<PAGE>   1

      As filed with the Securities and Exchange Commission on June 21, 2001
                                                     Registration No. 333-______

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

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

                          MISSION RESOURCES CORPORATION
               (FORMERLY KNOWN AS BELLWETHER EXPLORATION COMPANY)
             (Exact name of Registrant as specified in its charter)



             DELAWARE                                          74-0437769
   (State or other jurisdiction                             (I.R.S. Employer
  of incorporation or organization)                       Identification Number)

    1331 LAMAR STREET, SUITE 1455                                77010
           HOUSTON, TEXAS                                      (Zip Code)
(Address of Principal Executive Offices)

            BELLWETHER EXPLORATION COMPANY 1996 STOCK INCENTIVE PLAN
                            (Full title of the plan)

                                  ROLAND SLEDGE
                                 GENERAL COUNSEL
                          1331 LAMAR STREET, SUITE 1455
                              HOUSTON, TEXAS 77010
                                 (713) 495-3000
                   (Name and address, including zip code, and
                     telephone number of agent for service)

                                    Copy to:
                             HAYNES AND BOONE, LLP
                           1000 LOUISIANA, SUITE 4300
                              HOUSTON, TEXAS 77002
                            ATTN: GEORGE G. YOUNG III
                                 (713) 547-2000
                             ----------------------

================================================================================
                         CALCULATION OF REGISTRATION FEE

<TABLE>
<CAPTION>
                                                            PROPOSED MAXIMUM       PROPOSED MAXIMUM       AMOUNT OF
         TITLE OF SECURITIES              AMOUNT TO BE     OFFERING PRICE PER     AGGREGATE OFFERING    REGISTRATION
           TO BE REGISTERED                REGISTERED           SHARE(1)               PRICE(1)              FEE
--------------------------------------- ----------------- ---------------------- ---------------------- --------------
<S>                                     <C>                <C>                    <C>                    <C>
Common Stock, par value $0.01(1)        2,000,000 shares         $7.325               $14,650,000         $3,662.50
</TABLE>
================================================================================

(1) Computed pursuant to Rule 457(c) and (h) of the Securities Act of 1933 based
    on the average of the high and low sale prices on the NASDAQ National Market
    on June 20, 2001

(2) Includes associated Rights to purchase shares of the Registrant's Preferred
    Stock. The Rights are not currently separable from the shares of common
    stock, par value $0.01 per share, of Registrant and are not currently
    exercisable.


<PAGE>   2

                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

ITEM 1. PLAN INFORMATION.*

ITEM 2. REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION.*

         *The documents containing the information specified in Part I of Form
S-8 will be sent or given to participants as specified by the Securities Act of
1933 (the "Securities Act") Rule 428(b)(1). Such documents need not be filed
with the Securities and Exchange Commission (the "SEC") either as part of this
Registration Statement or as prospectuses or prospectus supplements pursuant to
Securities Act Rule 424. These documents, which include the statement of
availability required by Item 2 of Form S-8 and the documents incorporated by
reference in this Registration Statement pursuant to Item 3 of Form S-8 (Part II
hereof), taken together, constitute a prospectus that meets the requirements of
Section 10(a) of the Securities Act.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents previously filed with the SEC by the
Registrant, pursuant to the Securities Exchange Act of 1934, as amended (the
"Exchange Act"), are incorporated herein by reference:

         o  Annual Report on Form 10-K/A for the fiscal year ended December 31,
            2000;

         o  Quarterly Report on Form 10-Q for the quarter ended March 31, 2001;

         o  Current Reports on Form 8-K filed on January 19, 2001, January 26,
            2001, March 27, 2001, May 17, 2001 and May 24, 2001; and

         o  The description of the Registrant's Common Stock contained in the
            Registration Statement on Form 8-A (File No. 0-9498).

         All documents filed by Registrant pursuant to Sections 13(a), 13(c), 14
or 15(d) of the Exchange Act, subsequent to the effective date of this
Registration Statement, prior to the filing of a post-effective amendment to
this Registration Statement indicating that all securities offered hereby have
been sold or deregistering all securities then remaining unsold, shall be deemed
to be incorporated by reference herein and to be a part hereof from the date of
filing of such documents. Any statement contained herein or in any document
incorporated or deemed to be incorporated by reference herein shall be deemed to
be modified or superseded for purposes of this Registration Statement to the
extent that a statement contained in any other subsequently filed document which
also is or is deemed to be incorporated by reference herein modifies or
supersedes such statement. Any such statement so modified or superseded shall
not be deemed to constitute a part of this Registration Statement, except as so
modified or superseded.

