Method for Visualizing Fractures Induced by Laboratory-Based Hydraulic Fracturing and Its Application to Shale Samples

Energies

Yuto Tomonaga¹  Youqing Chen¹  Makoto Naoi²  Tsuyoshi Ishida²  Takashi Akai³  Hiroyuki Tanaka³  Sunao Takagi³ 

[1] Graduate School of Energy Science, Kyoto University, Yoshida-Honmachi, Sakyo-ku, Kyoto 606-8501, Japan;Graduate School of Engineering, Kyoto University, Kyoto daigaku-katsura C-cluster, Nishikyo-ku, Kyoto 615-8540, Japan;Japan Oil, Gas and Metals National Corporation, Toranomon Twin Building 2-10-1 Toranomon, Minato-ku, Tokyo 105-0001, Japan;

关键词: hydraulic fracturing;    shale;    fracture pattern;    laboratory test;    polarization microscope observation;    visualization;   

DOI  :  10.3390/en11081976

来源: DOAJ

【 摘 要 】

A better understanding of the process of stimulation by hydraulic fracturing in shale gas and oil reservoirs is necessary for improving resource productivity. However, direct observation of hydraulically stimulated regions including induced fractures has been difficult. In the present study, we develop a new approach for directly visualizing regions of shale specimens impregnated by fluid during hydraulic fracturing. The proposed laboratory method uses a thermosetting resin mixed with a fluorescent substance as a fracturing fluid. After fracturing, the resin is fixed within the specimens by heating, and the cut sections are then observed under ultraviolet light. Based on brightness, we can then distinguish induced fractures and their surrounding regions impregnated by the fluid from other regions not reached by the fluid. Polarization microscope observation clearly reveals the detailed structures of tortuous or branched fractures on the micron scale and interactions between fractures and constituent minerals. The proposed experimental and observation method is useful for understanding the process of stimulation by hydraulic fracturing and its relationship with microscopic rock characteristics, which is important for fracturing design optimization in shale gas and oil resource development.

【 授权许可】

Unknown