Document:

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EXHIBIT 4.20

                          PACIFIC ENERGY RESOURCES LTD.
                      111 West Ocean Boulevard, Suite 1240
                          Long Beach, California 90802

                        SUBSCRIPTION AGREEMENT FOR UNITS
                                (U.S. RESIDENTS)

TO:  Pacific Energy Resources Ltd. (the "CORPORATION")

The undersigned (the "SUBSCRIBER") hereby irrevocably subscribes for and agrees
to purchase from the Corporation units ("UNITS") of the Corporation in the
number set forth below at a subscription price equal to CAD$2.20 per Unit (the
"SUBSCRIPTION PRICE"), with each Unit consisting of one (1) share of common
stock of the Corporation (a "COMMON SHARE") and one-half (1/2) Common Share
purchase warrant of the Corporation ("WARRANT"). Each one (1) whole Warrant
shall entitle the holder to acquire one (1) Common Share (a "WARRANT SHARE") at
a price equal to CAD$2.65 per Warrant Share for a period of 18 months from the
date of issue of the Warrants. The Subscriber agrees to be bound by the attached
terms and conditions of subscription (the "TERMS AND CONDITIONS") and agrees
that the Corporation and its agents and attorneys may rely upon the
representations, warranties and covenants contained therein and in the
Subscriber Certificate (as hereinafter defined). This subscription, plus the
Terms and Conditions of the completed and executed Subscriber Certificate, are
collectively referred to as the "SUBSCRIPTION AGREEMENT" or the "AGREEMENT".

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                                               SUBSCRIPTION AND SUBSCRIBER INFORMATION

                  PLEASE PRINT ALL INFORMATION (OTHER THAN SIGNATURES), AS APPLICABLE, IN THE SPACE PROVIDED BELOW

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                                                                         Number of Units:
-----------------------------------------------------                                    ------------------------------------
 (Name of Subscriber - please print)                                    ----------------------------------------------------------

 By:                                                                    ----------------------------------------------------------
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    (Authorized Signature)                                               Aggregate Subscription Price:
                                                                                                      ------------------------
------------------------------------------------------                  ----------------------------------------------------------
(Official Capacity or Title - please print)
                                                                        ----------------------------------------------------------
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(Please print name of individual whose signature appears above          If the Subscriber is signing as agent for a principal
if different than the name of the subscriber printed above.)            and is not purchasing as trustee or agent for accounts
                                                                        fully managed by it, complete the following and ensure
------------------------------------------------------                  that the applicable Exhibit(s) are completed on behalf
(Subscriber's Address)                                                  of such principal:

------------------------------------------------------                  ------------------------------------------------------
(Subscriber's Address)                                                  (Name of Principal)

------------------------------------------------------                  ------------------------------------------------------
(Telephone Number)                  (E-Mail Address)                    (Principal's Address)

------------------------------------------------------                  ------------------------------------------------------
(Social Security Number or Federal Taxpayer Identification              (Social Security Number or Federal Taxpayer
 Number)                                                                Identification Number)

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DELIVER THE UNITS AS SET FORTH BELOW:
-------------------------------------

------------------------------------------------------
(Name)

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(Account reference, if applicable)

------------------------------------------------------
(Contact Name)

------------------------------------------------------
(Address)

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(Address)

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                 THIS IS THE FIRST PAGE OF AN AGREEMENT COMPRISED OF 12 PAGES (NOT INCLUDING EXHIBITS "A" AND "B").
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ACCEPTANCE:     The Corporation hereby accepts the subscription as set forth
above on the terms and conditions contained in this Subscription Agreement.

October _____, 2007

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

PACIFIC ENERGY RESOURCES LTD.                          Subscription No:

By:
   -----------------------------------------           -----------------------

              THE REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK

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                 TERMS AND CONDITIONS OF SUBSCRIPTION FOR UNITS

                                   DEFINITIONS

1.1   In this Agreement, which includes the cover page and all of the
      appendices, the following words have the following meanings unless
      otherwise indicated:

      (a)   "1933 ACT" means Securities Act of 1933, as amended, and the rules
            and regulations promulgated thereunder;

      (b)   "CLOSING" means the completion of the issue and sale of the Units to
            the Subscriber hereunder;

      (c)   "COMMON SHARE" has the meaning ascribed to it on the cover page of
            this Agreement;

      (d)   "CORPORATION" means Pacific Energy Resources Ltd.;

      (e)   "DISCLOSURE DOCUMENT" has the meaning ascribed to it in paragraph
            4.1(m);

      (f)   "EXCHANGE" means the Toronto Stock Exchange;

      (g)   "OFFERING" means this private placement;

      (h)   "REGISTRATION RIGHTS AGREEMENT" means the registration rights
            agreement attached hereto as Exhibit "B";

      (i)   "REGULATION D" means Regulation D promulgated under the 1933 Act;

      (j)   "SEC" means the United States Securities and Exchange
            Commission;

      (k)   "SECURITIES" means collectively, the Units, the
            Common Shares, the Warrants and the Warrant Shares.

      (l)   "SUBSCRIBER" has the meaning ascribed to it on the cover page of
            this Agreement;

      (m)   "SUBSCRIBER CERTIFICATE" means the accredited investor certificate
            attached hereto as Exhibit "A";

      (n)   "UNIT" has the meaning ascribed to it on the cover pages of this
            Agreement;

      (o)   "WARRANT" has the meaning ascribed to it on the cover page of this
            Agreement; and

      (p)   "WARRANT SHARES" has the meaning ascribed to it on the cover page of
            this Agreement.

1.2   All capitalized terms in this Agreement not defined above have the
      meanings ascribed to them in this Agreement.

                                       3

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2.    PURCHASE AND SALE OF UNITS

The Subscriber acknowledges that:

2.1   the Common Shares will be registered in the name of the Subscriber;

2.2   the Corporation shall have the right to reject this Subscription Agreement
      if it believes for any reason that the Subscriber is not an "accredited
      investor" within the meaning of Rule 501 of Regulation D promulgated by
      the SEC as presently in effect, or for any other reason in its sole and
      absolute discretion. Acceptance is evidenced only by execution of this
      Subscription Agreement by the Corporation in the space provided above;

2.3   fractional Warrants will not be issued to the Subscriber. Instead, the
      number of Warrants issued to any one Subscriber will be rounded down to
      the nearest whole number of Warrants issuable to such Subscriber at the
      Closing; and

2.4   the issuance of the Common Shares and the Warrants will not restrict or
      prevent the Corporation from obtaining any other financing, or from
      issuing additional securities from time to time.

