Options For Carbon Recycling From Hydrocarbon Production
Authors: Espie A.A. , Christopher C.A. , Wilkinson M.B. , Middleton P. 
Published: December 2007

BP has accepted the growing consensus that there may be a link between emissions of anthropogenic CO2 and climate change and that it is appropriate to take prudent precautionary measures now. Improvements in energy efficiency and more generally in energy management represent the best options for reducing CO2 emissions from power generated from fossil fuels using current technology. In the longer term, renewable energy sources coupled to carbon free energy carriers such as hydrogen offer considerable potential. However, in the interim period, options to remove additional CO2 over and above that achievable from energy management are likely to be required. Capture and geological storage of CO2 is a key option to meet this anticipated demand.

A carbon recycling system comprises the following elements : sources of CO2, separation and capture facilities, a transportation network and geological storage sites. CO2 may be produced as a natural part of the reservoir stream or generated by combustion of the hydrocarbon stream for power production etc. The unit costs for separation of CO2 from produced gas are much lower than those for capture from combustion flue gas. When recycling CO2 to the sub-surface the option of choice is injection into producing oil reservoirs to enhance recovery. Alternative options are depleted reservoirs, coal beds or saline formations or possibly producing gas reservoirs.

South East Asia is characterised by having a significant number of hydrocarbon reservoirs with a naturally high CO2 content. An overview will show that the region is well placed to be able to meet future growth in energy demand without increasing CO2 emissions through the capture and storage in geologic formations.

Introduction

Oil producers in the South-East Asia region are actively considering gas injection to maximise the potential of national oil reserves.

A successful gas flood requires two key criteria be satisfied. Firstly, the injected gas must be able to mobilise additional oil. Secondly, the flood must be able to sweep the mobilised oil to producers.

Often in mature developments, the reservoir pressure is significantly below miscibility conditions with available hydrocarbon gases. Thus the ability of the injection gas to mobilise oil is limited to pressure maintenance benefits. CO2 has two key benefits as an injection gas. Firstly, miscibility is achieved at pressures much closer to current reservoir pressures than with lean hydrocarbon gas. Secondly, the use of CO2 for injection would release hydrocarbon gas for alternative uses.

South East Asia has multiple sources of CO2. The simplest to access is CO2 produced as a component of oil and gas operations. The second source is from combustion processes. The technology for separation of CO2 from associated gas is widely available with applications throughout Asia. The technology for capture and separation of CO2 from combustion processes is less mature and the costs are correspondingly higher. This area is the subject of significant technology development activity.

Climate Change Overview

Global warming is considered by many scientists to be one of the most serious environmental problems of our time.