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Execution Version

Exhibit 10.31

FIRST AMENDMENT TO TAX SHARING AGREEMENT

between

FOREST OIL CORPORATION

AND ITS AFFILIATES

and

LONE PINE RESOURCES INC.

AND ITS AFFILIATES

Dated as of March 21, 2012

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FIRST AMENDMENT TO TAX SHARING AGREEMENT

        This First Amendment (this "Amendment") to the Tax Sharing Agreement is
made and entered into as of March 21, 2012, by and between Forest Oil
Corporation ("Forest"), a New York corporation, and Lone Pine Resources Inc.
("Lone Pine"), a Delaware corporation. Capitalized terms used herein and not
otherwise defined are used as defined in the Tax Sharing Agreement, dated as of
May 25, 2011, between Forest and Lone Pine (as amended, the "Tax Sharing
Agreement").

        WHEREAS, the parties intend that for United States federal income tax
purposes the Recapitalization will qualify as tax-free reorganizations pursuant
to Sections 368(a)(1)(E) and (F) of the Code;

        WHEREAS, the parties intend that for United States federal income tax
purposes the Contribution and the Distribution, taken together, will qualify as
a tax-free reorganization under Sections 355 and 368(a)(1)(D) of the Code;

        WHEREAS, the parties entered into the Tax Sharing Agreement to
(a) provide for the payment of Tax Liabilities and entitlement to refunds
thereof, allocate responsibility for, and cooperation in, the filing of Tax
Returns and provide for certain other matters relating to Taxes, and (b) set
forth certain covenants and indemnities relating to the preservation of the
tax-free status of the Contribution and the Distribution under Sections 355 and
368(a)(1)(D) of the Code;

        WHEREAS, the parties have agreed to amend Section 6.2(b) of the Tax
Sharing Agreement, which sets forth certain covenants relating to the
preservation of the tax-free status of the Contribution and the Distribution
under Sections 355 and 368(a)(1)(D) of the Code, in a manner intended to
preserve the tax-free status of the Contribution and the Distribution under
Sections 355 and 368(a)(1)(D) of the Code.

        NOW, THEREFORE, in consideration of the mutual promises and undertakings
contained herein, the parties agree as follows:

ARTICLE I

AMENDMENT

        Section 6.2(b) of the Tax Sharing Agreement shall be amended and
restated in its entirety to read as follows:

        "(b) issue any capital stock or other equity interests, options, or
rights to acquire capital stock or other equity interests, or any other
instruments convertible into or exchangeable for, or that could otherwise result
in the issuance of, capital stock or other equity interests (collectively,
"Capital Stock"); provided, however, that, after the Distribution, Lone Pine may
issue up to an aggregate of 10% of the amount of its Capital Stock outstanding
immediately after the IPO pursuant to the Lone Pine Resources Inc. 2011 Stock
Incentive Plan and pursuant to the Lone Pine Resources Inc. 2012 Employee Stock
Purchase Plan."

ARTICLE II

MISCELLANEOUS

        2.1    Full Force and Effect.    Except to the extent modified hereby,
the Tax Sharing Agreement shall remain in full force and effect.

        2.2    Governing Law.    This Amendment will be governed by and
construed in accordance with the laws of the State of New York, without
reference to its conflicts of laws principles.

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        2.3    Confidentiality.    Each party will hold and cause its directors,
officers, employees, advisors and consultants to hold in strict confidence,
unless compelled to disclose by judicial or administrative process or, in the
opinion of its counsel, by other requirements of law, all information (other
than any such information relating solely to the business or affairs of such
party) concerning the other parties hereto furnished to it by such other party
or its representatives pursuant to this Amendment (except to the extent that
such information can be shown to have been (i) in the public domain through no
fault of such party, (ii) later lawfully acquired from other sources not known
to be under a duty of confidentiality by the party to which it was furnished, or
(iii) independently developed), and each party will not release or disclose such
information to any other Person, except its directors, officers, employees,
auditors, attorneys, financial advisors, bankers and other consultants who will
be advised of and agree to be bound by the provisions of this Section 2.3. Each
party will be deemed to have satisfied its obligation to hold confidential
information concerning or supplied by the other party if it exercises the same
care as it takes to preserve confidentiality for its own similar information.

        2.4    Effective Date.    This Amendment is effective as of the date
hereof.

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        IN WITNESS WHEREOF, each of the parties has caused this Amendment to the
Tax Sharing Agreement to be executed on its behalf by its officers thereunto
duly authorized, all as of the day and year first written above.

    FOREST OIL CORPORATION
 
 
By:
 
/s/ CYRUS D. MARTER IV

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        Name:   Cyrus D. Marter IV         Title:   Senior Vice President,
General Counsel and Secretary
 
 
LONE PINE RESOURCES INC.
 
 
By:
 
/s/ EDWARD J. BEREZNICKI

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        Name:   Edward J. Bereznicki         Title:   Executive Vice President
and Chief Financial Officer

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QuickLinks

Execution Version

Exhibit 10.31

FIRST AMENDMENT TO TAX SHARING AGREEMENT between FOREST OIL CORPORATION AND ITS
AFFILIATES and LONE PINE RESOURCES INC. AND ITS AFFILIATES Dated as of March 21,
2012
FIRST AMENDMENT TO TAX SHARING AGREEMENT
ARTICLE I AMENDMENT
ARTICLE II MISCELLANEOUS