FIRST AMENDMENT TO FOURTH AMENDED AND RESTATED CREDIT AGREEMENT

Exhibit 4.1

FIRST AMENDMENT TO

FOURTH AMENDED AND RESTATED CREDIT AGREEMENT

dated as of

June 15, 2009

among

WHITING PETROLEUM CORPORATION,
as Parent Guarantor,

WHITING OIL AND GAS CORPORATION,
as Borrower,

JPMORGAN CHASE BANK, N.A.,
as Administrative Agent,

and

The Lenders Party Hereto

BANK OF AMERICA, N.A. and
WELLS FARGO BANK, N.A.,
as Syndication Agents

CALYON NEW YORK BRANCH and
COMPASS BANK,
as Documentation Agents

J.P. MORGAN SECURITIES INC.,
as Sole Lead Arranger and Sole Bookrunner

FIRST AMENDMENT TO FOURTH AMENDED AND RESTATED CREDIT AGREEMENT

      THIS FIRST AMENDMENT TO FOURTH AMENDED AND RESTATED CREDIT AGREEMENT (this “ First Amendment ”) dated as of June 15, 2009, is among WHITING PETROLEUM CORPORATION , a Delaware corporation, as the Parent Guarantor, WHITING OIL AND GAS CORPORATION, a Delaware corporation, as the Borrower, JPMORGAN CHASE BANK , N.A. , as Administrative Agent, and the other Agents the Lenders party hereto.

R E C I T A L S

     A. The Parent Guarantor, the Borrower, the Administrative Agent, other parties as agents and the Lenders are parties to that certain Fourth Amended and Restated Credit Agreement dated as of April 28, 2009 (the “ Credit Agreement ”), pursuant to which the Lenders have made certain loans to and extensions of credit for the account of the Borrower.

     B. The Borrower has requested and the Majority Lenders have agreed to amend certain provisions of the Credit Agreement.

     C. NOW, THEREFORE, in consideration of the premises and the mutual covenants herein contained, for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

Section 1. Defined Terms . Each capitalized term used herein but not otherwise defined herein has the meaning given such term in the Credit Agreement. Unless otherwise indicated, all article and section references in this First Amendment refer to articles and sections of the Credit Agreement.

Section 2. Amendments to Credit Agreement.

     2.1 Amendments to Section 1.02.

          (a) The definition of “ Agreement ” is hereby deleted and replaced in its entirety to read as follows:

     “ Agreement ” means this Credit Agreement, as amended by the First Amendment and as the same may from time to time be amended, modified, supplemented or restated.

          (b) The following definitions are hereby added where alphabetically appropriate to read as follows:

     “ First Amendment ” means the First Amendment to Fourth Amended and Restated Credit Agreement dated as of June 15, 2009 among the Parent Guarantor, the Borrower, the Administrative Agent and the other Agents and the Lenders party thereto.

     “ Designated Preferred Convertible Stock ” means any series of the Parent Guarantor’s cumulative perpetual convertible preferred Equity Interests which (a) have liquidation preference to common Equity Interests of the Parent Guarantor, (b) are convertible at the option of the holder or the Parent Guarantor into shares of common Equity Interests of the Parent Guarantor, (c) are not Disqualified Capital Stock, (d) have a stated dividend rate not to exceed 7% per annum and (e) have terms reasonably acceptable to the Administrative Agent; provided that the aggregate liquidation preference of all Designated Preferred Convertible Stock outstanding shall not exceed $345,000,000.00 at any time.

     2.2 Restricted Payments . Section 9.04(a) is hereby deleted and replaced in its entirety to read as follows:

     (a) Restricted Payments. The Parent Guarantor will not, and will not permit any Credit Party to, declare or make, or agree to pay or make, directly or indirectly, any Restricted Payment, return any capital to its stockholders on account of such Equity Interests or make any distribution of its Property to its Equity Interest holders on account of such Equity Interests, except

     (i) the Parent Guarantor may declare and pay dividends with respect to its Equity Interests payable solely in additional shares of its Equity Interests (other than Disqualified Capital Stock),

     (ii) Subsidiaries may declare and pay dividends ratably with respect to their Equity Interests,

     (iii) the Parent Guarantor may make Restricted Payments pursuant to and in accordance with equity incentive plans, stock option plans or arrangements or other benefit plans or arrangements for management, employees or directors of the Parent Guarantor and the Credit Parties in an amount not to exceed $5,000,000 during any fiscal year and $10,000,000 during the term of this Agreement,

     (iv) if no Default, Event of Default or Borrowing Base Deficiency exists at the time of payment, then the Parent Guarantor may pay cash dividends on its Designated Preferred Convertible Stock during the term hereof in an aggregate amount not to exceed, as of the date of payment, the product of (A) the lesser of (1) $6,250,000 and (2) the aggregate liquidation preference of each outstanding series of Designated Preferred Convertible Stock issued prior to July 31, 2009 times one fourth of the corresponding