Analysis of the spatial variability on a fracture network based on an oriented semivariogram

Abstract

Using an oriented semivariogram in geostatistics, this paper studied the spatial variability of the fissure network of Lianhuashan fault and Wuzhishan anticline in Gejiu Gaosong Ore Field. First, the field outcrop fracture network was digitized based on ArcGIS, and the fracture density and intensity were extracted. Then, based on GSLIB, the fracture density and intensity maps were calculated along the azimuth angle of 0-175°, 36 experimental semivariograms were created and Kriging interpolation was carried out, and finally, normalized semivariogram graphs were created to quantify the two-dimensional spatial variability of individual fracture intensity and density. It was indicated that the closer to the fault, the greater the spatial variation of the fracture density and intensity, and the its spatial variability was featured in significant anisotropy. The direction with the smallest spatial variability was parallel and close to the fault, the largest direction was perpendicular and close to the fault, the direction with the smallest spatial variability at the proximal fold was parallel to the axial direction of the fold, and the largest direction was perpendicular to the axial direction of the fold. The spatial variability of the fracture network reflected the different effects of faults and folds on the development of the fracture network and provided a reference for the establishment of a three-dimensional fracture network spatial distribution model in the ore field.

Keywords

• geostatistics
• fracture network
• spatial variability
• gaosong ore field
• kriging interpolation