ABSTRACT:

A set of hydro-fracturing tests were conducted to obtain the geostress in II measuring segment of 2 boreholes ranging in depth from 164.92 to 373.98 mat locations of Gaocun Iron Mine of the Ma'anshan site in the east of China. Results of all hydro-fracturing tests showed that all of the HFT parameters increase with depth. Roughly, the relation among these parameters is SH > Sv > Sh. And the orientation of the maximum horizontal main stress is N326.5°W~N338.2°W with an average value of N332°W It shows that the orientation of the main stress is close to NNW, and the ratio of maximum horizontal principal stress (hc) to vertical principal stress (Sv) is 0.94~1.40 with an average value of 1.18 in 10 measuring points. Logging data and laboratory observations of core samples reveal the cracks oriented at N332°W±6°. This paper describes the various applications of the result of hydro fracturing. The gestures measurement results provide a solid basis for mining design.

1 INTRODUCTION

Geostress is a natural stress that exists in the strata. Knowledge of Geo-stress is very important in many problems related to rocks in civil and mining engineering. Hydro-fracturing stress measurements for determining in situ stresses are used in different areas such as mine and tunnel construction, earthquake prediction, and oil and gas source designing all over the world (Goodman 1989, Cardy & Brown 1993, Ziaie et al. 2012, Haimson & Fairhust 1970, Haimson & Rummel 1970, Hubbert & Willis 1957, Shadizadeh et al. 2009).

Several studies have been carried out on hydraulic fracturing methods in China (Cai 2000, Gao & Ding 1990, Liu 1998, Wang 2000, Liu & Li 1991, Jing et al. 2007, Chen & Li 1998, Xiao & Luo 2005). They performed an extreme test program to find out the best layer to perform hydraulic fracturing tests. The stated the formation could be a good candidate for this.

The aim of this study is to analyze and assess the results of hydraulic fracturing tests at the Gaocun Iron mine, china, to determine the magnitude and orientation of the principal stresses.

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