Quantitative Analysis And Application Of Three-Dimensional Geostress Distribution In The Target Area

Accurate description of faults and natural fractures is one of the key problems in3D geostress modeling of complex strata.In this paper,the Ying Xi area in western Qaidam Basin is taken as the target area.Through the analysis of lithology data,seismic data and data provided by field engineers,it can be confirmed that the target area is a fracture-corrosion cavity carbonate reservoir.The rock mechanics parameters and one-dimensional geostress profile of the target formation are calculated and analyzed by using the laboratory rock mechanics experimental data and logging data.The elastic constants of faults and natural fractures in the target area are calculated by using the theory of equivalent elastic constants of fault structures and corresponding calculation methods.On this basis,the three-dimensional geostress model of the target block is established.The results show that the target block is a strike-slip fault model,and the minimum horizontal geostress is distributed in the range of 78–96MPa,the maximum horizontal geostress is distributed in the range of 95–115MPa,the pressure of overlying strata is distributed in the range of 86–100MPa,and the horizontal geostress difference is in the range of 6–16MPa.The azimuth of regional crustal stress varies greatly,and the maximum horizontal crustal stress is NE25~o-90~o.Horizontal stress difference IV layer is the highest,V layer is the lowest,and VI layer is the lowest.The simulation results show that the fracturing effect of VI layer is better under the same fracturing construction conditions;the greater the angle between natural fracture and horizontal minimum ground stress,the better the fracturing effect;the engineering and geological desserts of the design well are given by evaluation,which has guiding significance for field construction.