Document:

EX-4.1

 Exhibit 4.1 

This Note is a Global Security within the meaning of the Indenture hereinafter referred to and is registered in the name of the Depository
named below or a nominee of the Depository. This Note is not exchangeable for Notes registered in the name of a Person other than the Depository or its nominee except in the limited circumstances described herein and in the Indenture, and no
transfer of this Note (other than a transfer of this Note as a whole by the Depository to a nominee of the Depository or by a nominee of the Depository to the Depository or another nominee of the Depository) may be registered except in the limited
circumstances described herein. 
 Unless this certificate is presented by an authorized representative of The Depository Trust Company, a
New York corporation (the “Depository”), to the Company or its agent for registration of transfer, exchange, or payment, and any certificate issued is registered in the name of Cede & Co. or in such other name as is requested by
an authorized representative of the Depository (and any payment is made to Cede & Co. or to such other entity as is requested by an authorized representative of the Depository), ANY TRANSFER, PLEDGE, OR OTHER USE HEREOF FOR VALUE OR
OTHERWISE BY OR TO ANY PERSON IS WRONGFUL inasmuch as the registered owner hereof, Cede & Co., has an interest herein. 

CITIGROUP INC. 
 2.500%
Notes due September 26, 2018 
  

			
	REGISTERED	 	REGISTERED
		
		 	 CUSIP: 172967 HC 8

ISIN: US172967HC80
 Common Code:
097509476

		
	No. R-0001	 	$500,000,000

 CITIGROUP INC., a Delaware corporation (the “Company”, which term includes any successor Person
under the Indenture), for value received, hereby promises to pay to Cede & Co., or registered assigns, the principal sum of $500,000,000 on September 26, 2018 and to pay interest thereon from and including September 26, 2013 or
from the most recent Interest Payment Date to which interest has been paid or duly provided for, semi-annually, on March 26 and September 26 of each year, commencing March 26, 2014 at the rate of 2.500% per annum, until the
principal hereof is paid or made available for payment. The interest so payable, and punctually paid or duly provided for, on any Interest Payment Date will, as provided in the Indenture, be paid to the Person in whose name this Note is registered
at the close of business on the Record Date for such interest, which shall be the Business Day immediately preceding such Interest Payment Date. 

 Any such interest not so punctually paid or duly provided for will forthwith cease to be payable
to the holder on such Record Date and may either be paid to the Person in whose name this Note is registered at the close of business on a subsequent Record Date, such subsequent Record Date to be not less than five days prior to the date of payment
of such defaulted interest, notice whereof shall be given to holders of Notes of this series not less than 15 days prior to such subsequent Record Date, or be paid at any time in any other lawful manner not inconsistent with the requirements of any
securities exchange on which the Notes of this series may be listed, and upon such notice as may be required by such exchange, all as more fully provided in the Indenture. 

Interest hereon will be calculated on the basis of a 360-day year comprised of twelve 30-day months. 

If either an Interest Payment Date or the Maturity of the Notes falls on a day that is not a Business Day, such Interest Payment Date or
Maturity will be the next succeeding Business Day. If a date for payment of interest or principal on the Notes falls on a day that is not a business day in the place of payment, such payment will be made on the next succeeding business day in such
place of payment as if made on the date the payment was due. No interest will accrue on any amounts payable for the period from and after the due date for payment of such principal or interest. 

For these purposes, “Business Day” means any day which is a day on which commercial banks settle payments and are open for general
business in The City of New York. 
 Payment of the principal of and interest on this Note will be made at the office or agency of the
Trustee maintained for that purpose in The City of New York. 
 Reference is hereby made to the further provisions of this Note set forth on
the reverse hereof, which further provisions shall for all purposes have the same effect as if set forth at this place. 
 Unless the
certificate of authentication hereon has been executed by the Trustee or by an authenticating agent on behalf of the Trustee by manual signature, this Note shall not be entitled to any benefit under the Indenture or be valid or obligatory for any
purpose. 

  
 2 

 IN WITNESS WHEREOF, the Company has caused this instrument to be duly executed under its
corporate seal. 
 Dated: September 26, 2013 
  

			
	CITIGROUP INC.
		
	By:	 	  

	Title:	 	Deputy Treasurer

  

			
	ATTEST:
		
	By:	 	  

	Title:	 	Assistant Secretary

  
 3 

 This is one of the Notes of the series issued under the within-mentioned Indenture. 

Dated: September 26, 2013 
  

			
	THE BANK OF NEW YORK MELLON,
	as Trustee
		
	By:	 	  

	Name:	 	
	Title:	 	
	
	-or-
	
	 CITIBANK, N.A.,
 as Authenticating
Agent

		
	By:	 	  

	Name:	 	
	Title:	 	

  
 4 

 This Note is one of a duly authorized issue of Securities of the Company (the “Notes”),
issued and to be issued in one or more series under the Indenture, dated as of March 15, 1987 (as amended and supplemented to date, the “Indenture”), between the Company and The Bank of New York Mellon, formerly known as The Bank of
New York, as Trustee (the “Trustee”, which term includes any successor trustee under the Indenture), to which Indenture and all indentures supplemental thereto reference is hereby made for a statement of the respective rights, limitations
of rights, duties and immunities thereunder of the Company, the Trustee and the holders of the Notes and of the terms upon which the Notes are, and are to be, authenticated and delivered. This Note is one of the series designated on the face hereof,
initially limited in aggregate principal to $1,750,000,000. 
 If an event of default (as defined in the Indenture) with respect to Notes of
this series shall occur and be continuing, the principal of the Notes of this series may be declared due and payable in the manner and with the effect provided in the Indenture. 

The Indenture contains provisions for defeasance at any time of the entire indebtedness of this Note upon compliance by the Company with
certain conditions set forth in Sections 11.03 and 11.04 thereof, which provisions apply to this Note. 
 The Indenture contains provisions
permitting the Company and the Trustee, without the consent of the holders of the Securities, to establish, among other things, the form and terms of any series of Securities issuable thereunder by one or more supplemental indentures, and, with the
consent of the holders of not less than 66 2/3% in aggregate principal amount of Securities at the time outstanding which are affected thereby, to modify the Indenture or any supplemental indenture or the rights of the holders of Securities of such
series to be affected, provided that no such modification will (i) extend the fixed maturity of any Securities, reduce the rate or extend the time of payment of interest thereon, reduce the principal amount thereof or the premium, if any,
thereon, reduce the amount of the principal of Original Issue Discount Securities payable on any date, change the currency in which Securities are payable, or impair the right to institute suit for the enforcement of any such payment on or after the
maturity thereof, without the consent of the holder of each Security so affected, or (ii) reduce the aforesaid percentage of Securities of any series the consent of the holders of which is required for any such modification without the consent
of the holders of all Securities of such series then outstanding, or (iii) modify, without the written consent of the Trustee, the rights, duties or immunities of the Trustee. 

No reference herein to the Indenture and no provision of this Note or of the Indenture shall alter or impair the obligation of the Company,
which is absolute and unconditional, to pay the principal of and interest on this Note at the times, place and rate, and in the coin or currency, herein prescribed. 

This Note is a Global Security registered in the name of a nominee of the Depository. This Note is exchangeable for Notes registered in the
name of a person other than the Depository or its nominee only in the limited circumstances hereinafter described. Unless and until it is exchanged in whole or in part for definitive Notes in certificated form, this Note may not be transferred
except as a whole by the Depository to a nominee of the Depository or by a nominee of the Depository to the Depository or another nominee of the Depository. 

  
 R-1 

 The Notes represented by this Global Security are exchangeable for definitive Notes in
certificated form of like tenor as such Notes in denominations of $1,000 and whole multiples of $1,000 in excess thereof only if (i) the Depository notifies the Company that it is unwilling or unable to continue as Depository for the Notes or
(ii) the Depository ceases to be a clearing agency registered under the Securities Exchange Act of 1934, as amended, or (iii) the Company in its sole discretion decides to allow the Notes to be exchanged for definitive Notes in registered
form. Any Notes that are exchangeable pursuant to the preceding sentence are exchangeable for certificated Notes issuable in authorized denominations and registered in such names as the Depository shall direct. As provided in the Indenture and
subject to certain limitations therein set forth, the transfer of definitive Notes in certificated form is registrable in the register maintained by the Company in The City of New York for such purpose, upon surrender of the definitive Note for
registration of transfer at the office or agency of the registrar, duly endorsed by, or accompanied by a written instrument of transfer in form satisfactory to the Company and the registrar duly executed by, the holder thereof or his attorney duly
authorized in writing, and thereupon one or more new Notes of this series and of like tenor, of authorized denominations and for the same aggregate principal amount, will be issued to the designated transferee or transferees. Subject to the
foregoing, this Note is not exchangeable, except for a Global Security or Global Securities of this issue of the same principal amount to be registered in the name of the Depository or its nominee. 

No service charge shall be made for any such registration of transfer or exchange, but the Company may require payment of a sum sufficient to
cover any tax or other governmental charge payable in connection therewith. 
 Prior to due presentment of this Note for registration of
transfer, the Company, the Trustee and any agent of the Company or the Trustee may treat the Person in whose name this Note is registered as the owner hereof for all purposes, whether or not this Note be overdue, and neither the Company, the Trustee
nor any such agent shall be affected by notice to the contrary. 
 The Company will pay additional amounts (“Additional Amounts”)
to the beneficial owner of any Note that is a non-United States person in order to ensure that every net payment on such Note will not be less, due to payment of U.S. withholding tax, than the amount then due
and payable. For this purpose, a “net payment” on a Note means a payment by the Company or a paying agent, including payment of principal and interest, after deduction for any present or future tax, assessment or other governmental charge
of the United States. These Additional Amounts will constitute additional interest on the Note. 
 The Company will not be required to pay
Additional Amounts, however, in any of the circumstances described in items (1) through (14) below. 

  
 R-2 

	 	(1)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is imposed or withheld solely by reason of the beneficial owner:

  

	 	(a)	having a relationship with the United States as a citizen, resident or otherwise; 

  

	 	(b)	having had such a relationship in the past or 

  

	 	(c)	being considered as having had such a relationship. 

  

	 	(2)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is imposed or withheld solely by reason of the beneficial owner:

  

	 	(a)	being treated as present in or engaged in a trade or business in the United States; 

  

	 	(b)	being treated as having been present in or engaged in a trade or business in the United States in the past or 

  

	 	(c)	having or having had a permanent establishment in the United States. 

  

	 	(3)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is imposed or withheld in whole or in part by reason of the beneficial owner
being or having been any of the following (as such terms are defined in the Internal Revenue Code of 1986, as amended): 

  

	 	(a)	personal holding company; 

  

	 	(b)	foreign personal holding company; 

  

	 	(c)	foreign private foundation or other foreign tax-exempt organization; 

  

	 	(d)	passive foreign investment company; 

  

	 	(e)	controlled foreign corporation or 

  

	 	(f)	corporation which has accumulated earnings to avoid United States federal income tax. 

  

	 	(4)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is imposed or withheld solely by reason of the beneficial owner owning or
having owned, actually or constructively, 10 percent or more of the total combined voting power of all classes of stock of the Company entitled to vote or by reason of the beneficial owner being a bank that has invested in a Note as an extension of
credit in the ordinary course of its trade or business. 

 For purposes of items (1) through (4) above, “beneficial owner”
means a fiduciary, settlor, beneficiary, member or shareholder of the holder if the holder is an estate, trust, partnership, limited liability company, corporation or other entity, or a person holding a power over an estate or trust administered by
a fiduciary holder. 

  
 R-3 

	 	(5)	Additional Amounts will not be payable to any beneficial owner of a Note that is a: 

  

	 	(a)	fiduciary; 

  

	 	(b)	partnership; 

  

	 	(c)	limited liability company or 

  

	 	(d)	other fiscally transparent entity 

 or that is not the sole beneficial owner of the Note, or any
portion of the Note. However, this exception to the obligation to pay Additional Amounts will only apply to the extent that a beneficiary or settlor in relation to the fiduciary, or a beneficial owner or member of the partnership, limited liability
company or other fiscally transparent entity, would not have been entitled to the payment of an Additional Amount had the beneficiary, settlor, beneficial owner or member received directly its beneficial or distributive share of the payment. 

 

	 	(6)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is imposed or withheld solely by reason of the failure of the beneficial
owner or any other person to comply with applicable certification, identification, documentation or other information reporting requirements. This exception to the obligation to pay Additional Amounts will only apply if compliance with such
reporting requirements is required by statute or regulation of the United States or by an applicable income tax treaty to which the United States is a party as a precondition to exemption from such tax, assessment or other governmental charge.

  

	 	(7)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is collected or imposed by any method other than by withholding from a
payment on a Note by the Company or a paying agent. 

  

	 	(8)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is imposed or withheld by reason of a change in law, regulation, or
administrative or judicial interpretation that becomes effective more than 15 days after the payment becomes due or is duly provided for, whichever occurs later. 

  

	 	(9)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is imposed or withheld by reason of the presentation by the beneficial owner
of a Note for payment more than 30 days after the date on which such payment becomes due or is duly provided for, whichever occurs later. 

  

	 	(10)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any: 

  
 R-4 

	 	(a)	estate tax; 

  

	 	(b)	inheritance tax; 

  

	 	(c)	gift tax; 

  

	 	(d)	sales tax; 

  

	 	(e)	excise tax; 

  

	 	(f)	transfer tax; 

  

	 	(g)	wealth tax; 

  

	 	(h)	personal property tax or 

  

	 	(i)	any similar tax, assessment, withholding, deduction or other governmental charge. 

  

	 	(11)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment, or other governmental charge required to be withheld by any paying agent from a payment of principal or
interest on a Note if such payment can be made without such withholding by any other paying agent. 

  

	 	(12)	Additional amounts will not be payable if a payment on a Note is reduced as a result of any tax, assessment or other governmental charge that is required to be made pursuant to any European Union directive on the
taxation of savings income or any law implementing or complying with, or introduced to conform to, any such directive. 

  

	 	(13)	Additional amounts will not be payable if a payment on a Note is reduced as a result of any withholding, deduction, tax, duty assessment or other governmental charge that would not have been imposed but for a failure by
the holder or beneficial owner of a Note (or any financial institution through which the holder or beneficial owner holds the Note or through which payment on the Note is made) to take any action (including entering into an agreement with the
Internal Revenue Service, or a governmental authority of another jurisdiction if the holder is entitled to the benefits of an intergovernmental agreement between that jurisdiction and the United States) or to comply with any applicable
certification, documentation, information or other reporting requirement or agreement concerning accounts maintained by the holder or beneficial owner (or any such financial institution), or concerning ownership of the holder or beneficial owner, or
any substantially similar requirement or agreement. 

