8-K/A

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K/A

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of

The Securities Exchange Act of 1934

Date of Report (Date of earliest event reported) September 21, 2005

ATP Oil & Gas Corporation

(Exact name of registrant as specified in its charter)

Texas	000-32261	76-0362774
(State or other jurisdiction	(Commission	(IRS Employer
of incorporation)	File Number)	Identification No.)

4600 Post Oak Place, Suite 200, Houston, Texas	77027
(Address of principal executive offices)	(Zip Code)

Registrant’s telephone number, including area code (713) 622-3311

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ATP Oil & Gas Corporation (“ATP” or the “Company”) hereby files by amendment to its Current Report on Form 8-K filed on September 21, 2005 audited financial statements and unaudited pro forma financial information relating to the acquisition of certain King’s Peak properties from BP Exploration & Production Inc. (“BP”). The completion of the acquisition is described in item 2.01 below and the audited financial statements and pro forma financial information are described in item 9.01 below and, where applicable, filed as exhibits to this report.

Item 2.01 Completion of Acquisition or Disposition of Assets.

On September 21, 2005, the Company acquired all of BP’s 55% working interest in four federal oil and gas leases covering Mississippi Canyon Blocks 173/217 and Desoto Canyon Blocks 133/177, offshore Gulf of Mexico, an oil and gas discovery area named “King’s Peak.” The Company will operate this field which includes two producing subsea wells, in addition to proved undeveloped, probable and possible reserves, and all of BP’s interest (19.25%) in the Canyon Express Pipeline System (“CEPS”). CEPS is a 56-mile pipeline system operated by TotalFinaElf that gathers production from King’s Peak and two other fields. Consideration paid in cash at closing, after closing adjustments, was $18.6 million.

Item 9.01 Financial Statements and Exhibits.

(a) Financial Statements of Businesses Acquired. The following audited financial statements of the King’s Peak Properties are included as Exhibit 99.1 hereto and incorporated herein by reference:

1 Independent Auditors’ Report

2 Statements of Revenues and Direct Operating Expenses for the Period January 1, 2005 through September 21, 2005 and the Years Ended December 31, 2004 and 2003

3 Notes to Statements of Revenues and Direct Operating Expenses

(b) Pro Forma Financial Information. The following pro forma financial information of the Company giving effect to the acquisition of the King’s Peak properties and certain other transactions described in such pro forma financial information is included as Exhibit 99.2 hereto and incorporated herein by reference:

1 Unaudited Pro Forma Combined Statement of Operations for the Nine Months Ended September 30, 2005

2 Unaudited Pro Forma Combined Statement of Operations for the Year Ended December 31, 2004

3 Notes to the Unaudited Pro Forma Financial Statements

(c) Exhibits:

Number	Description:
23.1	Consent of Independent Accountants.
23.2	Consent of Independent Petroleum Engineers.
99.1	Statements of Revenues and Direct Operating Expenses of King’s Peak Properties.
99.2	Unaudited Pro Forma Financial Statements.

SIGNATURES

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

	ATP OIL & GAS CORPORATION
Date: December 5, 2005	By	/S/    ALBERT L. REESE, JR.
		Albert L. Reese, Jr.
		Chief Financial Officer

EX-23.1

Exhibit 23.1

CONSENT OF INDEPENDENT ACCOUNTANTS

The Board of Directors

ATP Oil & Gas Corporation:

We consent to the incorporation by reference in Registration Statement Nos. 333-105699 and 333-121662 on Form S-3, and Registration Statement No. 333-60762 on Form S-8 of the ATP Oil & Gas Corporation Subsidiaries of our report dated December 5, 2005, with respect to the statements of revenues and direct operating expenses of the oil and gas properties (the “King’s Peak Properties”) for the period January 1, 2005 through September 21, 2005 and each of the years in the two-year period ended December 31, 2004, which report appears herein this Form 8-K/A of ATP Oil & Gas Corporation .

/s/ Pannell Kerr Forster of Texas, P.C.

Houston, Texas

December 5, 2005

EX-23.2

Exhibit 23.2

CONSENT OF INDEPENDENT PETROLEUM ENGINEERS

The undersigned hereby consents to the reference to our firm in the form and context in which they appear in Amendment No. 1 to Current Report on Form 8-K/A of ATP Oil & Gas Corporation (the “Company”) dated September 21, 2005. We hereby further consent to the use of information contained in our report setting forth the estimates of revenues from oil and gas reserves as of September 21, 2005 for properties located in the King’s Peak area of the Gulf of Mexico acquired by ATP Oil & Gas Corporation from BP Exploration & Production, Inc.

