
(in thousands)	Estimated Useful Lives	December 31, 2024		September 30, 2024
Drilling services equipment	4 - 15 years	$	6,713,200	$	6,671,975
Tubulars	4 years	539,876		552,773
Real estate properties	10 - 45 years	49,061		48,617
Other	2 - 23 years	465,604		460,857
Construction in progress1		132,367		106,183
		7,900,108		7,840,405
Accumulated depreciation		(4,890,748)		(4,824,128)
Property, plant and equipment, net		$	3,009,360	$	3,016,277

(1)Included in construction in progress are costs for projects in progress to upgrade or refurbish certain rigs in our existing fleet. Additionally, we include other advances for capital maintenance purchase-orders that are open/in process. As these various projects are completed, the costs are then classified to their appropriate useful life category.

Depreciation expense during the three months ended December 31, 2024 and 2023 was $97.0 million and $92.4 million, including abandonments of $0.7 million and $0.5 million, respectively. During the three months ended December 31, 2024, depreciation expense included $1.2 million of accelerated depreciation for components on rigs that are scheduled for conversion in fiscal year 2025 compared to $0.9 million in the three months ended December 31, 2023. These expenses are recorded within Depreciation and amortization on our Unaudited Condensed Consolidated Statements of Operations.

We recognized a gain of $9.4 million and $7.5 million during the three months ended December 31, 2024 and 2023, respectively, related to customer reimbursement for the current replacement value of lost or damaged drill pipe. Gains related to these asset sales are recorded in Gain on reimbursement of drilling equipment within our Unaudited Condensed Consolidated Statements of Operations.