  

	 	(14)	Additional Amounts will not be payable if a payment on a Note is reduced as a result of any combination of items (1) through (13) above. 

Except as specifically provided herein, the Company will not be required to make any payment of any tax, assessment or other governmental
charge imposed by any government or a political subdivision or taxing authority of such government. 

  
 R-5 

 As used in this Note, “United States person” means: 

 

	 	(a)	any individual who is a citizen or resident of the United States; 

  

	 	(b)	any corporation, partnership or other entity created or organized in or under the laws of the United States; 

  

	 	(c)	any estate if the income of such estate falls within the federal income tax jurisdiction of the United States regardless of the source of such income and 

 

	 	(d)	any trust if a United States court is able to exercise primary supervision over its administration and one or more United States persons have the authority to control all of the substantial decisions of the trust.

 Additionally, “non-United States person” means a person who is not a
United States person, and “United States” means the states of the United States of America and the District of Columbia, but excluding its territories and its possessions. 

Except as provided below, the Notes may not be redeemed prior to maturity. 

 

	 	(1)	The Company may, at its option, redeem the Notes if: 

  

	 	(a)	the Company becomes or will become obligated to pay Additional Amounts as described above; 

  

	 	(b)	the obligation to pay Additional Amounts arises as a result of any change in the laws, regulations or rulings of the United States, or an official position regarding the application or interpretation of such laws,
regulations or rulings, which change is announced or becomes effective on or after September 19, 2013 and 

  

	 	(c)	the Company determines, in its business judgment, that the obligation to pay such Additional Amounts cannot be avoided by the use of reasonable measures available to it, other than substituting the obligor under the
Notes or taking any action that would entail a material cost to the Company. 

  

	 	(2)	The Company may also redeem the Notes, at its option, if: 

  

	 	(a)	any act is taken by a taxing authority of the United States on or after September 19, 2013, whether or not such act is taken in relation to the Company or any affiliate, that results in a substantial probability
that the Company will or may be required to pay Additional Amounts as described above; 

  

	 	(b)	the Company determines, in its business judgment, that the obligation to pay such Additional Amounts cannot be avoided by the use of reasonable measures available to it, other than substituting the obligor under the
Notes or taking any action that would entail a material cost to the Company and 

  

	 	(c)	the Company receives an opinion of independent counsel to the effect that an act taken by a taxing authority of the United States results in a substantial probability that the Company will or may be required to pay the
Additional Amounts described under above, and delivers to the Trustee a certificate, signed by a duly authorized officer, stating that based on such opinion the Company is entitled to redeem the Notes pursuant to their terms. 

  
 R-6 

 Any redemption of the Notes as set forth in clauses (1) or (2) above shall be in whole, and not in
part, and will be made at a redemption price equal to 100% of the principal amount of the Notes Outstanding plus accrued interest thereon to the date of redemption. Holders shall be given not less than 30 days nor more than 60 days prior notice by
the Trustee of the date fixed for such redemption. 
 All terms used in this Note which are defined in the Indenture shall have the meanings
assigned to them in the Indenture. The Notes are governed by the laws of the State of New York. 

  
 R-7EX-4.1

 Exhibit 4.1 

Execution Version 
  

 
  

WHITING PETROLEUM CORPORATION 
 (a
Delaware corporation) 
 $400,000,000 Aggregate Principal Amount of 

5.750% Senior Notes due 2021 

PURCHASE AGREEMENT 
 Dated:
September 23, 2013 
  
  

 

 WHITING PETROLEUM CORPORATION 

(a Delaware corporation) 

$400,000,000 Aggregate Principal Amount of 

5.750% Senior Notes due 2021 

Purchase Agreement 

September 23, 2013 
 Wells Fargo Securities,
LLC, 
 as Representative of the 
 several Initial Purchasers
listed 
 in Schedule 1 hereto 
 c/o Wells Fargo
Securities, LLC 
 375 Park Avenue 
 New York, New York 10152

 Ladies and Gentlemen: 
 Whiting Petroleum
Corporation, a Delaware corporation (the “Company”), proposes to issue and sell to the several initial purchasers listed in Schedule 1 hereto (the “Initial Purchasers”), for whom you are acting as
representative (the “Representative”), $400,000,000 aggregate principal amount of its 5.750% Senior Notes due 2021 (the “Notes”). The Notes will be guaranteed (the “Guarantee”) by Whiting Oil and
Gas Corporation, a Delaware corporation (the “Guarantor”). The Notes and the Guarantee are collectively referred to herein as the “Securities.” The Securities will be issued pursuant to an indenture (the
“Base Indenture”) dated as of September 12, 2013, among the Company, the Guarantor and The Bank of New York Mellon Trust Company, N.A., as trustee (the “Trustee”), as supplemented by the Third Supplemental
Indenture to the Base Indenture, dated as of the Closing Date (the “Third Supplemental Indenture” and, together with the Base Indenture, the “Indenture”). The Notes will have identical terms, other than with respect
to the registration rights referred to herein and restrictions on transfer, as the Company’s previously issued $800,000,000 aggregate principal amount of 5.750% Senior Notes due 2021 (the “Existing Notes”) issued pursuant to
the Base Indenture, as supplemented by the Second Supplemental Indenture to the Base Indenture, dated as of September 12, 2013 (the “Second Supplemental Indenture” and together with the Base Indenture, the “Existing
Notes Indenture”), but will be issued under the Indenture as a separate class of securities and will therefore not be fungible with the Existing Notes, unless and until such time as they are exchanged for notes issued under the Existing
Notes Indenture pursuant to the terms of a Registration Rights Agreement, to be dated the Closing Date (as defined below) (the “Registration Rights Agreement”). 

 The Securities will be sold to the Initial Purchasers in a transaction not registered under the
Securities Act of 1933, as amended (the “Securities Act”), and the rules and regulations of the Securities and Exchange Commission (the “Commission”) thereunder (the “Securities Act Regulations”),
in reliance upon an exemption therefrom. The Company and the Guarantor have prepared a preliminary offering memorandum dated September 23, 2013 (the “Preliminary Offering Memorandum”) and will prepare an offering memorandum
dated the date hereof (the “Offering Memorandum”) setting forth information concerning the Company and the Securities. Copies of the Preliminary Offering Memorandum have been, and copies of the Offering Memorandum will be, delivered
by the Company to the Initial Purchasers pursuant to the terms of this purchase agreement (this “Agreement”). The Company hereby confirms that it has authorized the use of the Preliminary Offering Memorandum, the other Time of Sale
Information (as defined below), the Recorded Road Show (as defined below) and the Offering Memorandum in connection with the offering and resale of the Securities by the Initial Purchasers in the manner contemplated by this Agreement. Capitalized
terms used but not defined herein shall have the meanings given to such terms in the Preliminary Offering Memorandum. References herein to the Preliminary Offering Memorandum, the Time of Sale Information and the Offering Memorandum shall be deemed
to refer to and include any document incorporated by reference therein. 
 At or prior to 3:15 p.m. (Eastern Standard Time) on
September 23, 2013, which is before the time when sales of the Securities were first made (the “Time of Sale”), the following information shall have been prepared (collectively, the “Time of Sale Information”):
the Preliminary Offering Memorandum, as supplemented and amended by the written communications listed on Annex A hereto. 
 Holders
of the Securities (including the Initial Purchasers and their direct and indirect transferees) will be entitled to the benefits of the Registration Rights Agreement, pursuant to which the Company and the Guarantor will agree to file one or more
registration statements with the Commission providing for the registration under the Securities Act of the resale of the Securities or the offer and issuance of the notes to be issued by the Company and guaranteed by the Guarantor under the Existing
Notes Indenture containing terms identical to the Securities (except that they will not be subject to restrictions on transfer or to any increase in annual interest rate for failure to comply with the Registration Rights Agreement) and to be offered
to Holders of Securities in exchange for Securities pursuant to the Registration Rights Agreement (the “Exchange Securities”). 

The Company and the Guarantor hereby confirm their agreement with the several Initial Purchasers concerning the purchase and resale of the
Securities, as follows: 
 1. Purchase and Resale of the Securities. (a) On the basis of the representations, warranties and
agreements set forth herein and subject to the conditions set forth herein, the Company agrees to issue and sell the Securities to the several Initial Purchasers as provided in this Agreement, and each Initial Purchaser agrees, severally and not
jointly, to purchase from the Company, the respective principal amount of Securities set forth opposite such Initial Purchaser’s name in Schedule 1 hereto at a price equal to 100.000% of the principal amount thereof plus accrued interest
on the respective principal amount of Securities from September 12, 2013. The Company will not be obligated to deliver any of the Securities, except upon deposit of cash in the amount of the aggregate purchase price to be paid for all the
Securities by the Initial Purchasers pursuant hereto. 

  
 3 

 (b) The Company understands that the Initial Purchasers intend to offer the Securities for resale
on the terms set forth in the Time of Sale Information. Each Initial Purchaser, severally and not jointly, represents, warrants and agrees that: 

(i) it is a qualified institutional buyer within the meaning of Rule 144A under the Securities Act (a
“QIB”) and an accredited investor within the meaning of Rule 501(a) under the Securities Act; 
 (ii)
it has not solicited offers for, or offered or sold, and will not solicit offers for, or offer or sell, the Securities or in any manner involving a public offering within the meaning of Section 4(a)(2) of the Securities Act; and 

(A) it has not sold the Securities as part of their initial offering except within the United States to persons whom it
reasonably believes to be QIBs in transactions pursuant to Rule 144A under the Securities Act (“Rule 144A”) and in connection with each such sale, it has taken or will take reasonable steps to ensure that the purchaser of
the Securities is aware that such sale is being made in reliance on Rule 144A; or 
 (B) it has not solicited offers
for, or offered or sold, and will not solicit offers for, or offer or sell, the Securities as part of their initial offering except in accordance with the restrictions set forth in Annex E hereto. 

(c) Each Initial Purchaser acknowledges and agrees that the Company and, for purposes of the “no registration” opinions to be
delivered to the Initial Purchasers pursuant to Sections 6(g) and 6(i), Foley & Lardner LLP as counsel for the Company, and Vinson & Elkins LLP, as counsel for the Initial Purchasers, respectively, may rely upon
the accuracy of the representations and warranties of the Initial Purchasers, and compliance by the Initial Purchasers with their agreements, contained in paragraph (b) above (including Annex E hereto), and each Initial Purchaser
hereby consents to such reliance. 
 (d) The Company acknowledges and agrees that the Initial Purchasers may offer and sell Securities to or
through any affiliate of an Initial Purchaser and that any such affiliate may offer and sell Securities purchased by it to or through any Initial Purchaser. 

(e) The Company and the Guarantor acknowledge and agree that each of the Initial Purchasers is acting solely in the capacity of an arm’s
length contractual counterparty to the Company and the Guarantor with respect to the offering of Securities and the Guarantee contemplated hereby (including in connection with determining the terms of the offering) and not as a financial advisor or
fiduciary to, or an agent of, the Company, the Guarantor or any other person. Additionally, neither the Representative nor any other Initial Purchaser is advising the Company, the Guarantor or any other person as to any legal, tax, investment,
accounting or regulatory matters in any jurisdiction. The Company and the Guarantor shall consult with their own respective advisors concerning such matters and shall be responsible for making their own respective independent investigation and
appraisal of the transactions contemplated hereby, and 

  
 4 

 
neither the Representative nor any other Initial Purchaser shall have any responsibility or liability to the Company or the Guarantor with respect thereto. Any review by the Representative
(whether acting on behalf of the Initial Purchasers or itself) or any other Initial Purchaser of the Company, the Guarantor, and the transactions contemplated hereby or other matters relating to such transactions will be performed solely for the
benefit of the Representative or such Initial Purchaser, as the case may be, and shall not be on behalf of the Company or the Guarantor. 

2. Payment and Delivery. 

(a) Payment of the purchase price for, and delivery of one or more global notes representing the Securities (collectively, the “Global
Note”) shall be made via facsimile and email and at the office of Whiting Petroleum Corporation, 1700 Broadway, Suite 2300, Denver, Colorado 80290-2300, or at such other place as shall be agreed upon by the Representative and the Company,
at 9:00 A.M. (Eastern Daylight Time) on the third (fourth, if the pricing occurs after 4:30 P.M. (Eastern Daylight Time) on any given day) business day after the date hereof (unless postponed in accordance with the provisions of Section 10), or
such other time not later than ten business days after such date as shall be agreed upon by the Representative and the Company (such date being herein called the “Closing Date” and the time and date of payment and delivery being
herein called the “Closing Time.” 
 (b) Payment for the Securities shall be made by wire transfer in immediately available
funds to a bank account designated by the Company, against delivery to the nominee of The Depository Trust Company (“DTC”), for the account of the Initial Purchasers, of one or more Global Note, with any transfer taxes payable in
connection with the sale of the Securities duly paid by the Company. The Global Note will be made available for inspection by the Representative not later than 1:00 p.m., New York City time, on the business day prior to the Closing Date. 

3. Representations and Warranties of the Company and the Guarantor. The Company and the Guarantor jointly and severally represent and
warrant to each Initial Purchaser as of the date hereof, the Time of Sale and as of the Closing Time that: 
 (a) Preliminary
Offering Memorandum, Time of Sale Information and Offering Memorandum. The Preliminary Offering Memorandum, as of its date, did not, the Time of Sale Information, at the Time of Sale, did not, and at the Closing Date, will not, and the Offering
Memorandum, in the form first used by the Initial Purchasers to confirm sales of the Securities and as of the Closing Date, will not, contain any untrue statement of a material fact or omit to state a material fact necessary in order to make the
statements therein, in the light of the circumstances under which they were made, not misleading; provided that the Company and the Guarantor make no representation or warranty with respect to any statements or omissions made in reliance upon
and in conformity with information relating to any Initial Purchaser furnished to the Company in writing by such Initial Purchaser through the Representative expressly for use in the Preliminary Offering Memorandum, the Time of Sale Information or
the Offering Memorandum. 
 (b) Additional Written Communications; Permitted General Solicitations. The Company and the
Guarantor (including their agents and representatives, other than the Initial  

  
 5 

 
Purchasers in their capacity as such) have not prepared, made, used, authorized, approved or referred to and will not prepare, make, use, authorize, approve or refer to (x) any written
communication that constitutes an offer to sell or solicitation of an offer to buy the Securities (each such communication by the Company and the Guarantor or their agents and representatives (other than a communication referred to in
clauses (i), (ii) and (iii) below) an “Issuer Written Communication”) other than (i) the Preliminary Offering Memorandum, (ii) the Offering Memorandum, (iii) the documents listed on
Annex A hereto, including a term sheet substantially in the form of Annex B hereto, which constitute part of the Time of Sale Information, and (iv) any electronic road show (the “Recorded Road Show”) or other
written communications other than any Permitted General Solicitation (as defined below), in each case used in accordance with Section 4(c) or (y) any general solicitation other than any such solicitation (i) listed on Annex
A hereto or (ii) in accordance with Section 4(n) hereof (each such solicitation referred to in clause (i) and (ii) a “Permitted General Solicitation”). Each such Issuer Written Communication or Permitted
General Solicitation, when taken together with the Time of Sale Information, did not, and at the Closing Date will not, contain any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements
therein, in the light of the circumstances under which they were made, not misleading; provided that the Company and the Guarantor make no representation and warranty with respect to any statements or omissions made in each such Issuer
Written Communication in reliance upon and in conformity with information relating to any Initial Purchaser furnished to the Company in writing by such Initial Purchaser through the Representative expressly for use in any Issuer Written
Communication. Each Issuer Written Communication does not conflict with the Time of Sale Information or the Offering Memorandum. 
 (c)
Incorporated Documents. The documents incorporated or deemed to be incorporated by reference in the Time of Sale Information and the Offering Memorandum, at the time they were or hereafter are filed with the Commission, complied and will
comply in all material respects with the requirements of the Securities and Exchange Act of 1934, as amended (the “Exchange Act”), and the rules and regulations of the Commission thereunder (the “Exchange Act
Regulations”), and, when read together with the other information in the Time of Sale Information at the earlier of the time the Time of Sale Information was first used and the date and time of the first contract of sale of Securities in
this offering and at the Closing Time, did not and will not contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein not misleading. 

