Note 2 - Basis of Presentation and Summary of Significant Accounting Policies (Details Textual)	1 Months Ended	3 Months Ended		4 Months Ended	12 Months Ended	20 Months Ended
	Dec. 31, 2020 USD ($) shares	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Aug. 21, 2020 USD ($)
Accounts Receivable, after Allowance for Credit Loss, Current, Total	$ 7,722,000	$ 16,915,000		$ 16,915,000	$ 7,722,000
Income Taxes Receivable	3,200,000	3,200,000		3,200,000	3,200,000
Oil and Gas Joint Interest Billing Receivables	345,000	311,000		311,000	345,000
Accounts Receivable, Allowance for Credit Loss, Current	$ 0	0		0	0
Class of Warrant or Right, Exercised During Period (in shares) | shares	312,711
Proceeds from Warrant Exercises	$ 3,600,000	5,466,000
Subscription Receivable, Current	3,596,000	0		0	3,596,000
Inventory, Raw Materials and Supplies, Gross, Total	120,000	109,000		109,000	120,000
Inventory, LIFO Reserve	0	0		0	0
Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance	237,000	285,000		285,000	237,000
Payments of Debt Issuance Costs		2,000
Amortization of Debt Issuance Costs		29,000
Accounts Payable and Accrued Liabilities, Current, Total	22,400,000	34,800,000		34,800,000	$ 22,400,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total		0		0
Income Tax Expense (Benefit), Total		$ 1,115,000				$ 0
Number of Operating Segments		1
Domestic Tax Authority [Member] | Internal Revenue Service (IRS) [Member]
Open Tax Year					2017 2018 2019 2020
Minimum [Member]
Oil and Natural Gas Marketing Contracts, Term Over Which Consideration is Received from Purchaser (Month)		30 days
Maximum [Member]
Oil and Natural Gas Marketing Contracts, Term Over Which Consideration is Received from Purchaser (Month)					60 days
Revolving Credit Facility [Member]
Payments of Debt Issuance Costs		$ 2,000		407,000
Amortization of Debt Issuance Costs		$ 29,000	$ 0
Technology Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)		3 years
Transportation Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)		5 years
Field Equipment [Member]
Property, Plant and Equipment, Useful Life (Year)		7 years
Crude Oil, Natural Gas and Natural Gas Liquids [Member]
Accounts Receivable, after Allowance for Credit Loss, Current, Total	$ 4,200,000	$ 13,400,000		$ 13,400,000	$ 4,200,000