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Enhanced Oil Recovery Institute of Wyoming documents, studies & presentations relating to the topic of engineering.


Ash Minnelusa Unit Conclusions

• Monitor, monitor, monitor. Make changes based upon reservoir response.
• Improved understanding of the problem improves process application and results
• Volumetric sweep (gels) should be applied before mobility control
• Implement gel processes early for maximum benefits
• Incremental oil expected to exceed 400,000 BBLS (18.4%%5 OOIP) for $0.88/BBL
• Field experience is critical with gel processes. Experience at Ash can be applied to other reservoirs

The purpose of this study was to report on the effectiveness of the Hyperscratcher tool in improving production or injection by cleaning out boreholes that have reported problems with scale, paraffin, or asphaltene build-up.

The Hyperscratcher tool was initially designed and used in California in the 1980s for workovers; as yet it has not been widely used in Wyoming.

Test results show use of the Hyperscratcher Tool significantly improved production in 7 of the 8 wells tested with production improvement varying from 20% to 120%.

Polymer-augmented waterflooding of the Minnelusa in Wyoming has proven to be a successful method for improving production in most cases compared to normal waterfloods. Polymer is a lowcost, low-risk option when considering a method for enhancing production of a particular field. Its primary function is to improve the mobility ratio of the injected water by increasing its viscosity, thereby improving the volumetric sweep and conformance within the reservoir.

Advantages of using polymer include: (1) low cost, (2) preventing early water breakthrough, (3) improving volumetric sweep and conformance, (4) increasing oilwater ratios, (5) mobilizing oil that would likely have been bypassed under normal waterflood conditions, (6) mitigating heterogeneous permeabilities within the reservoir, and (7) other enhanced oil recovery injection technologies can still be applied after the polymer flood. Most, but not all, Minnelusa fields examined exhibited improved recoveries using polymer compared to fields under conventional waterfloods. Uneconomical polymer floods can be caused by a variety of factors, chief of which is the failure to properly understand the internal architecture of the reservoir prior to initiating the flood.

Recent studies have shown that methane leak rates from abandoned oil and gas (AOG) wells may constitute a significant portion of a state’s emissions inventory. These emissions were shown to vary by region which introduces large uncertainty in the US national emissions inventory. In Wyoming, there are currently around 1900 wells identified as “orphaned” which indicates that they are both abandoned and unplugged. In this study, ten orphaned coalbed methane wells were sampled to characterize AOG emission rates in the Powder River Basin in Wyoming. The mean methane emission rate measured at these wells was 645 mg CH4/hr with the majority of these wells emitting in the 100-1000 mg CH4/hr range.