Property and equipment consisted of the following at December 31, 2023 and 2022 (in thousands):


	2023			2022
Equipment	$	8,506,727		$	7,551,099
Oil and natural gas properties		238,337			236,156
Buildings		248,693			175,212
Rental equipment		119,653			—
Land		38,811			23,610
Total property and equipment		9,152,221			7,986,077
Less accumulated depreciation, depletion, amortization and impairment		(5,811,809	)		(5,725,501	)
Property and equipment, net	$	3,340,412		$	2,260,576

Depreciation, depletion, amortization and impairment — The following table summarizes depreciation, depletion, amortization and impairment expense related to property and equipment and intangible assets for 2023, 2022 and 2021 (in thousands):


	2023		2022		2021
Depreciation and impairment expense	$	682,672	$	472,969	$	818,999
Amortization expense		41,521		2,891		24,606
Depletion expense		7,223		8,085		5,573
Total	$	731,416	$	483,945	$	849,178

On a periodic basis, we evaluate our fleet of drilling rigs for marketability based on the condition of inactive rigs, expenditures that would be necessary to bring inactive rigs to working condition and the expected demand for drilling services by rig type. The components comprising rigs that will no longer be marketed are evaluated, and those components with continuing utility to our other marketed rigs are transferred to other rigs or to our yards to be used as spare equipment. The remaining components of these rigs are abandoned. There were no impairments in 2022 or 2023. In the fourth quarter of 2021, we identified 43 legacy non-super-spec rigs and equipment to be abandoned. Based on the strong customer preference across the industry for super-spec drilling rigs, we believed the 43 rigs that were abandoned had limited commercial opportunity. We recorded a $220 million charge related to this abandonment in the fourth quarter of 2021.

We also periodically evaluate our other drilling service assets. In the fourth quarter of 2021, we abandoned certain directional drilling equipment totaling $2.5 million and recorded a charge on our developed technology intangible asset of $11.4 million due to advances in technology that rendered those assets, and their related spare parts inventory, obsolete. There were no similar charges in 2022 or 2023.

We also periodically evaluate our completion services assets for marketability based on the condition of inactive equipment, expenditures that would be necessary to bring the equipment to working condition and the expected demand for such equipment. The components of equipment that will no longer be marketed are evaluated, and those components with continuing utility will be used as parts to support active equipment. The remaining components of this equipment are abandoned. In the fourth quarter of 2021, we recorded a charge of $32.2 million related to the abandonment of approximately 0.2 million horsepower within our completion services fleet. The majority of these units were frac pumps but also included pump down units. These units were abandoned due to changes in customer preferences for dual fuel, advancements in technology, and prohibitive reactivation costs. There were no similar charges in 2022 or 2023.

We also periodically evaluate our drilling products assets for marketability based on the condition of inactive equipment, expenditures that would be necessary to bring the equipment to working condition and the expected demand for such equipment. There have been no impairment charges recorded since the acquisition of these assets as part of the Ulterra acquisition in the third quarter of 2023.