In the process of image regional recognition process, the set method has some problems such as large data volume, high time complexity, ect. Here we proposed a theory based on path reduction "label absorption" approach. This method can reduce the height of the search tree and reduce the time complexity. And it just needs to scan the image for one time to complete the identification of regional connectivity. This paper discusses in detail the whole process of implementation of the method and application in oil and gas development. And we have achieved good results.