Additional Operations and Balance Sheet Information (Tables)

12 Months Ended

Dec. 31, 2019

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Significant purchasers / operators

Purchaser / Operator	2019			2018			2017
Sunoco Partners Marketing		21	%		18	%		18	%
Targa Midstream Services, LLC		8	%		9	%		13	%
Bedrock Production LLC		8	%		0	%		0	%
Enlink Gas Marketing, LTD.		8	%		10	%		13	%
ETX Energy, LLC formerly New Gulf Resources		6	%		5	%		7	%
Eastex Crude Company		5	%		3	%		7	%
Barnett Gathering, LP		5	%		4	%		1	%
ACE Gathering, Inc.		4	%		4	%		2	%
Peveler Pipeline, LP		3	%		0	%		0	%
Shell Trading (US) Company		3	%		4	%		4	%
Pruet Production Co.		3	%		3	%		3	%
Phillips 66		3	%		1	%		1	%
Hunt Crude Oil Supply		3	%		0	%		0	%
ETC Texas Pipeline, Ltd		2	%		4	%		2	%
Midcoast Energy Partners LP		2	%		3	%		4	%
Land and Natural Resource Develomeent		1	%		2	%		0	%
Enlink Crude Purchasing, LLC		1	%		0	%		0	%
FDL Operating LLC		1	%		1	%		0	%
Valero Energy Corporation		1	%		1	%		3	%
Empire Pipeline Corp.		1	%		1	%		1	%
DCP Midstream, LP		1	%		4	%		3	%
XTO Energy, Inc.		1	%		1	%		1	%
OXY USA, Inc.		1	%		1	%		2	%
Range Resources Corporation		1	%		1	%		1	%
Sandridge Energy, Inc.		1	%		1	%		1	%
White Knight Production, LLC		1	%		0	%		0	%
Webb Energy Resources, Inc.		0	%		1	%		1	%
Enervest Operating, LLC		0	%		10	%		3	%
Courson Oil & Gas, Inc.		0	%		0	%		1	%
LPC Crude Oil Marketing LLC		0	%		2	%		3	%
Lucid Energy Group II (Formerly Agave Energy Co.)		0	%		1	%		2	%
Enterprise Crude Oil, LLC		0	%		1	%		0	%
Ward Petroleum Corporation		0	%		0	%		1	%

Revenues, costs and expenses related to the Company's oil and gas operations

	Year Ended December 31,
	2019			2018			2017
Capitalized costs relating to oil and gas
producing activities:
Unproved properties	$	1,876,000		$	1,896,000		$	1,891,000
Proved properties		25,062,000			25,996,000			26,675,000
Total capitalized costs		26,938,000			27,892,000			28,566,000
Accumulated amortization		(24,848,000	)		(24,454,000	)		(24,015,000	)
Total capitalized costs, net	$	2,090,000			3,438,000			4,551,000

	Year Ended December 31,
	2019		2018		2017
Costs incurred in oil and gas property
acquisitions, exploration and development:
Acquisition of properties	$	214,000	$	354,000	$	3,629,000
Development costs		72,000		191,000		856,000
Total costs incurred	$	286,000	$	545,000	$	4,485,000

	Year Ended December 31,
	2019		2018		2017
Results of operations from producing activities:
Sales of oil and gas	$	4,631,000	$	5,848,000	$	4,495,000
Production costs		2,582,000		2,491,000		2,058,000
Amortization of oil and gas properties		394,000		439,000		458,000
Total production costs		2,976,000		2,930,000		2,516,000
Total net revenue	$	1,655,000	$	2,918,000	$	1,979,000

	Year Ended December 31,
	2019		2018		2017
Sales price per equivalent Mcf	$	3.97	$	5.16	$	4.85
Production costs per equivalent Mcf	$	2.21	$	2.20	$	2.22
Amortization per equivalent Mcf	$	0.34	$	0.39	$	0.49

	Year Ended December 31,
	2019		2018		2017
Results of operations from gas gathering
and equipment rental activities:
Revenue	$	125,000	$	136,000	$	126,000
Operating expenses		32,000		49,000		40,000
Depreciation		2,000		1,000		5,000
Total costs		34,000		50,000		45,000
Total net revenue	$	91,000	$	86,000	$	81,000