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v3.21.2

Schedule of Revenue by Major Customers by Reporting Segments (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Oct. 31, 2021 | Oct. 31, 2020 | Oct. 31, 2021 | Oct. 31, 2020
Product Information [Line Items] |  |  |  |
Revenues | $ 247 | $ 118 | $ 519 | $ 287
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Eni S.p.A [Member] |  |  |  |
Product Information [Line Items] |  |  |  |
Revenues | 14 | 72 | 14 | 99
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Department of Energy [Member] |  |  |  |
Product Information [Line Items] |  |  |  |
Revenues | 81 |  | 81 |
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | EGP [Member] |  |  |  |
Product Information [Line Items] |  |  |  |
Revenues | 14 | 42 | 163 | 157
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Clark Hill [Member] |  |  |  |
Product Information [Line Items] |  |  |  |
Revenues | 30 |  | 37 |
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Matthews [Member] |  |  |  |
Product Information [Line Items] |  |  |  |
Revenues | 30 |  | 30 |
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Valaris [Member] |  |  |  |
Product Information [Line Items] |  |  |  |
Revenues | 47 |  | 135 |
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Other [Member] |  |  |  |
Product Information [Line Items] |  |  |  |
Revenues | 31 | 4 | 59 | 31
Revenue Benchmark [Member] | Customer Concentration Risk [Member] | Customer [Member] |  |  |  |
Product Information [Line Items] |  |  |  |
Revenues | $ 247 | $ 118 | $ 519 | $ 287

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