Sincerely,

/s/ Collarini Associates        

December 5, 2005

EX-99.1

Exhibit 99.1

BP EXPLORATION & PRODUCTION, INC.

KING’S PEAK PROPERTIES

Statements of Revenues and Direct Operating Expenses

Period January 1, 2005 through September 21, 2005 and

the years ended December 31, 2004 and 2003

(With Independent Auditors’ Report)

INDEPENDENT AUDITORS’ REPORT

Board of Directors and Shareholders

BP Exploration & Production, Inc.:

We have audited the accompanying statements of revenues and direct operating expenses of the oil and gas property (the “King’s Peak Properties”) for the period January 1, 2005 through September 21, 2005 and the years ended December 31, 2004 and 2003. These statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on these statements based on our audits.

We conducted our audits in accordance with auditing standards generally accepted in the United States of America. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the statements of revenues and direct operating expenses are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements. An audit includes consideration of internal controls over financial reporting as a basis for designing audit procedures that are appropriate in the circumstances, but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion. An audit also includes assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

The accompanying statements of revenue and direct operating expenses were prepared for the purpose of complying with the Rules and Regulations of the Securities and Exchange Commission as described in Note 1 and are not intended to be a complete presentation of the Company’s interests in the King’s Peak Properties.

In our opinion, the statements of revenues and direct operating expenses referred to above present fairly, in all material respects, the revenues and direct operating expenses of the King’s Peak Properties for the period January 1, 2005 through September 21, 2005 and the years ended December 31, 2004 and 2003 in conformity with U.S. generally accepted accounting principles.

/s/ Pannell Kerr Forster of Texas, P.C.

Pannell Kerr Forster of Texas, P.C.

Houston, Texas

December 5, 2005

BP EXPLORATION & PRODUCTION, INC.

KING’S PEAK PROPERTIES

Statements of Revenues and Direct Operating Expenses

(In thousands)

	Period January 1, 2005 through September 21, 2005		Year Ended December 31,
			2004		2003
Revenues:
Oil and gas sales	$	26,996	$	75,620	$	167,070
Direct operating expenses:
Lease operating expenses		4,157		4,953		13,379
Revenues in excess of direct operating expenses	$	22,839	$	70,667	$	153,691

See accompanying notes to statements of revenues and direct operating expenses.

Notes to Statements of Revenues and Direct Operating Expenses

Period January 1, 2005 through September 21, 2005 and

Years Ended December 31, 2004 and 2003

(1) Basis of Presentation

On September 21, 2005, BP Exploration & Production, Inc. (the “Company”) disposed of its working interest (55%) in four federal oil and gas leases covering Mississippi Canyon Blocks 173/217 and Desoto Canyon Blocks 133/177, offshore Gulf of Mexico, an oil and gas discovery area named “King’s Peak.” The Company also disposed if its interest (19.25%) in the Canyon Express Pipeline System (“CEPS”). Consideration received in cash at closing, after closing adjustments, was $18.6 million.

Oil and natural gas revenues in the accompanying statements of revenues and direct operating expenses are recognized on the sales method. Under this method, revenues are recognized based on actual volumes of oil and gas sold to purchasers. Direct operating expenses are recognized on the accrual method.

During the periods presented, the King’s Peak Properties were not accounted for or operated as a separate division by the owners. Accordingly, full separate financial statements prepared in accordance with generally accepted accounting principles do not exist and are not practicable to obtain in these circumstances.

These financial statements were prepared for the purpose of complying with the Rules and Regulations of the Securities and Exchange Commission and are not intended to be a complete presentation of the Company’s interest in the King’s Peak Properties. The accompanying statements of revenues and direct operating expenses vary from an income statement in that they do not show certain expenses, which were incurred in connection with the ownership of the King’s Peak Properties, such as general and administrative expenses, and income taxes. These costs were not separately allocated to the King’s Peak Properties in the previous owners’ historical financial records and any pro forma allocation would be both time consuming and expensive and would not be a reliable estimate of what these costs would actually have been had the King’s Peak Properties been operated historically as a stand-alone entity. In addition, these allocations, if made using historical general and administrative structures and tax burdens, would not produce allocations that would be indicative of the historical performance of the King’s Peak Properties had they been assets of the buyer, due to the greatly varying size, structure, and operations between the buyer and previous owners. This statement also does not include provisions for depreciation, depletion and amortization as such amounts would not be indicative of future costs and those costs which would be incurred by the buyer upon allocation of the purchase price. Accordingly, the statements of revenues and direct operating expenses and other information presented are not indicative of the financial condition and results of operations of the King’s Peak Properties.