3.    REPRESENTATIONS, WARRANTIES AND COVENANTS BY THE CORPORATION

3.1   The Corporation hereby represents and warrants to the Subscriber (and
      acknowledges that the Subscriber is relying thereon) that:

      (a)   the Corporation has the full corporate right, power and authority to
            execute and deliver this Subscription Agreement and to issue the
            Securities, and at Closing the Common Shares, the Warrants and the
            Warrant Shares will be duly and validly authorized, and the Common
            Shares when issued, and the Warrant Shares when issued upon exercise
            of the Warrants, as the case may be, will be fully paid and
            non-assessable;

      (b)   this Subscription Agreement and the Registration Rights Agreement
            each constitute a binding obligation of the Corporation enforceable
            in accordance with its terms except as enforceability may be limited
            by applicable bankruptcy, insolvency, reorganization, moratorium and
            other laws of general application affecting enforcement of
            creditors' rights generally and as limited by laws relating to the
            availability of specific performance, injunctive relief or other
            equitable remedies;

      (c)   the execution and delivery of, and the performance of the terms of
            this Subscription Agreement by the Corporation, including the issue
            of the Common Shares and the Warrants, and the issue of the Warrant
            Shares upon exercise of the Warrants, as the case may be, does not
            and will not constitute a breach of or default under the certificate
            of incorporation or bylaws of the Corporation or any law,
            regulation, order or ruling applicable to the Corporation or any
            agreement, contract or indenture to which the Corporation is a party
            or by which it is bound; and

      (d)   the Corporation is a duly incorporated and validly subsisting
            corporation under the laws of its jurisdiction of incorporation and
            has full corporate power and authority to perform each of its
            obligations as herein contemplated.

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4.    REPRESENTATIONS, WARRANTIES AND ACKNOWLEDGMENTS OF THE SUBSCRIBER

4.1   The Subscriber represents and warrants, as at the date of this Agreement
      and at the Closing, that:

      (a)   the Subscriber is purchasing the Securities as principal for the
            Subscriber's own account or for accounts fully-managed by it, for
            long-term investment, and not with a view to, or for sale in
            connection with, the distribution thereof. The Subscriber has no
            present intention of selling, granting any participation in, or
            otherwise distributing the Securities. The Securities will not be
            resold without registration under the 1933 Act and qualification
            under the securities laws of all applicable states and other
            jurisdictions, unless such sale would be exempt therefrom;

      (b)   the Subscriber is an "accredited investor" under Rule 501(a) of
            Regulation D promulgated under the 1933 Act; and

      (c)   the Subscriber has received, completed and returned to the
            Corporation the Subscriber Certificate relating to the eligibility
            to participate as an investor in a private offering, and hereby
            affirms the correctness of the Subscriber's answers in the
            Subscriber Certificate;

      (d)   the Subscriber (i) has adequate means of providing for his or her
            current needs and possible personal contingencies, and has no need
            for and may never have liquidity of his or her investment in the
            Corporation; (ii) can bear the economic risk of losing his or her
            entire investment herein and may lose the entire investment, which
            is highly speculative and very risky; (iii) has such knowledge and
            experience in financial and business matters that he or she is
            capable of evaluating the relative risks and merits of this
            investment; and (iv) has an overall commitment to investments which
            are not readily marketable that is not disproportionate to his or
            her net worth and the investment subscribed for herein will not
            cause such overall commitment to become excessive;

      (e)   the Subscriber is aware that no prospectus has been prepared or
            filed by the Corporation with any securities commission or similar
            authority in connection with the Offering;

      (f)   no prospectus or offering memorandum has been delivered to the
            Subscriber in connection with the Offering;

      (g)   the Subscriber's purchase of the Securities has not been made
            through or as a result of, and the distribution of the Securities is
            not being accompanied by and the Subscriber is not aware of, any
            advertisement of the Securities in printed media of general and
            regular paid circulation, radio, television or telecommunications,
            including electronic display (such as the Internet), or any other
            advertisement or general solicitation with respect to the
            Securities;

      (h)   no person has made to the Subscriber any written or oral
            representation:

            (i)   that any person will resell or repurchase any of the
                  Securities;

            (ii)  that any person will refund the purchase price of the
                  Securities;

            (iii) as to the future price or value of any of the Securities; or

                                       5

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            (iv)  that any of the Securities will be listed and posted for
                  trading on a stock exchange or that application has been made
                  to list and post any of the Securities for trading on a stock
                  exchange, other than the Exchange;

      (i)   none of the Securities are being purchased by the Subscriber with
            knowledge of any material fact about the Corporation that has not
            been generally disclosed;

      (j)   it never has been represented, guaranteed or warranted to Subscriber
            by the Corporation, its agents, or employees or any other person,
            expressly or by implication, any of the following:

            (i)   the approximate or exact length of time that Subscriber will
                  be required to remain as owner of the Securities;

            (ii)  the profit or return, if any, to be realized as a result of
                  the Corporation's venture; or

            (iii) that the past performance or experience on the part of the
                  Corporation or any affiliate, its agents, or employees or of
                  any other person, will in any way indicate the predictable
                  results of the ownership of the Securities or the overall
                  Corporation's venture;

      (k)   the Subscriber, if an individual, is at least twenty-one (21) years
            of age;

      (l)   the Subscriber has no reason to anticipate any change in the
            Subscriber's personal circumstances, financial or otherwise, which
            may cause or require any sale or distribution by the Subscriber of
            all or any part of the Securities subscribed for herein;

      (m)   the Subscriber has reviewed the documents regarding the Corporation
            available on SEDAR (www.sedar.com) and the Exchange's web site
            (www.tsx.com) (collectively, the "DISCLOSURE DOCUMENTS") carefully
            so as to be fully familiar with and understand the contents thereof
            and is responsible for conducting its own due diligence under the
            Offering in order to determine whether to proceed with a
            subscription under the Offering;

      (n)   the Subscriber has had the opportunity to review all facts
            concerning the Corporation which the Subscriber deems pertinent;

      (o)   the Subscriber, if a partnership, corporation, trust, or other
            entity, declares:

            (i)   the person executing this Subscription Agreement has the
                  necessary power and authority to do so; and

            (ii)  the Subscriber was not organized for the specific purpose of
                  acquiring the Securities;

      (p)   the exhibits to this Agreement will be completed truthfully and with
            reasonable diligence;

      (q)   as to the source of subscription funds,

            (i)   none of the subscription funds used for the purchase of the
                  Subscriber's Securities (A) have been or will be derived from
                  or related to any activity that is deemed criminal under the
                  laws of the United States or any other jurisdiction; or (B)
                  are being tendered on behalf of a person or entity who has not
                  been identified to the Subscriber; and

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            (ii)  the Subscriber will promptly notify the Corporation if the
                  Subscriber discovers that any of the representations in
                  subparagraph (q)(i) above ceases to be true, and to provide
                  the Corporation with appropriate information in connection
                  therewith;

      (r)   the Subscriber understands that the foregoing representations and
            warranties are to be relied upon by the Corporation as a basis for
            exemption of the sale of the Securities under the 1933 Act, and for
            other purposes;

      (s)   the Subscriber has had an opportunity prior to entering into this
            Agreement to ask questions of and receive answers from the
            Corporation concerning the terms and conditions of the Offering and
            to obtain additional information that the Corporation possesses or
            can acquire without unreasonable effort or expense necessary to
            verify the accuracy of information furnished or made available by
            the Corporation to the Subscriber that the Subscriber considers
            necessary or appropriate for deciding whether to purchase the
            Securities;

      (t)   the Subscriber, if an individual, has the legal capacity to enter
            into and execute this Agreement and to take all actions required
            pursuant to this Agreement;

      (u)   the Corporation's legal counsel are acting solely for the
            Corporation, and the Subscriber may not rely upon such counsel in
            any respect;

      (v)   the Subscriber is a citizen or legal resident of and permanently
            resides in the U.S.;

      (w)   the entering into of this Agreement and the transactions
            contemplated hereby will not result in the violation of any of the
            terms and provisions of any law applicable to, or the charter or
            governing documents of, the Subscriber or of any agreement, written
            or oral, to which the Subscriber may be a party or by which the
            Subscriber is or may be bound;

      (x)   this Agreement has been duly executed and delivered by the
            Subscriber and constitutes a legal, valid and binding agreement of
            the Subscriber enforceable against the Subscriber;

      (y)   the Subscriber warrants that the information herein provided to the
            Corporation by the Subscriber is true and correct as of the date
            hereof, and the Subscriber agrees to advise the Corporation, prior
            to its acceptance of this Subscription, of any material change in
            any such information; and

      (z)   the Subscriber agrees that the representations and warranties of the
            Subscriber set forth in this Section 4 shall survive the acceptance
            of this subscription, in the event the subscription is accepted.

