The energy produced by steam injected to bottom-hole can generate ultrasonic wave through ultrasonic generator connected at the bottom of the steam injection tubing string, which induces bottom-hole oil-water mixture to form supermicro emulsion. With continuous steam injection, the emulsion accmulates toward high permeable zone. Thus steam injection profile has been improved and steam overlap overcome. Good results have been obtained in lab experiments and field application in Le An Oilfield by using this technology. This paper presents the study and application of this technology and other effective technology for plugging in Le An oilfield.