(2) Use of Estimates

Preparation of the accompanying statements of revenues and direct operating expenses in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

(3) Supplemental Oil and Gas Reserve Information (Unaudited)

Supplemental oil and natural gas reserve information related to the King’s Peak Properties is reported in compliance with Statement of Financial Accounting Standards No. 69, Disclosures about Oil and Gas Producing Activities (“FAS 69”). Net proved oil and natural gas reserves of the King’s Peak Properties and the standardized measure of discounted future net cash flows related to those reserves as of September 21, 2005 were derived from data prepared by Collarini Associates as of August 1, 2005.

(a) Estimated Quantities of Proved Oil and Gas Reserves

Proved reserves are estimated quantities of crude oil and natural gas that geological and engineering data demonstrate with reasonable certainty to be recoverable in future years from known reservoirs under existing economic and operating conditions. Proved developed reserves are reserves that can be expected to be recovered through existing wells with existing equipment and operating methods.

The following table presents the estimated remaining net proved and proved developed oil and gas reserves attributable to the King’s Peak Properties at December 31, 2003 and 2004 and September 21, 2005, along with a summary of changes in the quantities of net remaining proved reserves during the years ended December 31, 2003 and 2004 and the period January 1, 2005 through September 21, 2005. Production volumes for prior periods were added back to the above referenced reserve amounts as of September 21, 2005 to arrive at reserve totals at January 1, 2003, December 31, 2003 and 2004.

	Oil and NGLs (MBbls)		Natural Gas (MMcf)		Natural Gas Equivalent (MMcfe)
Proved reserves, January 1, 2003	272		104,553		106,184
Production	(88	)	(32,431	)	(32,958	)
Revisions in estimates	—		140		140
Proved reserves, December 31, 2003	185		72,262		73,366
Production	(51	)	(12,874	)	(13,176	)
Revisions in estimates	—		—		—
Proved reserves, December 31, 2004	134		59,388		60,190
Production	(13	)	(3,738	)	(3,819	)
Revisions in estimates	—		212		212
Proved reserves, September 21, 2005	121		55,862		56,583
Proved developed reserves:
December 31, 2003	92		29,670		30,223
December 31, 2004	42		16,796		17,047
September 21, 2005	28		13,059		13,228

(b) Standardized Measure of Discounted Future Net Cash Flows of Proved Oil and Gas Reserves

In computing the Standardized Measure, future cash inflows were estimated by applying period-end oil and natural gas prices to the estimated future production of September 30, 2005 proved reserves, as adjusted for production. The average prices used for the September 21, 2005 calculations were $64.52 per Bbl for oil and natural gas liquids and $15.40 per Mcf for natural gas, and the prices used for the December 31, 2004 and 2003 calculations were $41.60 and $30.69 per Bbl for oil and NGLs and $6.08 and $5.86 per Mcf for natural gas, respectively. Future cash inflows were reduced by estimated future development, abandonment and production costs based on period-end costs in order to arrive at net cash flow before tax. Future income tax expense has not been considered as the King’s Peak Properties are not a tax paying entity. FAS 69 requires the use of a 10% discount rate.

Discounted future net cash flow estimates like those shown below are not intended to represent estimates of the fair market value of oil and gas properties. Estimates of fair market value should also consider probable reserves, anticipated future oil and gas prices, interest rates, changes in development and production costs and risks associated with future production. Because of these and other considerations, any estimate of fair market value is necessarily subjective and imprecise.

The standardized measure of discounted future net cash flows related to proved oil and natural gas reserves attributable to the King’s Peak Properties is as follows (in thousands):

	September 21, 2005			December 31,
				2004			2003
Future cash inflows	$	867,883		$	366,743		$	429,104
Future operating expenses	$	(53,127	)	$	(57,452	)	$	(62,406	)
Future development costs	$	(93,318	)	$	(93,963	)	$	(96,486	)
Future net cash flows	$	721,438		$	215,328		$	270,212
10% annual discount for estimating timing of cash flows	$	146,881		$	52,673		$	66,868
Standardized measure of discounted future net cash flows	$	574,557		$	162,655		$	203,344

EX-99.2

Exhibit 99.2

UNAUDITED PRO FORMA FINANCIAL STATEMENTS

On September 21, 2005, ATP Oil & Gas Corporation (the “Company”) acquired all of BP Exploration & Production Inc.’s (“BP”) 55% working interest in four federal oil and gas leases covering Mississippi Canyon Blocks 173/217 and Desoto Canyon Blocks 133/177, offshore Gulf of Mexico, an oil and gas discovery area named “King’s Peak.” The Company will operate this field which includes two producing subsea wells, in addition to proved undeveloped, probable and possible reserves, and all of BP’s interest (19.25%) in the Canyon Express Pipeline System (“CEPS”). CEPS is a 56-mile pipeline system operated by TotalFinaElf that gathers production from King’s Peak and two other fields. Consideration paid in cash at closing, after closing adjustments, was $18.6 million.

