SECURITIES AND EXCHANGE COMMISSION
                         WASHINGTON, DC 20549

                             ------------

                               FORM 8-K

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


   Date of report (Date of earliest event reported) -- May 21, 2004

           SOUTHWEST DEVELOPMENTAL DRILLING FUND 91-A, L.P.
     (Exact Name of Registrant as Specified in Charter or Limited
                        Partnership Agreement)


     Delaware                000-20426                     75-2387814
(State or Other Jurisdiction            (Commission File Number)
(I.R.S. Employer
 of Incorporation or Organization)
Identification No.)

                     407 N. BIG SPRING, SUITE 300
                                                 MIDLAND, TEXAS
                                 79701
                           (Address of Principal Executive Office)
                              (Zip Code)

 Registrant's telephone number, including area code -- (432) 686-9927



ITEM 1.  CHANGES IN CONTROL OF REGISTRANT

      Pursuant  to  an  Agreement  and Plan  of  Merger  (the  "Merger
Agreement"),  dated  May  3, 2004, by and among  Southwest  Royalties,
Inc.,  a Delaware corporation and the managing general partner of  the
registrant (the "Managing General Partner"), Clayton Williams  Energy,
Inc., a Delaware corporation ("Clayton Williams Energy") and CWEI-SWR,
Inc.,  a  Delaware corporation and wholly-owned subsidiary of  Clayton
Williams  Energy ("MergerCo"), on May 21, 2004, MergerCo  merged  with
and  into  the  Managing  General Partner with  the  Managing  General
Partner  surviving  in  the  merger as a  wholly-owned  subsidiary  of
Clayton  Williams Energy (the "Merger").  Due to the Managing  General
Partner's  control of the registrant, the registrant believes  that  a
change  in  control of the registrant occurred in the  Merger  upon  a
change  in  control  of  the Managing General Partner.   The  Managing
General  Partner continues to own a 10.0% interest as the sole general
partner  and  a 5.60% interest as a limited partner in the registrant.
Consequently, Clayton Williams Energy indirectly owns a 10.0%  general
partner  interest  and  a  5.60%  limited  partner  interests  in  the
registrant.   The  Merger did not result in any  change  of  financial
position, capitalization or business of the registrant.

      In  accordance  with the Merger Agreement,  each  share  of  the
Managing General Partner's common stock and Class A common stock (each
a  "Share") issued and outstanding prior to the effective time of  the
Merger  (other  than Shares held by stockholders who  properly  demand
appraisal  rights  with  respect to such  Shares  in  accordance  with
Section  262 of the General Corporation Law of the State of  Delaware)
was  cancelled and converted automatically into the right  to  receive
$45.01  per  share in cash, payable to the holder of such  Share  upon
surrender   of   a  stock  certificate.   The  aggregate   amount   of
consideration  paid  to  the  stockholders  was  approximately   $57.2
million.   The  Merger  was  funded by a new  senior  credit  facility
provided  by BankOne, N.A., as Administrative Agent, consisting  of  a
three-year, $300 million Revolving Credit Facility and a four-year $75
million  Senior  Term Credit Facility.  The Revolving Credit  Facility
established an initial borrowing limit of $180 million.

      Upon  consummation of the Merger, all officers and directors  of
the Managing General Partner prior to the Merger resigned, and the new
officers  and  directors  appointed by  Clayton  Williams  Energy  are
Clayton  W.  Williams (director and chairman of the  board),  L.  Paul
Latham  (director  and  president), Mel G. Riggs  (director  and  vice
president  and  treasurer),  T.  Mark  Tisdale  (vice  president   and
secretary).

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

     c)   Exhibits

The following exhibit is filed herewith:

Exhibit        Description
Number
     2.1       Agreement and Plan of Merger dated May 3, 2004 among
               Clayton Williams Energy, Inc., CWEI-SWR, Inc. and
               Southwest Royalties, Inc.

               *  All schedules to this Exhibit 2.1 filed herewith
               have been omitted in accordance with Item 601(b)(2) of
               Regulation S-K.  The Company will furnish
               supplementally a copy of any omitted schedule to the
               Commission upon request.


                              SIGNATURES

     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.


Date: June 3, 2004                      SOUTHWEST DEVELOPMENTAL
DRILLING FUND                                     91-A, L.P.

                                   BY:  SOUTHWEST ROYALTIES, INC.,

Managing General Partner

                                   By: /s/ Mel G. Riggs
                                     Mel G. Riggs, Vice President and
Treasurer


                             EXHIBIT INDEX




Exhibit        Description
Number
     2.1       Agreement and Plan of Merger dated May 3, 2004 among
               Clayton Williams Energy, Inc., CWEI-SWR, Inc. and
               Southwest Royalties, Inc.

