Visual representation and characterization of three-dimensional hydrofracturing cracks within heterogeneous rock through 3D printing and transparent models  

作　　者：Peng Liu Yang Ju Pathegama G. Ranjith Zemin Zheng Li Wang Ayai Wanniarachchi 

机构地区：[1]School of Mechanics and Civil Engineering, ChinaUniversity of Mining & Technology, Beijing 100083, China [2]State Key Laboratory of Coal Resources & Safe Mining,China University of Mining & Technology, Dll XueyuanRoad, Beijing 100083, China [3]State Key Laboratory for Geomechanics & Deep Underground Engineering, China University of Mining &Technology, Xuzhou 221116, China [4]Department of Civil Engineering, Monash University Clayton, Melbourne, VIC 3800, Australia

出　　处：《International Journal of Coal Science & Technology》2016年第3期284-294,共11页国际煤炭科学技术学报（英文）

基　　金：We gratefully acknowledge the financial support of the National Natural Science Foundation of China （Grants 51374213 and 51674251）, National Natural Science Fund for Distinguished Young Scholars of China （Grant 51125017）, Science Fund for Creative Research Groups of the National Natural Science Foundation of China （Grant 51421003）, Fund for Innovative Research and Development Group Program of Jiangsu Province （Grant 2014-27）, and the Priority Academic Program Development of Jiangsu Higher Education Institutions （Grant PAPD 2014）.

摘　　要：The heterogeneity of unconventional reservoir rock tremendously affects its hydrofracturing behavior. A visual representation and accurate characterization of the three-dimensional （3D） growth and distribution of hydrofracturing cracks within heterogeneous rocks is of particular use to the design and implementation of hydrofracturing stimulation of unconventional reservoirs. However, because of the difficulties involved in visually representing and quantitatively characterizing a 3D hydrofracturing crack-network, this issue remains a challenge. In this paper, a novel method is proposed for physically visualizing and quantitatively characterizing the 3D hydrofracturing crack-network distributed through a heterogeneous structure based on a natural glutenite sample. This method incorporates X-ray microfocus computed tomography （μCT）, 3D printing models and hydrofracturing triaxial tests to represent visually the heterogeneous structure, and the 3D crack growth and distribution within a transparent rock model during hydrofracturing. The coupled effects of material heterogeneity and confining geostress on the 3D crack initiation and propagation were analyzed. The results indicate that the breakdown pressure of a heterogeneous rock model is significantly affected by material heterogeneity and confining geostress. The measured breakdown pressures of heterogeneous models are apparently different from those predicted by traditional theories. This study helps to elucidate the quantitative visualization and characterization of the mechanism and influencing factors that determine the hydrofracturing crack initiation and propagation in heterogeneous reservoir rocks.

关 键 词：Hydrofracturing cracks Visual representation and characterization Transparentized structures Heterogeneous rock 3D printing Coupled effects of heterogeneity and geostress 

分 类 号：P631.819[天文地球—地质矿产勘探] TE2[天文地球—地质学]