A sedimentary rock is a solid that has formed due to processes occurying to other preexisting materials, that have undergone chemical and physical changes through millions of years since they were formed.
Rocks have a Cycle, but before we touch that subject, we need to know that there are three main types of rocks:
1. Igneous – Like Granite and Basalt
Granite example rock
Gneiss Metamorphic rock
3. Sedimentary – Like Sandstone
Sandstone rock showing layering
These types are all connected through the many changes they could experience through the cycle of rocks shown down here with the basalt – marble – sandstone example
The oil and gas are generally stored in sedimentary rocks, due to their abundance and properties (i.e. they are very porous and their pores are generally well connected, allowing the flow of oil and/or gas within it).
The sedimentary rocks are just clusters of rocks of any kind (even sedimentary) grouped into a defined structure.
There are three types of sedimentary rocks that differentiate among themselves because they form under different circumstances and from different kinds of materials (minerals).
1. Siliciclastic sedimentary rocks,
which are formed from preexisting clasts or rocks and are subclassified into SANDSTONES, CONGLOMERATES, and SHALES (MUDROCKS).
2. Carbonate sedimentary rocks,
which are LIMESTONES and DOLOMITES.
3. Others like Evaporites, Cherts, Phosphorites and Carbonaceous (coals, oil shale and bitumen).
Evaporites (ground) rock deposits
You wouldn’t imagine how much information can rocks give us to learn more about where to find oil.
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