Annual report pursuant to Section 13 and 15(d)

Crude Oil and Natural Gas Properties and Equipment (Narrative) (Details)

v3.20.4
Crude Oil and Natural Gas Properties and Equipment (Narrative) (Details)
$ in Thousands
 1 Months Ended 6 Months Ended 12 Months Ended
Jun. 20, 2026
Sep. 16, 2019
item
Sep. 26, 2018
USD ($)
Sep. 30, 2020
USD ($)
Mar. 31, 2020
USD ($)
Feb. 29, 2020
USD ($)
Dec. 31, 2019
USD ($)
item
Dec. 31, 2020
USD ($)
item
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Sep. 17, 2018
USD ($)
Dec. 31, 2012
Property, Plant and Equipment [Line Items]                        
Contractual obligation               $ 17,627        
Reduction in VAT receivable               (1,268) $ 275 $ (777)    
Deferred tax assets, basis difference in fixed assets             $ 26,590 27,995 26,590      
Impairment of proved crude oil and natural gas properties               30,625        
Property, net             $ 68,258 37,036 68,258      
Inventory adjustments               900        
Consortium [Member]                        
Property, Plant and Equipment [Line Items]                        
Contractual obligation               56,757        
Etame Marine Block [Member]                        
Property, Plant and Equipment [Line Items]                        
Allocated to proved leasehold cost               2,300        
Impairment of proved crude oil and natural gas properties         $ 30,600              
Property, net         $ 15,600              
Undeveloped leasehold value               $ 11,500        
Etame Marine Block [Member] | Government Of Gabon [Member]                        
Property, Plant and Equipment [Line Items]                        
Working interest ownership, percentage               7.50%        
Monthly royalty rate, based on production at the published price               13.00%        
Etame Marine Block [Member] | VAALCO Gabon S.A. [Member]                        
Property, Plant and Equipment [Line Items]                        
Working interest ownership, percentage               33.575%        
Block P Offshore Equatorial Guinea [Member]                        
Property, Plant and Equipment [Line Items]                        
Working interest ownership, percentage               43.00%       31.00%
Increase (decrease) in working interest ownership percentage               12.00%        
Undeveloped acreage               $ 10,000        
Potential payment               $ 3,100        
Period of development               25 years        
Scenario, Forecast [Member] | Etame Marine Block [Member] | Government Of Gabon [Member]                        
Property, Plant and Equipment [Line Items]                        
Working interest ownership, percentage 10.00%                      
Prior Production Sharing Contract, Through September 17, 2018 [Member]                        
Property, Plant and Equipment [Line Items]                        
Entitled percent for consortium after initial royalty percentage               70.00%        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Consortium [Member]                        
Property, Plant and Equipment [Line Items]                        
Entitled percent for consortium after initial royalty percentage               70.00%        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Government Of Gabon [Member]                        
Property, Plant and Equipment [Line Items]                        
Monthly royalty rate, based on production at the published price               13.00%        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Etame Marine Block [Member]                        
Property, Plant and Equipment [Line Items]                        
Number of exploitation areas | item               3        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Etame Marine Block [Member] | Consortium [Member]                        
Property, Plant and Equipment [Line Items]                        
Working interest ownership, percentage               7.50%        
Prior Production Sharing Contract, Through September 17, 2018 [Member] | Etame Marine Block [Member] | Government Of Gabon [Member]                        
Property, Plant and Equipment [Line Items]                        
Working interest ownership, percentage                   7.50%    
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member]                        
Property, Plant and Equipment [Line Items]                        
Deferred tax assets, basis difference in fixed assets               $ 18,600        
Deferred tax liabilities, basis difference in fixed assets               18,600        
Allocated to proved leasehold cost               22,500        
Allocated to unproved leasehold cost               $ 13,700        
Estimated costs of technical studies       $ 500                
Entitled percent for consortium after initial royalty percentage               80.00%        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Consortium [Member]                        
Property, Plant and Equipment [Line Items]                        
Period of agreement for exploitation areas               10 years        
Number of drilled wells required by agreement | item               2        
Number of appraisal wellbores required by agreement | item               2        
Number of wells drilled | item             1          
Number of wellbores drilled | item             1          
Number of technical studies required | item   2                    
Estimated costs of technical studies       $ 1,500                
Entitled percent for consortium after initial royalty percentage               80.00%        
Monthly royalty rate, based on production at the published price               13.00%        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Signing Bonus [Member]                        
Property, Plant and Equipment [Line Items]                        
Contractual obligation                     $ 21,800  
Payment of signing bonus, allocated to proved and unproved property     $ 11,800                  
Reduction in VAT receivable     8,400     $ 4,200            
Other accrued liabilities     1,700       $ 1,700   $ 1,700      
Allocated to unproved leasehold cost               $ 6,700        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Signing Bonus [Member] | Consortium [Member]                        
Property, Plant and Equipment [Line Items]                        
Contractual obligation                     $ 65,000  
Payment of signing bonus, allocated to proved and unproved property     35,000                  
Reduction in VAT receivable     25,000                  
Other accrued liabilities     $ 5,000                  
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Tax Impact [Member]                        
Property, Plant and Equipment [Line Items]                        
Allocated to unproved leasehold cost               $ 7,100        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Etame Marine Block [Member]                        
Property, Plant and Equipment [Line Items]                        
Number of exploitation areas | item               3        
Period of agreement for exploitation areas               10 years        
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Scenario, Forecast [Member] | Etame Marine Block [Member]                        
Property, Plant and Equipment [Line Items]                        
Increase (decrease) in working interest ownership percentage 0.80%                      
Production Sharing Contract, September 17, 2018 Through September 16, 2028 [Member] | Scenario, Forecast [Member] | Etame Marine Block [Member] | Government Of Gabon [Member]                        
Property, Plant and Equipment [Line Items]                        
Working interest ownership, percentage 10.00%                      
Increase (decrease) in working interest ownership percentage 2.50%                      
Production Sharing Contract, After September 16, 2028 [Member]                        
Property, Plant and Equipment [Line Items]                        
Entitled percent for consortium after initial royalty percentage               70.00%        
Production Sharing Contract, After September 16, 2028 [Member] | Consortium [Member]                        
Property, Plant and Equipment [Line Items]                        
Entitled percent for consortium after initial royalty percentage               70.00%        
Production Sharing Contract, After September 16, 2028 [Member] | Etame Marine Block [Member]                        
Property, Plant and Equipment [Line Items]                        
Number of contract extension periods | item               2        
Production license agreement term extended by government               5 years