ITEM 4.  DESCRIPTION OF SECURITIES.

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         Not applicable.



                                                                               2
<PAGE>   3


ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 145 of the General Corporation Law of the State of Delaware
(the "DGCL") provides generally and in pertinent part that a Delaware
corporation may indemnify its directors and officers against expenses,
judgments, fines, and settlements actually and reasonably incurred by them in
connection with any civil, criminal, administrative, or investigative suit or
action except actions by or in the right of the corporation if, in connection
with the matters in issue, they acted in good faith and in a manner they
reasonably believed to be in or not opposed to the best interests of the
corporation, and in connection with any criminal suit or proceeding, if in
connection with the matters in issue, they had no reasonable cause to believe
their conduct was unlawful. Section 145 further provides that in connection with
the defense or settlement of any action by or in the right of the corporation, a
Delaware corporation may indemnify its directors and officers against expenses
actually and reasonably incurred by them if, in connection with the matters in
issue, they acted in good faith and in a manner they reasonably believed to be
in or not opposed to the best interests of the corporation, except that no
indemnification may be made in respect to any claim, issue, or matter as to
which such person has been adjudged liable to the corporation unless the
Delaware Court of Chancery or other court in which such action or suit is
brought approves such indemnification. Section 145 further permits a Delaware
corporation to grant its directors and officers additional rights of
indemnification through bylaw provisions and otherwise, and to purchase
indemnity insurance on behalf of its directors and officers.

         Article Eight of the Registrant's Certificate of Incorporation and
Section 7.7 of its Bylaws provide, in general, that the Registrant may and
shall, respectively, indemnify its officers and directors to the full extent
permitted by Delaware law. Article Nine of the Registrant's Certificate of
Incorporation further provides that a director of the Registrant shall not be
personally liable to the Registrant or its stockholders for monetary damages or
breach of fiduciary duty as a director except for any breach of the director's
duty of loyalty, for acts or omissions not in good faith or which involved
intentional misconduct or a knowing violation of law, for unlawful payment of
dividends or unlawful stock purchases or redemptions, or for any transaction
from which the director derived a personal benefit.

         The Agreement and Plan of Merger dated as of January 24, 2001 by and
between Bargo Energy Company, a Texas corporation ("Bargo"), and Bellwether
Exploration Company, a Delaware corporation ("Bellwether"), provides that, for
six years after the effective time of the merger of Bargo with and into
Bellwether forming the Registrant (the "Merger"), the Registrant will indemnify
the former officers and directors of Bargo from liabilities arising out of
actions or omissions in their capacity as such prior to the effective time of
the Merger, to the full extent permitted under Delaware law or the Registrant's
certificate of incorporation or bylaws. In addition, the Registrant will
maintain Bargo's directors' and officers' insurance coverage for six years after
the effective time of the Merger but only to the extent of actions or omissions
prior to the effective time of the Merger; provided that the maximum aggregate
amount of premiums that the Registrant will be required to pay to maintain this
coverage is $50,000.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.

ITEM 8.  EXHIBITS


  EXHIBIT NO.                          DESCRIPTION
  -----------                          -----------

     4.1         Specimen stock certificate (incorporated by reference to
                 Exhibit 4.1 to the Registrant's Registration Statement on Form
                 S-1 (Reg. No. 33-76570)).

     4.2         Certificate of Incorporation of Bellwether Exploration Company
                 (incorporated by reference to Exhibit 3.1 to the Registration
                 Statement on Form S-1, File No. 33-76570).

     4.3         Certificate of Amendment to Certificate of Incorporation
                 (incorporated by reference to Exhibit 3.2 to Bellwether's
                 Annual Report on Form 10-K for the fiscal year ended June 30,
                 1997).


                                                                               3
<PAGE>   4


  EXHIBIT NO.                          DESCRIPTION
  -----------                          -----------

     4.4         Certificate of Designation, Preferences and Rights of Series A
                 Preferred Stock (incorporated by 4.4 reference to Exhibit 1 to
                 the Registration Statement on Form 8-A dated September 19,
                 1997).

     4.5         By-laws of Bellwether Exploration Company (incorporated by
                 reference to Exhibit 3.2 to the Registration Statement on Form
                 S-1, File No. 33-76570).

     4.6         Amendment to Article II, Section 2.2 of Bellwether Exploration
                 Company's Bylaws (incorporated by reference to Exhibit 3.5 to
                 Bellwether's Annual Report on Form 10-K for the transition
                 period ended December 31, 1997).

