Eogenetic karst and its control on reservoirs in the Ordovician Majiagou Formation, eastern Sulige gas field, Ordos Basin, NW China

XIE Kang,TAN Xiucheng,FENG Min,WANG Baobao,ZHONG Shoukang,YANG Mengying,NIE Wancai,QIAO Zhanfeng,ZENG Wei

Fig. 6. Upward-shallowing sequence and karst characteristics of section 3427.72-3430.83 m in Well T51. (a) Micrite dolomite with moldic pore, connected dissolved moldic pores are highly filled, cast thin section, single polarized light; (b) micrite dolomite with moldic pore, connected dissolved moldic pores are highly filled, cast thin section, single polarized light; (c) sparry grain dolomite, containing leaf-like gravel grain and freshwater dolomite cements, cast thin section, single polarized light; (d) micrite dolomite with moldic pore, cast thin section, single polarized light; (e) argillaceous micrite dolomite interbedded with micrite dolomite, ordinary thin section, single polarized light.