Summary
A microbial enhanced-oil-recovery (MEOR) process was successfully applied in
a mature waterflooded reservoir in Saskatchewan, Canada. A nutrient solution,
which was designed specifically for this reservoir to stimulate indigenous
microbes to grow, multiply, and help to release oil, was tested and piloted. A
significant decrease in water cut and increase in oil production have been
realized through the selective stimulation of bacteria using nutrient
injection.
The field is a mature waterflood averaging more than 95% water cut. To
combat the increasing water-cut issue, an in-situ microbial response analysis
(ISMRA) was performed on a typical high-water-cut producer in the area. The
test well was treated with a nutrient solution and then was shut in for a
number of days to allow indigenous microbes to grow and multiply. Upon return
to production, the well produced at an average of 200% more oil with a 10%
decrease in water cut for a year. Pretreatment rates averaged 1.2
m3/d of oil (8 BOPD) and post-ISMRA treatment daily production
peaked at 4.1 m3/d of oil (26 BOPD). The ISMRA provides a direct
support of laboratory studies and frequently increases oil production.
As a result of the successful ISMRA, a pilot project was initiated and the
nutrients were applied in three batch treatments on an injector with three
offset production wells. Three weeks after the first batch treatment, a
water-cut decrease was seen at one of the offset producers. This well's oil
production gradually increased from 1.4 to more than 8 m3/d (9 to 50
B/D). Oil production in another producer doubled from 1.5 to more than 3.0
m3/d (9 to 19 B/D). Subsequent treatments were tried on marginally
economic wells and on a reactivated idle producer. The average decrease in
water cut in these wells was more than 10%. On the idle well, oil production
increased from 0.5 m3/d (3 B/D) pretreatment to an average of 3.0
m3/d (19 B/D) post-treatment.
Throughout the world, there remains a huge target for enhanced-oil-recovery
(EOR) processes to target (Bryant 1991). This successful MEOR application will
have a tremendous impact on ultimate recovery in many of these reservoirs not
only through an increase in production, but a decrease in operating costs
through associated reduction in lifting costs with less water production.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
30 July 2009
- Meeting paper published:
5 October 2009
- Revised manuscript received:
22 January 2010
- Manuscript approved:
4 May 2010
- Published online:
11 October 2010
- Version of record:
27 October 2010
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