Under Financial Accounting Standards Board guidance, exploratory well costs should continue to be capitalized when the well has found a sufficient quantity of reserves to justify its completion as a producing well and the Company is making sufficient progress assessing the reserves and the economic and operating viability of the project.

As of March 31, 2023, the Company had total capitalized exploratory well costs for continuing operations pending the determination of proved reserves of $196.5 million. The following table reflects the net changes in capitalized exploratory well costs during the three-month periods ended March 31, 2023 and 2022.


(Thousands of dollars)	2023		2022
Beginning balance at January 1	$	171,860	$	179,481
Additions pending the determination of proved reserves	24,685		3,698

Capitalized exploratory well costs charged to expense	–		(10,473)
Balance at March 31	$	196,545	$	172,706

Capital well additions of $24.7 million are primarily related to Oso-1 well (Atwater Valley 138) in the Gulf of Mexico. In the first quarter of 2023, drilling of the Oso-1 well was temporarily suspended prior to reaching the objective. The Company plans to return to the well in the third quarter of 2023. There were no capitalized well costs charged to expense for the three months ended March 31, 2023.

The following table provides an aging of capitalized exploratory well costs based on the date the drilling was completed for each individual well and the number of projects for which exploratory well costs have been capitalized. The projects are aged based on the last well drilled in the project.


	March 31,
	2023				2022

(Thousands of dollars)	Amount		No. of Wells	No. of Projects	Amount		No. of Wells	No. of Projects
Aging of capitalized well costs:
Zero to one year	$	40,236	2	2	$	2,810	2	2
One to two years	13,171		2	2	–		–	–
Two to three years	–		–	–	23,667		3	3
Three years or more	143,138		5	4	146,229		8	2
	$	196,545	9	8	$	172,706	13	7

Of the $156.3 million of exploratory well costs capitalized more than one year at March 31, 2023, $97.2 million was in Vietnam, $37.0 million was in the U.S., $14.7 million was in Mexico, $4.7 million was in Canada, and $2.7 million was in Brunei. In all geographical areas, either further appraisal or development drilling is planned and/or development studies/plans are in various stages of completion.