     4.7         Amendment to Bellwether Exploration Company's bylaws adopted on
                 March 27, 1998 (incorporated by reference to Exhibit 3.6 to
                 Bellwether's Annual Report on Form 10-K for the transition
                 period ended December 31, 1997).

     4.8         Shareholders Rights Agreement between Bellwether and American
                 Stock Transfer & Trust Company (incorporated herein by
                 reference to the Registration Statement on Form 8-A as filed
                 with the Securities and Exchange Commission on September
                 19, 1997).

     4.9         Certificate of Merger of Bargo Energy Company with and into
                 Bellwether Exploration Company filed with the Delaware
                 Secretary of State on May 16, 2001 (incorporated herein by
                 reference to the Registration Statement on Form S-8, Reg.
                 No. 333-54798).

     4.10        Certificate of Amendment of the Certificate of Incorporation of
                 Mission Resources Corporation dated May 8, 2001 (incorporated
                 herein by reference to the Registration Statement on Form S-8,
                 Reg. No. 333-54798).

     5.1         Opinion of Haynes and Boone, LLP.

     23.1        Consent of KPMG LLP.

     23.2        Consent of Haynes and Boone, LLP (included in the opinion filed
                 as Exhibit 5.1 to this Registration Statement).

     24.1        Powers of Attorney (included on the signature page hereto).

     99.1        Bellwether's 1996 Stock Incentive Plan (incorporated by
                 reference to Exhibit 10.20 to the Registration Statement on
                 Form S-1, File No. 33-21813).

ITEM 9.  UNDERTAKINGS

(a)      The undersigned Registrant hereby undertakes:

         (1) To file, during any period in which offers or sales are being made,
         a post-effective amendment to this Registration Statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
                  the Securities Act;

                  (ii) To reflect in the prospectus any facts or events arising
                  after the effective date of the Registration Statement (or the
                  most recent post-effective amendment thereof) which,
                  individually or in the aggregate, represent a fundamental
                  change in the information set forth in the Registration
                  Statement. Notwithstanding the foregoing, any increase or
                  decrease in volume of securities offered

                                                                               4
<PAGE>   5

                  (if the total dollar value of securities offered would not
                  exceed that which was registered) and any deviation from the
                  low or high end of the estimated maximum offering range may be
                  reflected in the form of prospectus filed with the SEC
                  pursuant to Securities Act Rule 424(b) if, in the aggregate,
                  the changes in volume and price represent no more than 20
                  percent change in the maximum aggregate offering price set
                  forth in the "Calculation of Registration Fee" table in the
                  effective Registration Statement; and

                  (iii) To include any material information with respect to the
                  plan of distribution not previously disclosed in the
                  Registration Statement or any material change to such
                  information in the Registration Statement.

         Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
         apply if the Registration Statement is on Form S-3, Form S-8 or Form
         F-3, and the information required to be included in a post-effective
         amendment by those paragraphs is contained in periodic reports filed
         with or furnished to the SEC by the Registrant pursuant to Section 13
         or Section 15(d) of the Exchange Act that are incorporated by reference
         in the Registration Statement.

         (2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

         (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

(b) The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in the Registration Statement shall be deemed to be a
new Registration Statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

(h) Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the SEC such indemnification is against
public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Registrant of expenses incurred or
paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.


                                                                               5
<PAGE>   6


                                   SIGNATURES

         Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Houston, State of Texas, on June 21, 2001.

                                       Mission Resources Corporation



                                       By: /s/ Douglas G. Manner
                                          --------------------------------------
                                          Douglas G. Manner
                                          Chief Executive Officer




                                                                               6
<PAGE>   7


                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned
constitutes and appoints Douglas G. Manner and Jonathan M. Clarkson, and each of
them, either of whom may act without joinder of the other, his true and lawful
attorneys-in-fact and agents, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any and all
capacities, to sign any or all amendments to this Registration Statement, and to
file the same, with all exhibits thereto and other documents in connection
therewith, with the SEC, granting unto such attorneys-in-fact and agents, and
each of them, full power and authority to do and perform each and every act and
thing requisite and necessary to be done in and about the premises, as fully to
all intents and purposes as he might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents, and each of them, or the
substitute or substitutes of either of them, may lawfully do or cause to be done
by virtue hereof.

         Pursuant to the requirements of the Securities Act, this Registration
Statement on Form S-8 has been signed below by the following persons in the
capacities indicated on June 21, 2001.


