Exploration Expense

9 Months Ended

Sep. 30, 2020

Extractive Industries [Abstract]

Exploration Expense

Exploration Expense

A summary of our exploration expense for the Current Quarter, the Prior Quarter, the Current Period and the Prior Period is as follows:

	Three Months Ended September 30,				Nine Months Ended September 30,
	2020		2019		2020		2019
	($ in millions)
Impairments of unproved properties	$	3	$	1	$	402	$	26
Dry hole expense	—		8		7		8
Geological and geophysical expense and other	2		8		8		22
Exploration expense	$	5	$	17	$	417	$	56

Unproved oil and natural gas properties are periodically assessed for impairment by considering future drilling and exploration plans, results of exploration activities, commodity price outlooks, planned future sales and expiration of all or a portion of the projects. The exploration expense charges during the Current Period are the result of non-cash impairment charges in unproved properties, primarily in our Brazos Valley, Haynesville, Powder River Basin and Mid-Continent operating areas.