4.2   The Subscriber understands and acknowledges that:

      (a)   (on its own behalf and, if applicable, on behalf of each person on
            whose behalf the Subscriber is contracting) that the Securities
            subscribed for by it hereunder form part of a larger issuance and
            sale by the Corporation of up to CAD$75 million in Units;

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      (b)   no federal or state agency has made any finding or determination as
            to the fairness of the offering of the Securities for investment or
            any recommendation or endorsement of the Offering and no securities
            commission or similar regulatory authority has reviewed or passed on
            the merits of the Securities;

      (c)   the Securities have not been registered under the 1933 Act or
            qualified under any state securities laws in reliance on exemptions
            from registration and may not be offered or sold in the United
            States unless registered under the 1933 Act and the securities laws
            of all applicable states of the United States or an exemption from
            such registration requirements is available;

      (d)   the Common Shares and Warrant Shares will bear incidental
            registration rights in accordance with the terms of the Registration
            Rights Agreement; while the Common Shares and the Warrant Shares are
            expected to be listed on the Exchange, the Units and the Warrants
            will not be listed on the Exchange, there is no trading market for
            the Unites or the Warrants, and none is expected to develop;

      (e)   there are restrictions imposed by law on the Subscriber's ability to
            resell the Securities and it is the responsibility of the Subscriber
            to find out what those restrictions are and to comply with them
            before reselling any of the Securities;

      (f)   the offer and sale of the Securities is being made in reliance upon
            exemptions from the registration provisions of the 1933 Act under
            Section 4(2) and Regulation D of the 1933 Act, among others, on the
            basis that the transaction did not involve any public offering and
            the Subscriber is accredited with access to the kind of information
            registration would provide;

      (g)   Rule 144 under the 1933 Act permits limited public resales of
            securities acquired in non-public offerings, subject to the
            satisfaction of certain conditions. Under Rule 144, the conditions
            include, among other things: the availability of certain current
            public information about the issuer, the resale occurring not fewer
            than one (1) year or two (2) years, as applicable, after the party
            has purchased and paid for the securities to be sold, the sale being
            through a broker in an unsolicited "broker's transaction" and the
            amount of securities being sold during any three-month period not
            exceeding specified volume limitations. The Corporation may not be
            satisfying the current public information requirement of Rule 144 at
            the time the Subscriber wishes to sell any of the Securities, or
            other conditions under Rule 144 which are required of the
            Corporation.

      (h)   the Subscriber acknowledges and agrees with the Corporation that the
            Corporation shall refuse to register any transfer of the Securities
            not made pursuant to registration under the 1933 Act, or pursuant to
            an available exemption from registration under the 1933 Act;

      (i)   the Subscriber acknowledges that there are risks associated with the
            purchase of the Securities and that the Subscriber is aware that
            there is no government or other insurance covering the Securities;

      (j)   the Corporation may be required to provide applicable securities
            regulatory authorities with a list setting forth the identities of
            the beneficial purchasers of the Securities and the Subscriber
            acknowledges and agrees that it will provide, on request,
            particulars as to the identity of such beneficial purchasers as may
            be required by the Corporation in order to comply with the
            foregoing;

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      (k)   if required by applicable securities laws or the Corporation, the
            Subscriber will execute, deliver and file, or assist the Corporation
            in filing, such reports, undertakings and other documents with
            respect to the issue and/or sale of the Securities as may be
            required by any securities commission, stock exchange or other
            regulatory authority;

      (l)   by providing personal information to the Corporation, the Subscriber
            and each person for whom it is contracting hereunder, is consenting
            to the Corporation's collection, use and disclosure of that
            information for the purposes of the subscription of Securities and
            the offering in general, for corporate governance purposes and to
            contact the Subscriber as an investor. The Subscriber, and each
            person for whom it is contracting hereunder, acknowledges that, from
            time to time, the Corporation may be required to disclose such
            personal information and, by providing such personal information to
            the Corporation, the Subscriber and each person for whom it is
            contracting hereunder, hereby expressly consents to such disclosure,
            and the Subscriber and each person for whom it is contracting agrees
            and acknowledges that the Corporation may use and disclose personal
            information as follows:

            (i)   for internal use with respect to managing the relationships
                  between and contractual obligations of the Corporation and the
                  Subscriber and each person for whom it is contracting;

            (ii)  for use and disclosure for income tax related purposes,
                  including without limitation, where required by law,
                  disclosure to the Internal Revenue Service;

            (iii) disclosure to securities regulatory authorities and other
                  regulatory bodies with jurisdiction with respect to reports of
                  trades and similar regulatory filings;

            (iv)  disclosure to a governmental or other authority to which the
                  disclosure is required by court order or subpoena compelling
                  such disclosure and where there is no reasonable alternative
                  to such disclosure;

            (v)   disclosure to professional advisers of the Corporation in
                  connection with the performance of their professional
                  services;

            (vi)  disclosure to any person where such disclosure is necessary
                  for legitimate business reasons and is made with the prior
                  written consent of the Subscriber and each person for whom it
                  is contracting;

            (vii) disclosure to a court determining the rights of the parties
                  under this Agreement; or

            (viii) for use and disclosure as otherwise required or permitted by
                  law; and

      (m)   during the ten trading day period prior to the date hereof and the
            date of the Closing, the Subscriber has not purchased (except
            pursuant to this Agreement), sold or "sold short" any securities of
            the Corporation.

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5.    ISSUANCE OF UNITS

5.1   The Subscriber agrees to deliver to the Corporation, as soon as possible
      and, in any event, not later than 1:00 p.m. (Pacific time) on October 9,
      2007: (a) this duly completed and executed Subscription Agreement; (b) a
      duly executed U.S. Accredited Investor Certificate attached hereto as
      Exhibit "A"; (c) a duly executed Registration Rights Agreement attached
      hereto as Exhibit "B", together with a duly completed selling security
      holder questionnaire attached thereto as an exhibit; (d) such other
      documents as may be required under applicable securities laws; and (e) a
      certified cheque or bank draft payable to the Corporation for the
      aggregate subscription price or payment of the same amount in such other
      manner as is acceptable to the Corporation.

5.2   The Subscriber expressly waives and releases the Corporation from, to the
      fullest extent permitted by law, all rights of withdrawal to which it
      might otherwise be entitled pursuant to the provisions of securities laws
      of the state in which the Subscriber is resident.

5.3   Reasonably promptly following the Closing, the Corporation will forward to
      the Subscriber certificates representing the Common Shares and Warrants
      registered in the name of the Subscriber.

