Conditions for Forming Oil-Gas and Thoughts for Further Exploration in Tanzhuang-Shenqiu Depression

Tanzhuang-Shenqiu depression, with an area of 2800 km², locates in central Zhoukou basin and is a secondary structural unit which underw ent two stages of superposition of fault depression during Meso-Cenozoic. The exploration confirms that huge-thick early Cret aceous strata were deposited in Mesozoic in the depression (about 2000 km²), with the dark mudstone having an average thickness of 1250 m. Oil/gas show different in grade, number of layers, and thickness can be seen in many wells and oil/gas flow is foundin wells such as Zhoucan well No.10, Zhou No.11, Zhou No.12, and Zhou No.19, which indicates a favorable exploration prospect. However, no breakthrough has been achieved up tonow, showing the complexity of exploration in this area. Except for unfavorable source rocks, the poor preser vation condition resulting fromint ensivelater eformation and the unfavorable adopted areal so two major causes for having not achieved the breakt hrough. So, how to locate the slightly reformed, slightly destructed, and well preserved structure is very important for us to achieve a breakt hrough in oil/gas exploration and an appropriate technique is also a key factor.