Most leases only allow for the disposal of fluid produced on the lease itself or from other properties owned by both the mineral owner and the lease owner. The lease owner has several different properties leased from the same mineral owner.
Pump salt water out of one well on the lease, you can pump it back down another disposal well on the same lease.
If you lease your property for a disposal well, be it a commercial well or a disposal well used by the lease owner for disposal of fluids from their leases but different mineral owners, you would get paid for every barrel of fluid pumped in the ground from these other leases.
Thanks!