<TABLE>
<CAPTION>
SIGNATURE                                       TITLE
---------                                       -----
<S>                                             <C>
/s/ Douglas Manner                              Chairman of the Board, Chief Executive Officer and
---------------------------------------         Director
Douglas Manner                                  (Principal Executive Officer)



/s/ Jonathan M. Clarkson                        President, Chief Financial Officer and Director
---------------------------------------         (Principal Financial Officer)
Jonathan M. Clarkson



/s/ Judy Ley Allen                              Director
---------------------------------------
Judy Ley Allen



/s/ J. P. Bryan                                 Director
---------------------------------------
J. P. Bryan



---------------------------------------
Timothy J. Goff                                 Director



/s/ Habib Kairouz                               Director
---------------------------------------
Habib Kairouz



/s/ D. Martin Phillips                          Director
---------------------------------------
D. Martin Phillips
</TABLE>


                                                                               7
<PAGE>   8



                                INDEX TO EXHIBITS


  EXHIBIT NO.                          DESCRIPTION
  -----------                          -----------

     4.1         Specimen stock certificate (incorporated by reference to
                 Exhibit 4.1 to the Registrant's Registration Statement on Form
                 S-1 (Reg. No. 33-76570)).

     4.2         Certificate of Incorporation of Bellwether Exploration Company
                 (incorporated by reference to Exhibit 3.1 to the Registration
                 Statement on Form S-1, File No. 33-76570).

     4.3         Certificate of Amendment to Certificate of Incorporation
                 (incorporated by reference to Exhibit 3.2 to Bellwether's
                 Annual Report on Form 10-K for the fiscal year ended June 30,
                 1997).

     4.4         Certificate of Designation, Preferences and Rights of Series A
                 Preferred Stock (incorporated by 4.4 reference to Exhibit 1 to
                 the Registration Statement on Form 8-A dated September 19,
                 1997).

     4.5         By-laws of Bellwether Exploration Company (incorporated by
                 reference to Exhibit 3.2 to the Registration Statement on Form
                 S-1, File No. 33-76570).

     4.6         Amendment to Article II, Section 2.2 of Bellwether Exploration
                 Company's Bylaws (incorporated by reference to Exhibit 3.5 to
                 Bellwether's Annual Report on Form 10-K for the transition
                 period ended December 31, 1997).

     4.7         Amendment to Bellwether Exploration Company's bylaws adopted on
                 March 27, 1998 (incorporated by reference to Exhibit 3.6 to
                 Bellwether's Annual Report on Form 10-K for the transition
                 period ended December 31, 1997).

     4.8         Shareholders Rights Agreement between Bellwether and American
                 Stock Transfer & Trust Company (incorporated herein by
                 reference to the Registration Statement on Form 8-A as filed
                 with the Securities and Exchange Commission on September
                 19, 1997).

     4.9         Certificate of Merger of Bargo Energy Company with and into
                 Bellwether Exploration Company filed with the Delaware
                 Secretary of State on May 16, 2001 (incorporated herein by
                 reference to the Registration Statement on Form S-8, Reg.
                 No. 333-54798).

     4.10        Certificate of Amendment of the Certificate of Incorporation of
                 Mission Resources Corporation dated May 8, 2001 (incorporated
                 herein by reference to the Registration Statement on Form S-8,
                 Reg. No. 333-54798).

     5.1         Opinion of Haynes and Boone, LLP.

     23.1        Consent of KPMG LLP.

     23.2        Consent of Haynes and Boone, LLP (included in the opinion filed
                 as Exhibit 5.1 to this Registration Statement).

     24.1        Powers of Attorney (included on the signature page hereto).

     99.1        Bellwether's 1996 Stock Incentive Plan (incorporated by
                 reference to Exhibit 10.20 to the Registration Statement on
                 Form S-1, File No. 33-21813).

                                                                               8
[{"type": "S-8", "sequence": "1", "filename": "h88598s-8.txt", "description": "MISSION RESOURCES CORPORATION", "secsgml_size_bytes": 25347}]
{"company-data": {"conformed-name": "MISSION RESOURCES CORP", "cik": "0000319459", "assigned-sic": "1311", "irs-number": "760437769", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-63562", "film-number": "1664984"}, "business-address": {"street1": "1331 LAMAR", "street2": "SUITE 1455", "city": "HOUSTON", "state": "TX", "zip": "77010", "phone": "7134953000"}, "mail-address": {"street1": "1221 LAMAR", "street2": "STE 1600", "city": "HOUSTON", "state": "TX", "zip": "77010-3039"}, "former-company": {"former-conformed-name": "BELLWETHER EXPLORATION CO", "date-changed": "19920703"}}
1

