ale ▁were ▁located ▁at ▁the ▁same ▁location . ▁ ▁More ▁than ▁ 1 2 , 0 0 0   bar rel s ▁of ▁sh ale ▁oil ▁was ▁produced ▁during ▁this ▁period . ▁ ▁During ▁the ▁World ▁War ▁II , ▁three ▁N T U ▁ret ort s ▁were ▁operated ▁at ▁Mar ang ar oo , ▁New ▁South ▁Wales , ▁Australia . ▁ ▁Al most ▁ 5 0 0 , 0 0 0   bar rel s ▁of ▁sh ale ▁oil ▁was ▁produced ▁by ▁these ▁ret ort s ▁by ▁ret ort ing ▁local ▁tor ban ite . ▁ ▁Ret ort ▁The ▁N T U ▁ret ort ▁was ▁a ▁vertical ▁dow nd raft ▁ret ort , ▁which ▁used ▁internal ▁comb ust ion ▁to ▁generate ▁heat ▁for ▁an ▁oil ▁sh ale ▁py ro ly s is ▁( chem ical ▁decomposition ). ▁The ▁ret ort ▁was ▁designed ▁as ▁a ▁steel ▁cyl inder , ▁l ined ▁with ▁fire ▁br icks . ▁At ▁the ▁top ▁it ▁was ▁equ ipped ▁with ▁an ▁air ▁supply ▁pipe ▁and ▁at ▁the ▁bottom ▁it ▁was ▁equ ipped ▁with ▁an ▁exhaust ▁pipe . ▁ ▁The ▁batch ▁of ▁cr ushed ▁oil ▁sh ale ▁was ▁loaded ▁from ▁the ▁top ; ▁after ▁that ▁the ▁ret ort ▁was ▁se aled . ▁To ▁start ▁the ▁py ro ly s is ▁process ▁the ▁fuel ▁gas ▁was ▁ign ited ▁at ▁the ▁top ▁of ▁ret ort , ▁and ▁air ▁injection ▁into ▁the ▁ret ort ▁started . ▁The ▁supply ▁of ▁fuel ▁gas ▁stopped ▁after ▁the ▁upper ▁quarter ▁of ▁the ▁oil ▁sh ale ▁batch ▁started ▁to