Adaptability Of Acidizing Plug-removing Technique In Ansai Oil Field, Ordos Basin

The reservoir is of ultra-low permeability in Ansai Oil Field. Plugging is very common and serious in producing formations. As one of the plug-removing measures, acidizing plug-removing technique has been applied in the oil field to maintain and increase oil production. However, the result changed widely in different wells and was difficult to evaluate objectively, because the acidizing plug-removing technique are related with many factors.Based on the data from 188 oil wells, research was done on formation damage mechanism, plugging characteristics, reaction mechanism of acidizing fluid, sandstone matrix and formation fluid, compatibility of injected water and formation fluid, characteristics of kinds of acidizing fluid systems, factors to acidizing plug-removing technique and so on. As a consequence, the acidizing plug-removing technique is adaptabile to reservoirs in Ansai Oil Field. It is affected by physical property of reservoir, formation pressure, acidizing fluid system and so on.