(d) Financial Statements. The financial statements included in the Time of Sale Information and the Offering Memorandum,
together with the related schedules and notes, present fairly in all material respects, the financial position of the Company and its consolidated subsidiaries at the dates indicated and the statement of income, stockholders’ equity and cash
flows of Company and its consolidated subsidiaries for the periods specified; said financial statements have been prepared in conformity with generally accepted accounting principles in the United States (“GAAP”) applied on a
consistent basis throughout the periods involved. The supporting schedules, if any, included in the Time of Sale Information and the Offering Memorandum present fairly in all material respects in accordance with GAAP the information required to be
stated therein. The pro forma financial statements and the related notes thereto included in the Time of Sale Information and the Offering Memorandum present fairly in all material respects the information shown therein, have been prepared in
accordance with the  

  
 6 

 
Commission’s rules and guidelines with respect to pro forma financial statements and have been properly compiled on the bases described therein, and the assumptions used in the preparation
thereof are reasonable and the adjustments used therein are appropriate to give effect to the transactions and circumstances referred to therein. The summary financial information included in each of the Time of Sale Information and the Offering
Memorandum present fairly in all material respects the information shown therein and have been compiled on a basis consistent with that of the audited financial statements incorporated by reference in the Time of Sale Information and Offering
Memorandum. The Company’s ratio of earnings to fixed charges set forth in each of the Time of Sale Information and the Offering Memorandum have been calculated in compliance in all material respects with the requirements of Item 503(d) of
Regulation S-K under the Securities Act Regulations. The interactive data in eXtensible Business Reporting Language incorporated by reference in the Time of Sale Information and the Offering Memorandum fairly presents the information called for in
all material respects and has been prepared in accordance with the Commission’s rules and guidelines applicable thereto. 
 All
disclosures contained in the Time of Sale Information and the Offering Memorandum regarding “non-GAAP financial measures” (as such term is defined by the rules and regulations of the Commission) comply in all material respects with
Regulation G of the Exchange Act and Item 10 of Regulation S-K under the Securities Act, to the extent applicable. 
 (e) No
Material Adverse Change in Business. Since the respective dates as of which information is given in the Time of Sale Information and the Offering Memorandum, except as otherwise stated therein, (A) there has been no material adverse change
in the condition, financial or otherwise, or in the earnings, business affairs or business prospects of the Company, the Guarantor and their respective subsidiaries considered as one enterprise, whether or not arising in the ordinary course of
business (a “Material Adverse Effect”), (B) there have been no transactions entered into by Company, the Guarantor, or any of their respective subsidiaries, other than those in the ordinary course of business, which are
material with respect to the Company, the Guarantor and their respective subsidiaries considered as one enterprise, and (C) except as described in the Time of Sale Information and the Offering Memorandum, there has been no dividend or
distribution of any kind declared, paid or made by the Company on any class of its capital stock. 
 (f) Good Standing of the
Company. The Company has been duly organized and is validly existing as a corporation in good standing under the laws of the State of Delaware and has corporate power and authority to own, lease and operate its properties and to conduct its
business as described in the Time of Sale Information and the Offering Memorandum and to enter into and perform its obligations under this Agreement, the Indenture, the Securities, the Existing Notes Indenture, the Exchange Securities and the
Registration Rights Agreement (collectively, the “Transaction Documents”); and the Company is duly qualified as a foreign corporation to transact business and is in good standing in each other jurisdiction in which such
qualification is required, whether by reason of the ownership or leasing of property or the conduct of business, except where the failure so to qualify or to be in good standing would not result in a Material Adverse Effect. 

(g) Good Standing of Subsidiaries. The Guarantor has been duly organized and is validly existing as a corporation in good standing
under the laws of the jurisdiction of its 

  
 7 

 
incorporation, has corporate power and authority to own, lease and operate its properties and to conduct its business as described in the Time of Sale Information and the Offering Memorandum and
to enter into and perform its obligations under the Transaction Documents, and is duly qualified as a foreign corporation to transact business and is in good standing in each jurisdiction in which such qualification is required, whether by reason of
the ownership or leasing of property or the conduct of business, except where the failure so to qualify or to be in good standing would not result in a Material Adverse Effect; except as otherwise disclosed in the Time of Sale Information and the
Offering Memorandum, all of the issued and outstanding capital stock of the Guarantor has been duly authorized and validly issued, is fully paid and non-assessable and is owned by the Company, directly or
through subsidiaries, free and clear of any security interest, mortgage, pledge, lien, encumbrance, claim or equity; none of the outstanding shares of capital stock of the Guarantor was issued in violation of the preemptive or similar rights of any
securityholder of the Guarantor. As of the date of this Agreement, the only subsidiaries of the Company are the Guarantor, Whiting Programs, Inc., Sustainable Water Resources, LLC and Shaw Resources Limited, LLC. The subsidiaries of the Company,
other than the Guarantor, do not constitute a “significant subsidiary” as defined in Rule 1-02 of Regulation S-X. 
 (h)
Capitalization. The authorized, issued and outstanding capital stock of the Company is as included or incorporated by reference in the Time of Sale Information and the Offering Memorandum (except for subsequent issuances, if any, pursuant to
reservations, agreements or employee benefit plans referred to in the Time of Sale Information or the Offering Memorandum). The shares of issued and outstanding capital stock of the Company have been duly authorized and validly issued and are fully
paid and non-assessable; none of the outstanding shares of capital stock of the Company was issued in violation of the preemptive or other similar rights of any securityholder of the Company. 

(i) Authorization and Enforceability of Agreements. This Agreement has been duly authorized, executed and delivered by the Company and
the Guarantor; and the Registration Rights Agreement has been duly authorized by the Company and the Guarantor and on the Closing Date will be duly executed and delivered by the Company and the Guarantor and, when duly executed and delivered in
accordance with its terms by each of the parties thereto, will constitute a valid and legally binding agreement of the Company and the Guarantor, enforceable against the Company and the Guarantor in accordance with its terms, except as the
enforcement thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium or other similar laws relating to or affecting the rights and remedies of creditors or by general equitable principles (collectively, the
“Enforceability Exceptions”). 
 (j) The Securities. The Notes to be purchased by the Initial Purchasers from the
Company will be in the form contemplated by the Indenture, have been duly authorized by the Company for issuance and sale pursuant to this Agreement and the Indenture and, at the Closing Date, will have been duly executed by the Company and, when
issued and authenticated in the manner provided for in the Indenture and delivered against payment of the purchase price therefor, will constitute valid and legally binding obligations of the Company, enforceable against the Company in accordance
with their terms, except as the enforcement thereof may be limited by the Enforceability Exceptions, and will be entitled to the benefits of the Indenture. The Guarantee of the Notes will be in the respective forms contemplated by the Indenture,
have 

  
 8 

 
been duly authorized by the Guarantor for issuance and sale pursuant to this Agreement and the Indenture and, at the Closing Date, will have been duly executed by the Guarantor and, when the
Notes have been issued and authenticated in the manner provided for in the Indenture and delivered against payment of the purchase price therefor, will constitute valid and legally binding obligations of the Guarantor, enforceable in accordance with
their terms, except as the enforcement thereof may be limited by the Enforceability Exceptions, and will be entitled to the benefits of the Indenture. 

(k) The Exchange Securities. On the Closing Date, the Exchange Securities (including the related guarantee thereof by the Guarantor)
will have been duly authorized by the Company and the Guarantor and, when duly executed, authenticated, issued and delivered in accordance with the Existing Notes Indenture and as contemplated by the Registration Rights Agreement, will constitute
valid and legally binding obligations of the Company, as issuer, and the Guarantor, as guarantor, respectively, enforceable against the Company and the Guarantor in accordance with their terms, except as the enforcement thereof may be limited by the
Enforceability Exceptions, and will be entitled to the benefits of the Existing Notes Indenture. 
 (l) The Existing Notes Indenture.
The Existing Notes Indenture has been duly qualified under the Trust Indenture Act. Each of the Base Indenture and the Second Supplemental Indenture has been duly authorized by the Company and the Guarantor and has been duly executed and
delivered by the Company and the Guarantor and constitutes a valid and legally binding agreement of the Company and the Guarantor, enforceable against the Company and the Guarantor in accordance with its terms, except as the enforcement thereof may
be limited by the Enforceability Exceptions. 
 (m) The Third Supplement Indenture. The Third Supplemental Indenture has been duly
authorized by the Company and the Guarantor and, when duly executed and delivered in accordance with its terms by each of the parties thereto, the Third Supplemental Indenture will constitute a valid and legally binding agreement of the Company and
the Guarantor, enforceable against the Company and the Guarantor in accordance with its terms, except as enforcement thereof may be limited by the Enforceability Exceptions; and on the Closing Date, the Indenture will conform in all material
respects to the requirements of the Trust Indenture Act, and the rules and regulations of the Commission applicable to an indenture that is qualified thereunder. 

(n) Description of Transaction Documents. The Transaction Documents will, and the Existing Notes Indenture does, conform in all
material respects to the descriptions thereof in the Time of Sale Information and the Offering Memorandum under the captions “Description of the Notes.” 

(o) Regulations T, U and X. None of the transactions contemplated by this Agreement (including, without limitation, the use of the
proceeds from the sale of the Securities) will violate or result in a violation of Section 7 of the Exchange Act or the Exchange Act Regulations, including, without limitation, Regulations T, U, and X of the Board of Governors of the Federal
Reserve System. 
 (p) Absence of Defaults and Conflicts. Neither the Company, the Guarantor, nor any of their respective
subsidiaries is (A) in violation of its respective charter or by-laws or (B) in 

  
 9 

 
default in the performance or observance of any obligation, agreement, covenant or condition contained in any contract, indenture, mortgage, deed of trust, loan or credit agreement, note, lease
or other agreement or instrument to which the Company, the Guarantor, or any of their respective subsidiaries is a party or by which it or any of them may be bound, or to which any of the property or assets of the Company, the Guarantor, or any of
their respective subsidiaries is subject (collectively, “Agreements and Instruments”), except for such violations or defaults that would not result in a Material Adverse Effect; and the execution, delivery and performance of the
Transaction Documents and the consummation of the transactions contemplated herein and in the Time of Sale Information and the Offering Memorandum (including the offering, issuance and sale of the Securities pursuant to this Agreement and the use of
the proceeds to the Company from the sale of the Securities as described in the Time of Sale Information and the Offering Memorandum under the caption “Use of Proceeds”) and compliance by the Company with its obligations under the
Transaction Documents have been duly authorized by all necessary corporate action and do not and will not (X) whether with or without the giving of notice or passage of time or both, conflict with or constitute a breach of, or default or
Repayment Event (as defined below) under, or result in the creation or imposition of any lien, charge or encumbrance upon any property or assets of the Company, the Guarantor, or any of their respective subsidiaries pursuant to, the Agreements and
Instruments (except, with respect to this clause (X) for such conflicts, breaches, defaults or Repayment Events or liens, charges or encumbrances that would not result in a Material Adverse Effect), or (Y) result in any violation of
(i) the provisions of the charter or by-laws of the Company, the Guarantor, or any of their respective subsidiaries or (ii) any applicable law, statute, rule, regulation, judgment, order, writ or
decree of any government, government instrumentality or court, domestic or foreign, having jurisdiction over the Company, the Guarantor, or any of their respective subsidiaries or any of their assets, properties or operations (except, with respect
to this clause (Y)(ii), for such violations that would not result in a Material Adverse Effect). As used herein, a “Repayment Event” means any event or condition which gives the holder of any note, debenture or other evidence of
indebtedness (or any person acting on such holder’s behalf) the right to require the repurchase, redemption or repayment of all or a portion of such indebtedness by the Company, the Guarantor, or any of their respective subsidiaries. 

(q) Absence of Labor Dispute. No labor dispute with the employees of the Company, the Guarantor or any of their respective subsidiaries
exists or, to the knowledge of the Company or the Guarantor, is imminent, and the Company and the Guarantor are not aware of any existing or imminent labor disturbance by the employees of any of their or any subsidiary’s principal suppliers,
manufacturers, customers or contractors, which, in either case, would reasonably be expected to result in a Material Adverse Effect. 
 (r)
Absence of Proceedings. There is no action, suit, proceeding, inquiry or investigation before or brought by any court or governmental agency or body, domestic or foreign, now pending, or, to the knowledge of the Company or the Guarantor,
threatened, against or affecting the Company or any subsidiary of the Company, which is required to be disclosed in the Time of Sale Information or the Offering Memorandum (other than as disclosed therein), or which might reasonably be expected to
result in a Material Adverse Effect, or which might reasonably be expected to materially and adversely affect the properties or assets thereof or the consummation of the transactions contemplated in this Agreement or the performance by the Company
or the Guarantor of their respective obligations hereunder. The aggregate of all 

  
 10 

 
pending legal or governmental proceedings to which the Company, the Guarantor or any subsidiary of the Company is a party or of which any of their respective property or assets is the subject
which are not described in the Time of Sale Information or Offering Memorandum, including ordinary routine litigation incidental to the business, could not reasonably be expected to result in a Material Adverse Effect. 

(s) Incorporated Documents. The documents incorporated or deemed to be incorporated by reference in the Time of Sale Information or the
Offering Memorandum at the time they were or hereafter are filed with the Commission complied and will comply in all material respects with the requirements of the Exchange Act. 

