QuickLinks -- Click here to rapidly navigate through this document

SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT PURSUANT TO ~~SECION~~SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Date of report (Date of earliest event reported): August 15, 2003

~~March~~CARBON ~~24,~~ENERGY ~~2003~~CORPORATION (Exact Name of Registrant as Specified in Charter)

CARBON ENERGY CORPORATION

COLORADO		1-15639		84-1515097
(State of Other Jurisdiction of Incorporation)		(Commission File Number)		(IRS Employer Identification No.)

1700 BROADWAY, SUITE 1150, DENVER, COLORADO 80290 (~~Exact~~Address ~~Name~~and ofZip ~~Registrant~~Code asof ~~Specified~~Principal inExecutive ~~Charter~~Offices)

COLORADO	1-15639	84-1515097
(State of Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification No.)
1700 BROADWAY, SUITE 1150, DENVER, COLORADO 80290
(Address and Zip Code of Principal Executive Offices)
303-863-1555
(Registrant’s telephone number, including area code)

303-863-1555
(Registrant's telephone number, including area code)

~~Item~~ ~~2. Acquisition~~ orItem ~~Disposition~~7. ofFINANCIAL ~~Assets~~STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS.

99.1: Press released dated August 14, 2003—Carbon Energy Corporation Reports Increased Net Income for the United States and Canada for the Second Quarter of 2003.

On ~~March 24, 2003, Carbon Energy Corporation (Carbon or the Company)~~ ~~closed~~ ~~on the sale of the Company’s interests in 97 gross wells (23.3 net~~ ~~wells)~~Item ~~and 25,400 gross acres (8,200 net acres) located primarily in southeast New Mexico to Fasken Acquisition 02, Ltd~~12. ~~(Fasken). Net~~RESULTS ~~proved~~OF ~~reserves~~OPERATIONS atAND ~~December~~FINANCIAL ~~31, 2002 of the divested properties were 7~~CONDITION.3 billion cubic feet of natural gas and 172,000 barrels of oil and daily average net production from the properties was approximately 3,270 thousand cubic feet of gas and 130 barrels of oil. The adjusted purchase price was $15.7 million in cash, with an effective date of January 1, 2003. Proceeds from the sale were used to repay borrowings under the Company’s U.S. credit facility with Bank of Oklahoma. Subject to the completion of a proposed merger with Evergreen Resources, Inc. as previously reported, Carbon intended at the time of the sale to utilize borrowing capacity available as a result of the above-mentioned sale to accelerate Carbon's exploration and development drilling program in the Piceance and Uintah Basins.

~~Item~~ The ~~7. Financial~~information in this Current Report, including the attached Exhibit, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange ~~Statement~~Act ~~and~~of ~~Exhibits~~1934, as amended, or otherwise subject to the liabilities of that Section, nor shall it be deemed incorporated by reference into any filing under the Securities Act of 1933, as amended.

~~(b) Pro~~ On ~~Forma~~August 14, ~~Financial~~2003, ~~Statements~~Carbon Energy Corporation (~~UNAUDITED~~the "Company") issued a press release announcing the Company's financial results for the three and six months ended June 30, 2003, a copy of which is attached as Exhibit 99.1.

The accompanying pro forma balance sheet and pro forma statement of operations have been prepared to present the effect of Carbon’s sale of oil and gas properties to Fasken and are based upon assumptions set forth in the notes to such statements.

The pro forma financial statements are comprised of historical data which have been retroactively adjusted to reflect the effects of the above mentioned transaction on the historical financial statements. The historical information assumes that the transaction for which the pro forma effects are shown was consummated on December 31, 2002 for the pro forma balance sheet and January 1, 2002 for the pro forma statement of operations. The pro forma information should be read in conjunction with the Company’s audited financial statements and the related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2003.

CARBON ENERGY CORPORATION

PRO FORMA BALANCE SHEET

DECEMBER 31, 2002 (in thousands) (unaudited)

