Wyoming, perhaps more than any other state, is dependent on revenues generated from the development and sales of minerals within its borders and has a vested interest in ensuring that its resources are properly and efficiently exploited. Maximizing the efficiency of oil and gas production in Wyoming is one of the primary goals of the Enhanced Oil Recovery Institute (EORI). Potential methods or practices that can improve or enhance the recovery efficiency of oil and gas production in the state are of paramount interest. Likewise, those policies or practices that hinder such efforts are also important to discuss.

Wyoming has nearly one billion barrels of proved oil reserves, a significant portion of which is still on primary production. Assessing the potential for secondary recovery from current oil fields is always a daunting task and requires evaluations regarding whether any given field will respond favorably to secondary recovery efforts.

This paper makes general assumptions regarding the feasibility of using a water flood to enhance oil recovery in a field based on publicly available data. The conclusions resulting from these assumptions are meant to be a guideline for the potential of future water flooding and are not meant to provide detailed evaluations of any given field’s ultimate recovery.

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.