Characterizing Surface Roughness From Pressure-Joint Closure Measurements Using Inversion Procedure
Name
1991.6 Zhao_Toksoz.pdf
Size
460.44 KB
Format
Adobe PDF
Checksum (MD5)
4b0d217881153eef6d1f5b7f7948df19
Author(s)
Zhao, Xiaomin
Toksoz, M. Nafi
Date Issued
1991
Publisher
Massachusetts Institute of Technology. Earth Resources Laboratory
Series/Report no.
Earth Resources Laboratory Industry Consortia Annual Report;1991-06
Abstract
An inversion procedure has been formulated to estimate the surface roughness of a joint
(fracture) from the measured pressure-closure data. A gamma distribution for the local
minima (or maxima) on a topography profile was used to account for the skewness
in the measured distribution of the asperities. By using the distribution, the average
height [bar over z] and the standard deviation a of the profile can also be characterized. An inversion procedure was formulated based on the modification of the theory proposed by Brown and Scholz (1985) and has been successfully tested with synthetic data. The inversion finds average height [bar over z][subscript 1], standard deviation σ, and average aperture. These three parameters characterize the surface roughness and aperture of a fracture and are the topography parameters governing permeability, electric conductivity and other transport properties of the fracture. Pressure-closure data from laboratory measurement of a rough and a smooth joint were also inverted to find the joint properties. The results agree with the profile measurement quite well. The variations of transport properties of a fracture with pressure are also studied.
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