(t) Possession of Intellectual Property. The Company, the Guarantor and their respective subsidiaries own or possess, or can acquire on
reasonable terms, adequate patents, patent rights, licenses, inventions, copyrights, know-how (including trade secrets and other unpatented and/or unpatentable proprietary or confidential information, systems
or procedures), trademarks, service marks, trade names or other intellectual property (collectively, “Intellectual Property”) necessary to carry on the business now operated by them, and neither the Company, the Guarantor, nor any
of their respective subsidiaries has received any written notice or is otherwise aware of any infringement of or conflict with asserted rights of others with respect to any Intellectual Property or of any facts or circumstances which would render
any Intellectual Property invalid or inadequate to protect the interest of Company, the Guarantor, or any of their respective subsidiaries therein, and which infringement or conflict (if the subject of any unfavorable decision, ruling or finding) or
invalidity or inadequacy, singly or in the aggregate, would result in a Material Adverse Effect. 
 (u) Absence of Further
Requirements. No filing with, or authorization, approval, consent, license, order, registration, qualification or decree of, any court or governmental authority or agency is necessary or required for the Company’s and the Guarantor’s
execution, delivery and performance of the Transaction Documents, the issuance and delivery of the Securities or the consummation of the transactions contemplated hereby or by the Time of Sale Information and the Offering Memorandum with respect to
the Securities, except (1) as such as have been already obtained or made, (2) with respect to the Exchange Securities, as may be required under the Securities Act, the Securities Act Regulations, the Trust Indenture Act and applicable
state securities laws and (3) with respect to the purchase and resale of the Securities by the Initial Purchasers, as may be required under applicable state securities laws. 

(v) Absence of Manipulation. Neither the Company nor any affiliate of the Company has taken, nor will the Company or any affiliate
take, directly or indirectly, any action which is designed to or which has constituted or which would be expected to cause or result in stabilization or manipulation of the price of any security of the Company to facilitate the sale or resale of the
Securities or result in a violation of Regulation M under the Exchange Act. 
 (w) Possession of Licenses and Permits. The Company
and its subsidiaries possess such permits, licenses, approvals, consents and other authorizations (collectively, “Governmental Licenses”) issued by the appropriate federal, state, local or foreign regulatory agencies or bodies
necessary to conduct the business now operated by them, except where the failure so to possess would not, singly or in the aggregate, result in a Material Adverse Effect; the Company and its 

  
 11 

 
subsidiaries are in compliance with the terms and conditions of all such Governmental Licenses, except where the failure so to comply would not, singly or in the aggregate, result in a Material
Adverse Effect; all of the Governmental Licenses are valid and in full force and effect, except when the invalidity of such Governmental Licenses or the failure of such Governmental Licenses to be in full force and effect would not, singly or in the
aggregate, result in a Material Adverse Effect; and neither the Company, the Guarantor, nor any of their respective subsidiaries has received any written notice of proceedings relating to the revocation or modification of any such Governmental
Licenses which, singly or in the aggregate, if the subject of an unfavorable decision, ruling or finding, would result in a Material Adverse Effect. 

(x) Title to Property. The Company and its subsidiaries have good and marketable title to all real property owned by the Company and
its subsidiaries, including, without limitation, all oil and gas producing properties, and good title to all other properties owned by them, including, without limitation, all assets and facilities used by the Company and its subsidiaries in the
production and marketing of oil and gas, in each case, free and clear of all mortgages, pledges, liens, security interests, claims, restrictions or encumbrances of any kind except such as (a) are described in the Time of Sale Information and
Offering Memorandum or (b) do not, singly or in the aggregate, materially affect the value of such property and do not interfere with the use made and proposed to be made of such property by Company, the Guarantor, or any of their respective
subsidiaries; and all of the leases and subleases material to the business of the Company and its subsidiaries, considered as one enterprise, and under which Company, the Guarantor, or any of their respective subsidiaries holds properties described
in the Time of Sale Information and the Offering Memorandum, including, without limitation, all oil and gas producing properties of the Company and its subsidiaries and all assets and facilities used by the Company and its subsidiaries in the
production and marketing of oil and gas, are in full force and effect, except where such would not have a Material Adverse Effect, and neither the Company, the Guarantor, nor any of their respective subsidiaries has any written notice of any
material claim of any sort that has been asserted by anyone adverse to the rights of Company, the Guarantor, or any of their respective subsidiaries under any of the leases or subleases mentioned above, or affecting or questioning the rights of the
Company or such subsidiary to the continued possession of the leased or subleased premises under any such lease or sublease, except where such would not have a Material Adverse Effect. 

(y) Environmental Laws. Except as described in the Time of Sale Information and Offering Memorandum, and except as would not, singly or
in the aggregate, result in a Material Adverse Effect, (A) neither the Company, the Guarantor, nor any of their respective subsidiaries is in violation of any federal, state, local or foreign statute, law, rule, regulation, ordinance, code,
policy or rule of common law or any judicial or administrative interpretation thereof, including any judicial or administrative order, consent, decree or judgment, relating to pollution or protection of human health, the environment (including,
without limitation, ambient air, surface water, groundwater, land surface or subsurface strata) or wildlife, including, without limitation, laws and regulations relating to the release or threatened release of chemicals, pollutants, contaminants,
wastes, toxic substances, hazardous substances, petroleum or petroleum products, asbestos-containing materials or mold (collectively, “Hazardous Materials”) or to the manufacture, processing, distribution, use, treatment, storage,
disposal, transport or handling of Hazardous Materials (collectively, “Environmental Laws”), (B) the Company and its subsidiaries have all permits, authorizations and approvals required under any applicable Environmental

  
 12 

 
Laws and are each in compliance with their requirements, (C) there are no pending or, to the knowledge of the Company, threatened administrative, regulatory or judicial actions, suits,
demands, demand letters, claims, liens, notices of noncompliance or violation, investigation or proceedings relating to any Environmental Law against Company, the Guarantor, or any of their respective subsidiaries and (D) there are no events or
circumstances that would reasonably be expected to form the basis of an order for clean-up or remediation, or an action, suit or proceeding by any private party or governmental body or agency, against or affecting Company, the Guarantor, or any of
their respective subsidiaries relating to Hazardous Materials or any Environmental Laws. 
 (z) Independent Petroleum Engineers.
Cawley, Gillespie & Associates, Inc., whose report as of December 31, 2012 is referenced in the Time of Sale Information and the Offering Memorandum, was, as of the date of such report, and is, as of the date hereof, an independent
petroleum engineer with respect to the Company and its subsidiaries. 
 (aa) Accuracy of Reserve Information. The information
underlying the estimates of reserves of the Company and its subsidiaries, which was supplied by the Company to Cawley, Gillespie & Associates, Inc. for purposes of auditing the reserve reports and estimates of the Company and preparing the
letter (the “Reserve Report Letter”) of Cawley, Gillespie & Associates, Inc., including, without limitation, production, costs of operation and development, current prices for production, agreements relating to current and
future operations and sales of production, was true and correct in all material respects on the dates such estimates were made and such information was supplied and was prepared in accordance with customary industry practices; other than normal
production of the reserves and intervening spot market product price fluctuations described in the Time of Sale Information and the Offering Memorandum, neither the Company nor its subsidiaries is aware of any facts or circumstances that would
result in an adverse change in the reserves, or the present value of future net cash flows therefrom, as described in the Time of Sale Information and the Offering Memorandum and as reflected in the Reserve Report Letter, that would reasonably be
expected to result in a Material Adverse Effect; estimates of such reserves and present values as described in the Time of Sale Information and the Offering Memorandum and reflected in the Reserve Report Letter comply in all material respects with
the applicable requirements of Regulation S-X and Regulation S-K under the Securities Act. 
 (bb) Oil and Gas Agreements. The
participation agreements, joint development agreements, joint operating agreements, farm-out agreements and other agreements described in the Time of Sale Information and Offering Memorandum relating to the Company or its subsidiaries’ rights
with respect to the ownership, lease or operation of oil and gas properties, the acquisition of interests in oil and gas properties or the exploration for, development of or production of oil and gas reserves thereon, constitute valid and binding
agreements of the Company and its subsidiaries that are parties thereto and, to the best knowledge of the Company, of the other parties thereto, enforceable in accordance with their terms, except as the enforcement thereof may be limited by
bankruptcy, insolvency (including, without limitation, all laws relating to fraudulent transfers), reorganization, moratorium or similar laws affecting enforcement of creditors’ rights generally and except as enforcement thereof is subject to
general principles of equity (regardless of whether enforcement is considered in a proceeding in equity or at law). 

  
 13 

 (cc) Insurance. The Company and each of its subsidiaries maintain insurance covering their
properties, operations, personnel and businesses that, in the Company’s reasonable judgment, insures against such losses and risks as are adequate in accordance with customary industry practices to protect the Company and its subsidiaries and
their businesses. 
 (dd) Accounting Controls and Disclosure Controls. The Company and each of its subsidiaries maintain a system of
internal accounting controls sufficient to provide reasonable assurances that (1) transactions are executed in accordance with management’s general or specific authorization; (2) transactions are recorded as necessary to permit
preparation of financial statements in conformity with GAAP and to maintain accountability for assets; (3) access to assets is permitted only in accordance with management’s general or specific authorization; (4) the recorded
accountability for assets is compared with the existing assets at reasonable intervals and appropriate action is taken with respect to any differences; and (5) interactive data in eXtensible Business Reporting Language included or incorporated
by reference in the Time of Sale Information and the Offering Memorandum is prepared in accordance with the Commission’s rules and guidelines applicable thereto. Since the end of the Company’s most recent audited fiscal year, there has
been (I) no material weakness in the Company’s internal control over financial reporting (whether or not remediated) and (II) no change in the Company’s internal control over financial reporting that has materially affected, or is
reasonably likely to materially affect, the Company’s internal control over financial reporting. 
 The Company maintains disclosure
controls and procedures that are designed to ensure that information required to be disclosed by the Company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported, within the time periods
specified in the Commission’s rules and forms, and is accumulated and communicated to the Company’s management, including its principal executive officer or officers and principal financial officer or officers, as appropriate, to allow
timely decisions regarding disclosure. 
 (ee) No Unlawful Contributions or Other Payments. Neither the Company, the Guarantor, nor
any of their respective subsidiaries nor, to the knowledge of the Company and the Guarantor, any director, officer, agent, employee or affiliate of Company, the Guarantor, or any of their respective subsidiaries is aware of or has taken any action,
directly or indirectly, that would result in a violation by such persons of the Foreign Corrupt Practices Act of 1977, as amended, and the rules and regulations thereunder (the “FCPA”), including, without limitation, making use of
the mails or any means or instrumentality of interstate commerce corruptly in furtherance of an offer, payment, promise to pay or authorization of the payment of any money, or other property, gift, promise to give, or authorization of the giving of
anything of value to any “foreign official” (as such term is defined in the FCPA) or any foreign political party or official thereof or any candidate for foreign political office, in contravention of the FCPA, and the Company, its
subsidiaries and, to the knowledge of the Company, its affiliates have conducted their businesses in compliance with the FCPA. 
 (ff) No
Conflict with Money Laundering Laws. Except as would not reasonably be expected to result in a Material Adverse Effect, the operations of the Company, the Guarantor and their respective subsidiaries are and have been conducted at all times in
compliance with applicable financial recordkeeping and reporting requirements of the Currency and Foreign Transactions Reporting Act of 1970, as amended, the money laundering statutes of all applicable

  
 14 

 
jurisdictions, the rules and regulations thereunder and any related or similar rules, regulations or guidelines issued, administered or enforced by any governmental agency (collectively, the
“Money Laundering Laws”) and no action, suit or proceeding by or before any court or governmental agency, authority or body or any arbitrator involving Company, the Guarantor, or any of their respective subsidiaries with respect to
the Money Laundering Laws is pending or, to the best knowledge of the Company and the Guarantor, threatened. 
 (gg) Sarbanes-Oxley
Compliance. There is and has been no failure on the part of the Company and any of the Company’s directors or officers, in their capacities as such, to comply in all material respects with any provision of the Sarbanes-Oxley Act of 2002 and
the rules and regulations promulgated in connection therewith (the “Sarbanes-Oxley Act”), including Section 402 related to loans and Sections 302 and 906 related to certifications. 

(hh) No Conflict with OFAC Laws. Neither the Company, the Guarantor, nor any of their respective subsidiaries nor, to the knowledge of
the Company and the Guarantor, any director, officer, agent, employee or affiliate of Company, the Guarantor, or any of their respective subsidiaries is currently subject to any U.S. sanctions administered by the Office of Foreign Assets Control of
the U.S. Treasury Department (“OFAC”). 
 (ii) Company Not an “Investment Company”. Neither the Company nor the
Guarantor is, and after receipt of payment for the Securities and the application of the proceeds thereof as contemplated under the caption “Use of Proceeds” in the Time of Sale Information and the Offering Memorandum will be, an
“investment company” within the meaning of the Investment Company Act of 1940, as amended. 
 (jj) No Restrictions on
Dividends. The Guarantor is not currently prohibited, directly or indirectly, under any agreement or other instrument to which it is a party or is subject from paying any dividends to the Company, from making any other distribution on the
Guarantor’s shares of capital stock or other ownership interests, from repaying to the Company any loans or advances to the Guarantor from the Company or from transferring any of the Guarantor’s property or assets to the Company, except as
described in or contemplated by the Time of Sale Information and the Offering Memorandum. The Securities constitute “senior indebtedness” as such term is defined in any indenture or agreement governing any outstanding subordinated
indebtedness of the Company. 
 (kk) Ratings. Except as otherwise disclosed in the Time of Sale Information, no “nationally
recognized statistical rating organization” as such term is defined under Section 3(a)(62) under the Exchange Act has indicated to the Company that it is considering (a) the downgrading, suspension, or withdrawal of, or any review for
a possible change that does not indicate the direction of the possible change in, any rating so assigned or (b) any negative change in the outlook for any rating of the Company or any securities of the Company. 

(ll) Rule 144A Eligibility. On the Closing Date, the Securities will not be of the same class as securities listed on a
national securities exchange registered under Section 6 of the Exchange Act or quoted on an automated inter-dealer quotation system; and each of the Preliminary Offering Memorandum and the Offering Memorandum, as of its respective date,
contains or will contain all the information that, if requested by a prospective purchaser of the Securities, would be required to be provided to such prospective purchaser pursuant to Rule 144A(d)(4) under the Securities Act. 

  
 15 

 (mm) No Integration. Neither the Company nor any of its “affiliates” (as
defined in Rule 501(b) of Regulation D) has, directly or through any agent, sold, offered for sale, solicited offers to buy or otherwise negotiated in respect of, any security (as defined in the Securities Act), that is or will be
integrated with the sale of the Securities in a manner that would require registration of the Securities under the Securities Act. 

