We urge each stockholder to promptly sign and return the enclosed proxy card or to use telephone or Internet voting. See our Questions and Answers about the Meeting and Voting section for information about voting by telephone or Internet, how to revoke a proxy and how to vote shares in person.

IMPORTANT NOTICE REGARDING THE AVAILABILITY OF PROXY MATERIALS FOR

THE 2013 ANNUAL MEETING OF STOCKHOLDERS TO BE HELD ON APRIL 23, 2013.

The Company’s Proxy Statement for the 2013 Annual Meeting of Stockholders, Annual Report to Stockholders for the fiscal year ended December 31, 2012 and Annual Report on Form 10-K for the fiscal year ended December 31, 2012 are available at https://materials.proxyvote.com/655044.

A Proxy Statement is a document that the regulations of the Securities and Exchange Commission (“SEC”) require us to give you when we ask you to sign a proxy designating individuals to vote on your behalf. A proxy is your legal designation of another person to vote the stock you own. That other person is called a proxy. If you designate someone as your proxy in a written

document, that document is also called a proxy or a proxy card. We have designated two of our officers as proxies for the 2013 Annual Meeting of Stockholders. These officers are Charles D. Davidson and Kenneth M. Fisher.

By Written Proxy. All stockholders of record can vote by written proxy card. If you are a beneficial owner, you may request a written proxy card or a vote instruction form from your bank or broker.

By Telephone or Internet. All stockholders of record can also vote by touchtone telephone from the U. S. using the toll-free telephone number on the proxy card, or through the Internet, using the procedures and instructions described on the proxy card. Beneficial owners may vote by telephone or Internet if their bank or broker makes those methods available, in which case the bank or broker will include the instructions with the

proxy materials. The telephone and Internet voting procedures are designed to authenticate stockholders’ identities, to allow stockholders to vote their shares and to confirm that their instructions have been recorded properly.

In Person. All stockholders of record may vote in person at the meeting. Beneficial owners may vote in person at the meeting if they have a legal proxy, as described in the response to question 6.

If you are a stockholder of record, you will receive only one proxy card for all the shares of common stock you hold in certificate form, in book-entry form and in any Company benefit plan.

If you hold shares of common stock in any Company benefit plan and do not vote your shares or specify your voting instructions on your proxy card, the administrators of the benefit plans will not vote your benefit plan shares.

You need to bring documentation showing that you owned common stock on the record date, March 6, 2013. You also need to bring a photo ID to gain admission. Please note that the use of cameras, recording equipment, cellular telephones, smartphones or other similar equipment or packages will not be allowed in the meeting room. If you are a beneficial owner, bring the notice or voting instruction form you

received from your bank, brokerage firm or other nominee for admission to the meeting. You may also bring your brokerage statement reflecting your ownership of common stock as of March 6, 2013 with you to the meeting. Please note that you will not be able to vote your shares at the meeting without a legal proxy, as described in the response to question 6.

You will need to ask your broker, bank or other intermediary to furnish you with a legal proxy. You will need to bring the legal proxy with you to the meeting and hand it in with a signed ballot that will be provided to you at the meeting. You will not be able to vote your shares at the meeting without a legal proxy. In time, you can follow the procedures described in the response to question 5 to gain admission to the meeting. However, you will not be able to vote your shares at the meeting.

Accordingly, we encourage you to vote your shares in advance, even if you intend to attend the meeting.

Please note that if you request a legal proxy, any previously executed proxy will be revoked and your vote will not be counted unless you appear at the meeting and vote in person or legally appoint another proxy to vote on your behalf.

Directors in uncontested elections will be elected by a majority of the votes cast by the holders of the shares of our common stock voting in person or by proxy at the meeting. A majority of the votes cast means that the number of votes cast “for” a director nominee must exceed the number of votes cast “against” that director nominee. The proposals to ratify the appointment of the independent auditor and to approve executive compensation each require approval by holders of a majority of shares of our common stock represented in person or by proxy at the meeting. We also are requiring approval from holders of a majority of shares of our common stock represented at the meeting in person or by proxy for approval of the proposal to amend our By-Laws. The proposal to approve the amendment and restatement

of the 1992 Plan requires the affirmative vote of the majority of votes cast for such proposal, provided that the total votes cast (whether “for,” “against” or “abstain”) represent a majority of our outstanding shares of common stock. The proposal to amend our Certificate of Incorporation requires the approval of the holders of a majority of our outstanding shares of common stock.

As an advisory vote, the proposal to approve executive compensation is not binding upon the Company. However, the Compensation Committee, which is responsible for overseeing the Company’s executive compensation program, values the opinions expressed by stockholders and will consider the outcome of the vote when making future compensation decisions.

Stockholders should specify their choice for each matter on the proxy card. If no specific instructions are given, proxies which are signed and returned will be voted:

As a beneficial owner, in order to ensure your shares are voted in the way you would like, you must provide voting instructions to your bank, broker or other nominee by the deadline provided in the materials you receive from your bank, broker or other nominee. If you do not provide voting instructions to your bank, broker or other nominee, whether your shares can be voted by such person depends on the type of item being considered for vote.

Non-Discretionary Items. The election of directors, advisory proposal to approve executive compensation, amendment and restatement of the 1992 Stock Option

Plan, amendment of the Certificate of Incorporation and amendment of the By-Laws, are non-discretionary items and may not be voted on by brokers, banks or other nominees who have not received specific voting instructions from beneficial owners.

