In this paper various types of ring-like images have been studied systematically

which appear on remote sensing imagery

locate on outer and inner the oil-gas field of the loess plateau on the east part of Gansu province

Among them six different types of tonal ring-like images. on the south region of the study area were chosen and the related soil geochemical data from outer and inner the six tonal ring-like images have been analyzed. The results show that: （1） All of the tonal ring-like images on the imageries come from geochemical haloes. （2） The Y-1 ring covering a known oil-gas well is a oil-gas halo ring with a significant relationship between geochemical data and ground soil spectral response. By analyzing the tape lightness of the ring images

the regular variations of the lightness mean values between inner and outer the oil-gas halo rings have been discovered. One of them is the significant difference proved by the variance analysis. In order to identify the general applying significance of the Y-1 ring lightness varying regulations

another tonal ring covering a productive oil-gas well

a tonal ring-covering no oil-gas well

a tonal ring covering a nonsignificant productive oil-gas well and a known oil-gas region

which are located on north part of the study area that shows a slightly different in geographic conditions from the Y-l ring area

have been compared between each other for their lightness variation regulations. The researches are resulted in the following model for estimating oil-gas haloes from the remote sensing imagery:（1） On the colour composite imageries from the TM4（R）

TM5（G） and TM7（B）

the tonal ring-like image red tone on the inner ring and blue tone on the outer ring are suggested to be oil-gas halo ring.（2） The CCT tape lightness mean values of the outer rings are almost higher than that of the inner rings in the TM1-7 and TM5/7.（3） Except the TM4

the lightness mean values of all the TM bands give significant differences between inner and outer rings.