Topological Representative Element Volume of Fractured Rock Mass

Abstract

The representative element volume (REV) of the fractured rock mass is the basis for its homogenization, and is essential for the study of groundwater seepage. In order to determine a simple method for estimating REV, we studied the topological characteristics of the fractured network. We propose the concept of topological representative element volume (TREV) for estimating the fractured rock mass. The topological structure can reflect many properties of the fractured rock mass, to which a great deal of attention has been paid. We examine the applicability of eleven topological parameters as the equivalent parameters of the TREV. According to the selected equivalent parameter, the TREV of twenty-three kinds of fractured rock mass were calculated and then compared with the permeability representative element volume (PREV). The results show that the size of TREV and PREV are essentially the same for a given rock mass. In other words, the PREV can be estimated accurately using the TREV for the rock mass with orthogonal connected fracture networks. The advantage of using TREV to estimate PREV is that there is no need for complex seepage calculations, as the calculation of TREV only needs to account for the geometric characteristics of the fracture network.

A Volume Fracturing Percolation Model for Tight Reservoir Vertical Wells

“…The regional division is consistent with the five-area model of horizontal wells with volume fracturing. Although scholars have conducted extensive research on the seepage law of volume fracturing, there is relatively little research on multistage volume fracturing in vertical wells [25][26][27][28]. Currently, most of the seepage models for tight oil reservoirs with volume fracturing in vertical wells are radial composite models, and the assumption that the reconstruction area is a cylinder does not match the results of on-site microseismic monitoring [29][30][31][32].…”