The following unaudited pro forma financial information shows the pro forma effects of the consummation of the King’s Peak Properties acquisition (the “Transaction”). The accompanying audited statements of revenues and direct operating expenses for the King’s Peak Property were derived from the historical accounting records of BP. Although the statements do not include depreciation, depletion and amortization, asset retirement accretion, general administrative expenses, or income taxes, as described in Notes 3 and 4, these costs have been included on a pro forma basis. The pro forma statements of operations, however, are not indicative of the Company’s operations going forward, because these statements necessarily exclude various operating expenses attributable to the King’s Peak Properties. The unaudited pro forma combined statements of operations for the nine months ended September 30, 2005 and the year ended December 31, 2004 were prepared as if the Transaction occurred on January 1, 2004.

The unaudited pro forma combined financial statements reflect pro forma adjustments that are described in the accompanying notes and are based on available information and certain assumptions we believe are reasonable but are subject to change. In our opinion, all adjustments that are necessary to present fairly the pro forma information have been made. The following unaudited pro forma financial statements do not purport to represent what the Company’s financial position or results of operations would have been if the Transaction had occurred on January 1, 2004. These unaudited pro forma financial statements should be read in conjunction with the Company’s historical financial statements and related notes for the periods presented.

UNAUDITED PRO FORMA COMBINED STATEMENT OF OPERATIONS FOR THE

NINE MONTHS ENDED SEPTEMBER 30, 2005

(in thousands, except share and per share data)

	ATP Oil & Gas Corporation			King’s Peak Properties for the period January 1, 2005 through September 21, 2005		Pro Forma Adjustments			Pro Forma Combined
Oil and gas sales	$	96,810		$	26,996	$	—		$	123,806
Costs and expenses:
Lease operating		15,377			4,157		—			19,534
Exploration		5,574			—		—			5,574
General and administrative		13,247			—		—			13,247
Depreciation, depletion and amortization		47,993			—		1,828			49,821
Asset retirement accretion		1,801			—		869			2,670
Other		324			—		—			324
Total costs and operating expenses		84,316			4,157		2,697			91,170
Income from operations		12,494			22,839		(2,697	)		32,636
Other income (expense):
Interest income		3,006			—		—			3,006
Interest expense		(24,644	)		—		—			(24,644	)
Other income (expense)		2			—		—			2
Total other expense		(21,636	)		—		—			(21,636	)
Income (loss) before income taxes		(9,142	)		22,839		(2,697	)		11,000
Income tax expense		—			—		—			—
Net income (loss)		(9,142	)		22,839		(2,697	)		11,000
Preferred dividends		(3,756	)		—		—			(3,756	)
Net income (loss) available to common shareholders	$	(12,898	)	$	22,839	$	(2,697	)	$	7,244
Basic income (loss) per common share	$	(0.44	)						$	0.25
Diluted income (loss) per common share	$	(0.44	)						$	0.24
Weighted average number of common shares:
Basic		29,005								29,005
Diluted		29,833								29,833

See accompanying notes to unaudited pro forma combined financial statements.

UNAUDITED PRO FORMA COMBINED STATEMENT OF OPERATIONS FOR

THE YEAR ENDED DECEMBER 31, 2004

(in thousands, except share and per share data)

