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Summary of Significant Accounting Policies - Schedule of Revenue by Major Customers by Reporting Segments (Details) - Sales Revenue, Net [Member] - Customer Concentration Risk [Member] | 3 Months Ended
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Jul. 31, 2020 | Jul. 31, 2019
Revenues, percentage | 100.00% | 100.00%
Eni S.P.A [Member] |  |
Revenues, percentage | 17.00% | 14.00%
Premier Oil UK Limited [Member] |  |
Revenues, percentage | 16.00% | 47.00%
EGP [Member] |  |
Revenues, percentage | 67.00% | 0.00%
U.S. Navy [Member] |  |
Revenues, percentage | 0.00% | 26.00%
Other [Member] |  |
Revenues, percentage | 0.00% | 13.00%

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