Scanning Methods as Monitoring, Verification, and Accounting tools for CO₂ Sequestration in Unconventional Gas Reservoirs

• Main Author: Amante, Joseph David
• Other Authors: Mining and Minerals Engineering, Ripepi, Nino S., Karfakis, Mario G., Keim, Steven Anthony
• Format: Thesis
• Language: unknown
• Published: Virginia Tech 2015
• Subjects: Coal; environmental scanning electron microscope (ESEM); X-ray computed tomography; permeability; echometer; liquid level sensing; pressure build up test; desorption; sequestration; Carbonic acid
• Online Access: http://hdl.handle.net/10919/76047

Unconventional gas reservoirs in carbon dioxide sequestration activities is a relatively new and unexplored concept currently undergoing pilot scale testing. Sequestration has the potential for enhancing gas recovery while mitigating carbon dioxide to long term storage structures. Due to the extremely complex systems associated with these unconventional reservoirs, modeling becomes difficult to predict accurately. This thesis presents methods to increase the confidence of inferred parameter testing for unconventional reservoir sequestration in both seam coal bed methane wells and a shale wells. Various tests include the use of computed tomography coupled with Avizo modeling software, inductively coupled mass spectrometer fluid transport analysis, pressure transient build tests, liquid level detection, and desorption analysis coupled with cleat image analysis. Analyses of coals performed by both environmental scanning electron microscope (ESEM) and micro CT demonstrate that distributions of cleat porosity in coals are anisotropic and not correlated to the seam depth or location. ESEM is used with micro CT scanning to verify the results before and after the impregnation of the carbonic acid. The micro CT data in Avizo Fire was used calculate an increase in cleat permeability by 25%. The increase of major flow pathways is caused by the dissolution of carbonates. Changes in the structures were observed qualitatively through ESEM and micro CT and quantitatively through Avizo and inductively coupled mass spectrometry. The results of comparative study between the cleat structures and the desorption of various seams indicate a trend in the cleat porosity and the desorption rate of the coals as well as the cleat porosity and the total gas in various seams. Master of Science