      As filed with the Securities and Exchange Commission on June 21, 2001
                                                     Registration No. 333-______

================================================================================

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

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

                                    FORM S-8

                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

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

                          MISSION RESOURCES CORPORATION
               (FORMERLY KNOWN AS BELLWETHER EXPLORATION COMPANY)
             (Exact name of Registrant as specified in its charter)

             DELAWARE                                          74-0437769
   (State or other jurisdiction                             (I.R.S. Employer
  of incorporation or organization)                       Identification Number)

    1331 LAMAR STREET, SUITE 1455                                77010
           HOUSTON, TEXAS                                      (Zip Code)
(Address of Principal Executive Offices)

            BELLWETHER EXPLORATION COMPANY 1996 STOCK INCENTIVE PLAN
                            (Full title of the plan)

                                  ROLAND SLEDGE
                                 GENERAL COUNSEL
                          1331 LAMAR STREET, SUITE 1455
                              HOUSTON, TEXAS 77010
                                 (713) 495-3000
                   (Name and address, including zip code, and
                     telephone number of agent for service)

                                    Copy to:
                             HAYNES AND BOONE, LLP
                           1000 LOUISIANA, SUITE 4300
                              HOUSTON, TEXAS 77002
                            ATTN: GEORGE G. YOUNG III
                                 (713) 547-2000
                             ----------------------

================================================================================
                         CALCULATION OF REGISTRATION FEE
PROPOSED MAXIMUM       PROPOSED MAXIMUM       AMOUNT OF
         TITLE OF SECURITIES              AMOUNT TO BE     OFFERING PRICE PER     AGGREGATE OFFERING    REGISTRATION
           TO BE REGISTERED                REGISTERED           SHARE(1)               PRICE(1)              FEE
--------------------------------------- ----------------- ---------------------- ---------------------- --------------
Common Stock, par value $0.01(1)        2,000,000 shares         $7.325               $14,650,000         $3,662.50
================================================================================

(1) Computed pursuant to Rule 457(c) and (h) of the Securities Act of 1933 based
    on the average of the high and low sale prices on the NASDAQ National Market
    on June 20, 2001

(2) Includes associated Rights to purchase shares of the Registrant's Preferred
    Stock. The Rights are not currently separable from the shares of common
    stock, par value $0.01 per share, of Registrant and are not currently
    exercisable.
2

                                     PART I

              INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

ITEM 1. PLAN INFORMATION.*

ITEM 2. REGISTRANT INFORMATION AND EMPLOYEE PLAN ANNUAL INFORMATION.*

         *The documents containing the information specified in Part I of Form
S-8 will be sent or given to participants as specified by the Securities Act of
1933 (the "Securities Act") Rule 428(b)(1). Such documents need not be filed
with the Securities and Exchange Commission (the "SEC") either as part of this
Registration Statement or as prospectuses or prospectus supplements pursuant to
Securities Act Rule 424. These documents, which include the statement of
availability required by Item 2 of Form S-8 and the documents incorporated by
reference in this Registration Statement pursuant to Item 3 of Form S-8 (Part II
hereof), taken together, constitute a prospectus that meets the requirements of
Section 10(a) of the Securities Act.

                                     PART II

               INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

ITEM 3. INCORPORATION OF DOCUMENTS BY REFERENCE.

         The following documents previously filed with the SEC by the
Registrant, pursuant to the Securities Exchange Act of 1934, as amended (the
"Exchange Act"), are incorporated herein by reference:

         o  Annual Report on Form 10-K/A for the fiscal year ended December 31,
            2000;

         o  Quarterly Report on Form 10-Q for the quarter ended March 31, 2001;

         o  Current Reports on Form 8-K filed on January 19, 2001, January 26,
            2001, March 27, 2001, May 17, 2001 and May 24, 2001; and

         o  The description of the Registrant's Common Stock contained in the
            Registration Statement on Form 8-A (File No. 0-9498).

         All documents filed by Registrant pursuant to Sections 13(a), 13(c), 14
or 15(d) of the Exchange Act, subsequent to the effective date of this
Registration Statement, prior to the filing of a post-effective amendment to
this Registration Statement indicating that all securities offered hereby have
been sold or deregistering all securities then remaining unsold, shall be deemed
to be incorporated by reference herein and to be a part hereof from the date of
filing of such documents. Any statement contained herein or in any document
incorporated or deemed to be incorporated by reference herein shall be deemed to
be modified or superseded for purposes of this Registration Statement to the
extent that a statement contained in any other subsequently filed document which
also is or is deemed to be incorporated by reference herein modifies or
supersedes such statement. Any such statement so modified or superseded shall
not be deemed to constitute a part of this Registration Statement, except as so
modified or superseded.

