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

12 Months Ended

Dec. 31, 2018

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

	December 31,
	2018			2017
Oil and natural gas properties:
Unproved properties	$	482,475		$	459,549
Proved properties		2,188,233			1,896,081
Total oil and natural gas properties		2,670,708			2,355,630
Less accumulated depreciation, depletion and amortization		(1,380,650	)		(1,248,200	)
Net oil and natural gas properties	$	1,290,058		$	1,107,430

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,
	2018		2017		2016
Acquisition costs:
Unproved properties	$	107,862	$	57,498	$	24,764
Proved properties		4,072		—		—
Development cost		239,467		257,119		150,778
Exploration cost		20,957		18,791		20,127
Total acquisition, development and exploration costs	$	372,358	$	333,408	$	195,669

Proved Developed and Proved Undeveloped Reserves

The following table provides a roll-forward of the total proved reserves for the year ended December 31, 2018, 2017, and 2016 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, 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
Revisions		5.6			(8,307.5	)		231.2			(42.8	)
Extensions and discoveries		515.8			4,059.4			2,995.7			558.1
Acquisitions		9.9			551			522			16.3
Divestitures		(0.2	)		—			—			(0.2	)
Production		(90.0	)		(3,503.0	)		(2,377.8	)		(125.3	)
End of year, December 31, 2018		1,531.2			34,730.9			20,852.1			1,864.7
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
December 31, 2018		501.0			20,213.8			8,058.7			670.7
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
December 31, 2018		1,030.2			14,517.2			12,793.4			1,194.1

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, 2018, 2017, and 2016 (in thousands):

	December 31,
	2018			2017			2016
Future cash inflows (total revenues)	$	6,730,000		$	4,750,238		$	1,143,142
Future production costs		(2,964,098	)		(2,332,310	)		(725,724	)
Future development costs (capital costs)		(855,932	)		(879,399	)		(116,988	)
Future income tax expense		(136,472	)		—			—
Future net cash flows		2,773,498			1,538,529			300,430
10% annual discount for estimated timing of cash flows		(1,444,188	)		(808,843	)		(94,449	)
Standardized measure of Discounted Future Net Cash Flow	$	1,329,310		$	729,686		$	205,981

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,
	2018			2017			2016
Standardized Measure, beginning of the year	$	729,686		$	205,981		$	212,865
Net change in prices and production costs		369,578			653,347			(33,507	)
Net change in future development costs		87,466			(385,042	)		1,552
Sales, less production costs		(321,802	)		(226,324	)		(99,768	)
Extensions		363,708			135,734			79,941
Acquisitions		7,468			2,365			1,045
Divestitures		(20	)		—			(5,231	)
Revisions of previous quantity estimates		19,910			322,917			15,754
Previously estimated development costs incurred		65,035			34,102			4,886
Net changes in taxes		(37,345	)		—			—
Accretion of discount		72,969			20,598			21,287
Changes in timing and other		(27,343	)		(33,992	)		7,157
Standardized Measure, end of year	$	1,329,310		$	729,686		$	205,981

- 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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