thereby significantly increasing the recovery factor. Traditional tertiary recovery processes such as thermal methods, CO2 flooding, and chemical flooding require significant changes to field infrastructure and usually involve relatively high operating expenditures of up to USD 50 per incremental barrel of oil produced. Called Activated Environment for the Recovery of Oil (AERO), the technology used in this project represents a breakthrough in biologically based EOR by using a continuous injection of inorganic nutrients to stimulate indigenous microbes. The use of continuous injection (water and nutrients), which differentiates AERO from most previously attempted microbial EOR methods, prevents production disruptions and makes it easier to accurately measure, assess, and document the production benefits. The key advantages of this method are Decreased decline rates, enabling significant reserve gains Increased oil production Low capital expenditures Low operating costs Rapid response Biological EOR uses inorganic nutrients to activate indigenous microbes, those native to the field. Because no organic carbon is introduced, the microbial growth is restricted to the interface between the injection water and the oil, the carbon source for growing the microbes. The use of indigenous microbes is advantageous because they are perfectly suited to the local conditions and, unlike externally originated organisms, are neither costly to produce nor prone to rapid death in the reservoir and are thus in need of replacement. In addition, the concentrations of the nutrients required are relatively low, a major reason for the feasibility of continuous injection and stimulation. The technology is among the most inexpensive tertiary recovery methods available and requires only minimal changes to waterflood facilities for deployment. It can likewise be used with relatively minor modifications in fields without an operating waterflood, such as fields with a natural waterdrive or very mature fields where waterflooding has ceased. The biological EOR technology is producing a growing body of positive results, such as the following example from Canada.

Screening of Microorganisms With Oil-Diluting and Oil-Displacing Properties

“…The field was discovered in 1980, development began on September 1, 1992, and is currently in the late development stage. The depth of the productive horizons is 660-682 m, the initial reservoir pressure is 6.2 -12.8 MPa, the temperature is 40-48 0 C, the oil density is 842-905 kg / m3, the oils are low-sulfur (0.15-0.28%), lowparaffin -0.88% [12].…”

Microbial Biotechnology 2020; microbiology of fossil fuel resources

“…Nevertheless, despite issues of variability in production with time, evidence was provided for an increase in oil production for a sustained period, above the predicted production decline curve, leading to around a 2.5‐fold incremental increase in production (e.g. Havemann et al ., ). While the technology is proprietary, its basis is reported to be inorganic‐nutrient stimulated oil biodegradation by organisms indigenous to the reservoir.…”

“…While the technology is proprietary, its basis is reported to be inorganic‐nutrient stimulated oil biodegradation by organisms indigenous to the reservoir. An important part of the process is initial testing to demonstrate that the native microflora have the capacity to degrade a proportion of the oil under the conditions of the MEOR treatment (Havemann et al ., ). The precise basis for this MEOR technology has not been revealed, but the inference from the published results from these field trials suggests that it relies on a much more precise understanding of the response of the indigenous microbial communities to amendment with the inorganic nutrients used in the process than has been the case in previously deployed MEOR strategies.…”

“…(Rassenfoss, ). A proprietary MEOR system has been tested at field scale in Southwest Kansas, an Albertan oilfield and a Californian oilfield by a partnership of energy companies and a technology company developing MEOR technologies (Bauer et al ., ; Havemann et al ., ; Karicherla et al ., ). The results have been promising, but not completely predictable and in the Kansas field the enhanced production was primarily limited to a single well.…”