new to the oil industry

I'm trying to educate myself about the oil business and have put together some notes for myself, but they might be useful to others, so I've posted them here. Dont take these as gospel, there might be some mistakes. If you do see any errors please let us know.

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Exploration Wells
"1. Onshore exploration wells are cheaper- and if successful may be useable for production also. If discovery is made:
- If exceptionally good discovery, general practice is to case & suspend well. Flow tests and other analysis is done at later date. The cost of this is $800K- very expensive, so only done if there is a very high certainty [>75%] of commercial well.
- If only a normal discovery, DST test will be done immediately.
- If poor/no discovery, no testing done."
2. Offshore exploration wells are dear- generally not used for production. Evaluated using mini tests and wire logs, but no flow tests. It is normal practice, to plug and abandon them once they are evaluated.
Appraisal Wells
A discovery of oil made by a single well cannot by itself give an accurate indication of total size and grade etc of the reservoir. Gnerally need follow up drilling of 2+ appraisal wells to do this
Production Wells
A production well is one that has been drilled for the purpose of producing oil/gas. Such wells need to be well engineered and cased so as to sustain the anticipated flow rates
Spudding
This is the day drilling starts. An important milestone. Drilling normally starts with a wide hole, it is then cased with metal/cement to hold the loose soil in place. As drilling deepens, casing is no longer required as the hole can support itself.

WIRE LINE LOGS "State of the art electronics equipment that is lowered into the well to ascertain success
1. Rock Type and Porosity-the more porous the rock the better
- eg Sandstone is good, but not if it has high clay/silt content; claystone, siltstone, shale, slate is not good
2. Oil shows/ gas shows and fluoresence. Ultraviolet light examination to try and detect any oil/gas contained in the sample. Bright yellow is best, dull yellow/orange may be ok
3. Streaming Cut and Residue Ring. This is measure of how easy the oil will flow out of the rock. High streaming cut is best, moderate is ok; Strong residue ring is good, thin residue ring is not good.
Note - Instead of wireline logs, the above tests can be done manually on sludge samples that have been returned from the drilling."
DST TESTS "A Drill Stem Test [DST] is generally only done if things are looking positive. DST is a critical part of evaluating the success of a well. They'll stop the drill, and open up the pipe and see what comes out .
1. A good result is the pipe quickly and completely filling up with oil - look at Stuart's old releases about Worrior. They are good results. Anything over 1000 barrels of oil per day [bopd].
2. A kinda OK result is when the pipe fills up a bit, but slowly. Rookwood South and Ventura/Namur are examples of OK results. 150-1000 bopd.
3. Poor results are when there is a little bit of oil. Ventura/Murta is a poor result. Anything under 150 bopd.
4. Bad results are when they dont get any oil at all, or dont do a test they had planned for. Ventura/Hutton was a bad result (no test). Beach's Semaphore well was a bad result (no oil).
Of course, this is relative. A poor result in a layer where you were expecting nothing out is in fact a good result.

Initial DST tests generally neet to be confirmed by running them over many weeks and may need to follow up with additional appraisal wells, analysis, etc to further confirm."

Gross Profits
"Oil- Gross Profit
Onshore [5-50 mmbbls] >$25/ bbl
Offshore [100-250 mmbbls] >$10 / bbl

Gas- Gross Profit
Onshore [10-100 bcf] >$0.75 /gj
Offshore [300-1000 bcf] >$0.65 /gj

Assumptions
Oil price $US35 / bbl, $AUD1=$AU46.60 /bbl
Onshore opcosts $AU8 /bbl
Gas price $AU2.90 /gj
Offshore Oil Case - FPSO, Offshore Loading
Offshore Gas Case - Platform, Onshore Facilities"

"Cooper Basin

Oil
Initial discovery inground $A20/ bbl
Ready for Market Revenue $60 /bbl
Operating costs $20/ bbl
Net Profit $40 /bbl

Gas
Initial discovery inground $1/ 1kcf
Ready for market Revenue $2.50 /1kcf"