(nn) No General Solicitation or Directed Selling Efforts. None of the Company or any of its “affiliates” (as defined
in Rule 501(b) of Regulation D) or any other person acting on its or their behalf (other than the Initial Purchasers, as to which no representation is made) has (i) solicited offers for, or offered or sold, the Securities by means of
any form of general solicitation or general advertising within the meaning of Rule 502(c) of Regulation D other than by means of a Permitted General Solicitation or in any manner involving a public offering within the meaning of
Section 4(a)(2) of the Securities Act or (ii) engaged in any directed selling efforts within the meaning of Regulation S under the Securities Act (“Regulation S”), and all such persons have complied with the
offering restrictions requirement of Regulation S. The sale of the Securities pursuant to Regulation S is not part of a plan or scheme to evade the registration provisions of the Securities Act. 

(oo) Securities Law Exemptions. Assuming the accuracy of the representations and warranties of the Initial Purchasers contained in
Section 1(b) (including Annex E hereto) and their compliance with their agreements set forth therein, it is not necessary, in connection with the issuance and sale of the Securities to the Initial Purchasers and the offer, resale
and delivery of the Securities by the Initial Purchasers in the manner contemplated by this Agreement, the Time of Sale Information and the Offering Memorandum, to register the offer and sale of the Securities under the Securities Act or to qualify
the Indenture under the Trust Indenture Act. 
 (pp) Officer’s Certificates. Any certificate signed by any officer of
Company, the Guarantor, or any of their respective subsidiaries delivered to the Representative or to counsel for the Initial Purchasers shall be deemed a representation and warranty by the Company to each Underwriter as to the matters covered
thereby. 
 (qq) Independent Accountants. The accountants who certified the financial statements and supporting
schedules included or incorporated by reference in the Time of Sale Information and the Offering Memorandum are independent public accountants with respect to the Company as required by the Securities Act, the Exchange Act and the Public Accounting
Oversight Board. 
 4. Further Agreements of the Company and the Guarantor. The Company and the Guarantor jointly and
severally covenant and agree with each Initial Purchaser that: 
 (a) Delivery of Copies. The Company will deliver, without
charge, to the Initial Purchasers as many copies of the Preliminary Offering Memorandum, any other Time of Sale Information, any Issuer Written Communication and the Offering Memorandum (including all amendments and supplements thereto) as the
Representative may reasonably request. 

  
 16 

 (b) Offering Memorandum Amendments or Supplements. Before finalizing the Offering
Memorandum or making or distributing any amendment or supplement to any of the Time of Sale Information or the Offering Memorandum, or filing with the Commission any document that will be incorporated by reference therein, the Company will furnish
to the Representative and counsel for the Initial Purchasers a copy thereof for review, and will not distribute any such proposed Offering Memorandum, amendment or supplement or file any such document with the Commission to which the Representative
reasonably objects.  
 (c) Additional Written Communications. Before making, preparing, using, authorizing, approving
or referring to any Issuer Written Communication, the Company will furnish to the Representative and counsel for the Initial Purchasers a copy of such written communication for review and will not make, prepare, use, authorize, approve or refer to
any such written communication to which the Representative reasonably objects.  
 (d) Notice to the Representative.
The Company will advise the Representative promptly, and confirm such advice in writing, (i) if there has been an issuance by any governmental or regulatory authority of any order preventing or suspending the use of any of the Time of Sale
Information, any Issuer Written Communication, any Permitted General Solicitation or the Offering Memorandum or the initiation or, to its knowledge, threatening of any proceeding for that purpose; (ii) of the occurrence of any event at any time
prior to the completion of the initial offering of the Securities as a result of which any of the Time of Sale Information, any Issuer Written Communication, Permitted General Solicitation or the Offering Memorandum as then amended or supplemented
would include any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances existing when such Time of Sale Information, Issuer Written Communication,
Permitted General Solicitation or the Offering Memorandum is delivered to a purchaser, not misleading; and (iii) of the receipt by the Company of any notice with respect to any suspension of the qualification of the Securities for offer and
sale in any jurisdiction or the initiation or threatening of any proceeding for such purpose; and the Company will use its reasonable best efforts to prevent the issuance of any such order preventing or suspending the use of any of the Time of Sale
Information, any Issuer Written Communication or the Offering Memorandum or suspending any such qualification of the Securities and, if any such order is issued, to obtain as soon as possible the withdrawal thereof. 

(e) Time of Sale Information. If at any time prior to the Closing Date (i) any event shall occur or condition shall exist as a
result of which any of the Time of Sale Information as then amended or supplemented would include any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the
circumstances under which they were made, not misleading or (ii) it is necessary to amend or supplement any of the Time of Sale Information to comply with law, the Company will promptly notify the Initial Purchasers thereof and forthwith
prepare, at the expense of the Company, and, subject to paragraph (b) above, furnish to the Initial Purchasers such amendments or supplements to any of the Time of Sale Information (or any document to be filed with the Commission and
incorporated by reference therein) as may be necessary so that the statements in any of the Time of Sale Information as so amended or supplemented (including such document to be incorporated by reference therein) will not, in the light of the
circumstances under which they were made, be misleading or so that any of the Time of Sale Information will comply with law. 

  
 17 

 (f) Ongoing Compliance of the Offering Memorandum. If at any time prior to the completion
of the initial offering of the Securities (i) any event shall occur or condition shall exist as a result of which the Offering Memorandum as then amended or supplemented would include any untrue statement of a material fact or omit to state any
material fact necessary in order to make the statements therein, in the light of the circumstances existing when the Offering Memorandum is delivered to a purchaser, not misleading or (ii) it is necessary to amend or supplement the Offering
Memorandum to comply with law, the Company will promptly notify the Initial Purchasers thereof and forthwith prepare, at the expense of the Company, and, subject to paragraph (b) above, furnish to the Initial Purchasers such amendments
or supplements to the Offering Memorandum (or any document to be filed with the Commission and incorporated by reference therein) as may be necessary so that the statements in the Offering Memorandum as so amended or supplemented (including such
document to be incorporated by reference therein) will not, in the light of the circumstances existing when the Offering Memorandum is delivered to a purchaser, be misleading or so that the Offering Memorandum will comply with law. 

(g) Blue Sky Compliance. The Company will use its best efforts, in cooperation with the Initial Purchasers, to qualify the
Securities for offer and sale under the securities or Blue Sky laws of such jurisdictions as the Representative shall reasonably request and will continue such qualifications in effect so long as required for the offering and resale of the
Securities; provided that neither the Company nor the Guarantor shall be required to (i) qualify as a foreign corporation or other entity or as a dealer in securities in any such jurisdiction where it would not otherwise be required to so
qualify, (ii) file any general consent to service of process in any such jurisdiction or (iii) subject itself to taxation in any such jurisdiction if it is not otherwise so subject. 

(h) Clear Market. During a period of 90 days from the date of the Offering Memorandum, the Company will not, without the prior
written consent of Wells Fargo Securities, directly or indirectly, offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase or otherwise
transfer or dispose of any of the Company’s debt securities or any securities convertible into or exercisable or exchangeable for the Company’s debt securities or file any registration statement under the Securities Act with respect to any
of the foregoing (other than as contemplated by this Agreement and the Registration Rights Agreement), excluding any borrowings under the Guarantor’s credit agreement, the Securities sold pursuant to this Agreement and any Exchange Securities
issuable under the Registration Rights Agreement. 
 (i) Use of Proceeds. The Company will apply the net proceeds from
the sale of the Securities as described in each of the Time of Sale Information and the Offering Memorandum under the heading “Use of Proceeds.” 

(j) Supplying Information. While the Securities remain outstanding and are “restricted securities” within the meaning
of Rule 144(a)(3) under the Securities Act, the Company and the Guarantor will, during any period in which the Company is not subject to and in compliance with Section 13 or 15(d) of the Exchange Act, furnish to holders of the Securities
and prospective purchasers of the Securities designated by such holders, upon the request of such holders or such prospective purchasers, the information required to be delivered pursuant to Rule 144A(d)(4) under the Securities Act. 

  
 18 

 (k) DTC. The Company will assist the Initial Purchasers in arranging for the
Securities to be eligible for clearance and settlement through DTC. 
 (l) No Resales by the Company. The Company will
not, and will not permit any of its affiliates (as defined in Rule 144 under the Securities Act) to, resell any of the Securities that have been acquired by any of them, except for Securities purchased by the Company or any of its affiliates
and resold in a transaction registered under the Securities Act. 
 (m) No Integration. Neither the Company nor any of
its affiliates (as defined in Rule 501(b) of Regulation D) will, directly or through any agent, sell, offer for sale, solicit offers to buy or otherwise negotiate in respect of, any security (as defined in the Securities Act), that is or
will be integrated with the sale of the Securities in a manner that would require registration of the Securities under the Securities Act. 

(n) No General Solicitation or Directed Selling Efforts. None of the Company, the Guarantor or any of their respective
affiliates or any other person acting on its or their behalf (other than the Initial Purchasers, as to which no covenant is given) will (i) solicit offers for, or offer or sell, the Securities by means of any form of general solicitation or
general advertising within the meaning of Rule 502(c) of Regulation D without the prior written consent of the Representative or in any manner involving a public offering within the meaning of Section 4(a)(2) of the Securities Act or
(ii) engage in any directed selling efforts (within the meaning of Regulation S), and all such persons will comply with the offering restrictions requirement of Regulation S. 

(o) No Stabilization. Neither the Company nor the Guarantor will take, directly or indirectly, any action designed to or that
could reasonably be expected to cause or result in any stabilization or manipulation of the price of the Securities. 
 5. Certain
Agreements of the Initial Purchasers. Each Initial Purchaser hereby represents and agrees that it has not and will not use, authorize use of, refer to, or participate in the planning for use of, any written communication that constitutes an
offer to sell or the solicitation of an offer to buy the Securities other than (i) the Preliminary Offering Memorandum and the Offering Memorandum, (ii) a written communication that contains no “issuer information” (as defined in
Rule 433(h)(2) under the Securities Act) that was not included (including through incorporation by reference) in the Preliminary Offering Memorandum or the Offering Memorandum, (iii) any written communication listed on Annex A or
prepared pursuant to Section 4(c) above (including any electronic road show), (iv) any written communication prepared by such Initial Purchaser and approved by the Company in advance in writing or (v) any written communication
relating to or that contains the terms of the Securities and/or other information that was included (including through incorporation by reference) in the Preliminary Offering Memorandum or the Offering Memorandum. 

6. Conditions of Initial Purchasers’ Obligations. The obligation of each Initial Purchaser to purchase Securities on the Closing
Date as provided herein is subject to the performance by the Company and the Guarantor of their respective covenants and other obligations hereunder and to the following additional conditions: 

  
 19 

 (a) Representations and Warranties. The representations and warranties of the
Company and the Guarantor contained herein shall be true and correct on the date hereof and on and as of the Closing Date; and the statements of the Company and the Guarantor and their respective officers made in any certificates delivered pursuant
to this Agreement shall be true and correct on and as of the Closing Date. 
 (b) Reserved. 

(c) Officers’ Certificate. At Closing Time, there shall not have been, since the date hereof or since the respective dates
as of which information is given in the Time of Sale Information or Offering Memorandum (exclusive of any amendment or supplement thereto subsequent to the date of this Agreement), any material adverse change in the condition, financial or
otherwise, or in the earnings, business affairs or business prospects of the Company, the Guarantor and their respective subsidiaries considered as one enterprise, whether or not arising in the ordinary course of business, and the Representative
shall have received a certificate of the Chief Executive Officer, President or a Vice President of the Company and of the chief financial or chief accounting officer of the Company, dated as of Closing Time, to the effect that (i) there has
been no such material adverse change, (ii) the representations and warranties in Section 3 hereof are true and correct with the same force and effect as though expressly made at and as of Closing Time, (iii) there has been no issuance
by any governmental or regulatory authority of any order preventing or suspending the use of any of the Time of Sale Information, any Issuer Written Communication, any Permitted General Solicitation or the Offering Memorandum, or to prevent the
issuance or sale of the Securities or the issuance of the Guarantee, or the initiation or, to their knowledge, threatening of any proceeding for such purposes, and (iv) the Company has complied in all material respects with all agreements and
satisfied all conditions on its part to be performed or satisfied at or prior to Closing Time. 
 (d) Accountant’s
Comfort Letter. At the time of the execution of this Agreement, the Representative shall have received from Deloitte & Touche LLP a letter dated such date, in form and substance satisfactory to the Representative, together with signed
or reproduced copies of such letter for each of the other Initial Purchasers containing statements and information of the type ordinarily included in accountants’ “comfort letters” to underwriters with respect to the financial
statements and certain financial information contained in the Time of Sale Information. 
 (e) Bring-down Comfort
Letter. At Closing Time, the Representative shall have received from Deloitte & Touche LLP a letter, dated as of Closing Time, to the effect that they reaffirm the statements made in the letter furnished pursuant to subsection (d)
of this Section, except that the specified date referred to shall be a date not more than three business days prior to Closing Time. 

(f) Reserve Engineer Letters. At the Closing Time, the Initial Purchasers shall have received from Cawley, Gillespie &
Associates, Inc., a letter, in form and substance reasonably satisfactory to the Initial Purchasers, addressed to the Initial Purchasers and dated the date hereof covering the matters described in Annex F.  

(g) Opinion of Counsel for Company. At Closing Time, the Representative shall have received the favorable opinion, dated as of
Closing Time, in form and substance reasonably  

  
 20 

 
satisfactory to counsel for the Initial Purchasers, together with signed or reproduced copies of such letter for each of the other Initial Purchasers, of each of (i) Foley & Lardner
LLP, counsel for the Company; and (ii) Bruce R. DeBoer, Vice President, General Counsel and Corporate Secretary of the Company. 

(h) Letter from Counsel for Company. At Closing Time, the Representative shall have received a letter, dated as of Closing Time,
in form and substance reasonably satisfactory to counsel for the Initial Purchasers, together with signed or reproduced copies of such letter for each of the other Initial Purchasers, of Foley & Lardner LLP, counsel for the Company.

 (i) Opinion of Counsel for Initial Purchasers. At Closing Time, the Representative shall have received the favorable
opinion, dated as of Closing Time, of Vinson & Elkins L.L.P., counsel for the Initial Purchasers, together with signed or reproduced copies of such letter for each of the other Initial Purchasers in a form and substance satisfactory to, and
addressed to, the Initial Purchasers, with respect to the issuance and sale of the Notes, the Exchange Notes, the Registration Rights Agreement, the Time of Sale Information and the Offering Memorandum and other related matters as the Representative
may reasonably require.  
 (j) Form of Securities and Indenture. The Securities and the Indenture shall be executed by the
Company, or the Guarantor, as the case may be, in form and substance reasonably satisfactory to the Representative and the Trustee. 

