We recognize an estimated liability for future costs associated with the abandonment of our crude oil and natural gas properties, including facilities requiring decommissioning. A liability for the fair value of an asset retirement obligation and corresponding increase to the carrying value of the related long-lived asset are recorded at the time a well is drilled or acquired, or a facility is constructed. The increase in carrying value is included in proved properties in the accompanying balance sheets. We deplete the amount added to proved properties and recognize expense in connection with the accretion of the discounted liability over the remaining estimated economic lives of the respective long-lived assets. Cash paid to settle asset retirement obligations is included in the cash flows from operating activities section of our accompanying statements of cash flows.

Our estimated asset retirement obligation liability is based on historical experience plugging and abandoning wells, estimated plugging and abandonment cost, estimated economic lives, and regulatory requirements. The liability is discounted using the credit-adjusted risk-free rate estimated at the time the liability is incurred or revised.

A roll-forward of our asset retirement obligation is as follows (in millions):


	Amount
Balance as of December 31, 2024	$	458
Additional liabilities incurred with development activities and other	1
Additional liabilities incurred with acquisitions	2
Liabilities settled	(16)
Accretion expense	7


Balance as of March 31, 2025	$	452
Current portion(1)	$	59
Long-term portion	$	393

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