A BOREHOLE CORRECTION APPROACH FOR THREE-DIMENSIONAL GEOLOGICAL MODELING BASED ON TRIANGULAR PRISM

Since the emerging of three-dimensional geoscientific studies, borehole data have become the major data source for true three-dimensional geological modeling because of intuitiveness, accuracy and elaborateness. In the meantime, triangular prism (TP) has been widely applied in the studies in geological modeling as the most basic volume model. However, the real boreholes should always deviate due to the geological conditions and drilling technical level, which are not applicable in geological modeling based on TP volume featured by perpendicular lateral edges. This research takes borehole data as the original data and studies the spatial relationship between the geological objects constructed by real deviated and virtual vertical boreholes respectively in order to achieve a borehole correction approach for deviated borehole data. The principle of the correction approach is to maintain the original information provided by boreholes and ensure the restoration of factual borehole information when the model built by virtual boreholes is drilled by the same deviated boreholes. After preprocessing the real borehole points on the surface layer with Delaunay triangulation, this approach identifies the triangle of TIN constituted by virtual borehole points for each real borehole point and hence builds the connection between the real and virtual borehole points. According to the connection, the mathematical correction model would be established which is categorized into two types: equations of triangles which contains the real borehole points and virtual borehole points. The equations are solved to acquire the coordinates of the virtual borehole points which could be used to construct three-dimensional geological TP model afterwards. The experiments have been conducted under various conditions of boreholes and geology, and the result proves the effectiveness the proposed borehole correction approach, which would provide reliable and applicable borehole data for three-dimensional geological modeling based on TP.