Discretionary Items. The ratification of the appointment of the independent auditor is a discretionary item. Generally, brokers, banks and other nominees that do not receive voting instructions from beneficial owners may vote on this proposal in their discretion.

Stockholders can revoke a proxy prior to the completion of voting at the meeting by:

We will not disclose the votes of specific stockholders to directors, officers and employees except:

We will continue to retain an independent inspector of election to tabulate the proxies and certify the results.

We bear all expenses incurred in connection with the solicitation of proxies. We have engaged Okapi Partners LLC to assist with the solicitation of proxies for an estimated fee of $11,500 plus expenses. We will bear the reasonable expenses incurred by banks, brokerage

firms, custodians, nominees and fiduciaries in forwarding proxy material to beneficial owners. Our directors, officers and employees may also solicit proxies by mail, telephone and personal contact. They will not receive any additional compensation for these activities.

You may contact any member of our Board, any Board committee or any chair of any such committee by mail, electronically or by calling our independent, toll-free compliance line. To communicate by mail with our Board, any individual director, or any group or committee of directors, correspondence should be addressed to our Board or any individual director or group or committee of

directors by either name or title. All correspondence should be sent to the Company Secretary at the address shown in this Proxy Statement. To communicate with any of our directors electronically, stockholders should go to our website. Under the heading “About Us — Corporate Governance” you will find a link “Contact the Board” that may be used for writing an electronic

message to our Board, any individual director, or any group or committee of directors. In addition, stockholders may call our independent, toll-free compliance line listed on our website under the same link.

All stockholder communications properly received will be reviewed by the office of our General Counsel to

determine whether the contents represent a message to our directors. Any contents that are not in the nature of advertising, promotions of a product or service, or patently offensive material will be forwarded promptly to the appropriate director or directors.

We have attempted to include definitions for capitalized terms, abbreviations and acronyms at the place in this Proxy Statement where they are first used. We have

also included a quick reference glossary beginning on page 76.

Our website contains a number of documents helpful to your understanding of our corporate governance practices:

You may also obtain copies of these corporate governance documents by contacting the Company Secretary. Instructions on how to communicate with the Company’s directors are included in response to question 18 in the Questions and Answers section. (page 5)

The Board regularly reviews developments in corporate governance and updates its corporate governance documents and practices as it deems necessary and appropriate.

Chairman and Chief Executive Officer

Our Board currently combines the role of chairman of the board with the role of chief executive officer (“CEO”), and maintains a separate empowered lead independent director position to strengthen our governance structure. Our Board believes this provides an efficient and effective leadership model for the Company. Combining the two roles fosters clear accountability, effective decision-making and alignment on corporate strategy. We have not experienced any problematic governance or management issues resulting from our combining of the two roles and, in this combined role, Mr. Davidson has provided strategic, operational and technical expertise, vision and a proven ability to lead the Company.

Our Board recognizes that no single leadership structure is right for all companies and at all times and that, depending on the circumstances, other leadership models, such as a separate independent chairman of the board, might be appropriate.

Lead Independent Director

Our Lead Independent Director, currently Michael A. Cawley, is elected annually by our Board and has authority described in our Corporate Governance Guidelines that generally includes:

In 2012, our Board held 12 meetings and committees of the Board held 20 meetings. Each director attended 75% or more of the aggregate of all meetings of the Board and the committees on which the director served during 2012.

Our Board has the following four committees, each with a written charter adopted by the Board and available on our website:

The following table summarizes the primary purposes of each committee.

Our risk management program is overseen by our Board and its committees, with support from our management and external consultants.

Our Board

Our Audit Committee

Our Governance Committee

Our EH&S Committee

Our Compensation Committee

Our management

Our external consultants

Succession planning

A key responsibility of our CEO and Board in the area of risk management is ensuring that an effective process is in place to provide continuity of Company leadership over the long-term. Each year, a review of senior leadership succession is conducted by our Board. During this review, the CEO and the independent directors discuss candidates for senior leadership positions, succession timing for those positions and development plans for the highest-potential candidates. This process ensures continuity of leadership over the long-term and forms the basis upon which the Company makes ongoing leadership assignments.

We have adopted a Code of Business Conduct and Ethics that applies to our directors, officers and employees and sets out our policy regarding laws and business conduct, contains other policies relevant to business conduct and sets out a process for reporting violations thereof. On January 28, 2013, our Board approved an amendment to our code to include a compensation recoupment or

“clawback” provision, by which our Compensation Committee may recover incentive-based compensation from our current or former executive officers and other employees in cases involving restatements of financials or oil and gas reserves, or material noncompliance with our codes of ethics.

We have also adopted a Code of Ethics for Chief Executive and Senior Financial Officers, violations of which are to be reported to our Audit Committee.

A copy of these codes can be obtained free of charge from our website, or by written request to the attention of the Company Secretary. Amendments to these codes will be promptly posted on our website.

