Supplemental Oil and Natural Gas Information (unaudited) (Tables)

12 Months Ended

Dec. 31, 2017

A summary of the Company’s capitalized costs are contained in the table below (in thousands):

	December 31,
	2017			2016
Oil and natural gas properties:
Unproved properties	$	459,549		$	526,270
Proved properties		1,896,081			1,545,860
Total oil and natural gas properties		2,355,630			2,072,130
Less accumulated depreciation, depletion and amortization		(1,248,200	)		(1,131,378	)
Net oil and natural gas properties	$	1,107,430		$	940,752

Summary of Oil and Gas Property Acquisition and Development

A summary of the Company’s cost incurred in oil and natural gas property acquisition and development activities is set forth below (in thousands):

	December 31,
	2017		2016		2015
Acquisition costs:
Unproved properties	$	57,498	$	24,764	$	24,722
Proved properties		—		—		—
Development cost		257,119		150,778		259,655
Exploration cost		18,791		20,127		20,530
Total acquisition, development and exploration costs	$	333,408	$	195,669	$	304,907

Proved Developed and Proved Undeveloped Reserves

The following table provides a roll-forward of the total proved reserves for the year ended December 31, 2017, 2016, and 2015 as well as proved developed and proved undeveloped reserves at the beginning and end of each respective year:

	Natural Gas (Bcf)			Natural Gas Liquids (MBbl)			Oil (MBbl)			TOTAL (Bcfe)
End of year, December 31, 2014		256.3			10,879.0			5,697.4			355.8
Revisions		(115.3	)		(4,705.7	)		(1,550.1	)		(152.9	)
Extensions and discoveries		182.6			4,035.7			2,496.3			221.7
Production		(49.5	)		(2,450.3	)		(1,950.5	)		(75.8	)
End of year, December 31, 2015		274.1			7,758.7			4,693.1			348.8
Revisions		(0.1	)		1,273.7			1,196.8			14.8
Extensions and discoveries		175.4			2,156.0			1,300.2			196.1
Acquisitions		3.8			24.8			15.1			4.1
Divestitures		(5.9	)		(91.5	)		(703.7	)		(10.7	)
Production		(60.9	)		(2,446.2	)		(1,343.8	)		(83.7	)
End of year, December 31, 2016		386.4			8,675.5			5,157.7			469.4
Revisions		515.1			20,327.3			9,746.8			695.6
Extensions and discoveries		274.4			15,598.8			6,192.9			405.1
Acquisitions		1.6			42.6			5.8			1.9
Production		(87.4	)		(2,713.6	)		(1,622.4	)		(113.4	)
End of year, December 31, 2017		1,090.1			41,930.6			19,480.8			1,458.6
Proved developed reserves:
December 31, 2015		209.5			7,245.7			4,239.2			278.4
December 31, 2016		226.1			7,520.0			4,439.5			297.8
December 31, 2017		334.6			13,782.9			6,449.6			456.0
Proved undeveloped reserves:
December 31, 2015		64.5			513.0			453.9			70.3
December 31, 2016		160.4			1,155.5			718.1			171.6
December 31, 2017		755.5			28,147.7			13,031.2			1,002.6

Standard Measure of Discounted Future Net Cash Flows

The standardized measure of discounted future net cash flows relating to proved oil and natural gas reserves is as follows at December 31, 2017, 2016, and 2015 (in thousands):

	December 31,
	2017			2016			2015
Future cash inflows (total revenues)	$	4,750,238		$	1,143,142		$	975,664
Future production costs		(2,332,310	)		(725,724	)		(592,073	)
Future development costs (capital costs)		(879,399	)		(116,988	)		(83,532	)
Future income tax expense		—			—			—
Future net cash flows		1,538,529			300,430			300,059
10% annual discount for estimated timing of cash flows		(808,843	)		(94,449	)		(87,194	)
Standardized measure of Discounted Future Net Cash Flow	$	729,686		$	205,981		$	212,865

Summary of Changes in Standardized Measure of Discounted Net Cash Flows

A summary of the changes in the standardized measure of discounted future net cash flows are contained in the table below (in thousands):

	December 31,
	2017			2016			2015
Standardized Measure, beginning of the year	$	205,981		$	212,865		$	330,657
Net change in prices and production costs		653,347			(33,507	)		(372,664	)
Net change in future development costs		(385,042	)		1,552			79,244
Sales, less production costs		(226,324	)		(99,768	)		(121,646	)
Extensions		135,734			79,941			107,749
Acquisitions		2,365			1,045			—
Divestitures		—			(5,231	)		—
Revisions of previous quantity estimates		322,917			15,754			(97,210	)
Previously estimated development costs incurred		34,102			4,886			62,906
Accretion of discount		20,598			21,287			50,939
Net change in taxes		—			—			178,732
Changes in timing and other		(33,992	)		7,157			(5,842	)
Standardized Measure, end of year	$	729,686		$	205,981		$	212,865

- Definition

Tabular disclosure of the net quantities of an enterprise's interests in proved developed and undeveloped reserves of (a) crude oil (including condensate and natural gas liquids), (b) natural gas (including coal bed methane), (c) synthetic oil, (d) synthetic gas, and (e) other nonrenewable natural resources that are intended to be upgraded during the period as of the beginning of the period, changes in quantities during the period, and as of the end of the period.

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- Definition

Tabular disclosure of the future net cash flows relating to proved oil and gas reserves and oil and gas subject to purchase under long-term agreements in which the enterprise participates in the operation of the properties on which the oil and gas is located or otherwise serves as the producer. This information is presented in aggregate and for each geographic area for which reserve quantities are disclosed.

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