Note 11 - Asset Retirement Obligations - Estimated Amounts and Timing of Cash Flows and Assumptions Used for ARO Estimates (Details)	Jan. 31, 2023 USD ($)	Jul. 31, 2022 USD ($)
Undiscounted amount of estimated cash flows
Minimum [Member]
Undiscounted amount of estimated cash flows
Minimum [Member] | Measurement Input, Expected Term [Member]
Asset retirement obligations, measurement input	1	1
Minimum [Member] | Measurement Input, Inflation Rate [Member]
Asset retirement obligations, measurement input	0.0156	0.0156
Minimum [Member] | Measurement Input, Discount Rate [Member]
Asset retirement obligations, measurement input	0.0372	0.0372
Maximum [Member]
Undiscounted amount of estimated cash flows	$ 29,212	$ 28,739
Maximum [Member] | Measurement Input, Expected Term [Member]
Asset retirement obligations, measurement input	23	23
Maximum [Member] | Measurement Input, Inflation Rate [Member]
Asset retirement obligations, measurement input	0.0532	0.0532
Maximum [Member] | Measurement Input, Discount Rate [Member]
Asset retirement obligations, measurement input	0.0635	0.0635