|
Supplemental Information on Oil and Gas Producing Activities - Additional Information (Detail) (USD $)
|
12 Months Ended |
3 Months Ended |
1 Months Ended |
|
|
Dec. 31, 2014
|
Dec. 31, 2013
|
Dec. 31, 2012
|
Dec. 31, 2013
|
Nov. 30, 2012
|
Dec. 31, 2011
MBbls
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Exploration expense |
$ 13,300,000us-gaap_ResultsOfOperationsDryHoleCosts
|
$ 23,900,000us-gaap_ResultsOfOperationsDryHoleCosts
|
$ 37,300,000us-gaap_ResultsOfOperationsDryHoleCosts
|
|
|
|
| Future development costs |
52,800,000us-gaap_CostsIncurredDevelopmentCosts
|
|
|
|
|
|
| Development cost to company |
14,800,000egy_DevelopmentCostToCompany
|
|
|
|
|
|
| Oil |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Proved Developed Reserves |
3,224us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_OilReservesMember
|
3,305us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_OilReservesMember
|
3,750us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_OilReservesMember
|
3,305us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_OilReservesMember
|
|
3,854us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_OilReservesMember
|
| Gas |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Proved Developed Reserves |
1,406,000us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_NaturalGasReservesMember
|
1,333,000us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_NaturalGasReservesMember
|
1,544,000us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_NaturalGasReservesMember
|
1,333,000us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_NaturalGasReservesMember
|
|
856,000us-gaap_ProvedDevelopedReservesVolume
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_NaturalGasReservesMember
|
| Avouma and South Tchibala |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Proved Developed Reserves |
1,500us-gaap_ProvedDevelopedReservesVolume
/ dei_LegalEntityAxis
= egy_AvoumaAndSouthTchibalaMember
|
|
1,200us-gaap_ProvedDevelopedReservesVolume
/ dei_LegalEntityAxis
= egy_AvoumaAndSouthTchibalaMember
|
|
|
|
| Etame |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Proved Developed Reserves |
1,100us-gaap_ProvedDevelopedReservesVolume
/ dei_LegalEntityAxis
= egy_EtameMember
|
800us-gaap_ProvedDevelopedReservesVolume
/ dei_LegalEntityAxis
= egy_EtameMember
|
1,000us-gaap_ProvedDevelopedReservesVolume
/ dei_LegalEntityAxis
= egy_EtameMember
|
800us-gaap_ProvedDevelopedReservesVolume
/ dei_LegalEntityAxis
= egy_EtameMember
|
|
|
| Period of development |
20 years
|
|
|
|
|
|
| Expiration of development |
expire in 2021
|
|
|
|
|
|
| Exploration area expiration year |
expired in July 2014
|
|
|
|
|
|
| Ebouri |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Proved Developed Reserves |
300us-gaap_ProvedDevelopedReservesVolume
/ dei_LegalEntityAxis
= egy_EbouriMember
|
|
|
|
|
|
| Period of development |
20 years
|
|
|
|
|
|
| Expiration of development |
expire in 2026
|
|
|
|
|
|
| Consortium |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of production |
70.00%egy_PercentageOfProductionRemainingAfterDeductingRoyalty
/ dei_LegalEntityAxis
= egy_ConsortiumMember
|
|
|
|
|
|
| Net cost account |
36,800,000egy_AmountInCostAccountForCompany
/ dei_LegalEntityAxis
= egy_ConsortiumMember
|
|
|
|
|
|
| Cost Recovered |
907,400egy_CostRecoveredQuantity
/ dei_LegalEntityAxis
= egy_ConsortiumMember
|
929,400egy_CostRecoveredQuantity
/ dei_LegalEntityAxis
= egy_ConsortiumMember
|
367,000egy_CostRecoveredQuantity
/ dei_LegalEntityAxis
= egy_ConsortiumMember
|
|
|
|
| Theoretical Cost |
935,800egy_TheoreticalCostQuantity
/ dei_LegalEntityAxis
= egy_ConsortiumMember
|
1,079,300egy_TheoreticalCostQuantity
/ dei_LegalEntityAxis
= egy_ConsortiumMember
|
1,197,000egy_TheoreticalCostQuantity
/ dei_LegalEntityAxis
= egy_ConsortiumMember
|
|
|
|
| Consortium | Minimum |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of contract area |
50.00%egy_PercentageOfContractArea
/ dei_LegalEntityAxis
= egy_ConsortiumMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
|
|
|
|
|
|
| Consortium | Maximum |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of contract area |
60.00%egy_PercentageOfContractArea
/ dei_LegalEntityAxis
= egy_ConsortiumMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
|
|
|
|
|
|
| Avouma |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Period of development |
20 years
|
|
|
|
|
|
| Expiration of development |
expire in 2025
|
|
|
|
|
|
| Mutamba Iroru |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of production |
70.00%egy_PercentageOfProductionRemainingAfterDeductingRoyalty
/ dei_LegalEntityAxis
= egy_MutambaIroruMember
|
|
|
|
|
|
| Net cost account |
36,400,000egy_AmountInCostAccountForCompany
/ dei_LegalEntityAxis
= egy_MutambaIroruMember
|
|
|
|
|
|
| Proved reserves |
0egy_ProvedReserves
/ dei_LegalEntityAxis
= egy_MutambaIroruMember
|
|
|
|
|
|
| Mutamba Iroru | Minimum |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of contract area |
