More Hydrogen Acid System Performance And Adaptability Research

The choice of the acid system is the key factor to the the success of sandstone matrix acidizing. The multi-hydrogen acid which is a new acid system has been researched and applied widely in oil field. At the present, the study to the multi-hydrogen acid has concentrated in the properity of the acid system, but the study about the adaptability is relative less, resulting in the application of the multi-hydrogen acid in oil field that exist plenty of blindness and randomness. On the basis of fully understanding the properity of the retarding, wetting and secondary precipitate-inhibiting, the adaptability of mud acid and multi-hydrogen acid on the different types of sandstone formation was studied both macroscopically and microscopically.Starting from the multi-level ionization and chemical adsorption properity of the multi-hydrogen acid, the theoretical analysis and experimental comparative study is provide for the retarding properity of multi-hydrogen acid. The hydrogen ions which multi-hydrogen acid disassociate gradually is reacted with ammonium bifluoride to produce HF in the acidizing treatment. when the reaction with the formation starts, an alumium-silicate-phosphonate plating is formed over the clays by chemi-adsorption, dissolution experiment showed that the dissolution and dissolution rate of multi-hydrogen acid on montmorillonite and natural sandstone was less than mud acid; the properity of the wetting was studied comparatively. The wetting angles of multi-hydrogen acid with quarts was smaller, the dissolution abilities of multi-hydrogen acid with quarts was extremely high. The chelating test show that the multi-hydrogen acid had a strong ability of chelating to calcium and iron ions, at the same time.the dissolution and the concentration testing of the ions in the residual acid show that the multi-hydrogen acid could effectively inhibit the secondary precipitate of fluoride and fluorosilicate.By the experiments of core flow stimulation effect test, scanning electron microscopy analyzing, ions concentration analyzing in the residual acid, the adaptability of mud acid and multi-hydrogen acid on the diffierent types of sandstone was studied comparatively. The following conclusions can be drawn according to this studies:(1)The reacttion rate of multi-hydrogen acid on the rock is more slowly and the activity of acid can keep for a long time, for shaly sand, loose consolidation sandstone formation, the multi-hydrogen acid that does not destroy the rock matrix structure, while deeply acidizing can be obtained.(2)The multi-hydrogen acid has the properity of good retarded acidizing and a effectiv role in acidizing penetration distance, for the long-term injection deeply damage formation, the objective of deeply acidizing can be obtained by applying multi-hydrogen acid.(3) The multi-hydrogen acid has a strong ability to dissolve quartz, for long stone quartz sandstone formation, the multi-hydrogen acid can further dissolve rock matrix, increas the rock pore radius and thereby enhance the porosity and permeability.of formation.(4)The multi-hydrogen acid hold a advantaged properity of secondary precipitate-inhibiting, for low permeability high clay sandstone formation, the multi-hydrogen acid can reduce the secondary deposition and the risk of formation damage.The result of this study has great significance to the choice of the acid system for sandstone matrix acidizing. Improved the specific application of multi-hydrogen acid in oil field, and promoted the theory of sandstone formation acidizing of multi-hydrogen acid technology.