Developing an algorithm to estimate in situ stresses using a hybrid numerical method based on local stress measurement

The main contribution of this paper is to develop an algorithm to estimate in situ stress using a hybrid numerical method based on data of local stress measurement. Suggested hybrid method, first, estimates field stresses using an adverse Boundary Element Method (BEM3D) and local stresses are then calculated by Finite Element (FEM3D) or Finite Difference Methods (FDM3D) under certain conditions. Also it is possible to reach arbitrary accuracy for stress estimation. To show the applicability of this algorithm, it is applied for the Seymare Dam (SD) site to determine the stress field. Based on the local stresses measured by Hydraulic Fracturing (HF), the stress state at SD is estimated by the proposed algorithm in which the far-field stress state has been calculated using a 3D boundary element code, after which the local in situ stresses are calculated using a 3D finite element code. Finally, the results are compared with those elicited from the HF method. The finite element results, considering 10% allowable error, roughly coincides with the measured results.

► A new algorithm for determination in situ stresses by a hybrid method based on stress measurements is developed in this paper. ► Proposed method is, also, applied on Seymare Dam site. ► Results show how the estimated stresses coincide well with the measured in situ stress data by HF. ► It also shows that if the number of stress measurement data is adequate, it will be applicable to estimate the stress state with arbitrary accuracy in an unknown location.