CO2-Sequestration Potential in Austrian Oil and Gas Fields
Authors: Scharf Claudia , Clemens Torsten 
Published: December 2007

Austria committed to reduce greenhouse gas (GHG) emissions by 13 % based on emissions in 1990. However, the emissions in Austria increased by 16.6 % until 2003. To meet the reduction target, greenhouse gas emissions have to be reduced by at least 2.3 MM t CO2/year.

One possibility to decrease greenhouse gas emissions to the atmosphere is geological storage of these gases. Austria is a highly industrialised country with a long history of oil and gas production. The basins from which hydrocarbons are produced are not too far from industry sites. Hence, geological storage of CO2 generated by industrial processes could be economically attractive. Injecting CO2 into gas reservoirs leads to limited incremental gas recovery and additional income accordingly. CO2 injection into oil reservoirs is a common enhanced oil recovery method and might result in substantial incremental oil recovery dependent on the reservoir conditions.

To evaluate the potential of CO2 geological storage in Austria, first, the maximum storage capacity was estimated based on expected total hydrocarbon production. Next, the eleven largest oil and thirteen largest gas fields in Austria were investigated in more detail.

The storage capacity of these fields was determined as 465 MM t CO2. 430 MM t CO2 could be stored in fields located in the Vienna Basin and 35 MM t CO2 in the Molasse Basin between Linz and Salzburg.

The results indicate that CO2 geological storage might significantly contribute to achieving the Kyoto targets of Austria.

Introduction

The ideas of the society concerning energy use and its impact on environment have been subject to continuous change over the past 30 years: In 1973, the oil crisis triggered international awareness that energy reserves are not infinite. In the late seventies, acid rain coming from the use of fossil fuels for energy production due to emissions of SO2 and NOx was considered the major problem. Since the late eighties/early nineties, a more serious and fundamental problem has led to increasing concern among science, politics and industry: Global warming.

The concentrations of Greenhouse Gases (GHG), essentially carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) in the atmosphere all have drastically increased since the industrial revolution (Figure 1). Resulting from the continuous burning of fossil fuels and at the same time deforestation, the concentration of CO2 in the atmosphere has risen by over 30 % since the pre-industrial age level from approximately 280 ppm to almost 380 ppm today[1].

These measurements usually result from the analysis of ice cores in the Antarctica[2]. Due to the extremely low temperatures, the fallen snow was able to accumulate for thousands of years and with time was compressed to ice and formed the Antarctic ice sheet which has in the meantime an average thickness of 2,500 m. Drilling from the surface down into the ice is equivalent to drilling back in time and cores which are several thousand years old can be taken, releasing information on the Earth's environment and climate at the time of precipitation.

It is not only possible to gain knowledge on the chemical and physical properties of the ice itself but also on the properties of the air which was trapped in the ice, representing the actual atmospheric conditions at that time. Using this method, the alarming increase of the concentration of CO2 and other GHG in the air since 1800 could be detected.