At a low depth, the total weight of the jell-o above the injection point (overburden stress load) is small, smaller than any of the stresses acting laterally on the injecting straw. Thus, the fracture at 0:14 initiates and propagates "transversely" (on a plane lateral with respect) to the straw. Fractures like this one (tensile/open-mode/"Mode I") open-up by doing work against the smallest stress acting on their propagation domain. In this case, the vertical (overburden) stress is the smallest, parallel to the straw, therefore the fracture propagates (grows) perpendicularly to the straw "opening-up" against the smaller vertical stress, parallel to the straw. When the injection point is moved deeper at 0:32, the total weight above the injection point is much higher surpassing the stresses acting laterally to the injecting straw. Thus, the fracture "opens-up" perpendicular to the straw, propagating "longitudinally" (on a plane axial with respect) to the straw. Very good way of demonstrating the impact of the overburden stress on fracture orientation (longitudinal vs. transverse). I know that in the '80s it was struggle to achieve longitudinal fractures (ideal orientation for productivity purposes) from vertical wells drilled in diatomite in California due to the low weight of the diatomite (kitty litter) yielding low overbuden stresses.
If you use concentrations around 12-14 wt. %, the resulting jell-o mixture has Young's modulus of 5-6 psi. When used as a reservoir analogue in lab conditions (true-triaxial block tests) it scales quite well with a typical field-scale frac job considering a dimensional scaling analysis. It may not scale as good as cement, but it does bear some significant advantages like transparency, practicality, and price.
At a low depth, the total weight of the jell-o above the injection point (overburden stress load) is small, smaller than any of the stresses acting laterally on the injecting straw. Thus, the fracture at 0:14 initiates and propagates "transversely" (on a plane lateral with respect) to the straw. Fractures like this one (tensile/open-mode/"Mode I") open-up by doing work against the smallest stress acting on their propagation domain. In this case, the vertical (overburden) stress is the smallest, parallel to the straw, therefore the fracture propagates (grows) perpendicularly to the straw "opening-up" against the smaller vertical stress, parallel to the straw.
When the injection point is moved deeper at 0:32, the total weight above the injection point is much higher surpassing the stresses acting laterally to the injecting straw. Thus, the fracture "opens-up" perpendicular to the straw, propagating "longitudinally" (on a plane axial with respect) to the straw.
Very good way of demonstrating the impact of the overburden stress on fracture orientation (longitudinal vs. transverse). I know that in the '80s it was struggle to achieve longitudinal fractures (ideal orientation for productivity purposes) from vertical wells drilled in diatomite in California due to the low weight of the diatomite (kitty litter) yielding low overbuden stresses.
That is not in any way what hydraulic Fracturing is. It's hydraulic jelly donut injecting.
If you use concentrations around 12-14 wt. %, the resulting jell-o mixture has Young's modulus of 5-6 psi. When used as a reservoir analogue in lab conditions (true-triaxial block tests) it scales quite well with a typical field-scale frac job considering a dimensional scaling analysis. It may not scale as good as cement, but it does bear some significant advantages like transparency, practicality, and price.