(k) Registration Rights Agreement. The Representative shall have received a counterpart of the Registration Rights Agreement
that shall have been executed and delivered by a duly authorized officer of the Company and the Guarantor. 
 (l) DTC. The
Securities shall be eligible for clearance and settlement through DTC. 
 (m) Additional Documents. On or prior to the Closing
Date, the Company and the Guarantor shall have furnished to the Representative such further certificates and documents as the Representative may reasonably request. 

All opinions, letters, certificates and evidence mentioned above or elsewhere in this Agreement shall be deemed to be in compliance with the
provisions hereof only if they are in form and substance reasonably satisfactory to counsel for the Initial Purchasers. 
 If any condition
specified in this Section 6 shall not have been fulfilled when and as required to be fulfilled, this Agreement may be terminated by the Representative by notice to the Company at any time at or prior to Closing Time and such termination shall
be without liability of any party to any other party except as provided in Section 11 and except that Sections 3, 7, and 13 shall survive any such termination and remain in full force and effect. 

7. Indemnification and Contribution. 

(a) Indemnification of the Initial Purchasers. The Company and Guarantor jointly and severally agree to indemnify and hold
harmless each Initial Purchaser, it directors, its officers, its affiliates, as such term is defined in Rule 501(b) under the Securities Act (each, an “Affiliate”) and each person, if any, who controls (within the meaning of
Section 15 of the  

  
 21 

 
Securities Act or Section 20 of the Exchange Act) such Initial Purchaser, and the successors and assigns of all the foregoing persons, from and against any and all losses, claims, damages
and liabilities (including, without limitation, legal fees and other expenses incurred in connection with any suit, action or proceeding or any claim asserted, as such fees and expenses are incurred), joint or several, that arise out of, or are
based upon, any untrue statement or alleged untrue statement of a material fact contained or incorporated by reference in the Preliminary Offering Memorandum, any of the other Time of Sale Information, any Issuer Written Communication, Recorded Road
Show, any Permitted General Solicitation or the Offering Memorandum (or any amendment or supplement thereto) or any omission or alleged omission to state therein a material fact necessary in order to make the statements therein, in the light of the
circumstances under which they were made, not misleading, in each case except insofar as such losses, claims, damages or liabilities arise out of, or are based upon, any untrue statement or omission or alleged untrue statement or omission made in
reliance upon and in conformity with any information relating to any Initial Purchaser furnished to the Company in writing by such Initial Purchaser through the Representative expressly for use therein, it being understood and agreed that the only
such information furnished by any Initial Purchaser consists of the information described as such in paragraph (b) below. 
 (b)
Indemnification of the Company and the Guarantor. Each Initial Purchaser agrees, severally and not jointly, to indemnify and hold harmless the Company and the Guarantor, each of their respective directors and officers and each person, if any,
who controls the Company or the Guarantor (within the meaning of Section 15 of the Securities Act or Section 20 of the Exchange Act) to the same extent as the indemnity set forth in paragraph (a) above, but only with respect to
any losses, claims, damages or liabilities that arise out of, or are based upon, any untrue statement or omission or alleged untrue statement or omission made in reliance upon and in conformity with any information relating to such Initial Purchaser
furnished to the Company in writing by such Initial Purchaser through the Representative expressly for use in the Preliminary Offering Memorandum, any of the other Time of Sale Information, any Issuer Written Communication, any Permitted General
Solicitation or the Offering Memorandum (or any amendment or supplement thereto), it being understood and agreed that the only such information consists of the following: the information contained in the third and fourth sentences of the tenth
paragraph and the thirteenth paragraph, respectively, under the caption “Plan of Distribution” in the Preliminary Offering Memorandum and the Offering Memorandum. 

(c) Notice and Procedures. If any suit, action, proceeding (including any governmental or regulatory investigation), claim or demand
shall be brought or asserted against any person in respect of which indemnification may be sought pursuant to either paragraph (a) or (b) above, such person (the “Indemnified Person”) shall promptly notify
the person against whom such indemnification may be sought (the “Indemnifying Person”) in writing; provided that the failure to notify the Indemnifying Person shall not relieve it from any liability that it may have under
paragraph (a) or (b) above except to the extent that it has been materially prejudiced (through the forfeiture of substantive rights or defenses) by such failure; and provided, further, that the failure to
notify the Indemnifying Person shall not relieve it from any liability that it may have to an Indemnified Person otherwise than under paragraph (a) or (b) above. If any such proceeding shall be brought or asserted against an
Indemnified Person and it shall have notified the Indemnifying Person thereof, the Indemnifying Person shall retain counsel reasonably satisfactory to the Indemnified Person (who shall not, without the consent of the Indemnified

  
 22 

 
Person, be counsel to the Indemnifying Person) to represent the Indemnified Person and any others entitled to indemnification pursuant to this Section 7 that the Indemnifying Person
may designate in such proceeding and shall pay the fees and expenses of such proceeding and shall pay the fees and expenses of such counsel related to such proceeding, as incurred. In any such proceeding, any Indemnified Person shall have the right
to retain its own counsel, but the fees and expenses of such counsel shall be at the expense of such Indemnified Person unless (i) the Indemnifying Person and the Indemnified Person shall have mutually agreed in writing to the contrary;
(ii) the Indemnifying Person has failed within a reasonable time to retain counsel reasonably satisfactory to the Indemnified Person; (iii) the Indemnified Person shall have reasonably concluded that there may be legal defenses available
to it that are different from or in addition to those available to the Indemnifying Person; or (iv) the named parties in any such proceeding (including any impleaded parties) include both the Indemnifying Person and the Indemnified Person and
representation of both parties by the same counsel would be inappropriate due to actual or potential differing interests between them. It is understood and agreed that the Indemnifying Person shall not, in connection with any proceeding or related
proceeding in the same jurisdiction, be liable for the reasonably incurred fees and expenses of more than one separate firm (in addition to any local counsel) for all Indemnified Persons, and that all such fees and expenses shall be paid or
reimbursed as they are incurred. Any such separate firm for any Initial Purchaser, its affiliates, agents, directors and officers and any control persons of such Initial Purchaser shall be designated in writing by the Representative and any such
separate firm for the Company, the Guarantor, their respective directors and officers and any control persons of the Company and the Guarantor shall be designated in writing by the Company. The Indemnifying Person shall not be liable for any
settlement of any proceeding effected without its written consent (which shall not be unreasonably withheld), but if settled with such consent or if there be a final judgment for the plaintiff, the Indemnifying Person agrees to indemnify each
Indemnified Person from and against any loss or liability in accordance with Section 7(a) by reason of such settlement or judgment. Notwithstanding the foregoing sentence, if at any time an Indemnified Person shall have requested that an
Indemnifying Person reimburse the Indemnified Person for fees and expenses of counsel as contemplated by this paragraph (c), the Indemnifying Person shall be liable for any settlement of any proceeding effected without its written
consent if (1) such settlement is entered into more than 45 days after receipt by such Indemnifying Person of the request, (2) such Indemnifying Person shall have received notice of the terms of such settlement at least 30 days prior to
such settlement being entered into and (3) the Indemnifying Person shall not have reimbursed the Indemnified Person in accordance with such request prior to the date of such settlement. No Indemnifying Person shall, without the written consent
of the Indemnified Person (which shall not be unreasonably withheld), effect any settlement of any pending or threatened proceeding in respect of which any Indemnified Person is or could have been a party and indemnification could have been sought
hereunder by such Indemnified Person, unless such settlement (x) includes an unconditional release of such Indemnified Person, in form and substance reasonably satisfactory to such Indemnified Person, from all liability on claims that are the
subject matter of such proceeding and (y) does not include any statement as to or any admission of fault, culpability or a failure to act by or on behalf of any Indemnified Person. 

(d) Contribution. If the indemnification provided for in paragraphs (a) and (b) above is unavailable to an
Indemnified Person or insufficient in respect of any losses, claims, damages or liabilities referred to therein, then each Indemnifying Person under such paragraph, in lieu of 

  
 23 

 
indemnifying such Indemnified Person thereunder, shall contribute to the amount paid or payable by such Indemnified Person as a result of such losses, claims, damages or liabilities (i) in
such proportion as is appropriate to reflect the relative benefits received by the Company and the Guarantor on the one hand and the Initial Purchasers on the other from the offering of the Securities or (ii) if the allocation provided by
clause (i) above is not permitted by applicable law, in such proportion as is appropriate to reflect not only the relative benefits referred to in clause (i) above but also the relative fault of the Company and the Guarantor
on the one hand and the Initial Purchasers on the other in connection with the statements or omissions that resulted in such losses, claims, damages or liabilities, as well as any other relevant equitable considerations. The relative benefits
received by the Company and the Guarantor on the one hand and the Initial Purchasers on the other shall be deemed to be in the same respective proportions as the net proceeds (before deducting expenses) received by the Company from the sale of the
Securities and the total discounts and commissions received by the Initial Purchasers in connection therewith, as provided in this Agreement, bear to the aggregate offering price of the Securities. The relative fault of the Company and the Guarantor
on the one hand and the Initial Purchasers on the other shall be determined by reference to, among other things, whether the untrue or alleged untrue statement of a material fact or the omission or alleged omission to state a material fact relates
to information supplied by the Company or the Guarantor or by the Initial Purchasers and the parties’ relative intent, knowledge, access to information and opportunity to correct or prevent such statement or omission. 

(e) Limitation on Liability. The Company, the Guarantor and the Initial Purchasers agree that it would not be just and equitable if
contribution pursuant to this Section 7 were determined by pro rata allocation (even if the Initial Purchasers were treated as one entity for such purpose) or by any other method of allocation that does not take account of the
equitable considerations referred to in paragraph (d) above. The amount paid or payable by an Indemnified Person as a result of the losses, claims, damages and liabilities referred to in paragraph (d) above shall be deemed to
include, subject to the limitations set forth above, any legal or other expenses incurred by such Indemnified Person in connection with any such action or claim. Notwithstanding the provisions of this Section 7, in no event shall an
Initial Purchaser be required to contribute any amount in excess of the amount by which the total discounts and commissions received by such Initial Purchaser with respect to the offering of the Securities exceeds the amount of any damages that such
Initial Purchaser has otherwise been required to pay by reason of such untrue or alleged untrue statement or omission or alleged omission. No person guilty of fraudulent misrepresentation (within the meaning of Section 11(f) of the Securities
Act) shall be entitled to contribution from any person who was not guilty of such fraudulent misrepresentation. The Initial Purchasers’ obligations to contribute pursuant to this Section 7 are several in proportion to their
respective purchase obligations hereunder and not joint. 
 (f) Non-Exclusive Remedies. The remedies provided for in this
Section 7 are not exclusive and shall not limit any rights or remedies that may otherwise be available to any Indemnified Person at law or in equity. 

8. Effectiveness of Agreement. This Agreement shall become effective upon the execution and delivery hereof by the parties hereto. 

  
 24 

 9. Termination. 

(a) The Representative may terminate this Agreement, by notice to the Company, at any time at or prior to Closing Time (i) if there has
been, since the time of execution of this Agreement or since the respective dates as of which information is given in the Preliminary Offering Memorandum (exclusive of any amendment or supplement thereto subsequent to the date of this Agreement) or
the Time of Sale Information, any material adverse change in the condition, financial or otherwise, or in the earnings, business affairs or business prospects of the Company, the Guarantor and their respective subsidiaries considered as one
enterprise, whether or not arising in the ordinary course of business, or (ii) if there has occurred after the date hereof and prior to the Closing Time any material adverse change in the financial markets in the United States or the
international financial markets, any outbreak of hostilities or escalation thereof or other calamity or crisis or any change or development involving a prospective change in national or international political, financial or economic conditions, in
each case the effect of which is such as to make it, in the reasonable judgment of the Representative, impracticable or inadvisable to proceed with the offering, sale or delivery of the Securities or to enforce contracts for the sale of the
Securities, or (iii) if trading in any securities of the Company has been suspended or materially limited by the Commission or the New York Stock Exchange, or if trading generally on the American Stock Exchange or the New York Stock Exchange or
in the Nasdaq National Market has been suspended or materially limited, or minimum or maximum prices for trading have been fixed, or maximum ranges for prices have been required, by any of said exchanges or by such system or by order of the
Commission, FINRA or any other governmental authority, or (iv) if a material disruption has occurred in commercial banking or securities settlement or clearance services in the United States, or (v) if a banking moratorium has been
declared by either federal or New York authorities. 
 (b) If this Agreement is terminated pursuant to this Section, such termination shall
be without liability of any party to any other party except as provided in Section 11 hereof, and provided further that Section 3, 7 and 19 shall survive such termination and remain in full force and effect. 

10. Defaulting Initial Purchaser. 

(a) If, on the Closing Date, any Initial Purchaser defaults on its obligation to purchase the Securities that it has agreed to purchase
hereunder, the non-defaulting Initial Purchasers may in their discretion arrange for the purchase of such Securities by other persons satisfactory to the Company on the terms contained in this Agreement. If, within 36 hours after any such default by
any Initial Purchaser, the non-defaulting Initial Purchasers do not arrange for the purchase of such Securities, then the Company shall be entitled to a further period of 36 hours within which to procure other persons satisfactory to the
non-defaulting Initial Purchasers to purchase such Securities on such terms. If other persons become obligated or agree to purchase the Securities of a defaulting Initial Purchaser, either the non-defaulting Initial Purchasers or the Company may
postpone the Closing Date for up to five full business days in order to effect any changes that in the opinion of counsel for the Company or counsel for the Initial Purchasers may be necessary in the Time of Sale Information, the Offering Memorandum
or in any other document or arrangement, and the Company agrees to promptly prepare any amendment or supplement to the Time of Sale Information or the Offering Memorandum that effects any such changes. As used in

  
 25 

 
this Agreement, the term “Initial Purchaser” includes, for all purposes of this Agreement unless the context otherwise requires, any person not listed in Schedule 1 hereto
that, pursuant to this Section 10, purchases Securities that a defaulting Initial Purchaser agreed but failed to purchase. 

(b) If, after giving effect to any arrangements for the purchase of the Securities of a defaulting Initial Purchaser or Initial Purchasers by
the non-defaulting Initial Purchasers and the Company as provided in paragraph (a) above, the aggregate principal amount of such Securities that remains unpurchased does not exceed 10% of the aggregate principal amount of all the
Securities, then the Company shall have the right to require each non-defaulting Initial Purchaser to purchase the principal amount of Securities that such Initial Purchaser agreed to purchase hereunder plus such Initial Purchaser’s pro
rata share (based on the principal amount of Securities that such Initial Purchaser agreed to purchase hereunder) of the Securities of such defaulting Initial Purchaser or Initial Purchasers for which such arrangements have not been made. 

