Research On Microscopic Pore Structure Of Core Based On Geometric Modeling

The microscopic pore structure of core is an important factor that affects the macroscopic properties of the reservoir and the exploitation of petroleum resources.Reconstruction of digital core and pore network based on core image for microscopic flow simulation becomes a research hotspot in the field of core micro-analysis in recent years.Although many algorithms for construction of digital core and pore network model have been developed,they still exist many deficiencies.In this paper,the microscopic flow simulation of core is performed by the geometric method.The pore network extracted by the central axis method combined with the geometrical method is studied.A geometrical method is also used to divide the multi-morphology of pore and throat.A visual software platform for microscopic pore structure analysis of core is developed by C++ programming language based on core tomographic CT scan sequence images.The process from construction of the software platform to the algorithm research mainly includes these following aspects.When establish the geometric modeling for microscopic flow simulation of core,a digital core was firstly set based on tomographic CT scan sequence images.Then,the MC algorithm was used to construct the pore space surface model under the concept of digital core.Holes in the surface model was repaired and its structure was optimized.Finally,the microscopic flow simulation of core was performed through FLUENT,a fluid dynamics analysis software.For the construction of pore network model,a new algorithm is proposed,which is constructed based on pore network model of the medial axis and solid model.Firstly,the medial axis of the pore space was extracted by using a refinement algorithm aiming at the digital core.Then,taking the optimized pore space surface model as the constraint,the pore space solid model was established by adopting the Delaunay tetrahedron splitting algorithm.Thirdly,the model was divided into pore and throat combined with the medial axis and the solid model,and pore network model of core was finally completed.In the aspect of multi-modality division of pore and throat,we proposed a new algorithm for the multi-modality division of the throat based on the medial axis and surface model of pore space.Firstly,the actual throat segmentation is divided according to the center axis and the pore space surface model.Then the cross-sectional shape factor was calculated and classified to complete the multi-morphological division of pore and throat.In order to build a visual software platform,the system framework of the software platform was built based on VS2010 MFC module,the data structure of the software platform was designed,the human-machine interaction function of the software platform was realized,and the shared data interface of SOLIDWORKS and Rhinoceros software was written.Then,the programming of various algorithms was completed,and the 3D visualization of the model was realized combined with OpenGL technology.