ITEM 4.  DESCRIPTION OF SECURITIES.

         Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL

         Not applicable.

                                                                               2
3

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Section 145 of the General Corporation Law of the State of Delaware
(the "DGCL") provides generally and in pertinent part that a Delaware
corporation may indemnify its directors and officers against expenses,
judgments, fines, and settlements actually and reasonably incurred by them in
connection with any civil, criminal, administrative, or investigative suit or
action except actions by or in the right of the corporation if, in connection
with the matters in issue, they acted in good faith and in a manner they
reasonably believed to be in or not opposed to the best interests of the
corporation, and in connection with any criminal suit or proceeding, if in
connection with the matters in issue, they had no reasonable cause to believe
their conduct was unlawful. Section 145 further provides that in connection with
the defense or settlement of any action by or in the right of the corporation, a
Delaware corporation may indemnify its directors and officers against expenses
actually and reasonably incurred by them if, in connection with the matters in
issue, they acted in good faith and in a manner they reasonably believed to be
in or not opposed to the best interests of the corporation, except that no
indemnification may be made in respect to any claim, issue, or matter as to
which such person has been adjudged liable to the corporation unless the
Delaware Court of Chancery or other court in which such action or suit is
brought approves such indemnification. Section 145 further permits a Delaware
corporation to grant its directors and officers additional rights of
indemnification through bylaw provisions and otherwise, and to purchase
indemnity insurance on behalf of its directors and officers.

         Article Eight of the Registrant's Certificate of Incorporation and
Section 7.7 of its Bylaws provide, in general, that the Registrant may and
shall, respectively, indemnify its officers and directors to the full extent
permitted by Delaware law. Article Nine of the Registrant's Certificate of
Incorporation further provides that a director of the Registrant shall not be
personally liable to the Registrant or its stockholders for monetary damages or
breach of fiduciary duty as a director except for any breach of the director's
duty of loyalty, for acts or omissions not in good faith or which involved
intentional misconduct or a knowing violation of law, for unlawful payment of
dividends or unlawful stock purchases or redemptions, or for any transaction
from which the director derived a personal benefit.

         The Agreement and Plan of Merger dated as of January 24, 2001 by and
between Bargo Energy Company, a Texas corporation ("Bargo"), and Bellwether
Exploration Company, a Delaware corporation ("Bellwether"), provides that, for
six years after the effective time of the merger of Bargo with and into
Bellwether forming the Registrant (the "Merger"), the Registrant will indemnify
the former officers and directors of Bargo from liabilities arising out of
actions or omissions in their capacity as such prior to the effective time of
the Merger, to the full extent permitted under Delaware law or the Registrant's
certificate of incorporation or bylaws. In addition, the Registrant will
maintain Bargo's directors' and officers' insurance coverage for six years after
the effective time of the Merger but only to the extent of actions or omissions
prior to the effective time of the Merger; provided that the maximum aggregate
amount of premiums that the Registrant will be required to pay to maintain this
coverage is $50,000.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED

         Not applicable.

ITEM 8.  EXHIBITS

  EXHIBIT NO.                          DESCRIPTION
  -----------                          -----------

     4.1         Specimen stock certificate (incorporated by reference to
                 Exhibit 4.1 to the Registrant's Registration Statement on Form
                 S-1 (Reg. No. 33-76570)).

     4.2         Certificate of Incorporation of Bellwether Exploration Company
                 (incorporated by reference to Exhibit 3.1 to the Registration
                 Statement on Form S-1, File No. 33-76570).

     4.3         Certificate of Amendment to Certificate of Incorporation
                 (incorporated by reference to Exhibit 3.2 to Bellwether's
                 Annual Report on Form 10-K for the fiscal year ended June 30,
                 1997).

                                                                               3
4

  EXHIBIT NO.                          DESCRIPTION
  -----------                          -----------

     4.4         Certificate of Designation, Preferences and Rights of Series A
                 Preferred Stock (incorporated by 4.4 reference to Exhibit 1 to
                 the Registration Statement on Form 8-A dated September 19,
                 1997).