	Historical			Property Sale			Pro Forma
ASSETS
Current assets:
Cash	$	—		$	—		$	—
Accounts receivable, trade	3,240			—			3,240
Prepaid expenses and other	918			—			918
Total current assets	4,158			—			4,158
Property and equipment, at cost:
Oil and gas properties, using the full cost method of accounting:
Unproved properties	7,080			—			7,080
Proved properties	71,223			(15,721		)(a)	55,502
Furniture and equipment	894			—			894
	79,197			(15,721		)	63,476
Less accumulated depreciation, depletion and amortization	(31,503		)	—			(31,503		)
Property and equipment, net	47,694			(15,721		)	31,973
Deposits and other long-term assets	452			—			452
Total assets	$	52,304		$	(15,721	)	$	36,583
LIABILITIES AND STOCKHOLDERS’ EQUITY
Current liabilities:
Accounts payable and accrued expenses	$	4,914		$	—		$	4,914
Accrued production taxes payable	337			—			337
Undistributed revenue and other	1,462			—			1,462
Current derivative liability	1,116			—			1,116
Total current liabilities	7,829			—			7,829
Long-term debt	22,709			(15,721		)(a)	6,988
Other long-term liabilities	37			—			37
Deferred income taxes	3,093			—			3,093
Minority interest	28			—			28
Stockholders’ equity:
Preferred stock, no par value: 10,000,000 shares authorized, none outstanding	—			—			—
Common stock, no par value: 20,000,000 shares authorized, 6,116,295 shares issued and outstanding	31,987			—			31,987
Accumulated deficit	(12,017		)	—			(12,017		)
Accumulated other comprehensive loss	(1,362		)	—			(1,362		)
Total stockholders’ equity	18,608			—			18,608
Total liabilities and stockholders’ equity	$	52,304		$	(15,721	)	$	36,583

The accompanying notes are an integral part of this pro forma balance sheet.

CARBON ENERGY CORPORATION

PRO FORMA STATEMENT OF OPERATIONS

FOR THE YEAR ENDED DECEMBER 31, 2002

(in thousands)

(unaudited except per share data)

	Historical			Property Sale			Pro Forma
Revenues:
Oil and gas sales	$	16,176		$	(4,209	)(b)	$	11,967
Marketing and other, net	344			—			344
	16,520			(4,209		)	12,311
Expenses:
Oil and gas production costs	5,027			(1,140		)(b)	3,887
Depreciation, depletion and amortization	6,142			(1,334		)(c)	4,808
Full cost ceiling impairment	13,218			—			13,218
General and administrative, net	4,887			—			4,887
Interest and other, net	1,054			(581		)(d)	473
Total operating expenses	30,328			(3,055		)	27,273
Loss before income taxes	(13,808		)	(1,154		)	(14,962		)
Income tax provision:
Current	13			—			13
Deferred	734			—		(e)	734
Total taxes	747			—			747
Net loss	$	(14,555	)	$	(1,154	)	$	(15,709	)
Average number of common shares outstanding:
Basic	6,101			6,101			6,101
Diluted	6,101			6,101			6,101
Loss per share — basic	$	(2.39	)	$	(.18	)	$	(2.57	)
Loss per share — diluted	$	(2.39	)	$	(.18	)	$	(2.57	)

The accompanying notes are an integral part of this pro forma statement of operations.

Carbon Energy Corporation

Notes to Unaudited Pro Forma Financial Statements

(a) To reflect Carbon’s sale of oil and gas properties to Fasken and the related utilization of net sale proceeds to repay borrowings under the Company’s credit facility.

(b) To reflect the reduction in revenues and operating expenses associated with the sold properties.

(c) Represents the estimated decrease in depreciation, depletion and amortization expense resulting from the exclusion of the sold properties from the Company’s full cost pool computed on the unit of production method.

(d) Represents the estimated decrease in interest expense as a result of the utilization of net sale proceeds from the property sale to repay borrowings under the Company’s credit facility.

(e) Assumes the Company would have recorded additional deferred tax asset valuation allowance related to the pro forma incremental loss.

2 Asset purchase and sale agreement dated January 15, 2003 by and between Carbon Energy Corporation (USA), formerly known as Bonneville Fuels Corporation, as Seller, and Fasken Acquisition 02, Ltd., as Buyer, incorporated by reference to Exhibit 10.10 of Carbon's Annual Report on Form 10-K for the year ended December 31, 2002.

First Amendment to asset purchase and sale agreement, dated March 19, 2003 by and between Carbon Energy Corporation (USA), formerly known as Bonneville Fuels Corporation as Seller and Fasken Acquisition 02, Ltd., as Buyer, incorporated by reference to Exhibit 10.11 on Carbon's Annual Report to Form 10-K for the year ended December 31, 2002.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

CARBON ENERGY CORPORATION

	CARBON ENERGY CORPORATION
Date: August 15, 2003	By:	/s/ KEVIN D. STRUZESKI
	Name:	Kevin D. Struzeski
	Title:	Chief Financial Officer and Treasurer

Date: April 8, 2003	By:	/s/ Kevin D. Struzeski
	Name:	Kevin D. Struzeski
	Title:	Chief Financial Officer and Treasurer

EXHIBIT INDEX

Exhibit Number		Description
99.1		Press Release dated August 14, 2003—Carbon Energy Corporation Reports Increased Net Income for the United States and Canada for the Second Quarter of 2003

QuickLinks

Item 7. FINANCIAL STATEMENTS, PRO FORMA FINANCIAL INFORMATION AND EXHIBITS.

Item 12. RESULTS OF OPERATIONS AND FINANCIAL CONDITION.

SIGNATURE
EXHIBIT INDEX

Filing Compare · CARBON ENERGY CORP