6.    REGISTRATION RIGHTS

6.1   The Common Shares and Warrant Shares will bear incidental registration
      rights in accordance with the terms of the Registration Rights Agreement.

7.    LEGENDS

7.1   The certificates representing the Common Shares, the Warrants and the
      Warrant Shares will bear a legend denoting the restrictions on transfer.
      The Subscriber agrees to sell, assign or transfer the Securities only in
      accordance with such restrictions.

      The legend for certificates for the Common Shares, the Warrants and the
      Warrant Shares will be in substantially the following form:

      (i)   THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE
            SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR ANY STATE
            SECURITIES LAWS. THE SECURITIES REPRESENTED HEREBY MAY NOT BE
            OFFERED, SOLD, TRANSFERRED, PLEDGED, HYPOTHECATED OR OTHERWISE
            ASSIGNED EXCEPT PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT
            UNDER THE ACT OR PURSUANT TO AN EXEMPTION FROM THE REGISTRATION
            REQUIREMENTS OF THE ACT.

      and

      (ii)  "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE LISTED ON THE
            TORONTO STOCK EXCHANGE ("TSX"). HOWEVER, THE SAID SECURITIES CANNOT
            BE TRADED THROUGH THE FACILITIES OF TSX SINCE THEY ARE NOT FREELY
            TRANSFERABLE AND CONSEQUENTLY ANY CERTIFICATE REPRESENTING SUCH
            SECURITIES IS NOT "GOOD DELIVERY" IN SETTLEMENT OF TRANSACTIONS ON
            TSX."

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8.    RELIANCE UPON REPRESENTATIONS, WARRANTIES AND COVENANTS

8.1   The Subscriber acknowledges that the representations and warranties and
      covenants and acknowledgments contained in this Agreement are made with
      the intent that they may be relied upon by the Corporation in determining
      the Subscriber's eligibility to purchase the Securities and the Subscriber
      hereby agrees to indemnify the Corporation against all losses, claims,
      costs, expenses and damages or liabilities which it may suffer or incur
      caused or arising from its reliance thereon. The Subscriber further agrees
      that by accepting the Securities, the Subscriber shall be representing and
      warranting that the foregoing representations and warranties are true as
      at the date of Closing and as at the dates of exercise of the Warrants,
      with the same force and effect as if they had been made by the Subscriber
      on each such date, and that they shall survive the purchase by the
      Subscriber of the Securities and shall continue in full force and effect
      notwithstanding any subsequent disposition by the Subscriber of any of the
      Securities .

9.    MISCELLANEOUS

9.1   The Corporation shall be entitled to rely on delivery by facsimile machine
      of an executed copy of this subscription, and acceptance by the
      Corporation of such facsimile copy shall be equally effective to create a
      valid and binding agreement between the Subscriber and the Corporation in
      accordance with the terms hereof.

9.2   Without limitation, this Agreement and the transactions contemplated
      hereby are conditional upon and subject to the Corporation receiving
      Exchange approval of this Agreement and the transactions contemplated
      hereby.

9.3   This Agreement is not assignable or transferable by the parties hereto
      without the express written consent of the other party hereto.

9.4   Time is of the essence of this Agreement.

9.5   Except as expressly provided in this Agreement and in the agreements,
      instruments and other documents contemplated or provided for herein, this
      Agreement contains the entire agreement between the parties with respect
      to the Securities, and there are no other terms, conditions,
      representations or warranties whether expressed, implied, oral or written,
      by statute, by common law, by the Corporation or by anyone else.

9.6   The parties to this Agreement may amend this Agreement only in writing.

9.7   This Agreement inures to the benefit of and is binding upon the parties to
      this Agreement and their successors and permitted assigns.

9.8   A party to this Agreement will give all notices to or other written
      communications with the other party to this Agreement concerning this
      Agreement by hand or by registered mail or overnight courier addressed to
      the address given above.

9.9   This Agreement will be governed by and construed in accordance with the
      laws of the State of California, without regard to conflicts of law
      principles.

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9.10  This Agreement, including without limitation the representations,
      warranties and covenants contained herein and in the Subscriber
      Certificate, shall survive and continue in full force and effect and be
      binding upon the Corporation and the Subscriber, notwithstanding the
      completion of the purchase of the Securities by the Subscriber pursuant
      hereto, the completion of the Offering and any subsequent disposition by
      the Subscriber of the Securities.

                                [exhibits follow]

                                       12

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                                   EXHIBIT "A"

                      U.S. ACCREDITED INVESTOR CERTIFICATE

      Capitalized terms used herein have the meaning ascribed thereto in the
subscription agreement ("SUBSCRIPTION AGREEMENT") of which this Exhibit "A"
forms a part. The Subscriber, in connection with the acquisition of Units of the
Corporation pursuant to the Subscription Agreement, hereby makes the following
representations and warranties:

      The Subscriber understands that the Corporation is relying on this
information in determining to offer the Units to the Subscriber in a manner
exempt from the registration requirements of the Securities Act of 1933, as
amended (the "1933 ACT"), and applicable state securities laws.

1.    ACCREDITED INVESTOR

      The Subscriber represents and warrants that he, she or it falls within the
category (or categories) marked. PLEASE INDICATE EACH CATEGORY OF ACCREDITED
INVESTOR THAT YOU, THE SUBSCRIBER, SATISFY, BY PLACING YOUR INITIALS ON THE
APPROPRIATE LINE BELOW.

____    Category 1.     A bank, as defined in Section 3(a)(2) of the 1933 Act,
                        whether acting in its individual or fiduciary capacity;
                        or

____    Category 2.     A savings and loan association or other institution as
                        defined in Section 3(a) (5) (A) of the 1933 Act, whether
                        acting in its individual or fiduciary capacity; or

____    Category 3.     A broker or dealer registered pursuant to Section 15 of
                        the Securities Exchange Act of 1934; or

____    Category 4.     An insurance company as defined in Section 2(13) of the
                        1933 Act; or

____    Category 5.     An investment company registered under the Investment
                        Company Act of 1940; or

____    Category 6.     A business development company as defined in Section
                        2(a) (48) of the Investment Company Act of 1940; or

____    Category 7.     A small business investment company licensed by the U.S.
                        Small Business Administration under Section 301(c) or
                        (d) of the Small Business Investment Act of 1958; or

____    Category 8.     A plan established and maintained by a state, its
                        political subdivision or any agency or instrumentality
                        of a state or its political subdivisions, for the
                        benefit of its employees, with assets in excess of
                        US$5,000,000; or

____    Category 9.     An employee benefit plan within the meaning of the
                        Employee Retirement Income Security Act of 1974 in which
                        the investment decision is made by a plan fiduciary, as
                        defined in Section 3(21) of such Act, which is either a
                        bank, savings and loan association, insurance company or
                        registered investment advisor, or an employee benefit
                        plan with total assets in excess of US$5,000,000 or, if
                        a self-directed plan, the investment decisions are made
                        solely by persons who are accredited investors; or

                                      A-1

<page>

____    Category 10.    A private business development company as defined in
                        Section 202(a) (22) or the Investment Advisors Act of
                        1940; or

____    Category 11.    An organization described in Section 501(c)(3) of the
                        Internal Revenue Code, a corporation, a Massachusetts or
                        similar business trust, or a partnership, not formed for
                        the specific purpose of acquiring the Common Shares,
                        with total assets in excess of US$5,000,000; or