Director Independence

The standards applied by our Board in affirmatively determining whether a director is “independent” in compliance with the listing standards of the NYSE generally provide that a director is not independent if:

In addition to these objective standards, our Board has adopted a general standard, also in compliance with the NYSE listing standards, to the effect that no director qualifies as “independent” unless the Board affirmatively determines that the director has no material relationship with the Company that could interfere with the director’s ability to exercise independent judgment. Our Board exercises appropriate discretion in identifying and evaluating the materiality of any relationships directors may have with us or with parties that conduct business with us.

On February 4, 2013, and again on March 14, 2013, our Board reviewed our directors’ relationships with the Company (and those of their immediate family members), including information related to transactions, relationships or arrangements between the Company and our directors or parties related to our directors. The following table contains a description of relations and arrangements considered by our Board in confirming its determination that these directors are independent.

After reviewing these categories or types of transactions, relationships and arrangements, and after applying the NYSE independence standards described above, our Board affirmatively determined that no material relationship existed that would interfere with the ability of Messrs. Berenson, Cawley, Cox, Edelman, Grubman, Hedrick, Urban or Van Kleef to exercise independent judgment and that each is independent for Board membership purposes. On March 14, 2013, our Board conducted a similar review as to Ms. Williamson, likewise finding her to be independent for Board membership purposes. Our Board has also determined that all members of our Audit Committee, Compensation Committee and Governance Committee are independent under the NYSE independence standards and applicable SEC rules.

Related Person Transactions

We review all relationships and transactions in which the Company and our directors and executive officers or their immediate family members are participants to determine whether such persons have a direct or indirect material interest. We have developed and implemented processes and controls to obtain information from our directors and executive officers with respect to related person transactions and for then determining, based on the facts and circumstances, whether the Company or a related person has a direct or indirect material interest in the transaction.

As required under SEC rules, transactions that are determined to be directly or indirectly material to the Company or a related person are disclosed in our annual Proxy Statement. In addition, our Governance Committee or Board (if appropriate) reviews and approves or ratifies any related person transaction that is required to be disclosed. In the course of its review and approval or ratification of a disclosable related person transaction, consideration is given to:

Any director who is a related person with respect to a transaction under review may not participate in the deliberations or vote respecting approval or ratification of the transaction; but that director may be counted in determining the presence of a quorum at the meeting where the transaction is considered.

Since the beginning of fiscal year 2012, there have been no transactions in excess of $120,000 between the

Company and a related person in which the related person had a direct or indirect material interest.

As of the date of this Proxy Statement, our Board consists of ten directors, nine of whom are independent. The business experience of each nominee as well as the qualifications that led our Board to select each nominee

for election to the Board is discussed below. All directors are elected annually to serve until the next annual meeting and until their successors are elected.

Our By-Laws provide that the number of directors shall be determined by the Board, which has set the number at ten; and that in an election where the number of nominees does not exceed the number of directors to be elected, each director must receive the majority of the votes cast with respect to that director.

Our Board will nominate candidates for election or re-election who agree to tender, promptly following the annual meeting, irrevocable resignations that will be effective upon (a) the failure to receive the required vote at the next annual meeting and (b) acceptance by the Board. In addition, our Board will fill director vacancies and new directorships only with candidates who agree to

tender the same form of resignation promptly following their appointment to the Board.

If an incumbent director fails to receive the required vote for re-election, then, within 90 days following certification of the stockholder vote, our Governance Committee will act to determine whether to accept the director’s resignation and will submit its recommendation for prompt consideration by our Board. The Board will promptly act on the resignation, taking into account the recommendation of the Governance Committee, and publicly disclose its decision and rationale.

Our Governance Committee is responsible for identifying and evaluating nominees for director and for recommending to the Board a slate of nominees for election at each Annual Meeting of Stockholders. Nominees may be suggested by directors, members of management, stockholders or, in some cases, by a third-party firm.

Stockholders who wish the Governance Committee to consider their recommendations for nominees for the position of director should submit a recommendation in

writing to the Governance Committee, in care of the Company Secretary, at least 120 calendar days before the anniversary date of the immediately previous year’s annual meeting. Stockholder nominees for directors to be submitted for inclusion in our 2014 Proxy Statement must be received by us by December 24, 2013. Our Corporate Governance Guidelines specify the processes for evaluating nominees for director and the requirements for a stockholder recommendation for a director nominee.

Our Governance Committee believes that the minimum qualifications for serving as a director of the Company are that a nominee demonstrate, by significant accomplishment in his or her field, an ability to make a meaningful contribution to our Board’s oversight of the business and affairs of the Company and have an impeccable record and reputation for honest and ethical conduct in both his or her professional and personal activities. Nominees for director shall be those people who, after taking into account their skills, expertise, integrity, diversity, character, judgment, age, independence, corporate experience, length of service, potential conflicts of interest and commitments (including, among other things, service on the boards or comparable governing bodies of other public companies,

private business companies, charities, civic bodies or similar organizations) and other qualities, are believed to enhance our Board’s ability to manage and direct, in an effective manner, the affairs and business of the Company, including, when applicable, to enhance the ability of the committees of our Board to fulfill their duties and to satisfy any independence requirements imposed by law, regulation or listing standards of the NYSE.

In general, nominees for director should have an understanding of the workings of large business organizations such as the Company and senior level executive experience, as well as the ability to make independent, analytical judgments, the ability to be an effective communicator and the ability and willingness to

devote the time and effort to be an effective and contributing member of our Board. In addition, our Governance Committee will examine a candidate’s specific experiences and skills, time availability in light of other commitments, potential conflicts of interest and independence from management and the Company. Our Governance Committee will also seek to have our Board represent a diversity of backgrounds, experience, gender and race.

