One of the major environmental impacts of unconventional gas extraction from Marcellus Shale is the amount of NORM, most notably Ra-226, that is brought to the surface with produced water. Ra-226 has a rather long half-life (1600 years) and its abundance in the flowback/produced water raises serious concerns. The lack of Class II disposal wells in Pennsylvania and legislative activities in surrounding states requires the development of a new method for managing NORM in the produced water. The current method for NORM control, i.e., radium co-precipitation with barite (barium sulfate), is focused on the removal of NORM from the produced water once it has already reached the surface. Previous studies reported that celestite (strontium sulfate) has significantly higher distribution coefficient for Ra-226 than barite and it may be possible to take advantage of this unique property to offer better management approach for NORM in the produced water.<br/>The main focus of this study is on the ability of celestite to sequester radium and mechanisms associated with this process under relevant process conditions (i.e., solution chemistry and contact time). In addition to studying the ability of celestite to remove Ra-226 from produced water, this study evaluated the possibility of impregnating (coating) celestite onto the surface of the quartz sand that is used as a proppant in the hydraulic fracturing process to prevent the collapsing of cracks formed during the process and enable efficient extraction of natural gas. A small fraction of the celestite coated sand mixed with the proppant will be able to significantly decrease the amount of radium that is brought to the surface by sequestering it in the subsurface. The mechanism of radium removal by celestite, as well as its efficiency, coating methods and possibility for the practical use, are going to be discussed at the conference.<br/>

Development of celestite impregnated proppant for the control of Ra-226 in the Marcellus shale produced water

254th National Meeting (2017)

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