               *  All schedules to this Exhibit 2.1 filed herewith
               have been omitted in accordance with Item 601(b)(2) of
               Regulation S-K.  The Company will furnish
               supplementally a copy of any omitted schedule to the
               Commission upon request.
[{"type": "8-K", "sequence": "1", "filename": "a8k27.txt", "secsgml_size_bytes": 5774}]
{"company-data": {"conformed-name": "SOUTHWEST DEVELOPMENTAL DRILLING FUND 91-A LP", "cik": "0000871327", "assigned-sic": "1381", "irs-number": "752387814", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "000-20426", "film-number": "04848090"}, "business-address": {"street1": "407 N BIG SPRING STE 300", "city": "MIDLAND", "state": "TX", "zip": "79701", "phone": "9156869927"}, "mail-address": {"street1": "407 N BIG SPRING ST SUITE 300", "city": "MIDLAND", "state": "TX", "zip": "79701"}}
SECURITIES AND EXCHANGE COMMISSION
                         WASHINGTON, DC 20549

                             ------------

                               FORM 8-K

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

   Date of report (Date of earliest event reported) -- May 21, 2004

           SOUTHWEST DEVELOPMENTAL DRILLING FUND 91-A, L.P.
     (Exact Name of Registrant as Specified in Charter or Limited
                        Partnership Agreement)

     Delaware                000-20426                     75-2387814
(State or Other Jurisdiction            (Commission File Number)
(I.R.S. Employer
 of Incorporation or Organization)
Identification No.)

                     407 N. BIG SPRING, SUITE 300
                                                 MIDLAND, TEXAS
                                 79701
                           (Address of Principal Executive Office)
                              (Zip Code)

 Registrant's telephone number, including area code -- (432) 686-9927

ITEM 1.  CHANGES IN CONTROL OF REGISTRANT

      Pursuant  to  an  Agreement  and Plan  of  Merger  (the  "Merger
Agreement"),  dated  May  3, 2004, by and among  Southwest  Royalties,
Inc.,  a Delaware corporation and the managing general partner of  the
registrant (the "Managing General Partner"), Clayton Williams  Energy,
Inc., a Delaware corporation ("Clayton Williams Energy") and CWEI-SWR,
Inc.,  a  Delaware corporation and wholly-owned subsidiary of  Clayton
Williams  Energy ("MergerCo"), on May 21, 2004, MergerCo  merged  with
and  into  the  Managing  General Partner with  the  Managing  General
Partner  surviving  in  the  merger as a  wholly-owned  subsidiary  of
Clayton  Williams Energy (the "Merger").  Due to the Managing  General
Partner's  control of the registrant, the registrant believes  that  a
change  in  control of the registrant occurred in the  Merger  upon  a
change  in  control  of  the Managing General Partner.   The  Managing
General  Partner continues to own a 10.0% interest as the sole general
partner  and  a 5.60% interest as a limited partner in the registrant.
Consequently, Clayton Williams Energy indirectly owns a 10.0%  general
partner  interest  and  a  5.60%  limited  partner  interests  in  the
registrant.   The  Merger did not result in any  change  of  financial
position, capitalization or business of the registrant.

      In  accordance  with the Merger Agreement,  each  share  of  the
Managing General Partner's common stock and Class A common stock (each
a  "Share") issued and outstanding prior to the effective time of  the
Merger  (other  than Shares held by stockholders who  properly  demand
appraisal  rights  with  respect to such  Shares  in  accordance  with
Section  262 of the General Corporation Law of the State of  Delaware)
was  cancelled and converted automatically into the right  to  receive
$45.01  per  share in cash, payable to the holder of such  Share  upon
surrender   of   a  stock  certificate.   The  aggregate   amount   of
consideration  paid  to  the  stockholders  was  approximately   $57.2
million.   The  Merger  was  funded by a new  senior  credit  facility
provided  by BankOne, N.A., as Administrative Agent, consisting  of  a
three-year, $300 million Revolving Credit Facility and a four-year $75
million  Senior  Term Credit Facility.  The Revolving Credit  Facility
established an initial borrowing limit of $180 million.

      Upon  consummation of the Merger, all officers and directors  of
the Managing General Partner prior to the Merger resigned, and the new
officers  and  directors  appointed by  Clayton  Williams  Energy  are
Clayton  W.  Williams (director and chairman of the  board),  L.  Paul
Latham  (director  and  president), Mel G. Riggs  (director  and  vice
president  and  treasurer),  T.  Mark  Tisdale  (vice  president   and
secretary).

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

     c)   Exhibits

The following exhibit is filed herewith:

Exhibit        Description
Number
     2.1       Agreement and Plan of Merger dated May 3, 2004 among
               Clayton Williams Energy, Inc., CWEI-SWR, Inc. and
               Southwest Royalties, Inc.

               *  All schedules to this Exhibit 2.1 filed herewith
               have been omitted in accordance with Item 601(b)(2) of
               Regulation S-K.  The Company will furnish
               supplementally a copy of any omitted schedule to the
               Commission upon request.

                              SIGNATURES

     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.

Date: June 3, 2004                      SOUTHWEST DEVELOPMENTAL
DRILLING FUND                                     91-A, L.P.

                                   BY:  SOUTHWEST ROYALTIES, INC.,

Managing General Partner

                                   By: /s/ Mel G. Riggs
                                     Mel G. Riggs, Vice President and
Treasurer

                             EXHIBIT INDEX

Exhibit        Description
Number
     2.1       Agreement and Plan of Merger dated May 3, 2004 among
               Clayton Williams Energy, Inc., CWEI-SWR, Inc. and
               Southwest Royalties, Inc.

               *  All schedules to this Exhibit 2.1 filed herewith
               have been omitted in accordance with Item 601(b)(2) of
               Regulation S-K.  The Company will furnish
               supplementally a copy of any omitted schedule to the
               Commission upon request.