Property, plant and equipment (Tables)

12 Months Ended

Dec. 31, 2018

Summary of Property Plant and Equipment by Class of Assets

12.1.

By class of assets


	Land, buildings and improvement			Equipment and *other assets^()**			Assets under construction ^()**			Exploration and development costs (oil and gas producing properties) ^()*			Total
Balance at January 1,2017		6,982			78,724			38,569			51,195			175,470

Additions		2			1,167			11,031			31			12,231
Additions to / review of estimates of decommissioning costs		—			—			—			4,503			4,503
Capitalized borrowing costs		—			—			1,972			—			1,972
Write-offs		(14	)		(6	)		(545	)		(35	)		(600	)
Transfers^(****)		316			3,296			(7,631	)		3,079			(940	)
Depreciation, amortization and depletion		(437	)		(7,320	)		—			(5,366	)		(13,123	)
Impairment recognition		(145	)		(937	)		(568	)		(892	)		(2,542	)
Impairment reversal		52			831			165			692			1,740
Cumulative translation adjustment		(91	)		(753	)		(472	)		(745	)		(2,061	)

Balance at December 31, 2017		6,665			75,002			42,521			52,462			176,650

Cost		9,914			128,603			42,521			86,491			267,529
Accumulated depreciation, amortization and depletion		(3,249	)		(53,601	)		—			(34,029	)		(90,879	)

Balance at December 31, 2017		6,665			75,002			42,521			52,462			176,650

Additions		4			1,751			8,707			6			10,468
Additions to / review of estimates of decommissioning costs		—			—			—			4,778			4,778
Capitalized borrowing costs		—			—			1,810			—			1,810
Write-offs		(61	)		(16	)		(327	)		(27	)		(431	)
Transfers^(****)		(93	)		13,720			(18,667	)		4,086			(954	)
Depreciation, amortization and depletion		(359	)		(6,529	)		—			(5,028	)		(11,916	)
Impairment recognition		—			(742	)		(250	)		(1,686	)		(2,678	)
Impairment reversal		—			309			23			226			558
Cumulative translation adjustment		(946	)		(7,467	)		(4,891	)		(7,598	)		(20,902	)

Balance at December 31, 2018		5,210			76,028			28,926			47,219			157,383

Cost		7,829			128,711			28,926			77,141			242,607
Accumulated depreciation, amortization and depletion		(2,619	)		(52,683	)		—			(29,922	)		(85,224	)

Balance at December 31, 2018		5,210			76,028			28,926			47,219			157,383

Weighted average useful life in years		40 (25 to 50 (except land	) )		20 (3 to 31	)					Units of production method

(*)	It is composed of platforms, refineries, thermoelectric power plants, natural gas processing plants, pipelines, rights of use and other operating, storage and production plants, also including exploration and production assets depreciated based on the units of production method.

(**)	See note 30 for assets under construction by business area.

(***)

It is composed of exploration and production assets related to wells, abandonment and dismantling of areas, signature bonuses associated to proved reserves and other costs directly associated to the exploration and production of oil and gas.

(****)

It includes transfers to/from assets held for sale.

Summary of Estimated Useful Life of Property Plant and Equipment

12.2.

Estimated useful life


	Buildings and improvements, equipment and other assets
Estimated useful life	Cost		Accumulated depreciation			Balance at 2018
5 years or less		3,850		(2,914	)		936
6 - 10 years		10,038		(6,272	)		3,766
11 - 15 years		3,299		(1,515	)		1,784
16 - 20 years		34,267		(13,473	)		20,794
21 - 25 years		21,462		(4,733	)		16,729
25 - 30 years		13,942		(4,001	)		9,941
30 years or more		23,323		(6,843	)		16,480
Units of production method		26,059		(15,551	)		10,508

Total		136,240		(55,302	)		80,938

Buildings and improvements		7,529		(2,619	)		4,910
Equipment and other assets		128,711		(52,683	)		76,028

Summary of Effects of Unitization Agreements

The table below presents the effects of the agreements:


	12.31.2018
Equalization payables (*)		279
Indexation charges		2
Write-offs		(62	)
Payments maid		(100	)
Cumulative translation adjustments		(2	)

Remaining payables		118

(*)

It was accounted for within other income and expenses as set out note 26.