Abstract: Due to the inconsistent stratigraphic sequence of the stratum in the borehole sample, it is difficult to accurately determine the topological relation of each stratum in 3D stratum model based on borehole data. Hence, one of the key technologies in the 3D geological model is to make full use of the borehole data. Based on the theory of geological interpretation method, the stratigraphic sequences were confirmed automatically through the frequency of the stratum appearing at the upper location of all boreholes in the region. By using the surface modelling method, the recursive method of sub-drilling was first introduced to establish the 3D stratum model layer-by-layer from bottom to top. Meanwhile, this method can also adapt to the complex geological formation, such as strata pinch-out, stratigraphic overlap, and lens. The proposed 3D geological modelling algorithm with the advantages of precise geoscience meaning, good robustness, high efficiency and reliable operability, was already implemented into TJSG software and applied to some practical 3D geological modelling projects successfully. The research results indicate that the proposed algorithm can not only fully use all the borehole information to create a 3D geological model, but also has strong adaptability for complicated stratum.

Key words: 3D strata, borehole, stratigraphic sequences, recursive