PROPERTY, PLANT AND EQUIPMENT

3 Months Ended

Dec. 31, 2018

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT

NOTE 4 PROPERTY, PLANT AND EQUIPMENT

Property, plant and equipment as of December 31, 2018 and September 30, 2018 consisted of the following (in thousands):

	Estimated Useful Lives	December 31, 2018		September 30, 2018
Contract drilling equipment	4 - 15 years	$	8,534,720	$	8,442,081
Real estate properties	10 - 45 years		69,420		68,888
Other	2 - 23 years		478,604		471,310
Construction in progress			192,983		163,968
			9,275,727		9,146,247
Accumulated depreciation			(4,375,388)		(4,288,865)
Property, plant and equipment, net		$	4,900,339	$	4,857,382

Depreciation

Depreciation expense in the Unaudited Condensed Consolidated Statements of Operations of $140.0 million and $142.4 million includes abandonments of $1.0 million and $7.3 million for the three months ended December 31, 2018 and 2017, respectively.

During the three months ended December 31, 2018, we shortened the estimated useful life of certain components of rigs planned for conversion resulting in an increase in depreciation expense during the three months ended December 31, 2018 of approximately $2.5 million. This will also increase the depreciation expense for the next three months by approximately $0.7 million and will decrease the depreciation expense for fiscal years 2020, 2021, 2022, 2023, and 2024 by $0.6 million, $0.6 million, $0.4 million, $0.1 million, and $0.1 million, respectively and thereafter by $0.1 million.

Gain on Sale of Assets

We had a gain on sales of assets of $5.5 million and $5.6 million for the three months ended December 31, 2018 and 2017, respectively. These gains were primarily related to drill pipe damaged or lost in drilling operations.