UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934


                         Semgroup Energy Partners, L.P.
             -------------------------------------------------------
                                (Name of Issuer)


                                  Common Units
             -------------------------------------------------------
                         (Title of Class of Securities)


                                    81662W108
             -------------------------------------------------------
                                 (CUSIP Number)


                                December 11, 2008
             -------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

       [ ] Rule 13d-1(b)
       [X] Rule 13d-1(c)
       [ ] Rule 13d-1(d)

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).



CUSIP No.: 81662W108                  13G                      Page 2 of 8 Pages
--------------------------------------------------------------------------------
1.   Names of Reporting Persons:    Costa Brava Partnership III L.P.
     I.R.S. Identification Nos. of above persons (entities only): 04-3387028
--------------------------------------------------------------------------------
2.   Check the Appropriate Box if a Member of a Group (See Instructions)
     (a) [ ]
     (b) [ ]
--------------------------------------------------------------------------------
3.   SEC Use Only
------------------------------------------------------------------------------
4.   Citizenship or Place of Organization:

     A Delaware limited partnership
------------------------------------------------------------------------------
Number of                  5.      Sole Voting Power:         1,178,507(1)
Shares                     -----------------------------------------------------
Beneficially               6.      Shared Voting Power:       -0-
Owned by                   -----------------------------------------------------
Each Reporting             7.      Sole Dispositive Power:    1,178,507(1)
Person With                -----------------------------------------------------
                           8.      Shared Dispositive Power:  -0-
--------------------------------------------------------------------------------
9.   Aggregate Amount Beneficially Owned by Each Reporting Person:

     1,178,507(1)
--------------------------------------------------------------------------------
10.  Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
     Instructions):______
--------------------------------------------------------------------------------
11.  Percent of Class Represented by Amount in Row (9):

     5.5%(2)
--------------------------------------------------------------------------------
12.  Type of Reporting Person (See Instructions):

     PN
--------------------------------------------------------------------------------

----------------------
(1)  The Reporting Persons were the beneficial owners of 1,178,507 shares of the
     Issuer's common units on December 22, 2008.

(2)  The percentage ownership of the Reporting Persons in the Issuer's common
     units is based upon 21,275,000 issued and outstanding units as of May 2,
     2008, as reported by the Issuer in its filing on Form 10-Q for the fiscal
     quarter ended March 31, 2008.



CUSIP No.: 81662W108                  13G                      Page 3 of 8 Pages
--------------------------------------------------------------------------------
1.   Names of Reporting Persons:    Roark, Rearden & Hamot, LLC
     I.R.S. Identification Nos. of above persons (entities only): 10-0000708
--------------------------------------------------------------------------------
2.   Check the Appropriate Box if a Member of a Group (See Instructions)
     (a) [ ]
     (b) [ ]
--------------------------------------------------------------------------------
3.   SEC Use Only
--------------------------------------------------------------------------------
4.   Citizenship or Place of Organization:

     A Delaware limited liability company
--------------------------------------------------------------------------------
Number of                  5.      Sole Voting Power:         1,178,507(1)
Shares                     -----------------------------------------------------
Beneficially               6.      Shared Voting Power:       -0-
Owned by                   -----------------------------------------------------
Each Reporting             7.      Sole Dispositive Power:    1,178,507(1)
Person With                -----------------------------------------------------
                           8.      Shared Dispositive Power:  -0-
--------------------------------------------------------------------------------
9.   Aggregate Amount Beneficially Owned by Each Reporting Person:

     1,178,507(1)
------------------------------------------------------------------------------
10.  Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
     Instructions):______
--------------------------------------------------------------------------------
11.  Percent of Class Represented by Amount in Row (9):

     5.5%(2)
--------------------------------------------------------------------------------
12.  Type of Reporting Person (See Instructions):

     OO - Other
------------------------------------------------------------------------------

---------------------
(1)  The Reporting Persons were the beneficial owners of 1,178,507 shares of the
     Issuer's common units on December 22, 2008.

