DISCUSSION ON THE STRESS TRAPS OF OIL/GAS

The main factors of crust deformation are of the changes of stress fields and the geological stress itself.Therefore,the movements of all materials which include oil,gas and water in petroliferous formations and basins are controlled and driven by geological stresses.As the petroliferous formation are considered as elastic-plastic bodies with isotropic,homogeneous and continuous characters,a series of anti-clines and synclines would be analogous to deflection of solid materials which is due to unstable by force.Based on the relationship amound the isopleth distribution of tri-dimensional principal strsses,known oil/gas migration directions and the location of oil/gas accumulation,it is suggested that oil/gas migration direction is perpendicular to the trace of main pres-sure stresses(σ₃),and parallel to the trace of main tensile stresses(α₁).The oil/gas accumulation is located at low pressure zone in a closed tri-dimensional stress-gradient space composed by the traces of the main tensile stress(σ₁)and the central main stress(σ₂).