Representing the geological body heterogeneous property field using the quadratic generalized tri-prism volume function model (QGTPVF)

Abstract

3D geological modeling should be an effective tool for accurately representing the geometric structure boundary and internal property fields of geological body. However, conventional methods have rarely focused on the expression of geological heterogeneous properties, known as 4D modeling. A volume function is defined as a piecewise mathematic function that describes a parameterized geological property field and created by fitting the property functions of certain 3D voxels. The quadratic generalized tri-prism volume function (QGTPVF) model is proposed for representing geological property fields with a sedimentary strata structure based on the volume function method and generalized tri-prism (GTP) voxel model. A QGTPVF is designed for borehole sample points, and it interpolates geological properties by fitting quadratic volume functions combined with the influence of geological geometric structure constraints, including stratum interfaces and fault planes. This research mainly focuses on the QGTPVF definition and fitting method, single GTP volume function is a continuous quadratic function, and a property smoothing along directionally adjacent bedding GTPs method is also studied, so geological property field is also expressed by the smooth function. A preprocessing method of faults geological structures is given, and the general framework QGTPVF is also discussed for practical applications. The QGTPVF model could be converted to tetrahedron voxel and 3D grid models for calculation and analysis easily. An example on a porosity property field is studied to verify the method’s accuracy and reliability by comparing to Kriging and inverse distance weighted interpolation methods, and the result of accuracy and time complexity are better, so the QGTPVF provides a new solution for modeling geological property fields.