____    Category 12.    A director, executive officer or general partner of the
                        Corporation; or

____    Category 13.    A natural person whose individual net worth, or joint
                        net worth with that person's spouse, at the time of this
                        purchase exceeds US$1,000,000; or

____    Category 14.    A natural person who had an individual income in excess
                        of US$200,000 in each of the two most recent years or
                        joint income with that person's spouse in excess of
                        US$300,000 in each of those years and has a reasonable
                        expectation of reaching the same income level in the
                        current year; or

____    Category 15.    A trust, with total assets in excess of US$5,000,000,
                        not formed for the specific purpose of acquiring the
                        Common Shares, whose purchase is directed by a
                        sophisticated person as described in SEC Rule
                        506(b)(2)(ii); or

____    Category 16.    An entity in which all of the equity owners are
                        accredited investors.

2.    PURCHASING ENTIRELY FOR OWN ACCOUNT

      The Subscriber represents and warrants that he, she or it is purchasing
the Securities solely for Subscriber's own account for investment and not with a
view to or for sale or distribution of the Securities and without any present
intention of selling, offering to sell or otherwise disposing of or distributing
the Securities in any transaction other than a transaction complying with the
registration requirements of the 1933 Act, and applicable state securities or
"blue sky" laws, or pursuant to an exemption therefrom. The Subscriber also
represents that the entire legal and beneficial interest of the Securities is
being purchased for, and will be held for, the Subscriber's account only, and
neither in whole nor in part for any other person or entity.

3.    ECONOMIC RISK AND SUITABILITY

      The Subscriber represents and warrants as follows:

      (a)   The Subscriber realizes that the Subscriber's purchase of the
            Securities involves a high degree of risk and will be a highly
            speculative investment, and that he, she or it is able, without
            impairing Subscriber's financial condition, to hold the Securities
            for an indefinite period of time.

      (b)   The Subscriber alone, or with the assistance of professional
            advisors, has such knowledge and experience in financial and
            business matters, that the Subscriber is capable of evaluating the
            merits and risks of Subscriber's purchase of the Securities, or has
            a pre-existing personal or business relationship with the
            Corporation or any of its officers, directors, or controlling
            persons, of a duration and nature that enables the undersigned to be
            aware of the character, business acumen and general business and
            financial circumstances of the Corporation or such other person.

                                      A-2

<page>

      (c)   If the Subscriber is a partnership, trust, corporation or other
            entity, its principal place of business and principal office are
            located within the state set forth in its address below.

      (d)   The Subscriber has relied solely upon the documents and materials
            submitted therewith, advice of his or her representatives, if any,
            and independent investigations made by the Subscriber and/or his or
            her representatives, if any, in making the decision to purchase the
            Securities subscribed for herein and acknowledges that no
            representations or agreements other than those set forth in the
            Disclosure Documents have been made to the Subscriber in respect
            thereto.

      (e)   The Subscriber confirms that the Subscriber has received no general
            solicitation or general advertisement and has attended no seminar or
            meeting (whose attendees have been invited by any general
            solicitation or general advertisement) and has received no
            advertisement in any newspaper, magazine, or similar media,
            broadcast on television or radio regarding the offering of the
            Securities.

4.    RESTRICTED SECURITIES

      The Subscriber acknowledges that the Corporation has hereby disclosed to
the Subscriber in writing:

(a)   The Securities have not been registered under the 1933 Act, or the
      securities laws of any state of the United States, and the Common Shares
      must be held indefinitely unless a transfer of them is subsequently
      registered under the 1933 Act or an exemption from such registration is
      available; and

(b)   The Corporation will make a notation in its records of the above-described
      restrictions on transfer.

      IN WITNESS WHEREOF, the Subscriber has executed this Certificate as of
October ___, 2007.

                                         THE SUBSCRIBER

                                         ---------------------------------------
                                         (Signature and office, if applicable)

                                         ---------------------------------------
                                         (Print Name)

                                         ---------------------------------------
                                         (Address)

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

                                         ---------------------------------------
                                         (Area Code/Telephone Number)

                                      A-3<PAGE>

EXHIBIT 4.21

                          PACIFIC ENERGY RESOURCES LTD.
                      111 West Ocean Boulevard, Suite 1240
                          Long Beach, California 90802

                           UNIT SUBSCRIPTION AGREEMENT
                                (U.S. RESIDENTS)

TO:     Pacific Energy Resources Ltd. (the "CORPORATION")

The undersigned (the "SUBSCRIBER") hereby irrevocably subscribes for and agrees
to purchase from Pacific Energy Resources Ltd. (the "CORPORATION") units of the
Corporation (the "UNITS") in the number set forth below at a subscription price
equal to CAD$2.20 per Unit. Each Unit shall consist of one (1) share of common
stock of the Corporation (a "COMMON SHARE") and one-half (1/2) Common Share
purchase warrant of the Corporation ("WARRANT"). Each one (1) whole Warrant
shall entitle the holder to acquire one (1) Common Share (a "WARRANT SHARE") at
a price equal to CAD$2.65 per Warrant Share for a period of eighteen (18) months
from the date of issue of the Warrants. The Subscriber agrees to be bound by the
attached terms and conditions of subscription (the "TERMS AND CONDITIONS") and
agrees that the Corporation and its agents and attorneys may rely upon the
representations, warranties and covenants contained therein and in the
Subscriber Certificate (as hereinafter defined). This subscription, plus the
Terms and Conditions of the completed and executed Subscriber Certificate, are
collectively referred to as the "SUBSCRIPTION AGREEMENT" or the "AGREEMENT."

<TABLE>
<CAPTION>
<S>                                                                           <C>
                                               SUBSCRIPTION AND SUBSCRIBER INFORMATION
                  Please print all information (other than signatures), as applicable, in the space provided below

                                                                         Number of Units*:
--------------------------------------------------------------                            ------------------------------------------
(Name of Subscriber)
                                                                         Share Price:    X
Account Reference (if applicable):                                                            --------------------------------------
                                  ----------------------------
                                                                         Aggregate Subscription Price:
By:                                                                                                   ------------------------------
   -----------------------------------------------------------                            (the "SUBSCRIPTION PRICE")
   Authorized Signature

--------------------------------------------------------------           IF THE SUBSCRIBER IS SIGNING AS AGENT FOR A PRINCIPAL
(Official Capacity or Title - if the Subscriber is not an                (BENEFICIAL PURCHASER)AND IS NOTPURCHASING AS TRUSTEE OR
individual)                                                              AGENT FOR ACCOUNTS FULLY MANAGED BY IT, COMPLETE THE
                                                                         FOLLOWING AND ENSURE THAT THAT APPLICABLE EXHIBIT(S) ARE
                                                                         COMPLETED ON BEHALF OF SUCH PRINCIPAL:
--------------------------------------------------------------
(Name of individual whose signature appears above if different
than the name of the Subscriber printed above.)                          -----------------------------------------------------------
                                                                         (Name of Principal)
--------------------------------------------------------------
(Subscriber's Address, including State)                                  -----------------------------------------------------------
                                                                         (Principal's Address)
--------------------------------------------------------------
                                                                         -----------------------------------------------------------
--------------------------------------------------------------
(Telephone Number)                          (Email Address)

