Open AccessUsing logging while drilling resistivity imaging data to quantitatively evaluate fracture aperture based on numerical simulation
Author(s) -
Zhengming Kang,
Xin Li,
Weining Ni,
Fēi Li,
Xiao long Hao
Publication year - 2021
Publication title -
journal of geophysics and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.623
H-Index - 38
eISSN - 1742-2140
pISSN - 1742-2132
DOI - 10.1093/jge/gxab016
Subject(s) - fracture (geology) , aperture (computer memory) , geology , electrical resistivity and conductivity , contrast (vision) , finite element method , geotechnical engineering , mineralogy , structural engineering , optics , engineering , physics , electrical engineering
Fractured formations are strongly heterogenous, and thus exhibit a complex logging response mechanism. By using the logging while drilling (LWD) resistivity imaging tool, fractures can be visually identified and their aperture quantitatively calculated. Because physical fracture model simulation is time consuming and costly, we propose using a 3D finite element method (FEM) numerical simulation to interpret the LWD resistivity imaging tool logging responses in conjunction with a new aperture calculation model based on the forward model. First, we used the single fracture model to investigate the effect of fracture aperture and formation resistivity contrast on the maximum current contrast at the fracture. The results showed that the aperture is linearly related to the maximum current contrast, while the formation resistivity contrast exhibits a pronounced exponential relationship with the maximum current contrast. Both of these relationships are affected by the fracture's dip angle, so segmented fitting is required when the fracture dip angles differ. Next, using the forward model, we developed the fracture aperture calculation model based on the maximum current contrast. The aperture calculation model was established in three segments in accordance with the different fracture dips, and the influence factors affecting the fracture inverting inclination were analyzed using multi-fracture simulation images. Finally, the accuracy of the new model was verified with the simulated fracture images. The novel model for calculating fracture aperture is of great significance for processing and interpreting LWD resistivity imaging logging data.