Acquisitions and divestitures (Tables)

12 Months Ended

Dec. 31, 2013

Business Combinations [Abstract]

Purchase price allocation

The following table summarizes the consideration paid to acquire the properties and the amounts of the assets acquired and liabilities assumed as of December 18, 2013. The purchase price allocation is preliminary and subject to adjustment upon the final closing settlement that we expect to complete during the second quarter of 2014.

Consideration paid
Cash, net of purchase price adjustments	$	153,858
Fair value of identifiable assets acquired and liabilities assumed
Oil and natural gas properties
Proved	$	67,275
Unevaluated	87,663
Asset retirement obligations	(1,080		)
Fair value of net identifiable assets acquired	$	153,858

Unaudited pro forma information

The pro forma information below includes adjustments for depletion, depreciation, amortization and accretion expense, interest expense, acquisition costs, and related income tax effects.

	Year ended December 31,
	2013		2012
Revenues	$	690,564	$	599,344
Operating expenses	$	448,751	$	402,677
Net income	$	76,552	$	78,089