*Calculated based on a fixed exchange rate of US$1.00 = CAD$_______ (which is the noon buying rate as reported by the Federal
Reserve Bank of New York on the Closing Date)

<page>

ACCOUNT REGISTRATION INFORMATION:                                         DELIVERY INSTRUCTIONS AS SET FORTH BELOW:
--------------------------------                                          ----------------------------------------

--------------------------------------------------------------            ----------------------------------------------------------
(Name)                                                                    (Name)

--------------------------------------------------------------            ----------------------------------------------------------
(Account Reference, if applicable)                                        (Account Reference, if applicable)

                                                                          ----------------------------------------------------------
--------------------------------------------------------------            (Address)
(Address, including Zip Code)
                                                                          ----------------------------------------------------------
                                                                          (Contact Name)                         (Telephone Number)

Number and kind of securities of the Corporation held, if any:            State whether Subscriber is an insider* of the
                                                                          Corporation:
--------------------------------------------------------------
                                                                                         Yes / /              No / /
--------------------------------------------------------------
                                                                          * The term "insider" means a person who is a director or
                                                                          senior officer (chair, vice chair, president, vice
                                                                          president, secretary, treasurer or general manager) or
                                                                          holder of more than 10% of the voting rights attached to
                                                                          all outstanding voting securities of the Corporation.
</TABLE>

<page>

                          TYPE OF OWNERSHIP (CHECK ONE)

____   Individual Ownership                   ____   Joint Tenants with Right of
                                                       Survivorship
                                                       (both parties must sign)

____   Corporation*                           ____   Community Property
                                                       (Spouse's signature
                                                       required)

____   Partnership*                           ____   Tenants-in-common
                                                       (both parties must sign)

____   Trust or Pension Plan*

-------------------
*     Copy of Articles of Incorporation, Bylaws and Corporate Resolution,
      Partnership or Trust Agreement, as applicable, must be attached.

ACCEPTANCE: The Corporation hereby accepts the subscription as set forth above
on the terms and conditions contained in this Subscription Agreement.

PACIFIC ENERGY RESOURCES LTD.                                 ------------------
                                                               Subscription No.

By:                                                          ------------------
   ----------------------------
                                      October __, 2007

               THE REMAINDER OF THIS PAGE INTENTIONALLY LEFT BLANK

<page>

                 TERMS AND CONDITIONS OF SUBSCRIPTION FOR UNITS

1.    DEFINITIONS.

      1.1   In this Agreement, which includes the cover page and all of the
appendices, the following words have the following meanings unless otherwise
indicated:

            (a)   "1933 ACT" means Securities Act of 1933, as amended, and the
      rules and regulations promulgated thereunder.

            (b)   "CLOSING" means the completion of the issue and sale of the
      Units to the Subscriber hereunder.

            (c)   "COMMON SHARE" has the meaning ascribed to it on the cover
      page of this Agreement.

            (d)   "CORPORATION" means Pacific Energy Resources Ltd.

            (e)   "EXCHANGE" means the Toronto Stock Exchange.

            (f)   "OFFERING" means this private placement;

            (g)   "SEC" means the United States Securities and Exchange
      Commission.

            (h)   "SUBSCRIBER" has the meaning ascribed to it on the cover page
      of this Agreement.

            (i)   "SUBSCRIBER CERTIFICATE" means the accredited investor
      certificate attached hereto as Exhibit "A".

            (j)   "UNIT" has the meaning ascribed to it on the cover page of
      this Agreement.

            (k)   "WARRANT" has the meaning ascribed to it on the cover page of
      this Agreement.

            (l)   "WARRANT SHARE" has the meaning ascribed to it on the cover
      page of this Agreement.

      1.2   All capitalized terms in this Agreement not defined above have the
meanings ascribed to them in this Agreement.

2.    PURCHASE AND SALE OF UNITS.

      2.1   The Units will be registered in the name of the Subscriber.

      2.2   The issue of the Units will not restrict or prevent the Corporation
from obtaining any other financing, or from issuing additional securities from
time to time.

                                      -1-

<page>

      2.3   Closing will be completed at the offices of the Corporation, in Long
Beach, California, at 1:00 p.m. (Pacific Time), or such other place or time as
the Corporation may designate (the "CLOSING TIME") on October 18, 2007 (the
"CLOSING DATE").

      2.4   The Corporation shall have the right to reject this Subscription
Agreement if it believes for any reason that the Subscriber is not an
"accredited investor" within the meaning of Rule 501 of Regulation D promulgated
by the SEC as presently in effect, or for any other reason in its sole and
absolute discretion. Acceptance is evidenced only by execution of this
Subscription Agreement by the Corporation in the space provided above.

      2.5   Fractional Warrants will not be issued to the Subscriber. Instead,
the number of Warrants issued to any one Subscriber will be rounded down to the
nearest whole number of Warrants issuable to such Subscriber at the Closing.

3.    REPRESENTATIONS, WARRANTIES AND ACKNOWLEDGMENTS OF THE SUBSCRIBER.

      3.1   The Subscriber represents and warrants, as at the date of this
Agreement and at the Closing, that:

            (a)   the Subscriber is purchasing the Units for Subscriber's own
      account or for accounts fully-managed by Silver Point Capital, L.P., for
      long-term investment, and not with a view to, or for sale in connection
      with, the distribution thereof. The Subscriber has no present intention of
      selling, granting any participation in, or otherwise distributing the
      Units. The Units will not be resold without registration under the 1933
      Act and qualification under the securities laws of all applicable states,
      unless such sale would be exempt therefrom;

            (b)   the Subscriber is an "accredited investor" as that term is
      defined in Rule 501(a) of Regulation D promulgated under the 1933 Act;

            (c)   the Subscriber has received, completed and returned to the
      Corporation the Subscriber Certificate relating to his general ability to
      bear the risks of an investment in the Corporation and his suitability as
      an investor in a private offering, and hereby affirms the correctness of
      his answers in such Subscriber Certificate;

            (d)   the Subscriber (i) has adequate means of providing for his
      current needs and possible personal contingencies, without the need for
      liquidity of his investment in the Corporation; (ii) can bear the economic
      risk of losing his entire investment herein; and (iii) has such knowledge
      and experience in financial and business matters that he is capable of
      evaluating the relative risks and merits of this investment;

            (e)   it never has been represented, guaranteed or warranted to
      Subscriber by the Corporation, its agents, or employees or any other
      person, expressly or by implication, any of the following:

                  (i)   the approximate or exact length of time that Subscriber
            will be required to remain as owner of the Units;

                                      -2-

<page>

                  (ii)  THE PROFIT OR RETURN, IF ANY, TO BE REALIZED AS A RESULT
            OF THE CORPORATION'S VENTURE; or

                  (iii) that the past performance or experience on the part of
            the Corporation or any affiliate, its agents, or employees or of any
            other person, will in any way indicate the predictable results of
            the ownership of the Units or the overall Corporation's venture;

            (f)   the Subscriber, if an individual, is at least twenty-one (21)
      years of age;

            (g)   the Subscriber has no reason to anticipate any change in the
      Subscriber's personal circumstances, financial or otherwise, which may
      cause or require any sale or distribution by the Subscriber of all or any
      part of the Units subscribed for herein;

