Abstract

For decades to come, oil and gas will remain an energy source of choice to meet increasing demand. But oil and gas operators have to develop fields requiring much more processing and energy - i.e. very sour gases or extra heavy oils - while reducing the Green House Gases (GHG) emissions to mitigate the climate change consequences.

Among the possible options, carbon capture and geological storage (CCS) appears to be a promising option in addition to power efficiency increase or renewable energies use.

Total launched end 2006 an integrated CCS project in the South-West of France. It entails the conversion of a steam boiler into an oxy-fuel combustion unit, oxygen being used for combustion rather than air to obtain a more concentrated CO2 stream easier to capture. The pilot plant, which will produce some 40 t/h of steam for use other facilities, will emit up to 150,000 tons of CO2 over a 2-year period, which will be compressed and conveyed via pipeline to a depleted gas field, 30 kilometers away, where to be injected into a deep carbonate reservoir. CO2 injection is scheduled to begin end 2008. The paper presents the characteristics of the 30MWth oxyboiler,

one of the world first industrial oxy-combustion units. Then, it focuses on the critical issues that can be addressed with an integrated project of combustion CO2 injection into a geological formation: CO2 purity level required by each element of the CCS chain, validation of CO2 injection and migration models, and validation of the methodologies put in place to assess well and storage integrity. It discusses the potential application among others of such technology in an extra heavy oil "hot production" scheme with emphasis on the benefits to integrate all aspects of the CCS chain mentioned above for future large scale applications.

Introduction

For decades to come, oil and gas will remain an energy source of choice to meet increasing demand. But oil and gas operators have to develop fields requiring much more processing and energy - i.e. very sour gases or extra heavy oils - while reducing the Green House Gases (GHG) emissions to mitigate the climate change consequences.

Among the possible options, carbon capture and geological storage (CCS) is an important option for tackling greenhouse gases emissions. In their 2007 summary report for policy makers on "Mitigation of Climate Change"1, the Intergovernmental Panel on Climate Change (IPCC) describes this option as one of the key mitigation technologies and practices currently available.

While the worldwide CO2 atmospheric emission was around 30 billion tonnes in 20052, CO2 geological storage capacity could be very significant: 600–1,200 billion tonnes in oil and gas depleted fields, 3–200 billion tonnes in unmineable coal seams and up to 1,000–10,000 billion tonnes in deep saline formations2. This represents between 70 and 500 years of storage at current production rates.

But to ensure that CCS technology will be reliable on short and long term, energy efficient, accepted by the public and commercially viable, industrial pilot plants are necessary. Total launched end 2006 an integrated CCS project in the South-West of France. It entails the conversion of a steam boiler into an oxy-fuel combustion unit, oxygen being used for combustion rather than air to obtain a more concentrated CO2 stream easier to capture. The pilot plant, which will produce some 40 t/h of steam for use other facilities, will emit up to 150,000 tons of CO2 over a 2-year period at the Lacq existing facilities. Then the CO2 will be treated, compressed and conveyed via pipeline to the depleted gas field named Rousse, 30 kilometers away, where to be injected into a deep carbonate reservoir as shown on Figure 1.

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