ooze/sludge/silt... I have had much experience in purifying fuel and lubricating oils with my career and because crude oil is a fluid the word you need in this example is 'solids'. When crude oil is pumped out of the ground it is

'went to water'....the literal meaning is derived from ice melting. i.e. you go from a hard state to a soft or weak state. If two people have a heated argument and one then backs down, he is said to have 'went to water'

By using both terms this covers the entire process from when the oil is pumped out of the ground to when it is refined and sold to customers. So if this is included in the context of this author's article then my answer would be, yes...

Then you could word it... in 1979 an additional pipeline was built which linked/connected Omisalj on the island of Krk to Sisak (the Adriatic pipeline-Janaf)

I agree it needs to be broken down into smaller sentences. Maybe something along these lines... Pipeline systems are the simplest and cheapest means of transporting oil from the oil fields to the sea ports. From the ports it is pumped onto

Yes...in size and shape they are somewhat similar.

'Oil refining' is the common term to used. The oil is broken down into different 'grades' of refined petroleum products.

It is an Americanism...."something special" is probably the english equivalent.

"Just the basic shell of the house with no fittings"

In my country some or industries pay with an hourly rate. So if you exceed the normal agreed work hours and are required to work more hours, then you get paid overtime at "penalty rates" which is an agreed hourly rate in excess of your normal