Comparative Study on Acidizing and Fracturing Flowback Fluids Influence on Crude Oil Dehydration

The hydrogen ion in acidizing and fracturing flowback fluid activates naphthenic acid in crude oil, which increases the strength of oil-water emulsion film in crude oil, making it more difficult for demulsifier to replace oil-water interface, affecting the dehydration of crude oil and causing difficulty in crude oil demulsification. The ions content of acidizing and fracturing flowback fluids are tested, and the crude oil emulsion was made up by these fluids. In conditions of different amount of flowback fluids and various pH, the influences of flowback fluids on crude oil dehydration were comparatively studied. The results shows that with increase of fluids, both crude oil emulsion dehydration rates are also increased, while fracturing crude oil emulsion dehydration rate is relatively high, and easier to dehydrate; pH less than 7, both dehydration rates are low, and the lower the pH, the lower dehydration rate is; When the pH is increased to 7, both dehydration rates have been increased, while acidizing crude oil emulsion dehydration rate is significantly increased; When the pH is increased from 7 to 9, both dehydration rate are increased slightly, but some of them also is on the decline, so both crude oil emulsion in neutral and slight alkali environment are more advantageous to dehydrate; adjusting pH to reasonable range is effective measure to improve dehydration rate critical tensile bearing capacity and trap gas dissipation, and the comprehensive evaluation technology of trap dynamic sealing of reservoir gas storage under alternating load is formed. Scientifically guiding the optimization design of upper limit pressure and dynamic monitoring system, and supporting low cost and efficient reservoir construction are of great significance for similar reservoirs.