Our Governance Committee annually reviews its long-term plan for Board composition, giving consideration to the foregoing factors. Based on this review and subsequent discussions, the committee concluded that the Board would benefit by the addition of a director with broad experience in foreign policy, in particular with respect to the Company’s Eastern Mediterranean operations. As a result, on March 14, 2013, Molly K. Williamson was elected to the Board.

Upon recommendation of the Governance Committee, the Board has nominated Jeffrey L. Berenson, Michael A. Cawley, Edward F. Cox, Charles D. Davidson, Thomas J. Edelman, Eric P. Grubman, Kirby L. Hedrick, Scott D. Urban, William T. Van Kleef and Molly K. Williamson for election as director. All of the nominees are independent under NYSE corporate governance rules, except Charles D. Davidson.

Each of the director nominees currently serves on the Board and, with the exception of Ms. Williamson, was elected by the stockholders at the 2012 Annual Meeting of Stockholders. If elected, each nominee will hold office until the 2014 Annual Meeting of Stockholders and until his or her successor is elected and qualified.

We have no reason to believe that any of the nominees will be unable or unwilling to serve if elected. However, if any nominee should be unable for any reason or unwilling for good cause to serve, proxies may be voted for another person nominated as a substitute by the Board, or the Board may reduce the number of Directors.

The Board believes that the combination of the various qualifications, skills and experiences of the 2013 director nominees would contribute to an effective and well-functioning Board. The Board and the Governance Committee believe that, individually and as a whole, the Board possesses the necessary qualifications to provide effective oversight of the business and quality advice and counsel to the Company’s management.

Non-employee directors received the following cash fees for 2012, paid pro rata on a monthly basis:

Non-employee directors are also entitled to participate in our Non-Employee Director Fee Deferral Plan by which all or a portion of their director fees may be deferred for future payment by the Company. None elected to do so in 2012. We also reimburse directors for travel, lodging and related expenses they incur in attending Board and committee meetings and director continuing education programs relevant to their service on our Board.

The 2005 Stock Plan for Non-Employee Directors of Noble Energy, Inc. (the “2005 Plan”) provides for grants of stock options and awards of restricted stock to our non-employee directors.

Options are issued with an exercise price equal to the market price of our common stock on the date of grant and may be exercised beginning one year after the date of grant. The options expire ten years from the date of grant. Restricted stock is restricted for a period of one year from the date of award.

Newly elected non-employee directors receive on the date of initial election to our Board a grant and award

with a total value of $250,000 to be allocated one-half to stock options and one half to restricted stock. On December 5, 2011, our Board agreed to set annual equity grants and awards at a total value of $200,000, to be made effective on February 1 and allocated one-half to stock options and one-half to restricted stock.

Accordingly, our Board approved annual grants and awards to each non-employee director of 2,514 stock options and 982 shares of restricted stock effective February 1, 2012 and 2,355 stock options and 916 shares of restricted stock effective February 1, 2013. Ms. Williamson received a grant of 2,717 stock options and an award of 1,078 shares of restricted stock upon her election to our Board on March 14, 2013.

The Audit Committee of our Board has appointed the firm of KPMG LLP to serve as our independent auditor for the fiscal year ending December 31, 2013. This firm has audited our accounts since May 2002. Although action by our stockholders on this matter is not required, our Audit Committee believes that it is important to seek stockholder ratification of this appointment in light of the critical role played by our independent auditor in maintaining the integrity of our financial controls and reporting.

One or more representatives of KPMG LLP are expected to be present at our annual meeting and will be able to make a statement if they so desire and respond to appropriate questions.

Our Board recommends that stockholders vote FOR the ratification of the appointment of KPMG LLP as our independent auditor.

The Audit Committee approves all audit and non-audit services to be provided by our independent auditor prior to the receipt of such services. The Audit Committee Chair has the authority to pre-approve services of up to $25,000 rendered by our independent auditor. Any pre-approval of services by the Audit Committee Chair is reported to the Audit Committee at its next scheduled meeting.

All audit-related services, tax services and other services for 2012 set forth in the table above were pre-approved by the Audit Committee Chair or the Audit Committee, as provided above, which in either case determined that such services would not impair the independence of our auditor and are consistent with the SEC’s rules on auditor independence.

As we do each year, and as required by Section 14A of the Exchange Act, we provide our stockholders with the opportunity to vote to approve, on a nonbinding advisory basis, the compensation of our Named Executive Officers as disclosed in this Proxy Statement in accordance with the SEC’s compensation disclosure rules.

As described in our Compensation Discussion and Analysis in this Proxy Statement, we seek to link compensation strongly to performance through financial incentives that are tied to the Company’s operational and financial results. Our compensation programs are designed to reward our Named Executive Officers for the achievement of short- and long-term strategic and operational goals and the achievement of increased total stockholder return, while at the same time avoiding the encouragement of unnecessary or excessive risk-taking.

We believe the Company had a strong year in 2012. The Company’s total stockholder return was 9%, which was the seventh highest total stockholder return among our 15-company compensation peer group for that period, and our cumulative stockholder return for the past three fiscal years was 47%.

