In recent years the energy industry has experienced rapid growth due in part to evolving technologies such as hydraulic fracturing which have increased the efficiency and volume of gas recovery. Despite progress on the production side, there are critical problems that remain which must be overcome, specifically backflow waters contaminated with radioactive material. A well-documented example is radium, which is naturally present as cations or as a sparingly soluble salt, which can co-precipitate with barite (BaSO4) forming insoluble scale on the inside of well bore pipes which can decrease productivity and even result in failure. Radioactive backflow water creates potential nightmare event scenarios, which include drinking water contamination, catastrophic ecosystem impacts and numerous other public health issues.A promising remedy for radioactive contamination in backflow waters is radium substituted barite precipitation within naturally occurring pore space available in shales, such as those from the Marcellus and Eagle Ford formations. This approach entombs radium in a sparingly soluble barite phase within the shale, reducing the likelihood of radioactive cations contaminating groundwater or precipitating on wellhead pipe walls. In order to control precipitation, accessible pore size distribution control must be established. Results will be presented from experimental investigations probing optimum conditions for selective pore precipitation, the controlled evolution of porosity distributions as hydrocarbons and inorganic components are removed and the implications on the available pore space for radioactive mineral sequestration.

Pore size manipulation in Eagle Ford and Marcellus shales: Applications for radioactive contaminant sequestration

248th National Meeting (2014)

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