Abstract: Because tectonic stress coefficient from conventional horizontal stress model can hardly be obtained accurately, the corresponding mathematic expression is unable to make. By using the well logging data, formation breakdown test or hydraulic fracturing test, the minimal horizontal main stress can be measured accurately. Based on formation rock strength parameters acquired from logging data inversion calculation, the target well's horizontal main stress mathematic expression is established and the interpretation chart is drawn, and the maximal horizontal main stress can be calculated finally. In this new method, the overlying rock weight, the geologic structural stress and the formation pore pressure are all considered for the purpose of forecasting the horizontal main stress in target area for petroleum exploration.

Key words: complicated structure, ground stress model, interpretation chart, formation breakdown test, case history