            (h)   the Subscriber has reviewed the documents regarding the
      Corporation available on SEDAR (WWW.SEDAR.COM) and the Exchange's web site
      (www.tsx.com) carefully (collectively, the "DISCLOSURE DOCUMENTS"), is
      fully familiar with and understands the contents thereof;

            (i)   the Subscriber confirms that all documents, records and books
      pertaining to the Corporation and to the investment requested by the
      Subscriber have been made available to the Subscriber and that the
      Subscriber has been given an opportunity to make further inquiries of the
      Corporation and its representatives in order to verify the accuracy of the
      information contained in the Disclosure Documents and has had the
      opportunity to review all facts concerning the Corporation which the
      Subscriber deems pertinent;

            (j)   the Subscriber, if a partnership, corporation, trust, or other
      entity, declares:

                  (i)   the person executing this Subscription Agreement has the
            necessary power and authority to do so; and

                  (ii)  the Subscriber was not organized for the specific
            purpose of acquiring the Units;

            (k)   the exhibits to this Agreement will be completed truthfully
      and with reasonable diligence;

            (l)   as to the source of subscription funds,

                  (i)   to the best of the Subscriber's knowledge, none of the
            subscription funds used for the purchase of the Subscriber's Units
            (A) have been or will be derived from or related to any activity
            that is deemed criminal under the laws of the United States or any
            other jurisdiction, or (B) are being tendered on behalf of a person
            or entity who has not been identified to the Subscriber; and

                  (ii)  the Subscriber will promptly notify the Corporation if
            the Subscriber discovers that any of the representations in above
            subparagraph (l)(i) above ceases to be true, and to provide the
            Corporation with appropriate information in connection therewith;

                                      -3-

<page>

            (m)   the Subscriber warrants that the information herein provided
      to the Corporation by the Subscriber is true and correct as of the date
      hereof, and the Subscriber agrees to advise the Corporation, prior to its
      acceptance of this subscription, of any material change in any such
      information; and

            (n)   the Subscriber agrees that the representations and warranties
      of the Subscriber set forth in this Section 3 shall survive the acceptance
      of this subscription, in the event the subscription is accepted.

      3.2   The Subscriber understands and acknowledges that:

            (a)   no federal or state agency has made any finding or
      determination as to the fairness of the offering of Units for investment
      or any recommendation or endorsement of the offering;

            (b)   the Units have not been registered under the 1933 Act or
      qualified under any state securities laws in reliance on exemptions from
      registration provided thereunder;

            (c)   there are restrictions imposed by law on the Subscriber's
      ability to resell the Units and it is the responsibility of the Subscriber
      to find out what those restrictions are and to comply with them before
      selling the securities comprising the Units;

            (d)   the Subscriber acknowledges and agrees with the Corporation
      that the Corporation shall refuse to register any transfer of the Units
      not made pursuant to registration under the 1933 Act, or pursuant to an
      available exemption from registration under the 1933 Act (including
      Regulation S);

            (e)   the Corporation may be required to provide applicable
      securities regulatory authorities with a list setting forth the identities
      of the beneficial purchasers of the Units and the Subscriber acknowledges
      and agrees that it will provide, on request, particulars as to the
      identity of such beneficial purchasers as may be required by the
      Corporation in order to comply with the foregoing;

            (f)   by providing personal information to the Corporation, the
      Subscriber and each person for whom it is contracting hereunder, is
      consenting to the Corporation's collection, use and disclosure of that
      information for the purposes of the subscription of Units and the offering
      in general, for corporate governance purposes and to contact the
      Subscriber as an investor. The Subscriber, and each person for whom it is
      contracting hereunder, acknowledges that, from time to time, the
      Corporation may be required to disclose such personal information and, by
      providing such personal information to the Corporation, the Subscriber and
      each person for whom it is contracting hereunder, hereby expressly
      consents to such disclosure, and the Subscriber and each person for whom
      it is contracting agrees and acknowledges that the Corporation may use and
      disclose personal information as follows:

                                      -4-

<page>

                  (i)   for internal use with respect to managing the
            relationships between and contractual obligations of the Corporation
            and the Subscriber and each person for whom it is contracting;

                  (ii)  for use and disclosure for income tax related purposes,
            including without limitation, where required by law, disclosure to
            the Internal Revenue Service;

                  (iii) disclosure to securities regulatory authorities and
            other regulatory bodies with jurisdiction with respect to reports of
            trades and similar regulatory filings;

                  (iv)  disclosure to a governmental or other authority to which
            the disclosure is required by court order or subpoena compelling
            such disclosure and where there is no reasonable alternative to such
            disclosure;

                  (v)   disclosure to professional advisers of the Corporation
            in connection with the performance of their professional services;

                  (vi)  disclosure to any person where such disclosure is
            necessary for legitimate business reasons and is made with the prior
            written consent of the Subscriber and each person for whom it is
            contracting;

                  (vii) disclosure to a court determining the rights of the
            parties under this Agreement; or

                  (viii) for use and disclosure as otherwise required by law.

            (g)   during the ten trading day period prior to the date hereof,
      the Subscriber has not purchased (except pursuant to this Subscription
      Agreement), sold or "sold short" any securities of the Corporation.

4.    ISSUANCE OF UNITS.

      4.1   The Subscriber agrees to deliver to the Corporation, as soon as
possible and, in any event, not later than 9:00 a.m. (Pacific Standard time) on
October 18, 2007; (a) this duly completed and executed Subscription Agreement;
(b) a duly executed Accredited Investor Certificate attached hereto as Exhibit
"A"; and (c) a duly executed Flow of Funds and Direction letter attached hereto
as Exhibit "B" regarding payment of the Subscription Price as indicated on the
facing page hereof.

      4.2   Promptly following the Closing, the Corporation will forward to the
Subscriber certificates representing the Common Shares and Warrants registered
in the name of the Subscriber or its nominee as per the directions of the
Subscriber on the facing page of this Agreement.

                                      -5-

<page>

5.    CONDITION TO CLOSING.

      The obligation of the Subscriber to purchase and pay for the Units and the
Closing are subject to the execution and delivery to the Corporation prior to or
at the Closing of the Flow of Funds and Direction letter by all parties thereto.

6.    REGISTRATION STATEMENT.

      The Common Shares and the Warrant Shares will be "Registrable Shares" as
that term is defined in the Registration Rights Agreement dated as of November
30, 2006 by and between the Corporation, Goldman, Sachs & Co., SPCP Group,
L.L.C. and SPCP Group III LLC.

7.    LEGEND.

      The certificates representing the Common Shares, the Warrants and the
Warrant Shares will bear a legend denoting the restrictions on transfer. The
Subscriber agrees to sell, assign or transfer those securities only in
accordance with such restrictions.

      The legend will be in substantially the following form:

                  (i)   "THE SECURITIES REPRESENTED BY THIS CERTIFICATE ARE
            LISTED ON THE TORONTO STOCK EXCHANGE ("TSX"); HOWEVER, THE SAID
            SECURITIES CANNOT BE TRADED THROUGH THE FACILITIES OF TSX SINCE THEY
            ARE NOT FREELY TRANSFERABLE, AND CONSEQUENTLY ANY CERTIFICATE
            REPRESENTING SUCH SECURITIES IS NOT "GOOD DELIVERY" IN SETTLEMENT OF
            TRANSACTIONS ON TSX."