Noble Energy delivered significant growth in 2012. Expansion of our horizontal Niobrara and Marcellus Shale developments resulted in a 24% increase in Wattenberg (DJ Basin, Colorado) production and a fourfold increase in Marcellus Shale (Pennsylvania and West Virginia) production. We realized further production increase from major new developments at Aseng (offshore Equatorial Guinea) and Galapagos (deepwater Gulf of Mexico), which came on line in 2011 and 2012, respectively. We moved forward on our major development projects, each of which will yield significant new production in future years; discovered new resources at Big Bend in the deepwater Gulf of Mexico and Carla, offshore Equatorial Guinea; and farmed into new opportunities offshore the Falkland Islands and Sierra Leone. Finally, we enhanced our portfolio with selective divestitures of non-core, onshore U.S. and North Sea properties, and maintained our strong balance sheet.

2012 operational highlights include:

The vote on this resolution is not intended to address any specific element of compensation; rather, the vote relates to the compensation of our Named Executive Officers as disclosed in this Proxy Statement in accordance with the SEC’s compensation disclosure rules. The vote is advisory, which means that it is not binding on the Company, our Board or the Compensation Committee of our Board. To the extent there is any significant vote against our Named Executive Officer compensation as disclosed in this Proxy Statement, our Compensation Committee will evaluate whether any actions are necessary to address the concerns of stockholders.

Accordingly, we ask our stockholders to vote on the following resolution at our annual meeting:

“RESOLVED, that the Company’s stockholders approve, on an advisory basis, the compensation of the Named Executive Officers, as disclosed in the Company’s Proxy Statement for the 2013 Annual Meeting of Stockholders pursuant to the compensation disclosure rules of the Securities and Exchange Commission, including the Compensation Discussion and Analysis, the 2012 Summary Compensation Table and the other related tables and disclosure.”

Our Board recommends that stockholders vote FOR the approval of the compensation of our Named Executive Officers as disclosed in this Proxy Statement.

At the 2013 annual meeting, our stockholders are being asked to approve an amendment and restatement of the 1992 Plan that will increase the number of shares of common stock authorized for issuance under the plan

from 31,000,000 shares to 35,800,000 shares (an increase of 4,800,000 shares). Our Board approved this amendment on January 28, 2013, subject to stockholder approval at our annual meeting.

Our Board recommends approval of the amendment and restatement of the 1992 Plan. The proposed increase in the number of shares authorized for issuance under the plan would enable the continued use of the 1992 Plan for stock-based grants and awards consistent with the objectives of our compensation program.

We believe that the success of our compensation program, including the responsible use of equity compensation, is well-evidenced by the performance of our common stock over the last several years.

The use of stock-based grants and awards under the 1992 Plan continues to be an important part of our compensation program. Of the 31,000,000 shares currently authorized for issuance under the plan, 4,281,284 shares remain as of March 6, 2013. We do not believe that this leaves sufficient shares available for more than one additional year of grants and awards. By increasing the number of shares authorized for issuance

under the 1992 Plan by 4,800,000, a total of 35,800,000

shares would be available. This increase would give us the flexibility to continue to responsibly address our future equity compensation needs.

As of the record date of March 6, 2013, there were a total of 178,773,698 shares of our common stock issued and outstanding. In addition to the shares remaining available for issuance under the 1992 Plan, there were 450,705 shares available for grant or award under the 2005 Stock Plan for Non-Employee Directors of Noble Energy, Inc. The Company had a total of 7,087,462 stock options outstanding with a weighted average exercise price of $76.99 and a weighted average remaining term of 6.7 years, and 1,225,846 shares of restricted stock outstanding, as of the record date.

The proposed amendment will not be implemented unless approved by our stockholders. If the proposed amendment is not approved by our stockholders, the 1992 Plan will remain in effect in its present form.

General

Our 1992 Plan is an essential component of our compensation program and is designed to attract, retain and motivate high-quality employees by:

Cash awards may also be granted under the 1992 Plan, although no such awards have been made.

Shares Available for Issuance

The total number of shares of common stock currently available for issuance under the 1992 Plan is 31,000,000. Of those, no more than 7,000,000 shares

may be issued after April 26, 2011 pursuant to incentive options. The maximum number of shares of common stock for which options and stock appreciation rights (“SAR”) may be granted, and which may be awarded as restricted stock, to any one person during any calendar year is 400,000.

When determining the number of shares of common stock available for grants and awards made under the 1992 Plan on or after April 26, 2011, each share subject to an option is counted against the plan share limit as one (1) share, and each share of common stock awarded as restricted stock is counted against the plan share limit

as 2.39 shares. Prior to April 26, 2011, each share of common stock awarded as restricted stock counted against the plan share limit as one (1) share.

Shares of common stock covered by an option that expires or terminates prior to exercise and shares of restricted stock returned to the Company upon forfeiture are again available for grant or award. Shares of common stock tendered or withheld to satisfy an exercise price or tax withholding obligation for an option, SAR or restricted stock will not again be available for issuance under the 1992 Plan.

Our 1992 Plan contains anti-dilution provisions that apply in the event of a stock dividend or a stock split, combination or exchange of our shares that results from a recapitalization, merger or other restructuring in which the Company is the surviving company. In that event,

adjustments will be made in the maximum number of shares subject to the 1992 Plan and the number of shares and option prices under outstanding options.

