Lost title 26 15N 06W

My grandma left my Mom 5.66 mineral acres in the 60s. I have letters that shows she got $80 dollars for 5 year lease ($15 a year) in 1973. I figured out from the discussion and comments here to find there are two currently producing wells on this section. One drilled in the N says 160 acres lease and the newer one (2015) says 640 acre lease. Does this mean I may have royalties due from the newer well? It is in the SE and the 1973 papers say E2 SW4 26 15N 06W.

Help or comments appreciated -- Ferril