PETROLEUM GEOLOGY

Rocks Rock

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

2. Metamorphic

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).

Conglomerate rock

2. Carbonate sedimentary rocks,

which are LIMESTONES and DOLOMITES.

Limestone Rocks

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.

An Ancient River… how is it that it stores oil? Keep Posted

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2 comments

  1. Pingback: How everything starts | The Oily Blog
  2. Pingback: The Oily Blog | Is an ancient river your Gas Supply? – Part I

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