Administration

Our 1992 Plan is administered by the Compensation Committee, which is and will be composed of independent directors of the Company. Subject to the provisions of the 1992 Plan, the Compensation Committee has the authority to select the participants who will receive the grants and awards, to determine the type and terms of the grants and awards, and to interpret and administer the 1992 Plan. The Compensation Committee may delegate to our CEO the responsibility for the limited non-officer inducement grants to the extent not inconsistent with applicable laws or regulations.

Eligibility

All of our regular salaried executive officers and other employees and those of our affiliates are eligible to participate in the 1992 Plan. As of March 6, 2013, all of our executive officers and approximately 700 other current employees participate in the 1992 Plan.

Market Value

On March 6, 2013, the reported closing price per share of our common stock on the NYSE was $109.92.

Options granted under the 1992 Plan may be either incentive options or nonqualified options, or a combination. An option is exercisable at such times and upon such terms as the Compensation Committee determines; provided that no option may be exercisable more than ten years after the date of grant. Upon exercise, a participant may pay the option exercise price of a stock option in cash (or equivalents), in shares of Company common stock that he or she already owns, or such other consideration as the Compensation Committee approves.

SARs may be granted as part of an option. SARs generally will be subject to the same terms and exercisable to the same extent as the associated option. SARs are a right to receive a payment, in cash or shares of common stock or a combination (as determined by the Compensation Committee), equal to any excess of the fair market value (on the date of exercise) of a stated number of shares of common stock over the exercise price stated in the award agreement.

Option Price

The option exercise price may not be less than the “fair market value” of a share of common stock on the date of grant. The fair market value is the per share closing price of common stock on the applicable date, and if not a trading date, the closing price for the preceding day on which sales of common stock were made.

Restricted Stock

The Compensation Committee may award shares of common stock subject to specific restrictions to eligible individuals. The Compensation Committee will determine the nature and extent of the restrictions on the shares, the duration of the restrictions, and any circumstance of forfeiture. During the period of restriction, recipients will have the right to receive dividends and the right to vote the shares.

The Compensation Committee may waive any outstanding restrictions prior to the end of the restricted period. If the terms and conditions for the removal of the restrictions on the restricted stock are not satisfied, the restricted stock is forfeited and returned to the Company.

Cash Awards

Cash awards may be awarded by the committee to eligible recipients. Any cash award would be in addition to any payments or grants under our short-term incentive plan. A cash award provides for the payment of a cash bonus upon the achievement of stated performance goals. The committee determines the terms, restrictions and limitations that apply to a cash award. The maximum amount that may be paid under all cash awards to any one person under the 1992 Plan during any one calendar year may not exceed $4,000,000.

Performance Awards

The Compensation Committee may grant performance awards to eligible individuals that are contingent upon the achievement of one or more performance measures. Performance awards may be settled in cash or stock, as determined by the committee.

The performance criteria that may be used consist of objective tests based on the following:

Each agreement for a performance award will explain (a) the maximum amount that may be earned in the form of cash or shares of common stock, as applicable, (b) the performance goal or goals and level of achievement that will apply to the award, (c) the performance period over which performance is measured, and (d) other terms that the committee may determine that are not inconsistent with the 1992 Plan.

Prior to the payment of any compensation pursuant to a performance award, the Compensation Committee must determine and then certify in writing that the applicable performance goal or goals and other material terms of the award have been satisfied. The committee also has the authority to reduce, but not to increase, the amount payable in cash and the number of shares of common stock to be issued, retained or vested pursuant to a performance award.

The Board may at any time amend, suspend or terminate our 1992 Plan but may not, without the approval of the stockholders of the Company:

Additionally, the Board may not, without the consent of the recipient, amend or cancel any outstanding award in a manner that adversely affects the recipient in a material way.

The following is a summary of the U.S. federal income tax consequences arising from grants and awards under the 1992 Plan. The tax consequences vary depending upon particular circumstances, and the income tax laws, regulations and interpretations thereof change frequently. Participants should rely upon their own tax advisors for advice concerning the specific tax consequences applicable to them, including the applicability and effect of state, local, and foreign tax laws. This summary is not intended or written to be used, and cannot be used, by any person for the purpose of avoiding penalties that may be imposed under U.S. federal tax laws.

Nonqualified Options

A participant will not recognize taxable income upon the grant of a non-qualified stock option, but will have taxable income at the time of exercise equal to the excess of the fair market value of the shares on the date of exercise over the exercise price. We are entitled to a tax deduction for the same amount at the same time.

Incentive Options

A participant will not recognize taxable income upon the grant of an incentive stock option and also will not recognize income for federal income tax purposes at the time of exercise, but in some circumstances may be subject to alternative minimum tax as a result of the exercise. If the participant does not dispose of the shares acquired pursuant to an incentive stock option before the later of two years from the date of grant or one year from the date of exercise, any gain or loss realized on a subsequent disposition of the shares will be treated as a long-term capital gain or loss. Under these circumstances, we will not be entitled to any deduction for federal income tax purposes. If the participant fails to hold the shares for that period, the disposition is treated as a disqualifying disposition requiring the participant to recognize taxable income equal to the excess of the fair market value on the exercise date over the exercise price (but in most cases not more than the gain realized on the disposition). Any additional amount realized upon the disposition is taxable as long-term or short-term capital gain. If a disqualifying disposition occurs, we will be entitled to a tax deduction equal to the ordinary income amount the participant recognizes.

