Subsequent events (Tables)

9 Months Ended

Sep. 30, 2017

Subsequent Events [Abstract]

New commodity derivative contracts

After September 30,2017, the Company entered into the following oil price swaps, oil basis swaps and natural gas price swapsto hedge additional amounts of the Company’s estimated future production:

				First		Second		Third		Fourth
				Quarter		Quarter		Quarter		Quarter		Total
Oil Price Swaps: (a)
	2017:
		Volume (Bbl)								846,000		846,000
		Price per Bbl							$	51.29	$	51.29
	2018:
		Volume (Bbl)		953,000		600,000		407,000		296,000		2,256,000
		Price per Bbl	$	51.55	$	51.39	$	51.43	$	51.28	$	51.45
	2019:
		Volume (Bbl)		1,035,000		1,046,500		828,000		828,000		3,737,500
		Price per Bbl	$	51.25	$	51.25	$	51.14	$	51.14	$	51.20
Oil Basis Swaps: (b)
	2017:
		Volume (Bbl)								1,499,000		1,499,000
		Price per Bbl							$	(0.12)	$	(0.12)
	2018:
		Volume (Bbl)		540,000		546,000		276,000		276,000		1,638,000
		Price per Bbl	$	(0.21)	$	(0.21)	$	(0.38)	$	(0.38)	$	(0.27)
	2019:
		Volume (Bbl)		1,395,000		1,410,500		1,426,000		1,426,000		5,657,500
		Price per Bbl	$	(0.68)	$	(0.68)	$	(0.68)	$	(0.68)	$	(0.68)
Natural Gas Price Swaps: (c)
	2017:
		Volume (MMBtu)								3,660,000		3,660,000
		Price per MMBtu							$	3.02	$	3.02
	2018:
		Volume (MMBtu)		5,400,000		5,460,000		4,600,000		4,600,000		20,060,000
		Price per MMBtu	$	3.02	$	3.02	$	3.01	$	3.01	$	3.02
	2019:
		Volume (MMBtu)		1,800,000		1,820,000		1,840,000		1,840,000		7,300,000
		Price per MMBtu	$	2.86	$	2.86	$	2.86	$	2.86	$	2.86
(a)	The index prices for the oil price swaps are based on the NYMEX – WTI monthly average futures price.
(b)	The basis differential price is between Midland – WTI and Cushing – WTI.
(c)	The index prices for the natural gas price swaps are based on the NYMEX – Henry Hub last trading day futures price.