I did leave out depletion allowance. How much is that and how long can it be taken?
At what point is that calculated in? Do you have any idea what the average price paid
to producers is for this haynesville shale gas? regards to you too.. bonchase

Maybe his is how it works, Gregory. Say you own 1/4 the 640 acre unit (160 acres) [160 divided by 640 =.25} . Take that percentage of ownership and multiply it by your royalty amount.. say it is 25% [.25 x .25 =.0625} . Take the production per day x 30 days a month
[6100x30=183,000] times the price of gas (what I found, currently for a national average is $3.45) -631,350 times your .0625 =$39,459 per month. Subtract about 40% for taxes, subtract "at the well head" costs if you have to pay them. Those are costs of getting the gas from the well into the pipeline and can include pressure regulation, drying the gas, separating out water, ect.
I may be way off base, but like you, If I am not going about this estimate right I wuld welcome someone correcting my thinking and will watch for a post to that effect.
Congratulations on your well. I drive by it daily.