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Hi all, great forums!

Can anybody quickly explain what the difference is between secondary and primary porosity?

thanks in advance!

Basically Primary porosity is formed when the sediment is deposited. Secondary porosity is formed after sedimentary deposition (diagenisis).

That's the simplest way I can explain it!

Thanks petrobos! That's pretty simple indeed...

Can you also tell me what effective and ineffective porosity means??

Well, to understand that you must know that there are three types of morphologies to the pore spaces: Caternary , Cul-de-sac and Closed pore. Here's what these morphological forms mean:

i) Caternary: the pore opens to more than one throat passage; it is the best type because the hydrocarbons in the reservoir can be flushed from rocks
ii) Cul-de-sac: the pore opens to only one throat passage; the pores cannot be flushed, but they can produce hydrocarbons by release of pressure (e.g. gas expansion)
iii) Closed pore: where there is no connection with other pores and they cannot produce any type of hydrocarbons

Caternary and Cul-de-sac pores form the effective porosity because they allow hydrocarbons to move into and out of them. While closed pores form the ineffective porosity because no hydrocarbons can move in or out of the rock.

It's all about allowing the effective flow of fluids!

Thanks