The Enhanced Oil Recovery Institute’s Acting Director, Lon Whitman, is a contributor to an important and anticipated publication of the U.S. CO2 Enhanced Oil Recovery Survey.
The purpose of this updated survey is to provide a comprehensive status report of the 142 active CO2-EOR projects in the U.S., including enhanced production totals, reservoir characteristics, and other project parameters.
The Enhanced Oil Recovery Institute (EORI) has completed a map of thermal maturity of the Mowry Shale in the Powder River Basin (PRB). Thermal maturity, the degree to which the total organic carbon in a formation has been transformed from kerogen to producible hydrocarbons due to heat and pressure, is an important measure for not just the quality of a source rock, but also helps for delineating areas more favorable for unconventional drilling.
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.
The purpose of this survey is to provide a comprehensive status report of active CO2 EOR projects in the U.S., as of end-of-year 2019. This survey provides the first update of CO2 EOR project data since the final publication of the Oil & Gas Journal (OGJ) EOR Survey in 2014.
The 2019 U.S CO2 EOR survey shows that incremental oil recovery from CO2 EOR in the U.S. has held steady at approximately 300,000 barrels of oil per day. A total of 3.0 Bcf per day of CO2 is purchased for CO2 EOR, including 1.0 Bcf per day from “industrial” sources, which represents an increase of 30% over the last seven years.
The authors use multivariate statistics to highlight best practices in the drilling of Codell and Niobrara reservoirs of the northern Denver-Julesburg (DJ) Basin in southeastern Wyoming. The conclusions in this paper differ from a 2017 report by the Wyoming State Geological Survey on the same topic and illustrate why simple crossplots are not sufficient to properly analyze plays where a number of variables must be addressed and weighed simultaneously.
For the Codell, this study reveals that the attributes of Proppant Volume, Horizontal Length, Gas-Oil Ratio (GOR), and Treatment Rate have the greatest influence on 6-, 12-, and 18-month cumulative oil production. By examining the individual attribute responses, the current best design in the Codell is a lateral length of at least 9,600 feet (ft), a job size of 12 million (MM) lbs, a treatment rate of at least 40 barrels per minute (bpm), and a GOR of 570 standard cubic feet per barrel (scf/bbl). The type curves from decline curve analysis provided predictive monthly production. The best EURs were obtained with the optimized design and yielded better overall economics when entered into the economic model.