Abstract:

       Layer  thickness  is  fairly  important  for  the development of  structural  fractures  in carbonate  strata. According  to
statistical analys  is, of  the profile measuring  results of Dawangou, Qingsong and Penglaiba of Keping, Xinjiang,  the surface
densities of structural  fractures  in carbonate strata  is negatively correlated  to  layer  thicknesses. The  thicker  the  layer  is,  the
smaller  the  fracture densityis. But  the  scale of  fractures  is  relatively bigger; when  the  layer  thickness becoming  thinner，
the  fracture density  is  linearly  increasing, meanwhile,  the scale of  fractures  is getting  relatively smaller. Structural  fractures  in
carbonate strata own good  fractal characteristics. Statistics shows  that  there  is a negative correlation between  fracture  fractal
dimension and  layer  thickness. Fracture  fractal dimension becomes bigger when  layer  thickness gets smaller, which  indicates
a better  fracture development. Certain  linkage exists between  fractal dimension and density of  fractures, which can  together
quantitatively describe development  level of  fractures. Generally,  fracture  fractal dimension  increases wiih  increasing  fracture
density.  If  fractures have  the same density,  the bigger  fractal dimension  is,  the more uniform  the distribution of  fractures  is.
Meanwhile, permeability of the carbonate layers is poorer.

Key words:  Layer thickness；carbonate rock；structural fracture；surface density；fractal；fractal dimension