Catálogo de publicaciones - libros

In today's industrialized world, the generation (and emission) of greenhouse gases (GHG) is likely to continue. The reduction of greenhouse gas emissions through public outreach programs is one approach to mitigate this problem however, in practice, it has not yet been received well by the public due to economic costs. Therefore, permanent storage of these gases in underground reservoirs is believed to be one of the most suitable solutions for the mitigation of greenhouse gases. Sequestration of GHG is not cheap, however, and thus the injection of greenhouse gases into oil or gas reservoirs to enhance production may offset some of these associated costs. The use of CO for purely EOR purposes versus injection of CO primarily for sequestration are technically two different problems. Proper design practices and technology need to be developed and applied in order to inject CO into oil reservoirs not only for the purpose of tertiary oil recovery but also for permanent sequestration. In conventional CO injection projects the main purpose is to increase the amount of oil produced per amount of CO injected. In contrast optimization of CO injection for sequestration purposes requires “maximum oil production with the highest amount of CO storage„. Breakthrough time is a critical parameter in this exercise as recycling CO is undesirable due to economic and environmental constraints. This paper summarizes on-going research into the conditions that will maximize oil recovery while maximizing the underground sequestration of CO. Results obtained from numerical modeling of the injection process are discussed. Current efforts on CO injection in Canada are also presented.

The use of carbon dioxide and combustion gases in EOR technologies is of interest from the point of view of CO geological sequestration. During the period of 1980-1990 large-scale pilot tests were carried out in Russia to utilize carbon dioxide and combustion gases, formed at different petrochemical production plants, to enhance oil recovery in different hydrocarbon fields. The analysis of field data indicates that the greater part of CO injected into oil reservoirs was recovered from production wells during the 1-1.5 years of the experiment. The total amount of CO which was irreversibly stored in the reservoir was not measured. To reveal mechanisms of CO geological sequestration it is recommended to study in detail carbon dioxide interactions with oil, formation water and with the reservoir rocks under the conditions of miscible and immiscible oil displacement with carbon dioxide.

Pumping CO into oil reservoirs is one of the most promising methods to increase oil recovery. A significant drawback of the method is channelled flow of CO through the most permeable intervals in heterogeneous reservoirs. To control flow we used foam-emulsion systems generated both before pumping into the reservoir model and directly in the reservoir. This allows us to double the driving medium from high- to low-permeability reservoirs and presents a likely mechanism of flow redirection. Studying the regulating effect of foamemulsion systems using a transparent micro-model of the reservoir and the Hele-Shaw cell revealed a previously unknown effect of dynamic blocking of porous mediums and fractured structures during transformation of emulsions filtering through it.

The Federal Republic of Germany (FRG) is the greatest carbon emitter in Europe and is responsible for ~ 3.4% of the world's total fossil fuel-based carbon emissions. In the Kyoto Protocol and national climate protection programs Germany has committed to substantial reductions of CO emissions. Because of the German government's priority on sustainable energies and reduction of fossil energy consumption, R&D activities on CO capture and subsurface storage have so far played only a minor role. These activities are, however, increasing and several projects have been launched recently.

CO produced at the Sleipner gas field is being injected into the Utsira Sand, a major saline aquifer some 1000m beneath the North Sea. The injection plume is being monitored by geophysical methods. 3D seismic data were acquired in 1994, prior to injection, and again in 1999, 2001 and 2002; seabed gravimetric data were also acquired in 2002. The CO plume is imaged on the seismic data as a number of bright sub-horizontal reflections, growing with time, underlain by a prominent velocity pushdown. Quantitative modelling is based on plume reflectivity largely comprising tuned responses from thin layers of CO trapped beneath thin intra-reservoir mudstones, with layer thicknesses being mapped according to an amplitude-thickness tuning relationship. Between the layers a lesser component of much lower-saturation, dispersed CO is required to match the observed velocity pushdown. However, reservoir temperatures are subject to significant uncertainty, and inverse models of CO distribution, based on lower and higher temperature scenarios, can produce both the observed plume reflectivity and the velocity pushdown. Higher temperature models however require that the dispersed component of CO has a somewhat patchy rather than uniform saturation. Analysis of the datasets suggests that accumulations of CO as small as 500 tonnes may be detectable under favourable conditions, providing a basis for setting leakage criteria. To date, there is in fact no evidence of migration from the primary storage reservoir.