(2)  The percentage ownership of the Reporting Persons in the Issuer's common
     units is based upon 21,275,000 issued and outstanding units as of May 2,
     2008, as reported by the Issuer in its filing on Form 10-Q for the fiscal
     quarter ended March 31, 2008.



CUSIP No.: 81662W108                  13G                      Page 4 of 8 Pages
--------------------------------------------------------------------------------
1.   Names of Reporting Persons:    Seth W. Hamot
     I.R.S. Identification Nos. of above persons (entities only):
--------------------------------------------------------------------------------
2.   Check the Appropriate Box if a Member of a Group (See Instructions)
     (a) [ ]
     (b) [ ]
--------------------------------------------------------------------------------
3.   SEC Use Only
--------------------------------------------------------------------------------
4.   Citizenship or Place of Organization:

     A United States citizen
--------------------------------------------------------------------------------
Number of                  5.      Sole Voting Power:         1,178,507(1)
Shares                     -----------------------------------------------------
Beneficially               6.      Shared Voting Power:       -0-
Owned by                   -----------------------------------------------------
Each Reporting             7.      Sole Dispositive Power:    1,178,507(1)
Person With                -----------------------------------------------------
                           8.      Shared Dispositive Power:  -0-
--------------------------------------------------------------------------------
9.   Aggregate Amount Beneficially Owned by Each Reporting Person:

     1,178,507(1)
--------------------------------------------------------------------------------
10.  Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See
     Instructions):______
--------------------------------------------------------------------------------
11.  Percent of Class Represented by Amount in Row (9):

     5.5%(2)
--------------------------------------------------------------------------------
12.  Type of Reporting Person (See Instructions):

     IN, HC
--------------------------------------------------------------------------------

---------------------
(1)  The Reporting Persons were the beneficial owners of 1,178,507 shares of the
     Issuer's common units on December 22, 2008.

(2)  The percentage ownership of the Reporting Persons in the Issuer's common
     units is based upon 21,275,000 issued and outstanding units as of May 2,
     2008, as reported by the Issuer in its filing on Form 10-Q for the fiscal
     quarter ended March 31, 2008.



Item 1.

         (a)      Name of Issuer:

                  Semgroup Energy Partners, L.P.

         (b)      Address of Issuer's Principal Executive Offices:

                  Two Warren Place
                  6120 South Yale Avenue, Suite 700
                  Tulsa, OK 74136

Item 2.

         (a)      Name of Person Filing:

                  The name of the person filing is Costa Brava Partnership III
         L.P. Seth W. Hamot is the president of Roark, Rearden & Hamot, LLC,
         which is the general partner of Costa Brava Partnership III L.P. Each
         of the parties listed in the immediately preceding sentence is referred
         to individually as a "Reporting Person" and collectively as the
         "Reporting Persons." All of the common units that were beneficially
         owned by the Reporting Persons were held by Costa Brava Partnership III
         L.P.

         (b)      Address of Principal Business Office or, if None, Residence:

                  The principal business address of each of Costa Brava
         Partnership III L.P., Seth W. Hamot, and Roark, Rearden & Hamot, LLC is
         420 Boylston Street, Boston, MA 02116.

         (c)      Citizenship:

                  Costa Brava Partnership III L.P. is a Delaware limited
         partnership. Roark, Rearden & Hamot, LLC is a Delaware limited
         liability company. Seth W. Hamot is a United States citizen.

         (d)      Title of Class of Securities:

                  Common Units

         (e)      CUSIP Number:

                  81662W108

                               Page 5 of 8 Pages


Item 3.  If this statement is filed pursuant to ss.ss.240.13d-1(b) or
         240.13d-2(b) or (c), check whether the person filing is a:

(a) [ ]  Broker or dealer registered under section 15 of the Act (15 U.S.C.
         78o).
(b) [ ]  Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c).
(c) [ ]  Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C.
         78c).
(d) [ ]  Investment company registered under section 8 of the Investment Company
         Act of 1940 (15 U.S.C. 80a-8).
(e) [ ]  An investment adviser in accordance with ss.240.13d-1(b)(1)(ii)(E);
(f) [ ]  An employee benefit plan or endowment fund in accordance with
         ss.240.13d- 1(b)(1)(ii)(F);
(g) [ ]  A parent holding company or control person in accordance with ss.
         240.13d- 1(b)(1)(ii)(G);
(h) [ ]  A savings associations as defined in Section 3(b) of the Federal
         Deposit Insurance Act (12 U.S.C. 1813);
(i) [ ]  A church plan that is excluded from the definition of an investment
         company under section 3(c)(14) of the Investment Company Act of 1940
         (15 U.S.C. 80a-3);
(j) [ ]  Group, in accordance with ss.240.13d-1(b)(1)(ii)(J).

