UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D. C. 20549





FORM 10-K/A

Amendment No. 1







|x | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ------------------------------------------------------------------------------------

FOR THE YEAR ENDED DECEMBER 31, 2006



| ̈ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934
|- | ----------------------------------------------------------------------------------------

FOR THE TRANSITION PERIOD FROM  TO







|                       |  |                         |  |                        |  |                                   
|---------------------- |  | ----------------------- |  | ---------------------- |  | ----------------------------------
|Commission File Number |  | Registrant              |  | State of Incorporation |  | IRS Employer Identification Number
|1-7810                 |  | Energen Corporation     |  | Alabama                |  | 63-0757759                        
|2-38960                |  | Alabama Gas Corporation |  | Alabama                |  | 63-0022000                        





605 Richard Arrington Jr.
Boulevard North, Birmingham, Alabama 35203-2707

Telephone Number 205/326-2700

http://www.energen.com





Securities Registered
Pursuant to Section 12(b) of the Act:



|                                                    |  |                             
|--------------------------------------------------- |  | ----------------------------
|Title of Each Class                                 |  | Exchange on Which Registered
|Energen Corporation Common Stock, $0.01 par value   |  | New York Stock Exchange     
|Energen Corporation Preferred Stock Purchase Rights |  | New York Stock Exchange     

Securities Registered Pursuant to Section 12(g) of the Act: NONE





Indicate by check mark if the registrants are a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.    YES  x    NO   ̈

Indicate by check mark if the
registrants are not required to file reports pursuant to Section 13 or Section 15(d) of the Act.    YES   ̈    NO  x

Indicate by a check mark whether registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of
the Securities and Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrants were required to file such reports) and (2) have been subject to such filing requirements for the past 90
days.    YES  x    NO   ̈

Indicate by a check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (Section 229.405 of this chapter) is not contained herein and will not be contained, to the best of
registrants knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.   ̈

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, or a non-accelerated filer (as defined in Rule 12b-2 of
the Act).



|                        |  |                            |  |                      |  |                         
|----------------------- |  | -------------------------- |  | -------------------- |  | ------------------------
|Energen Corporation     |  | Large accelerated filer  x |  | Accelerated filer   ̈ |  | Non-accelerated filer   ̈
|Alabama Gas Corporation |  | Large accelerated filer   ̈ |  | Accelerated filer   ̈ |  | Non-accelerated filer  x

Indicate by check mark whether the registrants are a shell company (as defined in Rule 12b-2 of
the Exchange Act).    YES   ̈    NO  x

Aggregate market value of the voting stock held by non-affiliates of the registrants as of June 30, 2006:



| |  |                     |  |               
| |  | ------------------- |  | --------------
| |  | Energen Corporation |  | $2,727,928,993

Indicate number of shares outstanding of each of the registrants classes of common stock as
of February 5, 2007:



| |  |                         |  |                  
| |  | ----------------------- |  | -----------------
| |  | Energen Corporation     |  | 71,687,984 shares
| |  | Alabama Gas Corporation |  | 1,972,052 shares 

Alabama Gas Corporation meets the conditions set forth in General Instruction I(1) (a) and
(b) of Form 10-K and is therefore filing this form with the reduced disclosure format pursuant to General Instruction I(2).

DOCUMENTS INCORPORATED BY REFERENCE

Energen Corporation Proxy Statement to be filed on or about March 26, 2007 (Part
III, Item 10-14)









---

This amendment to the Form 10-K of Energen Corporation and Alabama Gas Corporation (Alagasco) for the
year ended December 31, 2006 is to provide separate certifications for Energen and Alagasco and to amend certain language with respect to Alagasco to conform to Item 601(b)(31) of Regulation S-K.

