Flow, Transport, and Controlled Sedimentation of Salt Solutions in Porous Formations with Enhanced Structural Properties

Abstract

Scaling phenomena caused by salt precipitation in pumps and wells are a frequent problem during oil production, CO2 storage, and other underground processes. Several studies have focused on the salt precipitation in porous media, and interesting results concerning salt precipitation have been obtained in the past. Salt precipitation in porous media is a complex phenomenon since it is highly dependent on supersaturation, which is usually not homogeneous along the porous channels. In the present study the coupled solution of the spatiotemporally varied flow and mass transport during mixing and selective precipitation of specific salts in unconsolidated and loosely consolidated porous media were investigated, with a strong dependence on the prevailing conditions. Specific salt solutions mixing, transfer, and deposition rates were studied, targeting the selective enhancement of salts deposition performance to facilitate consolidation of porous formations. Computational fluid dynamics methods have been applied for the transient flow and salt transport with homogeneous or heterogeneous nucleation of crystals on the walls of pores with specific mixing geometry. During modeling of flow in pore networks, the three-dimensional character of the process was taken into account, and the evolution of mass transport and deposition was monitored. The precipitation of salts in supersaturated and unsaturated porous medium and the crystals distribution along the porous medium have been evaluated. Comparison of the simulation results with similar experiments has been performed.

Mineral Scaling in Microchips: Effect of Substrate Wettability on CaCO3 Precipitation

“…As explained in detail earlier, 19,20,49 aragonite is less stable than calcite and the formation of less stable polymorphs is mainly due to higher SR values and to lower interface or surface energy. Comparison between experiments at similar SR values and for wettability of the walls of the microchannels, and considering that neutral wettability lowers surface free energy, the formation of aragonite could be attributed to the lowhydrophilic character of the walls of the microchannel.…”

“…The 2-D porous media used in previous studies − were homogeneously wet and were constructed on glass, 1-D channels were made of Plexiglas, and the packing material of the columns was sand grains. For simplicity, surface wettability was ignored in these studies; however, most of the porous media in the environment are mixed-wet, whereas water-wet porous media are rather rarely encountered in natural and/or engineered porous media. − Experimental studies of salt precipitation on surfaces of varying wettability on multiphase flow have shown that the presence of oil on hydrophobic surfaces did not favor crystal nucleation on the surfaces .…”

Crystallization in Confinement

“…The crystallization of minerals in heterogeneous porous media is a widespread phenomenon in geochemistry and building materials, and is observed in a wide range of settings and environments. [350][351][352] With relevance to processes including the degradation of rocks in natural systems, and of porous building materials such as stone, brick, cement and concrete, [11] the formation of ore deposits, [353] the storage of carbon dioxide [13,14] and sequestration of toxic metals in minerals, [15] and the extraction of oil, [354][355][356][357] this topic attracts enormous interest and is the subject of an extensive body of literature. Predicting the outcome of crystallization within these porous media is an extremely complex problem that depends on an ability to model both transport processes and crystal nucleation and growth within confined volumes.…”

“…[367][368][369] These issues can also occur in geothermal systems during the capturing of CO 2 in underground well systems. [356] In this section we aim to provide a brief overview of this topic, where we have chosen to highlight studies that focus on the influence of confinement on crystal nucleation and growth. Understanding of crystallization within porous rocks and manmade building materials is extremely challenging due to the heterogeneous structures of these media.…”

“…[ 367–369 ] These issues can also occur in geothermal systems during the capturing of CO 2 in underground well systems. [ 356 ]…”