50.00%egy_PercentageOfContractArea
/ dei_LegalEntityAxis
= egy_MutambaIroruMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
|
|
|
|
|
|
| Mutamba Iroru | Maximum |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of contract area |
63.00%egy_PercentageOfContractArea
/ dei_LegalEntityAxis
= egy_MutambaIroruMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
|
|
|
|
|
|
| Block 5 Production |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of production |
50.00%egy_PercentageOfProductionRemainingAfterDeductingRoyalty
/ dei_LegalEntityAxis
= egy_BlockFiveProductionMember
|
|
|
|
|
|
| Period of development |
20 years
|
|
|
|
|
|
| Proved reserves |
0egy_ProvedReserves
/ dei_LegalEntityAxis
= egy_BlockFiveProductionMember
|
|
|
|
|
|
| Royalty Payments |
0us-gaap_RoyaltyExpense
/ dei_LegalEntityAxis
= egy_BlockFiveProductionMember
|
|
|
|
|
|
| Block 5 Production | Minimum |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of contract area |
30.00%egy_PercentageOfContractArea
/ dei_LegalEntityAxis
= egy_BlockFiveProductionMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
|
|
|
|
|
|
| Block 5 Production | Maximum |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of contract area |
90.00%egy_PercentageOfContractArea
/ dei_LegalEntityAxis
= egy_BlockFiveProductionMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
|
|
|
|
|
|
| Block P Production |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of production |
70.00%egy_PercentageOfProductionRemainingAfterDeductingRoyalty
/ dei_LegalEntityAxis
= egy_BlockPProductionMember
|
|
|
|
|
|
| Period of development |
25 years
|
|
|
|
|
|
| Proved reserves |
0egy_ProvedReserves
/ dei_LegalEntityAxis
= egy_BlockPProductionMember
|
|
|
|
|
|
| Income tax on net profits |
25.00%egy_RateOfIncomeTaxOnNetProfits
/ dei_LegalEntityAxis
= egy_BlockPProductionMember
|
|
|
|
|
|
| Block P Production | Minimum |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Fixed royalty rate |
10.00%egy_RateOfFixedRoyaltyPayableUnderProductionSharingContract
/ dei_LegalEntityAxis
= egy_BlockPProductionMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
|
|
|
|
|
|
| Percentage of contract area |
10.00%egy_PercentageOfContractArea
/ dei_LegalEntityAxis
= egy_BlockPProductionMember
/ us-gaap_RangeAxis
= us-gaap_MinimumMember
|
|
|
|
|
|
| Block P Production | Maximum |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Fixed royalty rate |
16.00%egy_RateOfFixedRoyaltyPayableUnderProductionSharingContract
/ dei_LegalEntityAxis
= egy_BlockPProductionMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
|
|
|
|
|
|
| Percentage of contract area |
60.00%egy_PercentageOfContractArea
/ dei_LegalEntityAxis
= egy_BlockPProductionMember
/ us-gaap_RangeAxis
= us-gaap_MaximumMember
|
|
|
|
|
|
| Gabon |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Exploration expense |
|
|
|
11,700,000us-gaap_ResultsOfOperationsDryHoleCosts
/ us-gaap_StatementGeographicalAxis
= country_GA
|
|
|
| Unsuccessful exploration wells |
1us-gaap_DevelopmentWellsDrilledNetNonproductive
/ us-gaap_StatementGeographicalAxis
= country_GA
|
|
|
|
|
|
| Exploration license |
|
|
|
1,600,000us-gaap_ResultsOfOperationsExpenseOther
/ us-gaap_StatementGeographicalAxis
= country_GA
|
|
|
| Contractual price |
98.88egy_ContractualPricePerUnit
/ us-gaap_StatementGeographicalAxis
= country_GA
|
|
|
|
|
|
| Fixed royalty rate |
13.00%egy_RateOfFixedRoyaltyPayableUnderProductionSharingContract
/ us-gaap_StatementGeographicalAxis
= country_GA
|
|
|
|
|
|
| Equatorial Guinea |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Percentage of working interest acquired |
|
|
|
|
31.00%egy_PercentageOfWorkingInterestAcquired
/ us-gaap_StatementGeographicalAxis
= country_GQ
|
|
| Acquisition of Working Interest, cost |
|
|
|
|
10,000,000us-gaap_SignificantCostsIncurredToAcquireMineralInterestOfProvedReserves
/ us-gaap_StatementGeographicalAxis
= country_GQ
|
|
| United States |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Future development costs |
$ 8,000us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_StatementGeographicalAxis
= country_US
|
$ 113,000us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_StatementGeographicalAxis
= country_US
|
$ 9,689,000us-gaap_CostsIncurredDevelopmentCosts
/ us-gaap_StatementGeographicalAxis
= country_US
|
|
|
|
| United States | Oil |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Contractual price |
86.49egy_ContractualPricePerUnit
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_OilReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US
|
|
|
|
|
|
| United States | Gas |
|
|
|
|
|
|
| Costs Incurred Oil And Gas Property Acquisition Exploration And Development Activities [Line Items] |
|
|
|
|
|
|
| Contractual price |
5.19egy_ContractualPricePerUnit
/ us-gaap_ReserveQuantitiesByTypeOfReserveAxis
= us-gaap_NaturalGasReservesMember
/ us-gaap_StatementGeographicalAxis
= country_US
|
|
|
|
|
|