SARs

A participant will not recognize taxable income upon the grant of a stock appreciation right. Upon the exercise of

a stock appreciation right the participant must recognize taxable income equal to the amount of cash or the fair market value of the shares received on exercise, and we are entitled to a corresponding tax deduction in the same amount.

Restricted Stock

A participant will not recognize taxable income upon the receipt of an award of restricted stock (unless the participant elects to accelerate the income under Section 83(b) of the Internal Revenue Code). When the restrictions lapse, the participant will recognize taxable income in an amount equal to the excess of the fair market value of the shares at that time over the amount, if any, paid for the shares. We will be entitled to a corresponding tax deduction. Dividends on restricted stock accumulated during the restriction period that are paid to the participant at the end of the restricted period will also be compensation income to the participant and will be deductible as compensation expense by us.

Cash Awards

An individual who receives a cash award will recognize ordinary income subject to withholding for federal income tax purposes at the time the cash is received (or, if earlier, the date the cash is made available to the individual). We will be entitled to a deduction for the amount of the cash award at such time.

Performance Awards

A participant will not recognize taxable income upon the grant of a performance award, but will recognize taxable income at the time the award is paid equal to the amount of cash paid or the value of shares delivered, and we will be entitled to a corresponding tax deduction.

Limitations on the Company’s Compensation Deduction

Section 162(m) of the Internal Revenue Code limits the deduction that the Company may take for compensation payable to certain officers of the Company to the extent that compensation paid to any such officer for the year exceeds $1,000,000, but not counting any compensation that is performance-based. The 1992 Plan has been designed so that awards of nonqualified options and incentive options and SARs may qualify as performance- based compensation for this purpose. In addition, awards

of restricted stock and cash awards that are designed to

satisfy the requirements for performance awards are intended to qualify as performance-based compensation for this purpose.

Section 280G of the Internal Revenue Code limits deductions for compensation payable to certain individuals if the compensation constitutes an “excess parachute payment.” Accelerated vesting or payment of awards under the 1992 Plan upon a change in

ownership or control of the Company could result in excess parachute payments. A disqualified individual receiving an excess parachute payment is subject to a 20 percent excise tax on the amount of the payment.

Our Board recommends that stockholders vote FOR the approval of the proposed amendment and restatement of our 1992 Plan.

Our Board has approved, and recommends your approval of, an amendment to the Company’s Certificate of Incorporation to add a new Article which would provide that, unless the Company consents in writing to the selection of an alternative forum, the Court of Chancery of the State of Delaware will be the exclusive forum for (a) any derivative action or proceeding brought on behalf of the Company, (b) any action asserting a claim of breach of a fiduciary duty owed by any director, officer or other employee of the Company to the Company or its stockholders, (c) any action asserting a claim arising pursuant to any provision of the Delaware General Corporation Law, or (d) any action asserting a claim governed by the internal affairs doctrine, except for any such action in which the Court of Chancery in the State of Delaware concludes that an indispensable party is not subject to the jurisdiction of the Delaware courts or any such action in which a federal court has assumed exclusive jurisdiction of a proceeding.

The Board is aware that certain proxy advisors, and even some institutional holders, take the view that they will not support an exclusive forum clause until the company requesting it can show it already has suffered material harm as a result of multiple stockholder suits filed in different jurisdictions regarding the same matter. As a Company we have maintained strong governance practices, many of which are described in this Proxy Statement, including a highly independent board that is elected annually, a majority vote standard in uncontested director elections, a separate and empowered Lead Independent Director, the absence of a “poison pill” and a comprehensive risk management program. In light of those practices the Board believes that it is more prudent to take preventive measures before the Company and almost all of its stockholders are harmed by the increasing practice of lawsuits being filed in plaintiff’s favorite jurisdictions, not after.

The Board believes that our stockholders will benefit from having intra-company disputes litigated in the Delaware Chancery Courts. Although some plaintiffs might prefer to litigate matters in a forum outside of Delaware because another court may be more convenient or viewed as being more favorable to them (among other reasons), the Board believes that the benefits to the Company and its non-filing stockholders outweigh these concerns. Delaware offers a system of specialized Chancery Courts to deal with corporate law questions, with streamlined procedures and processes

that help provide relatively quick decisions. This accelerated schedule can limit the time, cost and uncertainty of litigation for all parties. These courts have developed considerable expertise in dealing with corporate law issues, as well as a substantial and influential body of case law construing Delaware’s corporate law and long-standing precedent regarding corporate governance. This provides stockholders and the Company with more predictability regarding the outcome of intra-corporate disputes. In addition, adoption of this amendment would reduce the risk that the Company could be involved in duplicative litigation in more than one forum, as well as the risk that the outcome of cases in multiple forums could be inconsistent, even though each forum purports to follow Delaware law. This amendment gives the Board the flexibility to consent to an alternative forum in the appropriate instances.

Although exclusive jurisdiction provisions such as is proposed here are becoming increasingly common, and we know of no reason a court in another state would not be willing to enforce its terms, we cannot be sure that such a court would enforce the provision and transfer any covered proceeding to the Delaware courts.

