Multi-scale and multi-component digital core construction and elastic property simulation

Abstract

The conventional digital core models are usually small in size and have difficulty in representing the complex structures of heterogeneous rocks; Therefore, the parameters of simulated rock physics are difficult to be referenced. In this study, we propose a feasible simulation method for obtaining multi-scale and multi-component digital cores based on three types of sandstone samples. In the proposed method, the plug and subplug samples are scanned via micro-computed tomography at different resolutions. Furthermore, the images are precisely registered using the proposed hybrid image registration method. In case of high-resolution images, the traditional segmentation method is used to segment the cores into pores and minerals. Subsequently, we established the relations between the gray values and the porosity/mineral content in case of the low-resolution images based on the registered domains and the relation curves were applied to the segmentation of the low-resolution images. The core images constitute the multi-scale and multi-component digital core models after segmentation. Further, the elastic properties of the three samples were simulated at both fine and coarse scales based on the multi-scale and multi-component digital core models, and four component models were considered. The results show that the multi-scale and multi-component digital core models can overcome the representative limits of the conventional digital core models and accurately characterize pores and minerals at different scales. The numerical results of the elastic modulus are more representative at large scales, and considerably reliable results can be obtained by appropriately considering the minerals.