Abstract: Mini-structure is small highs and lows exhibited on its overall background, with a height difference of less than 10m and covering an area of less than 0.3km 2 generally. These structures include positive mini-structures and negative mini-structures. The former ones are regions of oil and gas enrichment and the later ones are regions where severe water invasion occurs. According to developmental practice in Kenxi Oilfield, wells located on the positive mini-structures are better than those on negative mini-structures. In the designing of well locations, according to mini-structure, infull wells should be drilled on the positive structure areas and only injection wells are drilled in the negative mini-structure areas.