Transformed subordinate faults have many types and are of complex patterns, they are important subject of structure study, and also they are the important study base of ground surface stability.

Detailed interpretation of low-grade faults in horizontal well exploitation.;

Application of new seismic technique in identification of low-grade fault;

Taking Shengli Oilfield as an example, the remaining oil of this oilfield was controlled by the reservoir heterogeneity factors such as low-grade fault, interbed and the reservoir property.

Genetic types of low-grade faults and their geologic significance;

An experiment study on influence of subfault to petroleum migration and accumulation of Guantao Formation of Feiyantan area;

The method used such techniques as hierarchy diagnosis model, fault diagnosis tree, united empiristic diagnosis and principle diagnosis, which improved the precess of system development.

The concept,principle and method of hierarchy diagnosis are provided.