The course deals with the storage of fluids in deep geological formations. First, the concept of storing natural gas underground to balance the divergence between a constant gas supply and the seasonal and daily variability of gas consumption is introduced. Typical underground storage facilities include depleted oil and gas reservoirs, deep saline aquifers, and salt caverns. Methods for characterization, development and monitoring of underground storage facilities are presented and studied. Then, geologic sequestration of CO2 for reducing greenhouse gas in the atmosphere and mitigating climate change is investigated. Specific aspects of CO2 and CO2 storage – fluid properties and dynamics, trapping mechanisms, and site integrity - are examined. Also, the conversion of platforms originally designed for hydrocarbon production to store CO2 offshore is introduced and discussed. Projects around the world where geologic storage of CO2 is being successfully performed are presented. Eventually, the challenges posed by the emerging option of underground hydrogen storage are addressed.

Knowledge of the specificities of different underground storage types. Good understanding of the phenomena and mechanisms taking place when injecting natural gas, CO2, or hydrogen underground. Awareness of the requisites of storage sites to contain fluids. Skills to efficiently design, operate and monitor underground storage systems. A critical approach to review real data for site assessment and monitoring. Understanding of the technical and safety challenges affecting the process plants used for underground fluid injection and withdrawal. Communication skills, ability to use and understand the technical language and terminology adopted worldwide in the industries. Ability in increasing knowledge by selecting the appropriate technical and scientific literature.

Students should have the background provided by the following courses: Fluid Mechanics in Porous Media; Reservoir Engineering; Reservoir Geomechanics; Fundamentals of process plants and Thermodynamics.

- Characterization of depleted reservoirs, deep saline aquifers and salt caverns from the geological and fluid-flow perspectives. Necessary laboratory and field data. - Storage capacity - Working gas and cushion gas for underground natural gas storage - Well deliverability and injectivity - CO2 trapping mechanisms - Operating pressure conditions - Differences between depleted reservoirs and deep saline aquifers - Numerical simulation of the fluid-flow, geochemical, and geomechanical behavior of storage systems - Process plants for underground fluid injection and withdrawal; operational and safety issues - Main safety issues of storage systems and monitoring techniques

The main part of the course aims at addressing the scientific, technical, and operational aspects of underground fluid storage. A complementary part provides the fundamentals of the process plants needed to manage injection into and production from deep geological formations, including operational and safety issues, applied to fluid storage. Exercises are meant for the students to approach practical problems by applying the theory and methods discussed during the lectures. Calculations of storage capacity for depleted reservoirs and aquifers and well injectivity will be performed. For the injection plants, two study cases about the re-use of the topside infrastructures and depleted reservoirs will be developed. The first study case proposes the injection and production of a CH4–H2 mixture for temporary underground storage in a depleted reservoir to meet strategic energy supply. The second study case addresses the storage of the CO2 captured from the atmosphere in a depleted reservoir to reduce the atmospheric concentration of greenhouse gases from anthropogenic emissions. A focus on CO2-related safety issues completes the last study case.

Reports from international agencies and organizations. Scientific papers.

Slides;

Modalità di esame: Prova scritta (in aula);

Exam: Written test;

... The ability to critically examine a technical problem, also by integrating knowledge gained in other courses and contexts if needed, to select the appropriate models and methods and to correctly calculate the solution is expected. The exam is related to theoretical and applicative aspects and comprises true/false options, multiple choice questions, open questions, and mostly problem-solving. The exam is closed notes and closed books. Each answer will be assigned marks depending on the complexity of the question. The score is attributed by taking into account the correctness and completeness of the answers to the questions, the ability to elaborate the topics presented and discussed in class for problem-solving; the ability to support the discussion with a correct nomenclature and clear form and with graphs (when relevant/required).

Gli studenti e le studentesse con disabilità o con Disturbi Specifici di Apprendimento (DSA), oltre alla segnalazione tramite procedura informatizzata, sono invitati a comunicare anche direttamente al/la docente titolare dell'insegnamento, con un preavviso non inferiore ad una settimana dall'avvio della sessione d'esame, gli strumenti compensativi concordati con l'Unità Special Needs, al fine di permettere al/la docente la declinazione più idonea in riferimento alla specifica tipologia di esame.