	ATP Oil & Gas Corporation			King’s Peak Properties		Pro Forma Adjustments			Pro Forma Combined
Oil and gas sales	$	116,123		$	75,620	$	—		$	191,743
Costs and expenses:
Lease operating		19,531			4,953		—			24,484
Exploration		997			—		—			997
General and administrative		15,806			—		—			15,806
Credit facility expense		1,850			—		—			1,850
Depreciation, depletion and amortization		55,637			—		5,176			60,813
Asset retirement accretion		2,069			—		1,040			3,109
Gain on abandonment		(251	)		—		—			(251	)
Gain on disposal of properties		(6,011	)		—		—			(6,011	)
Other		400			—		—			400
Total costs and operating expenses		90,028			4,953		6,216			101,197
Income from operations		26,095			70,667		(6,216	)		90,546
Other income (expense):
Interest income		627			—		—			627
Interest expense		(22,262	)		—		—			(22,262	)
Loss on extinguishment of debt		(3,326	)		—		—			(3,326	)
Other income (expense)		280			—		—			280
Total other expense		(24,681	)		—		—			(24,681	)
Income (loss) before income taxes		1,414			70,667		(6,216	)		65,865
Income tax (expense) benefit		(58	)		—		—			(58	)
Net income (loss)	$	1,356		$	70,667	$	(6,216	)	$	65,807
Basic income (loss) per common share	$	0.05							$	2.64
Diluted income (loss) per common share	$	0.05							$	2.60
Weighted average number of common shares:
Basic		24,944								24,944
Diluted		25,271								25,271

See accompanying notes to unaudited pro forma combined financial statements.

NOTES TO THE UNAUDITED PRO FORMA FINANCIAL STATEMENTS

1. BASIS OF PRESENTATION

On September 21, 2005, ATP Oil & Gas Corporation (the “Company”) acquired all of BP Exploration & Production Inc.’s (“BP”) 55% working interest in four federal oil and gas leases covering Mississippi Canyon Blocks 173/217 and Desoto Canyon Blocks 133/177, offshore Gulf of Mexico, an oil and gas discovery area named “King’s Peak.” The Company will operate this field which includes two producing subsea wells, in addition to proved undeveloped, probable and possible reserves, and all of BP’s interest (19.25%) in the Canyon Express Pipeline System (“CEPS”). CEPS is a 56-mile pipeline system operated by TotalFinaElf that gathers production from King’s Peak and two other fields. Consideration paid in cash at closing, after closing adjustments, was $18.6 million.

The unaudited pro forma financial statements give effect to the consummation of the King’s Peak Properties acquisition. The unaudited pro forma financial statements do not reflect the pro forma effect of any of the Company’s other recent acquisitions.

The unaudited pro forma combined statements of operations for the nine months ended September 30, 2005 and the year ended December 31, 2004 were prepared as if the Transaction occurred on January 1, 2004.

The accompanying audited statements of revenues and direct operating expenses for the King’s Peak Properties were derived from the historical accounting records of the sellers and prior operators. Although the statements do not include depreciation, depletion and amortization, exploration expense, general administrative expenses, income taxes or interest expense, as described in Notes 3 and 4, these costs have been included on a pro forma basis. The pro forma statements of operations, however, are not indicative of the Company’s operations going forward, because these statements necessarily exclude various operating expenses attributable to the King’s Peak Properties.

The Company believes that the assumptions used provide a reasonable basis for presenting the significant effects directly attributable to this transaction.

These unaudited pro forma financial statements do not purport to represent what the Company’s financial position or results of operations would have been if the Transaction had occurred on September 30, 2005 or January 1, 2004, respectively. These unaudited pro forma financial statements should be read in conjunction with the Company’s historical financial statements and related notes for the periods presented.

Earnings per Share — Basic earnings per share is computed by dividing net income or loss available to common shareholders by the weighted average number of common shares outstanding during the period. Diluted earnings per share is determined on the assumption that outstanding stock options have been converted using the average price for the period. For purposes of computing earnings per share in a loss year, potential common shares have been excluded from the computation of weighted average common shares outstanding because their effect is antidilutive.

2. PRO FORMA ADJUSTMENTS TO THE STATEMENT OF OPERATIONS FOR THE NINE MONTHS ENDED SEPTEMBER 30, 2005 AND THE YEAR ENDED DECEMBER 31, 2004

The following adjustments have been made to the accompanying unaudited pro forma combined statements of operations for the nine months ended September 30, 2005 and the year ended December 31, 2004:

Depletion, Depreciation and Amortization — To record pro forma depletion expense giving effect to the acquisition of the King’s Peak Properties. The expense was calculated using the unit-of-production method, based on estimated proved reserves and production by field. The preliminary purchase price of approximately $19.3 million and estimated future asset retirement costs of $9.6 million related to the properties acquired were used in the calculation. To also record accretion of discount expense related to the estimated asset retirement obligations for wells and facilities acquired.

Income Taxes — No pro forma provision for income taxes has been provided. The Company has a net operating loss (“NOL”) carryforward for tax purposes that would have offset any tax liability generated by the properties. The NOL carryforward was fully reserved during the nine months ended September 30, 2005 and the year ended December 31, 2004 as the Company could not demonstrate that expected future income was sufficient to allow utilization of the NOLs.