Seismic surveys have proven to be useful for monitoring injected CO in the subsurface. In this work, we show how rock physics, poro-elastic modeling and 3D seismic tomography can be combined to detect the subtle changes in seismic properties related to changes in pore-fill. 3D seismic tomography yields the P- and S-wave velocity cubes, which are converted to petro-physical properties by using rock-physics models of partial saturation under varying temperature and pressure conditions, and seismic numerical modeling. The methodology is illustrated with field examples of time-lapse analysis and gashydrate detection.

According to a widely accepted forecast the global energy consumption, which is roughly 400 EJ today, will quadruple by the end of the century and the use of fossil fuels will probably increase until the middle of the century. Hence, the energy scenario definitely implies that the emission of greenhouse gases will also increase by a minimum 30%, leveling off at that value for the coming decades. Unfortunately, a simplified idea is that the use of fossil fuels is solely responsible for global warming, and hence climatic changes. Although the anthropogenic impact on climate is represented by only 15% of carbon dioxide emissions, this is the area where science and engineering can focus all efforts to influence its detrimental effects. The small anthropogenic effect on climate, however, clearly proves that the earth is extremely vulnerable to even marginal changes in the atmosphere, hydrosphere and lithosphere.

CO geological storage constitutes a relatively recent scientific technology which could play a major role for the solution of global warming. More research is needed, however at the same time already-available scientific knowledge has scarcely been disseminated. Thus researchers who work in this area are faced with two main problems: 1) get their work to be known and its relevance understood also outside research and academic circles 2) avoid possible misconceptions in the understanding of their research, which could result in negative reactions in public opinion and consequently to the refusal of geological storage. This contribution addresses the need to spread knowledge and make this technology better known for the exploitation of its potentialities. Methodological questions about effective dissemination are dealt with. A psycho-sociological approach is presented and discussed, focusing on: 1) how to develop in the public a positive attitude and interest for learning about geological storage; and 2) how to develop in the public a correct understanding of what geological storage is. This kind of approach works on both the cognitive and emotional levels, beginning with the scientists‚ representations of their own work and followed by studying the interactions people can develop when coming in contact with a new topic, what kind of reactions are stimulated and how they can be understood depending on specific social contexts, etc. Language study and image issues are explored with specific reference to geological research. Based on Italian experiences for geological research dissemination the role of cultural contexts and psychosocial representations are illustrated. The importance of the analysis of emotional processes is explained. The role of information, communication, storage sites‚ image and social context in relation to stakeholders decisions is analysed. A possible proactive image strategy is outlined.

The Sixth Framework Programme (FP6)- 2002-2006 - is the European Unions' main instrument for research funding in Europe. FP6 serves two main strategic objectives: to strengthen the scientific and technological bases of industry and to improve competitiveness and innovation in Europe through the promotion of increased co-operation and improved coordination between relevant actors at all levels. Within FP6, the Network of Excellence (NoE) instrument was developed to strengthen excellence on a particular research topic by tackling the fragmentation of European research. One such NoE, formed in 2004, is COGeoNet, which is made up of 13 research organizations from across Europe who have extensive experience and expertise in the study of the geological storage of CO. The principle goal of this consortium is to contribute to and form a durable integration of research into CO geological storage, in the European Research Area, as a means of mitigating anthropogenic mass loading of this greenhouse gas to the atmosphere and ocean, while there is continued use of fossil fuels.