Basins, Tight Sand, & Shale Plays, Oh My! (part 3)

I am finally at the last of my three part blog. The part I know you have all been waiting for.....Shale Plays! I am quite excited to blog about this subject.  Why, do you ask?  Because it is a big deal.  Living in the Houston area, the energy capital of the world, and now that I am in the oil and gas industry, I have heard this word is used in oodles of conversations.  

As you can see from the map below, the shale plays lie in the tight sand, within the basins and these geological formations are all over the United Sates of America.   The natural resources we get from shale is considered an unconventional resource. It's unconventional because you cannot drill into the shale just any 'ole way.  You have to use unconventional technology to get the natural resources.  

So come on y'all, we have a great deal to learn about Shale Plays.

croft production systems

Before we even dig into the meat and potatoes of this blog, let's get the burning question answered.  Why the heck is it called a shale "play"?!  There are now several oil shales and gas shales finding favor in the US. Any area of interest or an area that is liked by the oil and gas companies is called a "play." Thus a shale area of interest is called a shale play.  (Mind Blown)  

Moving On! defines shale as a fine-grain, sedimentary rock that forms from the compaction of silt and clay-sized mineral particles that we commonly call "mud". Because of its make up, shale is in a category of sedimentary rocks know a "mudstones".

What makes shale different than other mudstones?  They are fissiled and laminated.  "Laminated" means that the rock is made up of many thin layers. "Fissile" means the rock easily splits into thin pieces along the lamination. So, in a nutshell: shale is heavily compacted mud that can break into thin pieces with sharp edges.  

I discovered that there are different colors of shale. Your black shales usually indicate that there is organic material present in the shale.  Just a tiny percent of this material, around 1-2%, can make the shale dark grey or black.  When there is organic materials in the dark shale, guess what that can mean?  That's right, oil and gas. There is a catch though...The organic debris has to be heated and preserved the right way for it to produce a natural resource.  Shale can also be red, brown, yellow or even green.  The coloring really depends on what minerals are present.  The colored clay that comes from the shale is used in the bricks for the houses that are popping up all over the Houston suburbs.  Shale can also be crushed, mixed with limestone, and then heated.  A bunch of scientific stuff happens.... then POOF!  You have cement that hardens into concrete.  

I am going to give a very brief description of shale gas and oil.  There is so much information about how these natural resources are formed, drilled, utilized, etc....and, I could go on for a while, but I will save that for another time.

Basically, shale gas is a natural gas that is present is shale rock. Shale is a rock that the gas cannot flow through easily, because the shale is compact or has low permeability.  Shale gas and tight gas are both unconventional, because of the elaborate production methods it takes to get them from the ground.  Oil shale generally refers to any sedimentary rock that has large amounts of an organic material celled kerogen. The kerogen is the part of the rock that breaks down and releases hydrocarbons when heated. The hydrocarbons in oil shale can then be used as an energy resource.  Again, oil shale is unconventional because of how we drill for it.  The graphic below is a great example of just that:

There is a light blinking and the music is beginning to rise, so I know I have to wrap it up.  As I stated before, there are so many different rabbit holes I could go down, but I have to have materials for future blogs! I just hope my paraphrasing does all this knowledge justice.

Remember, this was the last part of a three part blog.  You can always go to to read the previous parts of this blog, or any of the blogs our company employees have written.  My ultimate goal is to gain knowledge and then share it with you! 

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I want to close with the really cool fact below.  Well, the Dr. Who loving, nerd inside me thinks it's cool.

Shale is also very common on Mars.  The photo below was taken by the mast camera of the Mars Curiosity Rover.  It shows thinly bedded fissile shales protruding out of the Gale Crater.  The rover drilled holes into the rocks of Gale Crater and identified clay minerals in the cuttings.  There is shale on Mars, people!


Amy Jerina

Amy Jerina is an Account Representative with Croft Production Systems which is located in Needville, Texas. At Croft she focuses on growing existing customer relationships & helps to develop new client prospects. With a focus on increasing sales of the organization’s products & services. Amy also works with the marketing & business development team members in the office to ensure CROFT is meeting its client needs. She collaborates with field representatives & engineers as a liaison between the company & clients. Amy provides unlimited support to customers over the phone & is able to conduct field visits with clients located in the Continental United States. Amy has over 10 years of management, training & sales experience & over 15 years of customer service skills. She is using this experience to break into the oil & gas industry. By writing this weekly blog Amy is growing her oil & gas knowledge and hope to share that knowledge with anyone who wants to learn.