Problems and Countermeasures for Comprehensive Utilization of “Tonstein”in China;

Acidizing is an effective method of rebuilding formation in sandstone formation, but it can also bring formation damage taken by forming oil-wetting formation, clay dispersing and flocculating, interfacial film and stringy milk.

Tested samples were taken from different sandstone formations of Changqing, Erlian, Jilin Oilfield, Sichuan and Tarim Basin and Venezuela and hydraulic fracturing treatments would be performed in these formations.

Observing the appearance of geological structure of fold break and joint etc resulted from the crustal stress, analyzing the characters of the joint relationship between the coal bearing seams, this paper discussed the formation mechanism of karst collapse column and gave a new theortlical basis for analyzing measuring the karst collapse column and putting it under control in a comperhensive way.

In this paper, a new method called Integrated Evaluation Model is proposed, which uses sonic and other related well log data to evaluate pore pressure, that is, with giving consideration to the effect of clay content, porosity, vertical effective stress of shale sand formation on sonic velocity.