Characteristics of Tight Dolostone Reservoir and Its Main Controlling Factors in the Submember Ma5₅ of Majiagou Formation in the Western Ordos Basin

Figure 2

Microphotographs showing the petrographic characteristics of the intercrystalline pore-type dolostone reservoir in the submember Ma5₅ in the western Ordos Basin (IP = intercrystalline pore; Idp = intercrystalline dissolved pore; Mp = micropore; Rt = residual texture; Py = pyrite; Rct = residual chondrum structure). ((a) Powder-fine dolostone with oolitic texture, 4040.05 m, well Y1117; (b) powder-fine calcite-containing dolostone with chondrum structure, 4088.50 m, well Y1165; (c) intercrystalline pore, 3710.80 m, well S22; (d) intercrystalline pore, 4040.50 m, well Y1117; (e) micropore, 3954.80 m, well Y1112; (f) intercrystalline dissolved pore, 4040.10 m, well Y1117).

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