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Karst Mesa and Their Relation with Cave Layer

Yuan Li, Xinbian Lu, and Zhongxian Cai
China University of Geosciences, Wuhan City, China

Tahe Oilfield is the largest marine oilfield in Palaeozoic, which was discovered in 1997. The reserve is over 90 percent in karstic-fractured reservoir, Ordovician, and the karstic-fractured system is the most important reservoir space type, Karstic-fractured reservoir in Ordovician is mainly controlled by multiphase karstification, caused by multiphase tectonization from Middle Caledonian to Early Hercynian. The stratum rise, Karst drainage base level is down, Karst water is down-cutting erosion, Karst mesa is Damage and the transformation, When the stratum in a relatively stable, Under the new period of action of karst, Karst water constantly adapt to the new drainage base level, Form new system of replenishment, runoff, drain, finally in a certain region, we divide karst geomorphology into three Karst mesa in Tahe Oilfield, At the same time in drilling data, it reveals the three cave layer.

The survey of the Qingjiang area shows that there are three karst mesa. The height of the level 1 karst mesa is about 1800-2000 meters, The height of the level 2 karst mesa is about 1600-1800 meters, The height of the level 3 karst mesa is about 1600-1800 meters, This area development Multilayer cave, It can divided into three concentrated distribution layer in vertical, The height of high altitude cave is about 1700-1800 meters, the height of medium altitude cave is about 1500-1700 meters , the height of low altitude cave is about 1300-1500 meters.

Contrasting the relation of Karst mesa and cave layer in Tahe oilfield and Qingjiang area, we propose that at the edge of drainage-way and drainage base level, no water-resisting layer. The same level of Karst mesa Control and developed horizontal cave which have the same height with Karst mesa.

AAPG Search and Discovery Article #90175©2013 AAPG Hedberg Conference, Beijing, China, April 21-24, 2013