Abstract

The Appalachian Basin states of New York, Pennsylvania, Ohio, West Virginia and Kentucky have a long, rich history of oil production, with current estimates of cumulative oil production at approximately 3.5 billion barrels of oil. However, estimates of the original oil in-place (OOIP) in the region's mature oil fields suggest that nearly 14 billion barrels were in-place prior to the beginning of production more than a century ago. Although early production data are often "best guesses", the remaining oil in place in this Basin appears to be on the order of 10 billion barrels. Without new efforts, this oil may remain permanently "stranded" following secondary recovery efforts and field closure.

One manner by which a portion of this stranded resource can be recovered is through the use of carbon dioxide enhanced oil recovery (CO2-EOR). The merits of CO2 miscible flooding are well documented and have been demonstrated for more than 30 years in Texas' Permian Basin, with CO2-EOR efforts currently increasing in the Gulf Coast and the Rocky Mountain Basins. With the current strong oil price situation, the oil producers in the Appalachian Basin may be interested in the CO2-EOR potential in the Basin.

This paper follows a series of reports entitled "Basin-Oriented CO2-EOR Assessment" of the United States 1 with an assessment of the Appalachian Basin oil producing states of New York, Pennsylvania, Ohio, West Virginia, and Kentucky. Reservoir simulation using detailed, respresentative data from major oilfields throughout the region indicate that 1,230 million barrels may become technically recoverable if advanced CO2-EOR technology is utilized. The economically recoverable resource will depend on future oil prices and CO2 costs.

Introduction

The CO2-EOR potential of the Appalachian Basin was not considered in recent studies published by the US Department of Energy 1. The Appalachian Basin's proximity to major markets gives it potential for CO2-EOR and for CO2 storage (Figure 1). Enhanced recovery could provide production boosts for this very mature oil basin and may also lead to options for CO2 storage from anthropogenic sources. Completing the goals of this study involved establishing the geological and reservoir characteristics of the major oil fields in the region; calculating enhanced oil recovery and CO2 storage capacity; and, examining the economic feasibility of applying CO2-EOR.

The Appalachian Basin in New York, Pennsylvania, Ohio, West Virginia, and Kentucky has an estimated original oil endowment of 14 billion barrels. Of this, nearly 3.5 billion barrels or 25% will be recovered using primary or secondary oil recovery. As such, about 10 billion barrels of oil will be left in the ground, or "stranded", once traditional oil recovery practices conclude. A major portion of this "stranded oil" is in reservoirs that may be technically and economically amenable to enhanced oil recovery (EOR) using carbon dioxide (CO2) injection.

CO2-EOR is a long-practiced method of enhanced oil recovery. Enhanced oil recovery efforts, utilizing CO2 flooding, were initiated in the Permian Basin of New Mexico and West Texas in the 1970's. More recently, CO2-EOR projects have begun in onshore Mississippi and Alabama and are expanding elsewhere.

Appalachian Basin oil producers are familiar with using technology for improving oil recovery. For example, producers have used waterflooding in many areas of the Bradford oil field of Pennsylvania and New York since the 1930's to improve oil recovery. CO2-EOR is not entirely new to the Appalachian Basin. A number of pilot-scale projects have been attempted over the past 30 years. Table 1 lists some of these projects. However, so far, the impact of these projects on enhancing the reserve base of the basin has been negligible.

The findings from this paper could assist in:

  1. formulating alternative public-private partnership strategies for developing lower-cost CO2 capture technology;

  2. launching R&D/pilot projects of advanced CO2 flooding technology; and,

  3. structuring royalty/tax incentives and policies that would help accelerate the application of CO2-EOR and CO2 storage.

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