PART IV

ITEM 15.
EXHIBITS AND FINANCIAL STATEMENT SCHEDULES

a. Documents Filed as Part of This Report



| | (3) | Exhibits
| | --- | --------

The exhibits listed on the accompanying Index to Exhibits are filed as part of this Form 10-K



2



---

Energen Corporation

Alabama Gas Corporation

INDEX TO EXHIBITS

Item 14(a)(3)



|              |  |                                                                                                          
|------------- |  | ---------------------------------------------------------------------------------------------------------
|ExhibitNumber |  | Description                                                                                              
|24            |  | Power of Attorney                                                                                        
|              | 
|31(a)         |  | Energen Corporation Certification of Chief Executive Officer pursuant to Rule 13a-14(a) or 15d- 14(a)    
|              | 
|31(b)         |  | Energen Corporation Certification of Chief Financial Officer pursuant to Rule 13a-14(a) or 15d-14(a)     
|              | 
|31(c)         |  | Alabama Gas Corporation Certification of Chief Executive Officer pursuant to Rule 13a-14(a) or 15d- 14(a)
|              | 
|31(d)         |  | Alabama Gas Corporation Certification of Chief Financial Officer pursuant to Rule 13a-14(a) or 15d- 14(a)



3



---

SIGNATURE

Pursuant to the requirements of Section 13 or 15(d) of the Securities and Exchange Act of 1934, the Registrants have duly caused this report to be signed on their behalf by the undersigned thereunto duly
authorized.

ENERGEN CORPORATION

(Registrant)

ALABAMA GAS CORPORATION

(Registrant)



|               |  |    |  |                                                                                                                                        
|-------------- |  | -- |  | ---------------------------------------------------------------------------------------------------------------------------------------
|March 24, 2008 |  | By |  | /s/ James T. McManus II                                                                                                                
|               |  |    |  | James T. McManus II                                                                                                                    
|               |  |    |  | Chairman, Chief Executive Officer and President of Energen Corporation; Chairman and Chief Executive Officer of Alabama Gas Corporation



4



---

SIGNATURES

Pursuant to the requirements of the Securities and Exchange Act of 1934, this report has been signed by the following persons on behalf of the Registrants and in the capacities and on the dates indicated:



|               |  |                         |  |                                                                                                                                        
|-------------- |  | ----------------------- |  | ---------------------------------------------------------------------------------------------------------------------------------------
|March 24, 2008 |  | By                      |  | /s/ James T. McManus II                                                                                                                
|               |  |                         |  | James T. McManus II                                                                                                                    
|               |  |                         |  | Chairman, Chief Executive Officer and President of Energen Corporation; Chairman and Chief Executive Officer of Alabama Gas Corporation
|               |  |                        
|March 24, 2008 |  | By                      |  | /s/ Charles W. Porter, Jr.                                                                                                             
|               |  |                         |  | Charles W. Porter, Jr.                                                                                                                 
|               |  |                         |  | Vice President, Chief Financial Officer and Treasurer of Energen Corporation and Alabama Gas Corporation                               
|               |  |                        
|March 24, 2008 |  | By                      |  | /s/ Paula H. Rushing                                                                                                                   
|               |  |                         |  | Paula H. Rushing                                                                                                                       
|               |  |                         |  | Vice President-Finance of Alabama Gas Corporation                                                                                      
|               | 
|March 24, 2008 |  | *                      
|               |  | Julian W. Banton       
|               |  | Director               
|               | 
|March 24, 2008 |  | *                      
|               |  | James S. M. French     
|               |  | Director               
|               | 
|March 24, 2008 |  | *                      
|               |  | T. Michael Goodrich    
|               |  | Director               
|               | 
|March 24, 2008 |  | *                      
|               |  | Judy M. Merritt        
|               |  | Director               
|               | 
|March 24, 2008 |  | *                      
|               |  | Wm. Michael Warren, Jr.
|               |  | Director               
|               | 
|March 24, 2008 |  | *                      
|               |  | David W. Wilson        
|               |  | Director               
|               |  |                        
|March 24, 2008 |  | *By                     |  | /s/ Charles W. Porter, Jr.                                                                                                             
|               |  |                         |  | Charles W. Porter, Jr.                                                                                                                 
|               |  |                         |  | Attorney-in-fact                                                                                                                       



5