{"title":"Active Reservoir Pressure Management with Guidance and Surveillance by Distributed Fiber-optic Strain Sensing","authors":"Yi Zhang, T. Hashimoto, X. Lei, Z. Xue","doi":"10.2139/ssrn.3821348","DOIUrl":"https://doi.org/10.2139/ssrn.3821348","url":null,"abstract":"CO2 injection and storage in aquifers can cause pore pressure build up and deformation of the aquifer-caprock system due to extra-fluid accumulation. Active reservoir pressure management, a concept that using brine production before or during CO2 injection to reduce reservoir pressure build up, has been suggested to avoid potential risks posed by geomechanical deformation during large-scale CO2 injection [1], [2]. Sedimentary formations usually develop heterogeneities in fluid properties and mechanical properties. When conducting CO2 injection or brine production, acquiring the in-situ information of pore pressure and fluid distribution and rock deformation would be much helpful for the project operating. In this presentation, we propose to give guidance and surveillance of the CO2 injection and brine production operations in real time using a distributed fiber optic strain sensing (DFOSS) system. We show the field and lab studies and numerical simulation results to demonstrate the feasibility and the advantages when using DFOSS for pressure management in a storage reservoir. Existing difficulties when using DFOSS are also presented.","PeriodicalId":117842,"journal":{"name":"GHGT-15: Advances in CO2 Geological Storage","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132114546","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Interaction of CO 2 Storage and Hydrocarbon Production in Vertically Communicating Subsurface Systems","authors":"S. Ghanbari, E. Mackay, G. Pickup","doi":"10.2139/ssrn.3820436","DOIUrl":"https://doi.org/10.2139/ssrn.3820436","url":null,"abstract":"The security of CO<sub>2</sub> storage requires all the injected CO<sub>2</sub> to be contained entirely within the storage site. CO<sub>2</sub> is not allowed to leave the subsurface system during and after cessation of injection. In stacked subsurface systems, the pore volume overlain or underlain by the CO<sub>2</sub> storage site might be used by another subsurface user, potentially with a different philosophy. For example, it might be used by a hydrocarbon producer where the philosophy is to deplete the site and reduce its pressure for maximum hydrocarbon exploitation. If the two systems become hydraulically connected, CO<sub>2</sub> may migrate from the storage site to the production site where it makes the security of storage more complex. In this study, we use numerical simulation to understand and address the characteristics of this phenomenon. We simulate CO<sub>2</sub> injection and hydrocarbon production in two vertically separated stacked systems. The modelling study represents two separate formations, one overlying the other, but separated by an impermeable shale layer. CO<sub>2</sub> injection is carried out in the one formation, whereas hydrocarbon is produced from the other formation. The two separated formations become connected via a well which penetrates through both formations and provides hydraulic communication between them. Different configurations of overlying and underlying CO<sub>2</sub> storage site relative to the hydrocarbon production site have been investigated in this study. Both pre- and post-storage hydrocarbon production have also been included in the analysis. Results show that in all the investigated scenarios, leakage of CO<sub>2</sub> is expected, though with different characteristics. CO<sub>2</sub> always migrates to the overlying production site due to combination of gravity and sufficient pressure gradient. Interestingly a reverse migration of CO<sub>2</sub> from the overlying storage to the underlying production site was also observed should a sufficient pressure difference between the two formation allows brine to migrate from the overlying CO<sub>2</sub> storage site to the underlying production site. Such brine migration dissolves CO<sub>2</sub> on its migration path and brings it to the production site. Results of this study illustrate the significance of correctly understanding this leakage phenomenon and including it in the overall long-term assessment of storage security in target storage sites.","PeriodicalId":117842,"journal":{"name":"GHGT-15: Advances in CO2 Geological Storage","volume":"432 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134139426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}