A new well is completed in the test reservoir. It will be producing through a single primary separator with the fluids to be commingled in the stock tanks. The stock tanks have vapor recovery. The gas$-$oil ratio for the primary separator is $724$ scf$/$STB$,$ and the oil shrinkage at the primary separator is $0\mathrm{.}888$ STB$/$bbl$.$

The reservoir oil formation volume factor is $1\mathrm{.}4927$ res bbl$/$STB$,$ and the gas$-$oil ratio for the first month$$s production averages $1,011$ scf$/$STB$.$

Calculate the GOR at the primary separator $($measured in scf$/$bbl of primary separator liquids$).$

Hint: Answer is rather close to $640$