Research On 3D Geological Modeling Method Based On Mud-Logging Data

Mud-logging data covers all kinds of information in the drilling process. It is the basis of geological analysis and interpretation and the guidance of exploration and exploitation. With the development of computer technology and the change of logging industries’needs, the traditional way that using two-dimensional graphic to express, analyze and process mud-logging data can not meet the requirements of deeply understanding of the geological structure. With advantage of expressing information more visually and more precisely, three-dimensional geological model has become an inevitable trend of development.This paper contains both property model and structure model in the 3D geological modeling method based on mud-logging data. The main research contents and results are as follows:1) This paper discusses the basic theory and widely used methods in 3D geological modeling. To lay the foundation for the research, it analyzes and compares with different methods, summarizes the advantages and disadvantages of each model.2) This paper studies of the use of different types of mud-logging data in 3D geological modeling, describes that the data hasn’t been through hierarchical processing, analyzes the spatial characteristics of mud-logging data and summarizes the requirements of mud-logging data on property modeling and structure modeling to clarify the research goal.3) This paper analyzes the basic theory of Ordinary Kriging method. The experimental semi-variogram function is calculated by searching the data according to altitude and classifying them into groups of different step width in this paper. To fit semi-variogram function better, locally weighted fitting method and cubic polynomial model are proposed. Through the estimation experiments both within and between wells, it’s verified that the cubic polynomial model provides high precision results and is much better for mud-logging data modeling.4) This paper studies of surface models and volume models in structure modeling. Based on grid model, triangular mesh surface method is proposed to rebuild the irregular structure of target layer and to reduce the dependence on the data points. With conversion between grid model and cuboids volume model, it realizes fast displaying of mud-logging data and to help do geological analysis at the same time.5) This paper analyzes and designs the 3D geological modeling system based on mud-logging data, discusses the system architecture and module division, designs the corresponding 3D database and finally implements the system. Through the practical examples, the feasibility and validity of the research of this paper is verified.The 3D modeling method proposed in this paper can realize the 3D display and analysis of mud-logging data with higher precision and meet the requirements properly. It has important practical significance for promoting the development of logging industry.