Forms of hydraulic fractures as deduced from field studies of sheet intrusions : Pollard, D D Proc 19th US Symposium on Rock Mechanics, Stateline, Nevada, 1–3 May 1978, V1, P1–9. Publ Reno: University of Nevada, 1978

Abstract

It is suggested that natural sheet intrusions may be good analogs for hydraulic fractures in that they are large, fluid-driven fractures that have an opening displacement mode. The natural intrusions are characterized as partial erosion at the earth's surface; dikes commonly nonequidimensional, sills roughly equidimensional; large surface areas; thickness-to-length ratios typically between 1/100 and 1/1000; systematic, linear, and radial patterns with spacing between dikes; sheet intrusions significantly varying from constant thickness or elliptical form; and separated, coalescing segments. Differences between the forms described and those employed in hydraulic fracture analysis are considered significant, such as the amount of deformation near continuous as opposed to discountinuous fractures. Also, fluid flow and convective heat transport within a discontinuous or offset fracture are expected to differ from those in a continuous, smooth-sided fracture. The 3-dimensional model studied attempted to incorporate realistic conditions to approximate more surely the results of hydraulic fracturing. 65 references.