Study of forming mechanism of "chimney-effect" (CE) has important significance for basic theory and applications of non-seismic geophysical and geochemical methods locating oil/gas reservoirs. The theoretical basis of comprehensive evaluation of mechanism of CE using principles of magnetism, geochemistry and mineralogy has been reviewed, with the problems to be solved: (i) study for the relationship between process of oil/gas migration and geochemical field; (ii) analysis of genesis of magnetic, geochemical and mineralogical anomaly; (iii) interpretation of surface soil magnetism and geochemical anomaly combined with seismic data.