Supplemental Information on Oil and Gas Operations - Summary of Changes in Standardized Measure (Details) - USD ($)	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
Reconciliation
Standardized measure, beginning of year	$ 6,935,000	$ 0
Sales of oil produced, net of production costs	388,000	0
Net changes in sales and transfer prices and in production costs and production costs related to future production	(4,245,000)	0
Previously estimated development costs incurred during the period	0	0
Changes in future development costs	5,365,000	0
Revisions of previous quantity estimates due to prices and performance	(5,180,000)	0
Accretion of discount	214,000	(7,000,000)
Discoveries, net future production and development costs associated with these extensions and discoveries	0	13,935,000
Purchases and sales of minerals in place	0	0
Timing and other	(1,338,000)	0
Standardized measure, end of year	$ 2,139,000	$ 6,935,000