Research On Characteristics And Constitutive Relations Of Volcanic Tuff Reservoir In Hailaer Basin

Xing'anling reservoir with volcanic tuff is the main oil resource of Hailaer oilfield, but the productivity with perforation completion is too low to economically develop. Since fracturing measures can improve productivity by 2-8 times, reasonable fracturing technology is the key to increase oil production from Xing'anling reservoir with volcanic tuff.But it's different from fracturing the conventional sandstone reservoir. The difficulties are: the sand blockage in early fracturing stage(the blockage occurred at sand ratio 3% in 97# layer in Bei16 well), low discharge ratio of fracturing liquid out of formation, and low success ratio. To increase success ratio of fracturing so as to improve the development of Xing'anling reservoir, it is essential to study the properties, characteristics and rock mechanism to provide theoretical support to the mechanism research and field operation of fracturing measures. This research project focuses on the following subjects:1. Based on generalization of the historical data of exploration, drilling and pilot experiments, the special characters of the reservoir with volcanic tuff in Hailaer basin are recognized; the development history is reviewed in this paper.2. Starting from characters research of the reservoir with volcanic tuff, the mechanical characteristics of the rocks, earth stress characteristics of the reservoir, mineralogical characteristics and hydration characteristics are studied.3. According to the feature that the constitutive relation varies obviously in the plastic stage of the reservoir with volcanic tuff, the constitutive equations with characteristics of strain-softening, ideal plasticity, and strain-hardening are respectively deduced.The research result builds up the theoretical basis for the following fracturing mechanism research and field fracturing experiment, it is practically important.