Theory And Application Of Three-Dimensional Simulation Of Hydrogeologic Structure Based On Transition Probability

The distribution of lithology is the main objective of geologic survey and the foundation of related research, such as hydrogeology. Generally, the accuracy of the spatial distribution of lithology can largely promote related geological research by providing their data basis. Based on geostatistics, this study implemented the Transition Probability Geostatistical Software (T-PROGS) to analyze and interpolate the borehole data from the study area, and then the simulated lithological distribution in the whole space domain was obtained.The progress of hydrogeological structure simulation in China, as well as abroad, was firstly reviewed in the dissertation. Then, basic theories of geostatistics were briefly introduced, followed by the principle, features, and operation steps of the T-PROGS. Thirdly, the main contributions of the dissertation were presented: 1) the source code of T-PROGS is modified to adapt to the study area, the Beijing plain region; 2) the parameters, mainly the horizontal and vertical Markov Chains, were optimized; 3) a format conversion program, from T-PROGS result to x, y, z, property datasheet, was composed and applied; 4) the simulated results were displayed in 3-dimensions using a scientific visualization software TECPLOT; 5) the accuracy rate was estimated by sampled boreholes using a composed program. Finally, the T-PROGS model, along with the laws obtained from the Beijing plain region, was applied in the North China Plain.This work focused the application of the transition probability based geostatistical method to the plain region of Beijing, which covers 4454 km~2. By considering the trade-off of runtime and accuracy, a mesh with 500 m×500 m×2 m is defined in the model, there are totally 261×185×65 meshes. Using 1135 boreholes to calculate transition probability on vertical between different intervals; On vertical, established Markvo chain model by using discrete transition probability; On horization, established embedded transition rate matrix and used embedded transition rate to set up Markov chain model; Finally, using the conditional simulation method to finish hydrogeological structural model for BeiJing Plain. The method will also be extended to a wider range of the North China Plain, a mess with 4000 m×4000 m×2 m built in the model.The post-processing and inspection of the model are also focuses in this article. T-PROGS simulate a rectangular model, according to the actual study area, set the properties of the data which are outside the study region a specific value. In the results test, interpolated the simulation results to get the same coordinates of the property value with the data used for test, compared the measured value to simulation and then obtained the accuracy of the model.From the results of the dissertation, it can be concluded that geostatistical methods are not only suitable for small to middle scale regions, but are also applicable in large regions with complicated lithological distribution. And the satisfiable accuracy rate of simulation makes it certain that hydrogeological structure models can provide the data basis of related geological research and applications.