Core Network Model Construction Based On Computational Geometry Method

In the micro pore scale,the core network model construction of the porous reservoir rock which is encountered in oil and gas production process has become an important means of pore structure characteristics analysis,but there are still some shortcomings.In this paper,a new method based on computational geometry method is proposed to construct the core network model which proposes a new research thought to the analysis of core pore space.In this paper,a visual software platform based on MFC single document platform and OpenGL technology is built with the basis of core CT images.The pore-throat recognition of core image,the construction of three-dimensional pore space solid model and the construction of core network model are realized.And,the study of core pore structure and microcosmic fluid flow theory is realized.In this paper,we study a series of modeling algorithms which aimed to build a core network model from CT images.The main contents of the thesis are as follow:In the aspect of core image processing,we select the mean filtering algorithm to reduce the noise of image,then we select the best threshold for image binary conversion and extract three-dimensional spatial data of core pore space from the segmented images.Next,we implement pore-throat recognition preprocessing through the image edge detection and image skeleton extraction based on the segmented binary image.Finally,we put forward the pore-throat recognition algorithm of core image based on maximal inscribed circle to complete the pore-throat recognition and data extraction of pore and throat.In the aspect of the construction of three-dimensional pore space solid model,firstly,we use linear Octree construction algorithm to construct the primary hexahedral unit network model of pore space based on the three-dimensional space data extracted from the pore space.Then we simplify the redundant parts of hexahedral unit network model and delete redundant data to complete the construction of three-dimensional pore space solid model.In the aspect of network model construction,a new method based on computational geometry method is proposed to construct the pore network model.Based on analyzing the hexahedral units of three-dimensional core solid model,we put forward a new network model construction algorithm based on the judgment of hexahedral units affiliation and the geometry transformation of hexahedral units.In the aspect of the analysis of core parameters,some appropriate parameter calculation methods are used to calculate the structure parameters of the core model.And a data interface of Excel is written for the calculation and analysis of model parameters by importing the model parameters into the Excel.A data interface of Rhinoceros is also written for model analysis and format conversion by importing the core model into the Rhinoceros.Then,the format transformed model is imported into the Fluent to complete the seepage flow simulation to obtain the seepage parameters.In the aspect of the establishment of the interactive operation and visualization software,the image pore-throat recognition algorithm,linear Octree modeling algorithm and pore network model construction algorithm,as well as the model parameters calculation are realized by computer programming.The array data structure and linked-list data structure are also established to realize the storage of the data results,the visualization of the network model and the interactive operation.