Abstract：The possibilities of our determining boundary,thickness,width，apexes,shape and other geological parameters of a hydrocarbon reser-voir by making use of direct-current resistivity method are discussed on the basis of experiment upon the hole-surface operation way(Source electrodes A and B are in hole and at an infinite distant place respec-tively while potential electrodes M and N for measuring apparent resis-tivity are on the ground surface).Under the favourable conditions of ideal hydrocarbon-reservoir re-sistivity that is much higher than enclosing rock resistivity,simple reservoir shape,uniform enclosing rock resistivity,fiat ground surface and easy removal of case noise,the direct-current resistivity method can be used to.determine quite well the boundary and horizontal distributions of the hydrocarbon reservoir on condition that the hole penetrates the re-servoir.·predict the thickness,width and boundary of the hydrocarbon reser-voir when the hole meets and fails to penetrate the reservoir，or pas-ses nearby the reservoir.·locate the reservoir top.·ascertain the shape and occurrence of the reservoir.·monitor reservoir development.