(c) If, after giving effect to any arrangements for the purchase of the Securities of a defaulting Initial Purchaser or Initial Purchasers by
the non-defaulting Initial Purchasers and the Company as provided in paragraph (a) above, the aggregate principal amount of such Securities that remains unpurchased exceeds 10% of the aggregate principal amount of all the Securities, or
if the Company shall not exercise the right described in paragraph (b) above, then this Agreement shall terminate without liability on the part of the non-defaulting Initial Purchasers. Any termination of this Agreement pursuant to this
Section 10 shall be without liability on the part of the Company or the Guarantor, except that the Company and each of the Guarantor will continue to be liable for the payment of expenses as set forth in Section 11 hereof and
except that the provisions of Section 7 hereof shall not terminate and shall remain in effect. 
 (d) Nothing contained herein
shall relieve a defaulting Initial Purchaser of any liability it may have to the Company, the Guarantor or any non-defaulting Initial Purchaser for damages caused by its default. 

11. Payment of Expenses. 

(a) Whether or not the transactions contemplated by this Agreement are consummated or this Agreement is terminated, the Company and the
Guarantor jointly and severally agree to pay or cause to be paid all costs and expenses incident to the performance of their respective obligations hereunder, including without limitation, (i) the costs incident to the authorization, issuance,
sale, preparation and delivery of the Securities and any transfer fees or taxes payable in that connection; (ii) the costs incident to the preparation, printing of the Preliminary Offering Memorandum, any other Time of Sale Information, any
Issuer Written Communication, any Permitted General Solicitation and the Offering Memorandum (including any amendment or supplement thereto) and the distribution thereof; (iii) the costs of reproducing and distributing each of the Transaction
Documents; (iv) the fees and expenses of the Company’s and the Guarantor’s counsel, the independent accountants and reserve engineers; (v) the fees and expenses incurred in connection with the registration or qualification and
determination of eligibility for investment of the Securities under the laws of such jurisdictions as the Representative may designate and the preparation, printing and distribution of a Blue Sky Memorandum (including the related fees and expenses
of counsel for the Initial Purchasers; 

  
 26 

 
provided that such counsel fees do not exceed $5,000); (vi) any fees charged by rating agencies for rating the Securities; (vii) the fees and expenses of the Trustee and any paying
agent (including related fees and expenses of any counsel to such parties); (viii) all expenses and application fees incurred in connection with any filing with, and clearance of the offering by, FINRA, and the approval of the Securities for
book-entry transfer by DTC; and (ix) the costs and expenses of the Company relating to investor presentations on any “road show” undertaken in connection with the marketing of the Securities, including without limitation, expenses
associated with the production of road show slides and graphics, fees and expenses of any consultants engaged in connection with the road show presentations, travel and lodging expenses of the representatives and officers of the Company and any such
consultants, and the cost of aircraft and other transportation chartered in connection with the road show. It is understood, however, that, except as provided in Section 7, Section 9 and Section 11 hereof, the Initial Purchasers will
pay all of their own costs and expenses, including the fees and expenses of their counsel. 
 (b) If this Agreement is terminated by the
Representative in accordance with the provisions of Section 6 or Section 9(a)(i) hereof, the Company shall reimburse the Initial Purchasers for all of their out-of-pocket expenses, up to $200,000, including the reasonable fees and
disbursements of counsel for the Initial Purchasers. 
 12. Persons Entitled to Benefit of Agreement. This Agreement shall inure to
the benefit of and be binding upon the parties hereto and their respective successors and any controlling persons referred to herein, and the affiliates, agents, officers and directors of each Initial Purchaser referred to in Section 7
hereof. Nothing in this Agreement is intended or shall be construed to give any other person any legal or equitable right, remedy or claim under or in respect of this Agreement or any provision contained herein. No purchaser of Securities from any
Initial Purchaser shall be deemed to be a successor merely by reason of such purchase. 
 13. Survival. The respective indemnities,
rights of contribution, representations, warranties and agreements of the Company, the Guarantor and the Initial Purchasers contained in this Agreement or made by or on behalf of the Company, the Guarantor or the Initial Purchasers pursuant to this
Agreement or any certificate delivered pursuant hereto shall survive the delivery of and payment for the Securities and shall remain in full force and effect, regardless of any investigation made by or on behalf of the Company, the Guarantor or the
Initial Purchasers. 
 14. Certain Defined Terms. For purposes of this Agreement, (a) except where otherwise expressly provided,
the term “affiliate” has the meaning set forth in Rule 405 under the Securities Act; (b) the term “business day” means any day other than a day on which banks are permitted or required to be closed in New York City;
(c) except where otherwise expressly provided, the term “subsidiary” has the meaning set forth in Rule 405 under the Securities Act; and (d) the term “written communication” has the meaning set forth in
Rule 405 under the Securities Act. 
 15. USA Patriot Act. The Company and the Guarantor acknowledge that, in accordance with
the requirements of the USA Patriot Act (Title III of Pub. L. 107-56 (signed into law October 26, 2001)), the Initial Purchasers are required to obtain, verify and record information that identifies their respective clients, including the
Company, which information may include the name and address of their respective clients, as well as other information that will allow the Initial Purchasers to properly identify their respective clients. 

  
 27 

 16. Miscellaneous. 

(a) Authority of the Representative. Any action by the Initial Purchasers hereunder may be taken by Wells Fargo Securities, LLC on
behalf of the Initial Purchasers, and any such action taken by Wells Fargo Securities, LLC shall be binding upon the Initial Purchasers. 

(b) Notices. All notices and other communications hereunder shall be in writing and shall be deemed to have been duly given if mailed
or transmitted and confirmed by any standard form of telecommunication. Notices to the Initial Purchasers shall be given to the Representative c/o Wells Fargo Securities, LLC, 375 Park Avenue, New York, New York 10152 (fax: (212) 214-5918);
Attention: Transaction Management Department. Notices to the Company and the Guarantor shall be given to them at Whiting Petroleum Corporation, 1700 Broadway, Suite 2300, Denver, Colorado 80290-2300; ATTN: James J. Volker. 

(c) Governing Law. This Agreement and any claim, controversy or dispute arising under or related to this Agreement shall be governed by
and construed in accordance with the laws of the State of New York. 
 (d) Counterparts. This Agreement may be signed in counterparts
(which may include counterparts delivered by any standard form of telecommunication), each of which shall be an original and all of which together shall constitute one and the same instrument. 

(e) Amendments or Waivers. No amendment or waiver of any provision of this Agreement, nor any consent or approval to any departure
therefrom, shall in any event be effective unless the same shall be in writing and signed by the parties hereto. 
 (f) Headings. The
headings herein are included for convenience of reference only and are not intended to be part of, or to affect the meaning or interpretation of, this Agreement. 

[Signature pages to follow] 

  
 28 

 If the foregoing is in accordance with your understanding, please indicate your acceptance of
this Agreement by signing in the space provided below. 
  

			
	Very truly yours,
	
	WHITING PETROLEUM CORPORATION
		
	By	 	 /s/ James J. Volker

	Name:	 	James J. Volker
	Title:	 	Chairman and Chief Executive Officer
	
	GUARANTOR:
	
	WHITING OIL AND GAS CORPORATION
		
	By:	 	 /s/ James J. Volker

	Name:	 	James J. Volker
	Title:	 	Chairman and Chief Executive Officer

  
 SIGNATURE PAGE TO
PURCHASE AGREEMENT 

 CONFIRMED AND ACCEPTED, 

as of the date first above written: 
 WELLS FARGO SECURITIES, LLC

 On behalf of itself and each of the several 
 Initial
Purchasers listed in Schedule 1 
 hereto. 
  

			
	By:	 	 /s/ Rob Johnson

		 	Authorized Signatory

  
 SIGNATURE PAGE TO
PURCHASE AGREEMENT 

 Schedule 1 
  

					
	 Name of Underwriter
	  	Principal Amount of
Notes	 
	 Wells Fargo Securities, LLC
	  	$	94,000,000	  
	 J.P. Morgan Securities LLC 
	  	 	94,000,000	  
	 Merrill Lynch Pierce Fenner & Smith Incorporated
	  	 	60,000,000	  
	 BBVA Securities Inc.
	  	 	16,000,000	  
	 SunTrust Robinson Humphrey, Inc.
	  	 	16,000,000	  
	 U.S. Bancorp Investments, Inc.
	  	 	16,000,000	  
	 Capital One Securities, Inc.
	  	 	12,000,000	  
	 CIBC World Markets Corp.
	  	 	12,000,000	  
	 RBC Capital Markets, LLC
	  	 	12,000,000	  
	 Mitsubishi UFJ Securities (USA), Inc.
	  	 	12,000,000	  
	 KeyBanc Capital Markets Inc.
	  	 	8,000,000	  
	 RB International Markets (USA) LLC
	  	 	8,000,000	  
	 Scotia Capital (USA) Inc.
	  	 	8,000,000	  
	 Santander Investment Securities Inc.
	  	 	8,000,000	  
	 Barclays Capital Inc.
	  	 	4,000,000	  
	 BOSC, Inc.
	  	 	4,000,000	  
	 Comerica Securities, Inc.
	  	 	4,000,000	  
	 Fifth Third Securities, Inc.
	  	 	4,000,000	  
	 Morgan Stanley & Co. LLC
	  	 	4,000,000	  
	 Raymond James & Associates, Inc.
	  	 	4,000,000	  
		  	  
	  
	 
	 Total
	  	$	400,000,000	  

  
 Schedule 1 

 ANNEX A 
  

	a.	Additional Time of Sale Information 

 1. Term sheet containing the terms of the
Securities, substantially in the form of Annex B. 
  

	b.	Permitted General Solicitation 

 1. Press release issued on September 23, 2013,
substantially in the form of Annex C hereto. 
 2. Press release issued on September 23, 2013, substantially in the form of
Annex D hereto. 

  
 Annex A-1 

 ANNEX B 

Pricing Term Sheet dated September 23, 2013 
 to Preliminary
Offering Memorandum dated September 23, 2013 
 (the “Preliminary Offering Memorandum”) 

$400,000,000 
 Whiting
Petroleum Corporation 
 5.750% Senior Notes due 2021 

This Pricing Term Sheet is qualified in its entirety by reference to the Preliminary Offering Memorandum. Capitalized terms used below have the meanings given
to them in the Preliminary Offering Memorandum. 
 The information in this Pricing Term Sheet supplements the Preliminary Offering Memorandum and supersedes
the information in the Preliminary Offering Memorandum to the extent inconsistent with the information in the Preliminary Offering Memorandum. 
 The
Notes have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), and are being offered only to qualified institutional buyers pursuant to Rule 144A under the Securities Act and outside the
United States to non-U.S. persons in accordance with Regulation S under the Securities Act. The Notes are not transferable except in accordance with the restrictions described under “Transfer Restrictions” in the Preliminary Offering
Memorandum. 
  

			
	Issuer:	  	Whiting Petroleum Corporation, a Delaware corporation (“WLL”)
		
	Guarantor:	  	Whiting Oil and Gas Corporation, a Delaware corporation
		
	Title of Securities:	  	 5.750% Senior Notes due 2021 (the “Notes”)
  

The Notes will have the same terms, other than with respect to the registration rights and restrictions on transfer referred to in the Preliminary Offering
Memorandum, as the $800.0 million aggregate principal amount of 5.750% Senior Notes due 2021 (the “Original Notes”) that WLL issued on September 12, 2013, but will be issued as a separate class of securities and will therefore not be
fungible with the Original Notes, unless and until such time as they are exchanged for additional Original Notes pursuant to the terms of the registration rights agreement described in the Preliminary Offering Memorandum.

		
	Distribution:	  	144A and Regulation S with registration rights as set forth in the Preliminary Offering Memorandum
		
	Principal Amount:	  	$400,000,000
		
	Net Proceeds After Expenses, Excluding Accrued Interest:	  	$399,263,000

  
 Annex B-1 

			
	Issue Price:	  	101.000% of face amount, plus accrued interest from September 12, 2013
		
	Coupon:	  	5.750%
		
	Interest Payment Dates:	  	September 15 and March 15, commencing March 15, 2014
		
	Date of Maturity:	  	March 15, 2021
		
	Yield to Worst:	  	5.580%
		
	Optional Redemption:	  	Make-whole call @ Treasury + 50 bps prior to December 15, 2020, then 100%
		
	Change of Control:	  	Put @ 101% of principal plus accrued interest
		
	CUSIP:	  	 144A: 966387 AJ1
 Reg S: U9650F
AC1

		
	ISIN:	  	 144A: US966387AJ12
 Reg S:
USU9650FAC15

		
	Trade Date:	  	September 23, 2013
		
	Settlement Date:	  	September 26, 2013 (T + 3)
		
	Joint Book-Running Managers:	  	 Wells Fargo Securities, LLC
 J.P. Morgan
Securities LLC
 Merrill Lynch, Pierce, Fenner & Smith Incorporated

		
	Senior Co-Managers:	  	 BBVA Securities Inc.
 SunTrust Robinson
Humphrey, Inc.
 U.S. Bancorp Investments, Inc.
 Capital One
Securities, Inc.
 CIBC World Markets Corp.
 RBC Capital
Markets, LLC
 Mitsubishi UFJ Securities (USA), Inc.

		
	Co-Managers:	  	 KeyBanc Capital Markets Inc.
 RB
International Markets (USA) LLC
 Scotia Capital (USA) Inc.

Santander Investment Securities Inc.
 Barclays Capital Inc. BOSC,
Inc.
 Comerica Securities, Inc.
 Fifth Third Securities,
Inc.
 Morgan Stanley & Co. LLC
 Raymond James &
Associates, Inc.

  
  

  
 Annex B-2 

 All information (including financial information) presented in the Preliminary Offering Memorandum is deemed
to have changed to the extent affected by the changes described herein. 
 This material is confidential and is for your information only and is not
intended to be used by anyone other than you. This information does not purport to be a complete description of these Notes or the offering. Please refer to the Preliminary Offering Memorandum for a complete description. 

This communication is being distributed in the United States solely to Qualified Institutional Buyers, as defined in Rule 144A under the Securities Act,
and outside the United States solely to Non-U.S. persons as defined in Regulation S under the Securities Act. 
  

 
 ANY DISCLAIMER
OR OTHER NOTICES THAT MAY APPEAR BELOW ARE NOT APPLICABLE TO THIS COMMUNICATION AND SHOULD BE DISREGARDED. SUCH DISCLAIMERS OR OTHER NOTICES WERE AUTOMATICALLY GENERATED AS A RESULT OF THIS COMMUNICATION BEING SENT VIA BLOOMBERG OR ANOTHER EMAIL
SYSTEM. 

