Note 4 - Property and Equipment

Net property and equipment as of September 30, 2018 and December 31, 2017, consists of the following:

(in thousands)	September 30, 2018			December 31, 2017

Oil and gas properties:
Proved oil and gas properties	$	215,620		$	114,893
Unproved properties not subject to depletion		3,616			1,947
Accumulated depreciation, depletion, amortization and impairment		(87,527	)		(80,715	)
Net oil and gas properties		131,709			36,125

Furniture and fixtures, computer hardware and software, and other equipment		3,783			1,758
Accumulated depreciation and amortization		(1,794	)		(1,021	)
Net other property and equipment		1,989			737

Total net property and equipment	$	133,698		$	36,862

We had approximately $3.6 million and $1.9 million, at September 30, 2018 and December 31, 2017, respectively, of unproved oil and gas properties not subject to depletion. At September 30, 2018 and December 31, 2017, our unproved properties consist principally of leasehold acquisition costs in the following areas:

(in thousands)	September 30, 2018		December 31, 2017

Ventura Basin	$	1,595	$	-
Illinois Basin:
Indiana		432		432
Illinois		142		136
Appalachian Basin:
Kentucky		952		915
Ohio		66		66
West Virginia		429		398

Total unproved properties not subject to depletion	$	3,616	$	1,947

During the three and nine months ended September 30, 2018 and 2017, there were no expiring leasehold costs that were reclassified into proved property. The excluded properties are assessed for impairment at least annually. Subject to industry conditions, evaluations of most of these properties and the inclusion of their costs in amortized capital costs is expected to be completed within five years.

We capitalized overhead applicable to acquisition, development and exploration activities of approximately $106,000 and $306,000 for the three and nine months ended September 30, 2018, respectively. For the three and nine months ended September 30, 2017, we capitalized overhead applicable to acquisition, development, and exploration activities of approximately $47,000 and $178,000, respectively.

Depletion expense related to oil and gas properties for the three and nine months ended September 30, 2018 was approximately $2.4 million, or $1.01 per Mcfe, and $5.6 million, or $0.88 per Mcfe, respectively. For the three and nine months ended September 30, 2017, depletion expense was approximately $521,000, or $0.38 per Mcfe, and $1.6 million, or $0.40 per Mcfe, respectively.