     4.5         By-laws of Bellwether Exploration Company (incorporated by
                 reference to Exhibit 3.2 to the Registration Statement on Form
                 S-1, File No. 33-76570).

     4.6         Amendment to Article II, Section 2.2 of Bellwether Exploration
                 Company's Bylaws (incorporated by reference to Exhibit 3.5 to
                 Bellwether's Annual Report on Form 10-K for the transition
                 period ended December 31, 1997).

     4.7         Amendment to Bellwether Exploration Company's bylaws adopted on
                 March 27, 1998 (incorporated by reference to Exhibit 3.6 to
                 Bellwether's Annual Report on Form 10-K for the transition
                 period ended December 31, 1997).

     4.8         Shareholders Rights Agreement between Bellwether and American
                 Stock Transfer & Trust Company (incorporated herein by
                 reference to the Registration Statement on Form 8-A as filed
                 with the Securities and Exchange Commission on September
                 19, 1997).

     4.9         Certificate of Merger of Bargo Energy Company with and into
                 Bellwether Exploration Company filed with the Delaware
                 Secretary of State on May 16, 2001 (incorporated herein by
                 reference to the Registration Statement on Form S-8, Reg.
                 No. 333-54798).

     4.10        Certificate of Amendment of the Certificate of Incorporation of
                 Mission Resources Corporation dated May 8, 2001 (incorporated
                 herein by reference to the Registration Statement on Form S-8,
                 Reg. No. 333-54798).

     5.1         Opinion of Haynes and Boone, LLP.

     23.1        Consent of KPMG LLP.

     23.2        Consent of Haynes and Boone, LLP (included in the opinion filed
                 as Exhibit 5.1 to this Registration Statement).

     24.1        Powers of Attorney (included on the signature page hereto).

     99.1        Bellwether's 1996 Stock Incentive Plan (incorporated by
                 reference to Exhibit 10.20 to the Registration Statement on
                 Form S-1, File No. 33-21813).

ITEM 9.  UNDERTAKINGS

(a)      The undersigned Registrant hereby undertakes:

         (1) To file, during any period in which offers or sales are being made,
         a post-effective amendment to this Registration Statement:

                  (i) To include any prospectus required by Section 10(a)(3) of
                  the Securities Act;

                  (ii) To reflect in the prospectus any facts or events arising
                  after the effective date of the Registration Statement (or the
                  most recent post-effective amendment thereof) which,
                  individually or in the aggregate, represent a fundamental
                  change in the information set forth in the Registration
                  Statement. Notwithstanding the foregoing, any increase or
                  decrease in volume of securities offered

                                                                               4
5

                  (if the total dollar value of securities offered would not
                  exceed that which was registered) and any deviation from the
                  low or high end of the estimated maximum offering range may be
                  reflected in the form of prospectus filed with the SEC
                  pursuant to Securities Act Rule 424(b) if, in the aggregate,
                  the changes in volume and price represent no more than 20
                  percent change in the maximum aggregate offering price set
                  forth in the "Calculation of Registration Fee" table in the
                  effective Registration Statement; and

                  (iii) To include any material information with respect to the
                  plan of distribution not previously disclosed in the
                  Registration Statement or any material change to such
                  information in the Registration Statement.

         Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) do not
         apply if the Registration Statement is on Form S-3, Form S-8 or Form
         F-3, and the information required to be included in a post-effective
         amendment by those paragraphs is contained in periodic reports filed
         with or furnished to the SEC by the Registrant pursuant to Section 13
         or Section 15(d) of the Exchange Act that are incorporated by reference
         in the Registration Statement.

         (2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

         (3) To remove from registration by means of a post-effective amendment
any of the securities being registered which remain unsold at the termination of
the offering.

(b) The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in the Registration Statement shall be deemed to be a
new Registration Statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

(h) Insofar as indemnification for liabilities arising under the Securities Act
may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the SEC such indemnification is against
public policy as expressed in the Securities Act and is, therefore,
unenforceable. In the event that a claim for indemnification against such
liabilities (other than the payment by the Registrant of expenses incurred or
paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.

                                                                               5
6

                                   SIGNATURES

         Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Houston, State of Texas, on June 21, 2001.

