Effect of sodium fluosilicate particles in acidification flowback fluid on emulsification stability of crude oil

Emulsification in the flowback fluid after the acidification of oil wells is too severe to be treated by electric dehydration. To study the emulsification mechanism of acidified flowback fluid, an emulsion of acidified crude oil was prepared according to the conventional treatment process of oil-well acidification. Fine white solid particles were formed after the neutralization of residual acid by NaOH. The main component of the white solid particles was sodium fluosilicate, as determined by X-ray diffraction analysis. The particle size range was measured and observed by laser particle size analysis and scanning electron microscopy, respectively, with the smallest observed particle size being ~1 μm. Then, based on the actual conditions of acidized oil wells, the drainage capacity of different solid particles in the crude oil emulsion was evaluated. The results showed that the emulsion with sodium fluosilicate particles added in the intermediate layer was the most stable, indicating that sodium fluosilicate was the main factor hindering the treatment of acidification flowback liquid. In addition, when the gum and asphaltene contents in the crude oil sample are high, the maximum voltage of the emulsion can be increased by appropriately increasing the experimental temperature, thus improving the effect of electric dehydration.