Interstitial space transformation resulting from acid treatment of Bashkirian carbonate reservoir rocks

Acid treatment for enhanced oil recovery is one of routine and efficient methods; and hydrochloric acid is the most commonly used one. Given the widespread occurrence of treatments with the use of hydrochloric acid, as well as substantial volume of acidic solutions pumped into wells (usually several tens of cubic metres per well), the question of the possibility of in situ organochlorine compounds formation resulting from interaction of hydrogen chloride with oil becomes relevant. The authors describe possibility of organochlorine compounds formation in oil after hydrochloric treatment. They examined the process of interaction of 0 to 24 % hydrochloric acid solution with oil at 80 °C, after which they determined content of organically bound chlorine using X-ray fluorescence analysis. The authors show that at the end of the study an increase in the organically bound chlorine amount in oil phase was observed compared to the "blank" experiment with distilled water. In addition, a scanning electron microscope was used to examine the influence of hydrochloric acid on structural features and mineral composition of carbonate deposits, which causes changes in reservoir porosity and permeability