--> --> Aspects of CO2-enhanced oil recovery, from initial field screening to project implementation: Beaver Creek and Big Sand Draw CO2-EOR projects, Wyoming

AAPG Pacific Section and Rocky Mountain Section Joint Meeting

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Aspects of CO2-enhanced oil recovery, from initial field screening to project implementation: Beaver Creek and Big Sand Draw CO2-EOR projects, Wyoming

Abstract

There are many oil fields in the United States that are at, or near, the end of their productive life cycles. These fields typically have produced near 40-50% of the original oil in place, and can have very high water cuts in relation to the amount of oil produced (often higher than 99% water), may have low to no reservoir energy, and are at the point where production is not economically viable. In some cases, CO2-Enhanced Oil Recovery (EOR) can be used to renew the productive cycle of an old oilfield and can possibly extend the economic life of a field for many years. The Beaver Creek and Big Sand Draw fields, located in the Western Wind River Basin of Wyoming, are both examples of oil fields where this is true. CO2 projects can be broken down into phases for implementation. This process varies from field to field, but typically involves 4 phases. Phase I is used to determine if a project is viable and typically involves gathering and reviewing data, geologic interpretation, sector modeling with history matching and simulation, and making recommendations for acquiring additional data and tests. Phase II typically involves more detailed lab work, full-field 3D modeling, drilling and re-completing existing wells, setting up field infrastructure, implementing a pilot test in the field, and continuous optimization of the pilot and simulation model. Phase III involves reviewing the results of the pilot test and incorporates the results into the full-field 3D model, and designing full-field implementation of CO2-EOR project including facilities, equipment, operating conditions, and logistics. Phase IV involves project construction, drilling and completions, initial CO2 injection, monitoring, and continual optimization. Devon Energy is currently injecting CO2 gas into the Beaver Creek and Big Sand Draw oilfields for enhanced oil recovery. The Beaver Creek CO2 flood began in July 2008 in the Madison Limestone reservoir. This project has been very successful with daily oil production increasing from a pre-injection baseline of 280 bopd to a peak of 5,136 bopd in January of 2012. The field is still producing over 3,000 bopd after nearly 8 years of CO2 injection. The Big Sand Draw project is still in the early phases of CO2 injection, with CO2 injection commencing in April 2014 into the Tensleep Sandstone reservoir. Although the field is still in the early implementation stages, production at Big Sand Draw has increased from a pre-flood baseline of 130 bopd to over 2,000 bopd. CO2 is being provided to these fields through a 47-mile pipeline that extends connects to the ExxonMobil CO2 pipeline near Jeffery City, Wyoming. This talk will review many of the technical aspects that are critical in making these and other CO2-EOR projects successful.