Construction Of 3D Geological Model In Beishan Gansu Province

The Beishan area in Gansu is an alternative site reservoir for deep geological disposal of high-level radioactive waste in China.It is affected by the extremely lack of borehole data,the low degree of basic geological research,and the different understanding of strata and fault structures The research in geology and hydrogeology is still in its infancy.Three-dimensional geological modeling is a combination of raw data and computer technology,through a series of mathematical models,supplemented by appropriate visualization methods,to form a computer technology that can reflect the basic elements of geological structure and the changing laws of various attributes within the geological body.By carrying out three-dimensional geological modeling,the thesis has important theoretical and practical significance for displaying the spatial changes of strata,faults and permeability parameters in the study area.Taking 3D geological structure modeling and attribute modeling as research goals,taking Beijing Grid World DepthInsight as a platform,combining 3D modeling theory and methods,using field geological survey,drilling core observation and the data Interpretation,profile restoration,and the increase of virtual wells have established a three-dimensional spatial distribution model of strata,structures,and rock bodies near the deep geological disposal site reservoir in Beishan area.Based on the structural model,using the existing borehole data,according to the diversity of rock physical properties,and using the spatial variation correlation characteristics generated by geostatistics to simulate the permeability coefficient changes,a permeability coefficient model of the site library is constructed.Through the establishment of three-dimensional models and permeability coefficient models at different scales,multi-source data information is transformed into more intuitive three-dimensional spatial visualization information,which can more intuitively observe the formation,lithology,fracture distribution and permeability coefficient changes,which are the foundation of numerical simulation and served the site selection of the high-level waste disposal repository in the study area well.The main achievements of the thesis include: 1)Using plane geological maps of different scales as the original data,supplemented by profile information,borehole information,and terrain information to establish a three-dimensional geological model.2)The generalization method of irregular rock mass exposure and the modeling method of stratum and aquifer are proposed.3)Two types of three-dimensional geological structure models and three-dimensional hydrogeological structure models have been established.4)On the basis of structural modeling,the inter-well interpolation method and random modeling are used to establish the aquifer system attribute model of the site library.