Publications Details
Aperture field measurement in Transparent Rough Walled Fractures Using Two-Dimensional Full Field Light Transmission
Experimentation in transparent fractures where light transmission techniques are used to measure aperture, dye concentration, and phase distribution fields can enhance our understanding of single and multi-phase flow and transport. Here, we evaluate and improve the method for aperture field measurement in transparent analog fractures and replicas of natural fractures. The primary sources of error in the measurements are: signal noise (both temporal and spatial) from the charge-coupled-device (CCD) used to measure light intensities transmitted through the fracture; non-linearity of light absorbance of the dyed solution used to fill the fracture; and refraction of light passing through the fracture. We find that each of these error sources can be minimized to optimize precision and accuracy. Our measurements of the aperture field of a -150 x 300 mm analog test fracture at a spatial resolution of 0.159 x 0.159 mm ( 2x106 points) demonstrate a root-mean- square error over the field of O.9% (0.002 mm) of the mean aperture (0.222 mm). Though the results presented here are specific to our test fracture and measurement system, the general approach can be applied to other digital imaging techniques based on energy absorbance.