  
 Annex B-3 

 ANNEX C 
  

 
  

			
	Company contact:	  	John B. Kelso, Director of Investor Relations
		  	303.837.1661 or john.kelso@whiting.com

 Whiting Petroleum Corporation to Offer $400 Million Aggregate Principal Amount of Senior Notes Due 2021 in a
Private Placement 
 DENVER – September 23, 2013 – Whiting Petroleum Corporation (NYSE: WLL) announced today that it intends to
sell $400 million aggregate principal amount of 5.750% senior notes due 2021 in a private placement to eligible purchasers. The notes will be unsecured and unconditionally guaranteed by Whiting’s wholly-owned subsidiary, Whiting Oil and Gas
Corporation. 
 Whiting expects to use the net proceeds from the sale of the notes for general corporate purposes including capital expenditures. 

These notes have not been registered under the Securities Act of 1933, as amended (the “Securities Act”), or the securities laws of any state and
may not be offered or sold in the United States absent registration or an exemption from the requirements of the Securities Act and applicable state securities laws. The notes are expected to be eligible for trading by qualified institutional buyers
under Rule 144A and non-U.S. persons under Regulation S. 
 This press release is being issued pursuant to Rule 135c under the Securities Act and does not
constitute an offer to sell or the solicitation of an offer to buy the notes, nor shall there be any sale of the notes, in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under
the securities laws of any such jurisdiction. 

  
 Annex C-1 

 About Whiting Petroleum Corporation 

Whiting Petroleum Corporation, a Delaware corporation, is an independent oil and gas company that explores for, develops, acquires and produces crude oil,
natural gas and natural gas liquids primarily in the Rocky Mountain, Permian Basin, Mid-Continent, Michigan and Gulf Coast regions of the United States. The Company’s largest projects are in the Bakken and Three Forks plays in North Dakota and
its Enhanced Oil Recovery field in Texas. The Company trades publicly under the symbol WLL on the New York Stock Exchange. 
 Forward-Looking
Statements 
 This news release contains statements that we believe to be “forward-looking statements” within the meaning of
Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements other than historical facts, including, without limitation, statements regarding our future financial position, business
strategy, projected revenues, earnings, costs, capital expenditures and debt levels, and plans and objectives of management for future operations, are forward-looking statements. When used in this news release, words such as we “expect,”
“intend,” “plan,” “estimate,” “anticipate,” “believe” or “should” or the negative thereof or variations thereon or similar terminology are generally intended to identify forward-looking
statements. Such forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, such statements. 

These risks and uncertainties include, but are not limited to: declines in oil, natural gas liquids or natural gas prices; our level of success in
exploration, development and production activities; adverse weather conditions that may negatively impact development or production activities; the timing of our exploration and development activities; our ability to obtain sufficient quantities of
CO2 necessary to carry out our enhanced oil recovery projects; inaccuracies of our reserve estimates or our assumptions underlying them; revisions to reserve estimates as a result of changes in commodity prices; risks related to our level of
indebtedness and periodic redeterminations of the borrowing base under our credit agreement; our ability to generate sufficient cash flows from operations to meet the internally funded portion of our capital expenditures budget; our ability to
obtain external capital to finance exploration and development operations and acquisitions; federal and state initiatives relating to the regulation of hydraulic fracturing; the potential impact of federal debt reduction initiatives and tax reform
legislation being considered by the U.S. Federal government that could have a negative effect on the oil and gas industry; our ability to identify and complete acquisitions and to successfully integrate acquired businesses; unforeseen
underperformance of or liabilities associated with acquired properties, including the properties subject to the Williston Basin acquisition; our ability to successfully complete potential asset dispositions and the risks related thereto; the impacts
of hedging on our results of operations; failure of our properties to yield oil or gas in commercially viable quantities; uninsured or underinsured losses resulting from our oil and gas operations; our inability to access oil and gas markets due to
market conditions or operational impediments; the impact and costs of compliance with laws and regulations governing our oil and gas operations; our ability to replace our oil and natural gas reserves; any loss of our senior management or technical
personnel; competition in the oil and gas industry in the regions in 

  
 Annex C-2 

 
which we operate; risks arising out of our hedging transactions; and other risks described under the caption “Risk Factors” in our final prospectus supplement dated September 9,
2013. We assume no obligation, and disclaim any duty, to update the forward-looking statements in this news release. 

  
 Annex C-3 

 ANNEX D 
  

 
  

			
	Company contact:	  	John B. Kelso, Director of Investor Relations
		  	303.837.1661 or john.kelso@whiting.com

 Whiting Petroleum Corporation Announces Pricing of $400 Million of Senior Notes Due 2021 

DENVER – September 23, 2013 – Whiting Petroleum Corporation (NYSE: WLL) today announced that it has priced $400 million aggregate
principal amount of 5.750% senior notes due 2021 in a private placement to eligible purchasers. The notes were priced at a premium of 101.000% of par. The notes will be unsecured and unconditionally guaranteed by Whiting’s wholly-owned
subsidiary, Whiting Oil and Gas Corporation. The private placement is expected to close on September 26, 2013. 
 Whiting expects to use the net
proceeds from the sale of the notes for general corporate purposes including capital expenditures. 
 These notes have not been registered under the
Securities Act of 1933, as amended (the “Securities Act”), or the securities laws of any state and may not be offered or sold in the United States absent registration or an exemption from the requirements of the Securities Act and
applicable state securities laws. The notes are expected to be eligible for trading by qualified institutional buyers under Rule 144A and non-U.S. persons under Regulation S. 

This press release is being issued pursuant to Rule 135c under the Securities Act and does not constitute an offer to sell or the solicitation of an offer to
buy the notes, nor shall there be any sale of the notes, in any jurisdiction in which such offer, solicitation or sale would be unlawful prior to the registration or qualification under the securities laws of any such jurisdiction. 

  
 Annex D-1 

 About Whiting Petroleum Corporation 

Whiting Petroleum Corporation, a Delaware corporation, is an independent oil and gas company that explores for, develops, acquires and produces crude oil,
natural gas and natural gas liquids primarily in the Rocky Mountain, Permian Basin, Mid-Continent, Michigan and Gulf Coast regions of the United States. The Company’s largest projects are in the Bakken and Three Forks plays in North Dakota and
its Enhanced Oil Recovery field in Texas. The Company trades publicly under the symbol WLL on the New York Stock Exchange. 
 Forward-Looking
Statements 
 This news release contains statements that we believe to be “forward-looking statements” within the meaning of
Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934. All statements other than historical facts, including, without limitation, statements regarding our future financial position, business
strategy, projected revenues, earnings, costs, capital expenditures and debt levels, and plans and objectives of management for future operations, are forward-looking statements. When used in this news release, words such as we “expect,”
“intend,” “plan,” “estimate,” “anticipate,” “believe” or “should” or the negative thereof or variations thereon or similar terminology are generally intended to identify forward-looking
statements. Such forward-looking statements are subject to risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, such statements. 

These risks and uncertainties include, but are not limited to: declines in oil, natural gas liquids or natural gas prices; our level of success in
exploration, development and production activities; adverse weather conditions that may negatively impact development or production activities; the timing of our exploration and development activities; our ability to obtain sufficient quantities of
CO2 necessary to carry out our enhanced oil recovery projects; inaccuracies of our reserve estimates or our assumptions underlying them; revisions to reserve estimates as a result of changes in commodity prices; risks related to our level of
indebtedness and periodic redeterminations of the borrowing base under our credit agreement; our ability to generate sufficient cash flows from operations to meet the internally funded portion of our capital expenditures budget; our ability to
obtain external capital to finance exploration and development operations and acquisitions; federal and state initiatives relating to the regulation of hydraulic fracturing; the potential impact of federal debt reduction initiatives and tax reform
legislation being considered by the U.S. Federal government that could have a negative effect on the oil and gas industry; our ability to identify and complete acquisitions and to successfully integrate acquired businesses; unforeseen
underperformance of or liabilities associated with acquired properties, including the properties subject to the Williston Basin acquisition; our ability to successfully complete potential asset dispositions and the risks related thereto; the impacts
of hedging on our results of operations; failure of our properties to yield oil or gas in commercially viable quantities; uninsured or underinsured losses resulting from our oil and gas operations; our inability to access oil and gas markets due to
market conditions or operational impediments; the impact and costs of compliance with laws and regulations governing our oil and gas operations; our ability to replace our oil and natural gas reserves; any loss of our senior management or technical
personnel; competition in the oil and gas industry in the regions in 

  
 Annex D-2 

 
which we operate; risks arising out of our hedging transactions; and other risks described under the caption “Risk Factors” in our final prospectus supplement dated September 9,
2013. We assume no obligation, and disclaim any duty, to update the forward-looking statements in this news release. 

  
 Annex D-3 

 ANNEX E 

Restrictions on Offers and Sales Outside the United States 

In connection with offers and sales of the Securities outside the United States: 

(a) Each Initial Purchaser acknowledges that the Securities have not been registered under the Securities Act and may not be offered or sold
within the United States or to, or for the account or benefit of, U.S. persons except pursuant to an exemption from, or in transactions not subject to, the registration requirements of the Securities Act. 

(b) Each Initial Purchaser, severally and not jointly, represents, warrants and agrees that: 

(i) Such Initial Purchaser has offered and sold the Securities, and will offer and sell the Securities, (A) as part of
their distribution at any time and (B) otherwise until 40 days after the later of the commencement of the offering of the Securities and the Closing Date, only in accordance with Regulation S under the Securities Act
(“Regulation S”) or Rule 144A or any other available exemption from registration under the Securities Act. 

(ii) None of such Initial Purchaser or any of its affiliates or any other person acting on its or their behalf has engaged or
will engage in any directed selling efforts with respect to the Securities, and all such persons have complied and will comply with the offering restrictions requirement of Regulation S. 

(iii) At or prior to the confirmation of sale of any Securities sold in reliance on Regulation S, such Initial Purchaser
will have sent to each distributor, dealer or other person receiving a selling concession, fee or other remuneration that purchases Securities from it during the distribution compliance period a confirmation or notice to substantially the following
effect: 
 “The Securities covered hereby have not been registered under the U.S. Securities Act of 1933, as amended (the
“Securities Act”), and may not be offered or sold within the United States or to, or for the account or benefit of, U.S. persons (i) as part of their distribution at any time or (ii) otherwise until 40 days after the later
of the commencement of the offering of the Securities and the date of original issuance of the Securities, except in accordance with Regulation S or Rule 144A or any other available exemption from registration under the Securities Act.
Terms used above have the meanings given to them by Regulation S.” 
 (iv) Such Initial Purchaser has not and will not
enter into any contractual arrangement with any distributor with respect to the distribution of the Securities, except with its affiliates or with the prior written consent of the Company. 

  
 Annex E-1 

 Terms used in paragraph (a) and this paragraph (b) and not otherwise defined in this Agreement have the
meanings given to them by Regulation S. 
 (c) Each Initial Purchaser, severally and not jointly, represents, warrants and agrees that:

 (i) it has only communicated or caused to be communicated and will only communicate or cause to be communicated an
invitation or inducement to engage in investment activity (within the meaning of Section 21 of the Financial Services and Markets Act of 2000 (the “FSMA”)) received by it in connection with the issue or sale of the Securities
in circumstances in which Section 21(1) of the FSMA does not apply to the Company; and 
 (ii) it has complied and will
comply with all applicable provisions of the FSMA with respect to anything done by it in relation to the Securities in, from or otherwise involving the United Kingdom. 

(d) Each Initial Purchaser acknowledges that no action has been or will be taken by the Company that would permit a public offering of the
Securities, or possession or distribution of any of the Time of Sale Information, the Offering Memorandum, any Issuer Written Communication or any other offering or publicity material relating to the Securities, in any country or jurisdiction where
action for that purpose is required. 

  
 Annex E-2 

 ANNEX F 

FORM OF RESERVE LETTER 
 TO BE
DELIVERED PURSUANT TO 
 SECTION 5(i) 

This letter, which is written at the request of Whiting Petroleum Corporation (the “Company”), is being delivered to the Initial
Purchasers pursuant to the terms of a purchase agreement between the Company and the Initial Purchasers relating to the offering of $400,000,000 aggregate principal amount of the Company’s 5.750% senior notes due 2021, which are being offered
by the Company pursuant to the offering memorandum dated September 23, 2013 (the “Offering Memorandum”). 
 Our report letter
dated as of January 11, 2013 to the Company presented our estimates of Proved Reserves, Probable Reserves, Possible Reserves and Future Net Revenues (including discounted values thereof) attributable to interests of the Company as of
December 31, 2012 (the “2012 Report”). In addition, we also delivered previous reports to the Company for the year ended December 31, 2010 and 2011 (the “Previous Reports”). The 2012 Report and the Previous Reports are
collectively referred to in this letter as the “Reports”. 
 In connection with the foregoing, we hereby inform you as follows:

  

	 	1.	As of the date of this letter and as of the date of the Reports, we are and were independent reserve engineers with respect to the Company as provided in the standards pertaining to the estimating and auditing of oil
and gas reserve information promulgated by the Securities and Exchange Commission (the “SEC”). Neither we, nor to our knowledge, any of our employees, officers or directors, own interests in the oil and gas properties included in the
Reports. We have not been employed by the Company on a contingent basis. 

  

	 	2.	All terms used in this letter, where applicable, conform to the definitions set forth in Rule 4-10 of Regulation S-X promulgated by the SEC. 

 

	 	3.	The estimates of the Company’s Proved Reserves, Probable Reserves, Possible Reserves, Future Net Revenues and the discounted values of Future Net Revenues contained in the Reports, and the computations made in
connection therewith, were, unless otherwise stated, made in accordance with the provisions of Rule 4-10 of Regulation S-X promulgated by the SEC and have been prepared in a manner consistent and in compliance with the standards and definitions
pertaining to the estimating and auditing of oil and gas reserve information promulgated by the SEC. 

  

	 	4.	The engineering projections included in the 2012 Report were based on the latest available production data, the majority through November 2012. Although we were not requested to review subsequent data concerning either
the performance of the wells or field operations, no additional information has been brought to our attention that would lead us to believe that there would be a material change in the estimated Proved Reserves, Probable Reserves, Possible Reserves,
or Future Net Revenues attributable to the Company’s interests reflected in the 2012 Report. 

  

	 	5.	You may rely upon our Reports in the same manner as if such report were addressed to you. 

  
 Annex F-1 

 We hereby consent to the references to our firm and the use of the Reports as set forth in the
Offering Memorandum. 
 This letter is solely for the information of the addressees and to assist the addressees in documenting their
investigations in connection with the offering of the securities covered by the Offering Memorandum. 

  
 Annex F-2

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00221-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00221-of-00352.parquet"}]]