One of the things I worked with to get my Ph.D.
D.I.S.L.A.S.H stands for Desktop Interface Separation Laboratory Apparatus for the Simulation of Hydra-frac. (I didn't come up with the name.)
For more details check out my on-line resume or below you can find a copy of the abstract from my Ph.D.
(As with any Ph.D. work, what went into the final version of the thesis is only a small protion of what I actually did.)
The effects of stratified permeability on hydraulic fracture propagation are modeled with an Interface Separation Apparatus. The existence of permeability barriers to hydraulic fracture growth is verified and the magnitude of the barriers is quantified as a function of material parameters. The analytical and experimental models focus on permeability contrasts, with fracture initiation in a low permeability region and propagation into a higher permeability zone. The permeable media are simulated using bonded granular materials which allow tight control over the material properties. An analytical model is developed describing the two-dimensional leakoff near the fracture tip. Experimental studies are compared against this tip leakage model to verify the steady state leakage approximations for circular geometries. The two-dimensional model predicts results which more accurately match laboratory experiments than simple one-dimensional models.
The analytical model is applied to describe leakoff behavior as the fracture tip reaches a higher permeability interface. A characteristic 'holding time' is derived to describe the time a fracture is delayed as the fracture propagates from a region of low permeability into a higher permeability zone. Experimental results for permeability variations of one to two orders of magnitude are compared against predicted values for fracture holding time.
The experimental data are also used to calibrate the stratified permeability coefficients in a lumped-parameter field simulator. A representative field case is then analyzed using those coefficients as model parameters. The simulator is found to predict fracture growth which matches other field evidence of fracture containment.
The analytical and experimental development provide the first basis for an accurate model to estimate levels of fracture containment under field conditions. Such a capability for analyzing fracture growth can be used to better predict the effect of permeability barriers when executing hydraulic fracture operations in the field.
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