Data interpretation method in HF stress measurement for the total stress tensor determination in rock mass

Abstract

The data interpretation method is validated for the hydraulic fracturing stress measurements for determining simultaneously all components of external stress tensor in rock mass in the vicinity of underground geotechnical structures. The analysis of the alternative patterns of 6 measurement boreholes reveals allowable drilling directions of boreholes to ensure the formulated problem resolvability. The analysis includes the solution of direct problems on finding “the normal stresses in the areas orthogonal to the axes of the boreholes at the known external stresses” and the solution of an inverse problem on finding the external stresses. In the proposed method, the input information may be the data obtained in the in-situ HF stress measurement. The numerical experiments with the synthetic input data determine allowable variations in orientation of measurement holes in directional drilling such that the measuring fault of external stresses is no thigher than 10%.