                                       Mission Resources Corporation

                                       By: /s/ Douglas G. Manner
                                          --------------------------------------
                                          Douglas G. Manner
                                          Chief Executive Officer

                                                                               6
7

                                POWER OF ATTORNEY

         KNOW ALL MEN BY THESE PRESENTS, that each of the undersigned
constitutes and appoints Douglas G. Manner and Jonathan M. Clarkson, and each of
them, either of whom may act without joinder of the other, his true and lawful
attorneys-in-fact and agents, with full power of substitution and
resubstitution, for him and in his name, place and stead, in any and all
capacities, to sign any or all amendments to this Registration Statement, and to
file the same, with all exhibits thereto and other documents in connection
therewith, with the SEC, granting unto such attorneys-in-fact and agents, and
each of them, full power and authority to do and perform each and every act and
thing requisite and necessary to be done in and about the premises, as fully to
all intents and purposes as he might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents, and each of them, or the
substitute or substitutes of either of them, may lawfully do or cause to be done
by virtue hereof.

         Pursuant to the requirements of the Securities Act, this Registration
Statement on Form S-8 has been signed below by the following persons in the
capacities indicated on June 21, 2001.
SIGNATURE                                       TITLE
---------                                       -----
/s/ Douglas Manner                              Chairman of the Board, Chief Executive Officer and
---------------------------------------         Director
Douglas Manner                                  (Principal Executive Officer)

/s/ Jonathan M. Clarkson                        President, Chief Financial Officer and Director
---------------------------------------         (Principal Financial Officer)
Jonathan M. Clarkson

/s/ Judy Ley Allen                              Director
---------------------------------------
Judy Ley Allen

/s/ J. P. Bryan                                 Director
---------------------------------------
J. P. Bryan

---------------------------------------
Timothy J. Goff                                 Director

/s/ Habib Kairouz                               Director
---------------------------------------
Habib Kairouz

/s/ D. Martin Phillips                          Director
---------------------------------------
D. Martin Phillips
7
8

                                INDEX TO EXHIBITS

  EXHIBIT NO.                          DESCRIPTION
  -----------                          -----------

     4.1         Specimen stock certificate (incorporated by reference to
                 Exhibit 4.1 to the Registrant's Registration Statement on Form
                 S-1 (Reg. No. 33-76570)).

     4.2         Certificate of Incorporation of Bellwether Exploration Company
                 (incorporated by reference to Exhibit 3.1 to the Registration
                 Statement on Form S-1, File No. 33-76570).

     4.3         Certificate of Amendment to Certificate of Incorporation
                 (incorporated by reference to Exhibit 3.2 to Bellwether's
                 Annual Report on Form 10-K for the fiscal year ended June 30,
                 1997).

     4.4         Certificate of Designation, Preferences and Rights of Series A
                 Preferred Stock (incorporated by 4.4 reference to Exhibit 1 to
                 the Registration Statement on Form 8-A dated September 19,
                 1997).

     4.5         By-laws of Bellwether Exploration Company (incorporated by
                 reference to Exhibit 3.2 to the Registration Statement on Form
                 S-1, File No. 33-76570).

     4.6         Amendment to Article II, Section 2.2 of Bellwether Exploration
                 Company's Bylaws (incorporated by reference to Exhibit 3.5 to
                 Bellwether's Annual Report on Form 10-K for the transition
                 period ended December 31, 1997).

     4.7         Amendment to Bellwether Exploration Company's bylaws adopted on
                 March 27, 1998 (incorporated by reference to Exhibit 3.6 to
                 Bellwether's Annual Report on Form 10-K for the transition
                 period ended December 31, 1997).

     4.8         Shareholders Rights Agreement between Bellwether and American
                 Stock Transfer & Trust Company (incorporated herein by
                 reference to the Registration Statement on Form 8-A as filed
                 with the Securities and Exchange Commission on September
                 19, 1997).

     4.9         Certificate of Merger of Bargo Energy Company with and into
                 Bellwether Exploration Company filed with the Delaware
                 Secretary of State on May 16, 2001 (incorporated herein by
                 reference to the Registration Statement on Form S-8, Reg.
                 No. 333-54798).

     4.10        Certificate of Amendment of the Certificate of Incorporation of
                 Mission Resources Corporation dated May 8, 2001 (incorporated
                 herein by reference to the Registration Statement on Form S-8,
                 Reg. No. 333-54798).

     5.1         Opinion of Haynes and Boone, LLP.

     23.1        Consent of KPMG LLP.

     23.2        Consent of Haynes and Boone, LLP (included in the opinion filed
                 as Exhibit 5.1 to this Registration Statement).

     24.1        Powers of Attorney (included on the signature page hereto).

     99.1        Bellwether's 1996 Stock Incentive Plan (incorporated by
                 reference to Exhibit 10.20 to the Registration Statement on
                 Form S-1, File No. 33-21813).

                                                                               8