Understanding and controlling crystal formation in a porous matrix carries huge potential environmental and economic benefit for applications such as CO2 sequestration, hydraulic fracturing, catalysis, and energy storage design. Barite is a common mineral which can change the permeability of a rock matrix during oil and gas extraction due to crystallization as well as incorporate contaminants such a strontium and radium. Overall, because of the complexity of natural systems careful evaluation and additional development of classical crystal nucleation and crystal growth theories is required. Previous in situ X-Ray computed tomography (XCT) experiments of our group on barite precipitation in micrometer size pores showed correlations between pore size, fluid velocity, and crystal nucleation rate. Our recent experiments performed on barite precipitation in porous systems formed by glass spheres packed into a capillary, have shown that the morphology of the precipitate depends on the flow rate and presence of impurities (strontium cations). For example, Fig. 1 shows the in situ XCT images of barite crystals precipitated in porous media. Pronounced differences between crystal formation in pure BaSO4 solution (Fig. 1A) and barite precipitation in presence of strontium cations (Fig. 1B) were observed. In the latter case, strontium affects not only crystal growth rate, but also the morphology of the precipitate, and probably its composition. As a result, a matrix with dual porosity is formed, where the micron sized pores of the initial system are filled with polycrystalline precipitate with pore sizes in the nanoscale range. Therefore, the nanoporous structure of polycrystalline barite precipitate reveals the important interplay between crystal nucleation rate, crystal growth rate, and reactant transport in microporous matrix.

Effects of strontium impurity on barite precipitation in mesoporous media

255th National Meeting (2018)

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