Jello Fracking Experiment
We will give a short PowerPoint explaining how fracking occurs. We will also touch on where you get deposits
(of natural gas or water): between different rock layers. We will mention the applications of fluid
injection (natural gas extraction, geothermal energy, stress
measurements). We will explain how the
fluid is injected at high pressures and therefore can push a crack wider and
support some of the stress (like how water can float things like a sponge).
Materials:
Cup with clear gelatin (one for each student)
Pipette
Cup of grape juice or another dark fluid (can share among several
students)
Plastic knife
Method:
1. Inject grape
juice to several levels of the gelatin.
a. All the way to
the bottom.
b. Half-way
through the gelatin.
2. Make a slit in
the gelatin
a. Inject juice
near the slit
3. Try the
injections at different rates (ie squeezing the juice in all at once vs.
squeezing it in slowly)
Summary:
We’ll ask for their observations and discuss as they come up:
1.
Creation of a reservoir between the bottom of the
cup and the bottom of the gelatin layer.
2.
Vertical cracks when you inject into the
middle. If you inject more slowly, the
crack spreads out more laterally. This
shows the fluid taking advantage of the pre-existing crack edges. You’re also injecting with less force, so the
crack remains thinner and has less fluid.
a. Which would be
more likely to have an earthquake, a fracture with more fluid or less fluid?
3.
When you inject on the pre-existing fracture, the
fluid migrates along that fracture rather than creating a new fracture.
Jello-Fracking
|
||
Plastic
cups
|
So that we
can see into the gelatin
|
~$5
|
1 pound
gelatin
|
To serve
as the analogue for the rock being fracked
|
Borrowed
from lab/professor
|
Grape
juice
|
Fracking
fluid
|
~$6
|
Pipettes
|
To inject
the fracking fluid
|
Borrowed
from lab/professor
|
Plastic
knife
|
To create
pre-existing fractures in gelatin
|
Borrowed
from lab/professor
|
Total
|
~$21
|
|
