Shale Multi-scale Pore Network Consctruction And Evaluation

The physical property of shale reservoir is extremely poor and most pores in shale are nano-scale.Multi-scale pore structure and various gas occurrences lead to the complication of shale gas percolation mechanism.As a result,the seepage mechanics in macro scope,such as Darcy's law,can no longer be used.To quantitatively study the micro percolation mechanism of shale gas,as well as obtain the macro seepage model and productivity prediction model of shale gas reservoir,we need to reestablish a three-dimensional digital image to accurate characterize the shale pore structure.Digital core and pore network model are the basis of the above research,which have gradually become a hot field at home and abroad.In this article,firstly we obtained a large amount of shale core 2D slice images by means of Scanning Electron Microscopy experiments.Through observing the images,we identified different types of pores in shale;secondly we acquired the 2D slice images of shale matrix and organic parts at two different resolutions respectively.Using Improved Simulated Annealing algorithm,we reestablished digital cores of the two parts respectively.Furthermore we extracted the pore network models respectively and then superposed them to get the multi-scale pore network model;finally we made the evaluation of the digital cores and multi-scale pore network model using relevant methods.The Results show that the multi-scale model can well reflect the pore structure of shale,which can be used as the foundation of flow simulation.