Silica-Templated Synthesis of Novel Zinc-DTPMP Nanomaterials: Their Transport in Carbonate and Sandstone Media During Scale Inhibition

In this study, a silica-templated synthesis route was adopted for fabrication of zinc phosphonate nanomaterials to expand their use in the delivery of phosphonate inhibitors into crushed formation materials for scale control. Transition divalent metal Zn(2+) was chosen because of its ability to significantly increase inhibitor retention and effectiveness. Zinc chloride was first adsorbed onto the surface of 22-nm silica particles, followed by gradual addition of diethylenetriaminepentakis (methylenephosphonic acid) (DTPMP) to form nanometer-sized particles in the presence of sodium dodecylbenzene sulfonate (SDBS) surfactant. The physical and chemical properties of the synthesized Si-Zn-DTPMP nanomaterial suspension (nanofluid) have been carefully evaluated. The nanofluid was stable at 70 degrees C in 1% KCl at pH 6.7 for over 12 hours. The transport of the synthesized nanofluid through columns of crushed calcite and sandstone has been investigated using column breakthrough experiments and modeled with a 1D advection-dispersion equation. The nanofluid was transportable through these media, and near-total breakthrough could be obtained by preflushing the media with an anionic SDBS surfactant solution. The nanofluid was transformed from an amorphous phase into a crystalline phase during diafiltration. The crystalline-phase materials demonstrated a much longer inhibitor lifetime compared with the untreated ones. The long-term flowback performance of the crystalline nanofluid was examined with a laboratory squeeze-simulation test where the nanomaterials gradually returned phosphonate inhibitors in the flowback brine solution, and the normalized return volume was greater than the previously reported nanomaterials squeeze treatments.