<p>Shale typically has a low permeability but shale is not technically impermeable.
Natural occurring faults, fractures and joints in shale can greatly increase the permeability of the rock.  This is why hydraulic fracturing (or fracking) is used to increase fluid flow (for both water, natural gas and petroleum wells) in host rock with low permeability.</p>

<p>Fractured shale can allow a significant amount of fluid because some shale can have porosity values greater than 10%.  Given the grain size of shale, this can be a significant amount of space available to hold fluids.</p>

<p>References:</p>

<ul>
<li><p><a href="https://www.nap.edu/read/2309/chapter/4" rel="nofollow noreferrer">Physical Characteristics of Fractures and Fracture Patterns</a></p></li>
<li><p><a href="https://www.spec2000.net/22-fracloc1.htm" rel="nofollow noreferrer">FRACTURED RESERVOIR BASICS</a></p></li>
<li><p><a href="https://en.wikipedia.org/wiki/Hydraulic_fracturing" rel="nofollow noreferrer">Hydraulic Fracturing</a></p></li>
<li><p><a href="http://www.geomore.com/porosity-and-permeability-2/" rel="nofollow noreferrer">Shale porosity</a></p></li>
</ul>

CC BY-SA 3.0
2017-03-09T12:05:40.293Z
2017-03-09T12:16:01.740Z
2017-03-09T12:16:01.740Z
Earth Science Expatriate
<p>How can oil can escape from a shale source rock into a reservoir rock if the shale itself is impermeable?</p>

<geology><structural-geology><gas>
How can oil can escape from a shale source rock into a reservoir rock?
Alvaro Morales
# How can oil can escape from a shale source rock into a reservoir rock?

(Asked by: username_0 on 2017-03-08)

How can oil can escape from a shale source rock into a reservoir rock if the shale itself is impermeable?

**Tags:** geology, structural-geology, gas


---

## 1 answers

### Answer by username_1 on 2017-03-09. Score: 1

Shale typically has a low permeability but shale is not technically impermeable.
Natural occurring faults, fractures and joints in shale can greatly increase the permeability of the rock. This is why hydraulic fracturing (or fracking) is used to increase fluid flow (for both water, natural gas and petroleum wells) in host rock with low permeability.

Fractured shale can allow a significant amount of fluid because some shale can have porosity values greater than 10%. Given the grain size of shale, this can be a significant amount of space available to hold fluids.

References:

* [Physical Characteristics of Fractures and Fracture Patterns](https://www.nap.edu/read/2309/chapter/4)
* [FRACTURED RESERVOIR BASICS](https://www.spec2000.net/22-fracloc1.htm)
* [Hydraulic Fracturing](https://en.wikipedia.org/wiki/Hydraulic_fracturing)
* [Shale porosity](http://www.geomore.com/porosity-and-permeability-2/)


---

