Abstract:  Horizontal wells, as one of the most efficient ways, are applied to develop the Triassic bottom water sandstone reservoir in district 9 of the Tahe Oilfield. Because of sufficient bottom water energy and serious heterogeneity, water coning can be formed along hypertonic paragraph, resulting in quick increasing of water content. Gels with strong plugging capacity and strong oil-water selectivity are used to block water channels. Water is blocked much more than oil even though gels enter into oil-water passage due to strong oil-water selectivity. This technology applies well in practice testing.