what is a shale？ it’s quite an important question depending on which geologist you speak to. You’ll get a different answer. But in a very basic sense: shale is mud stone. The mud that has been compressed over a thousands or millions of years and been turned into stone.
Now mud very so normal all that is the same. So therefore not all shales are the same. There are four main ingredients we get in mud that that can turn into shales. Those four things are clay, so different clay minerals, quartz silt or quartz (a common mineral will break down into small sized particles), calcium carbonate which is limestone effectively plankton and lots of other shell creatures make their shells out of. Carbon rich organic matter, so broken down bits of plantain and animal material. So those sort of four ingredients are what make up shales.
Shale normally tends to be thought of as this kind of rock: this gray fine-grained mud stone often with quite thin layers in it, that split and that’s where the lay’s are, But really anything that’s got mud sized particles in it is a shale. So something like picture-1 which looks rather different is actually still a shale. the reason is that this white color represents a lot of calcium carbonate. So this had a lot of plankton in it. With calcium carbonate shells whereas this one doesn’t this adds a lot more clay in it, and they can be quite different in terms of what they contain in terms of oil and gas. That’s why they’re interested in from shale oil and shale gas exploration.
In shale oil and shale gas exploration, The shales must be eliminated casue it impede the process of drilling. The main equipment of control those shale in mud called shale shaker.