                  (ii)  "[THIS WARRANT AND THE SECURITIES ISSUABLE UPON EXERCISE
            OF THIS WARRANT][THE SECURITIES REPRESENTED HEREBY] HAVE NOT BEEN
            REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED ("U.S.
            SECURITIES ACT"), OR ANY STATE SECURITIES LAWS. [THIS WARRANT AND
            THE SECURITIES ISSUABLE UPON EXERCISE OF THIS WARRANT][THE
            SECURITIES REPRESENTED HEREBY] MAY NOT BE OFFERED, SOLD,
            TRANSFERRED, PLEDGED, HYPOTHECATED OR OTHERWISE ASSIGNED EXCEPT
            PURSUANT TO AN EFFECTIVE REGISTRATION STATEMENT UNDER THE U.S.
            SECURITIES ACT OR PURSUANT TO AN EXEMPTION THEREFROM."

8.    RELIANCE UPON REPRESENTATIONS, WARRANTIES AND COVENANTS.

      The Subscriber acknowledges that the representations and warranties and
covenants and acknowledgments contained in this Agreement are made with the
intent that they may be relied upon by the Corporation in determining the
Subscriber's eligibility to purchase the Units and the Subscriber hereby agrees
to indemnify the Corporation against all losses, claims, costs, expenses and
damages or liabilities which it may suffer or incur caused or arising from its
reliance thereon. The Subscriber further agrees that the foregoing
representations and warranties shall survive the purchase by the Subscriber of
the Units and shall continue in full force and effect notwithstanding any
subsequent disposition by the Subscriber of any of the Units.

                                      -6-

<page>

9.    MISCELLANEOUS.

      9.1   The Corporation and the Subscriber shall be entitled to rely on
delivery by facsimile machine of an executed copy of this subscription, and
acceptance by the Corporation or the Subscriber of such facsimile copy shall be
equally effective to create a valid and binding agreement between the Subscriber
and the Corporation in accordance with the terms hereof.

      9.2   Without limitation, this subscription and the transactions
contemplated hereby are conditional upon and subject to the Corporation
receiving Exchange approval of this subscription and the transactions
contemplated hereby.

      9.3   This Agreement is not assignable or transferable by the parties
            hereto without the express written consent of the other party
            hereto.

      9.4   Time is of the essence of this Agreement.

      9.5   Except as expressly provided in this Agreement and in the
agreements, instruments and other documents contemplated or provided for herein,
this Agreement contains the entire agreement between the parties with respect to
the Units and there are no other terms, conditions, representations or
warranties whether expressed, implied, oral or written, by statute, by common
law, by the Corporation or by anyone else.

      9.6   The parties to this Agreement may amend this Agreement only in
writing.

      9.7   This Agreement inures to the benefit of and is binding upon the
parties to this Agreement and their successors and permitted assigns.

      9.8   A party to this Agreement will give all notices to or other written
communications with the other party to this Agreement concerning this Agreement
by hand or by registered mail or overnight courier addressed to the address
given above.

      9.9   This Agreement will be governed by and construed in accordance with
the laws of the State of California, without regard to conflicts of law
principles.

                                      -7-

<page>

                                   EXHIBIT "A"

                      U.S. ACCREDITED INVESTOR CERTIFICATE

      The undersigned ("SUBSCRIBER"), in connection with the acquisition of
units ("UNITS") of Pacific Energy Resources Ltd. ("PERL" or the "CORPORATION")
pursuant to that certain subscription agreement (the "AGREEMENT"), hereby makes
the following representations and warranties:

      The Subscriber understands that the Corporation is relying on this
information in determining to offer the Units to the undersigned in a manner
exempt from the registration requirements of the Securities Act of 1933, as
amended (the "1933 ACT"), and applicable state securities laws.

1.    ACCREDITED INVESTOR.

      The Subscriber represents and warrants that he, she or it falls within the
category (or categories) marked. PLEASE INDICATE EACH CATEGORY OF ACCREDITED
INVESTOR THAT YOU, THE SUBSCRIBER, SATISFY, BY PLACING YOUR INITIALS ON THE
APPROPRIATE LINE BELOW.

_____    Category 1.    A bank, as defined in Section 3(a)(2) of the 1933 Act,
                        whether acting in its individual or fiduciary capacity;
                        or

_____    Category 2.    A savings and loan association or other institution as
                        defined in Section 3(a) (5) (A) of the 1933 Act, whether
                        acting in its individual or fiduciary capacity; or

_____    Category 3.    A broker or dealer registered pursuant to Section 15 of
                        the Securities Exchange Act of 1934; or

_____    Category 4.    An insurance company as defined in Section 2(13) of the
                        1933 Act; or

_____    Category 5.    An investment company registered under the Investment
                        Company Act of 1940; or

_____    Category 6.    A business development company as defined in Section
                        2(a) (48) of the Investment Company Act of 1940; or

_____    Category 7.    A small business investment company licensed by the U.S.
                        Small Business Administration under Section 301(c) or
                        (d) of the Small Business Investment Act of 1958; or

_____    Category 8.    A plan established and maintained by a state, its
                        political subdivision or any agency or instrumentality
                        of a state or its political subdivisions, for the
                        benefit of its employees, with assets in excess of
                        US$5,000,000; or

                                      A-1

<page>

_____    Category 9.    An employee benefit plan within the meaning of the
                        Employee Retirement Income Security Act of 1974 in which
                        the investment decision is made by a plan fiduciary, as
                        defined in Section 3(21) of such Act, which is either a
                        bank, savings and loan association, insurance company or
                        registered investment advisor, or an employee benefit
                        plan with total assets in excess of US$5,000,000 or, if
                        a self-directed plan, the investment decisions are made
                        solely by persons who are accredited investors; or

_____    Category 10.   A private business development company as defined in
                        Section 202(a) (22) or the Investment Advisors Act of
                        1940; or

_____    Category 11.   An organization described in Section 501(c)(3) of the
                        Internal Revenue Code, a corporation, a Massachusetts or
                        similar business trust, or a partnership, not formed for
                        the specific purpose of acquiring the Units, with total
                        assets in excess of US$5,000,000; or

_____    Category 12.   A director, executive officer or general partner of the
                        Corporation; or

_____    Category 13.   A natural person whose individual net worth, or joint
                        net worth with that person's spouse, at the time of this
                        purchase exceeds US$1,000,000; or

_____    Category 14.   A natural person who had an individual income in excess
                        of US$200,000 in each of the two most recent years or
                        joint income with that person's spouse in excess of
                        US$300,000 in each of those years and has a reasonable
                        expectation of reaching the same income level in the
                        current year; or

_____    Category 15.   A trust, with total assets in excess of US$5,000,000,
                        not formed for the specific purpose of acquiring the
                        Units, whose purchase is directed by a sophisticated
                        person as described in SEC Rule 506(b)(2)(ii); or

_____    Category 16.   An entity in which all of the equity owners are
                        accredited investors.

                                      A-2

<page>

      IN WITNESS WHEREOF, Subscriber has executed this Certificate as of October
18, 2007.

SUBSCRIBER:
                                         ---------------------------------------
                                         (Signature and office, if applicable)

                                         ---------------------------------------
                                         (Print Name)

                                         ---------------------------------------
                                         (Address)

                                         ---------------------------------------
                                         (City/State/Zip Code)

                                         ---------------------------------------
                                         (Area Code/Telephone Number)

                                      A-3

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