         Not Applicable.

Item 4.  Ownership.

Provide the following information regarding the aggregate number and percentage
of the class of securities of the issuer identified in Item 1.

(a) through (c):

         The information requested hereunder is set forth in Items 5 through 9
         and 11 of the cover pages to this Schedule 13G.

Item 5.  Ownership of Five Percent or Less of a Class.

If this statement is being filed to report the fact that as of the date hereof
the reporting person has ceased to be the beneficial owner of more than five
percent of the class of securities, check the following [ ].

Item 6.  Ownership of More than Five Percent on Behalf of Another Person.

         Not Applicable.

Item 7.  Identification and Classification of the Subsidiary Which Acquired the
         Security Being Reported on By the Parent Holding Company or Control
         Person.

         Not Applicable.

                                Page 6 of 8 Pages


Item 8.  Identification and Classification of Members of the Group.

         Not Applicable.

Item 9.  Notice of Dissolution of Group.

         Not Applicable.

Item 10. Certification.

By signing below I certify that, to the best of my knowledge and belief, the
securities referred to above were not acquired and are not held for the purpose
of or with the effect of changing or influencing the control of the issuer of
the securities and were not acquired and are not held in connection with or as a
participant in any transaction having that purpose or effect.

The Reporting Persons have agreed that this Schedule may be filed by Costa Brava
Partnership III L.P. on behalf of all of them jointly pursuant to Rule
13d-1(k)(1). A copy of such agreement is attached as an Exhibit to this
Schedule.


                               Page 7 of 8 Pages


                                    SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify
that the information set forth in this statement is true, complete and correct.

                                       Date: December 22, 2008
                                             -----------------

                                       COSTA BRAVA PARTNERSHIP III L.P.

                                       By: Roark, Rearden & Hamot, LLC
                                           its General Partner

                                           By: /s/ Seth W. Hamot
                                               ---------------------------------
                                               Name:  Seth W. Hamot
                                               Title: President



Attention: Intentional misstatements or omissions of fact constitute Federal
           criminal violations (See 18 U.S.C. 1001).


                                Page 8 of 8 Pages


                                  EXHIBIT INDEX

Exhibit 1   Agreement Regarding the Joint Filing of Schedule 13G





                                    Exhibit 1

                               AGREEMENT REGARDING
                        THE JOINT FILING OF SCHEDULE 13G

The undersigned hereby agree as follows:

(i) Each of them is individually eligible to use the Schedule 13G to which this
Exhibit is attached, and such Schedule 13G is filed on behalf of each of them;
and

(ii) Each of them is responsible for the timely filing of such Schedule 13G and
any amendments thereto, and for the completeness and accuracy of the information
concerning such person contained therein; but none of them is responsible for
the completeness or accuracy of the information concerning the other persons
making the filing, unless such person knows or has reason to believe that such
information is inaccurate.

Dated: December 22, 2008

                                       COSTA BRAVA PARTNERSHIP III L.P.

                                       By: Roark, Rearden & Hamot, LLC,
                                           its General Partner

                                       By: /s/ Seth W. Hamot
                                           -------------------------------------
                                           Name:   Seth W. Hamot
                                           Title:  President


                                       ROARK, REARDEN & HAMOT, LLC

                                       By: /s/ Seth W. Hamot
                                           -------------------------------------
                                           Name:   Seth W. Hamot
                                           Title:  President


                                       SETH W. HAMOT

                                       By: /s/ Seth W. Hamot
                                           -------------------------------------
                                           Seth W. Hamot