The affirmative vote of the holders of a majority of our outstanding shares of common stock is required for approval of the proposed amendment to our Certificate of Incorporation. Abstentions will have the same effect as votes against approval of the proposed amendment. Shares of our common stock represented by executed but unmarked proxies will be voted for the proposed amendment.

If this amendment is approved by our stockholders, it will become effective upon the filing of a certificate of amendment with the Delaware Secretary of State, which we intend to do promptly following action by stockholders at the 2013 annual meeting. If this amendment is not approved by our stockholders, the certificate of amendment will not be filed with the Delaware Secretary of State. A copy of the proposed amendment is attached to this Proxy Statement as Appendix C.

Our Board recommends that stockholders vote FOR the approval of the proposed amendment to the Certificate of Incorporation.

Our Board has approved, and recommends your approval of, an amendment to the Company’s By-Laws to (a) clarify that broker non-votes and abstentions count towards a quorum but are not considered a vote for or against a proposal, (b) allow the Board to fix separate record dates for determining stockholders entitled to notice of, and to vote at, meetings, and (c) increase the age after which directors will not be eligible to be nominated for election from 70 to 75 years. A copy of the proposed amendment to our By-Laws is attached to this Proxy Statement as Appendix D.

Our Certificate of Incorporation expressly authorizes our Board to approve and enact amendments to our By-Laws and, consequently, stockholder approval of this proposal to amend our By-Laws is not required. Nevertheless, our Board values the opinions expressed by our stockholders and believes it is appropriate to present the proposed changes to our By-Laws to our stockholders for approval. If the proposed amendment to our By-Laws is not approved by our stockholders, our Board will not proceed with enactment of the amendment and, instead, will consider the outcome of the vote and reassess the proposed changes to our By-Laws at a later date.

Broker Non-Votes and Abstentions

Under the NYSE rules, brokers are prohibited from exercising discretionary authority to vote on “non-routine” items submitted at stockholder meetings when they have not received instructions from beneficial owners of shares of our common stock. In that instance, the beneficial owner of the shares may instruct the broker on how to vote those shares. However, when no instructions are received from beneficial owners with respect to such items (so-called “broker non-votes”), the shares they hold will have no effect on the vote.

The Company’s By-Laws specifically state that “abstentions” and “broker non-votes” will not be counted as a vote cast either “for” or “against” the election of a director of the Company. However, the By-Laws do not specify how abstentions and broker non-votes will affect the vote on other matters. The proposed revision to Article II, Section 9 of our By-Laws will resolve this ambiguity and specifically state that abstentions and broker non-votes will have no effect on the vote, regardless of the matter being considered.

Dual Record Dates

Companies typically set a single record date for determining stockholders entitled to receive notice of, and to vote at, a meeting. Because the SEC’s proxy rules generally require proxy materials to be distributed to stockholders several weeks in advance of a meeting, stockholders as of the record date may have sold their shares by the time of the meeting, creating a mismatch between voting rights and economic interest. To address this issue, Delaware law (which governs many public companies) was amended in 2009 to permit separate record dates for notice and voting.

The proposed revision to Article VII, Section 5 of our By-Laws would provide the Board the option of selecting both (a) an initial “notice” record date for the purpose of giving notice of the meeting to those stockholders owning shares on the initial date (which would be a date currently considered the “record date”) and then (b) a later “voting” record date (which could be a later date occurring before the date of the meeting) for the purpose of determining which stockholders would actually be entitled to vote at the meeting. Both dates would be identified to our stockholders in the initial notice of the stockholders meeting.

Director Mandatory Retirement Age

Article III, Section 1(b) of our By-Laws currently provides that a director candidate will not be eligible for election to our Board after his or her 70th birthday. Although the Board continues to believe that a mandatory retirement age for directors is appropriate, it recognizes that people are living longer, more productive lives than ever before, and therefore believes that a five-year increase in the maximum age of eligibility, from 70 years to 75 years, is appropriate. The Board believes that this revision will allow highly qualified and capable directors who have been able to develop, over a period of time, increasing insight into the Company and its operations, to provide ever more valuable advice to the Board as a whole.

We are requiring the affirmative vote of the holders of a majority of shares of common stock represented in person or by proxy and entitled to vote for approval of the proposed amendment to our By-Laws. Shares of our common stock represented by executed but unmarked proxies will be voted for the proposed amendment.

Our Board recommends that stockholders vote FOR the approval of the proposed amendment to the Company’s By-Laws.

Our goal continues to be to link compensation strongly to performance through financial incentives that are tied to the Company’s operational and financial results. 2012 was another strong year for the Company. The Company’s total stockholder return for 2012 was 9%, which was the seventh highest total stockholder return among our 15-company compensation peer group for that period. Our cumulative stockholder return for the past three fiscal years was 47%.

We delivered significant growth in 2012. Expansion of our horizontal Niobrara and Marcellus Shale developments resulted in a 24% increase in Wattenberg (DJ Basin, Colorado) production and a fourfold increase in Marcellus Shale (Pennsylvania and West Virginia) production. We realized further production increase from major new developments at Aseng (offshore Equatorial Guinea) and Galapagos (deepwater Gulf of Mexico), which came on line in 2011 and 2012, respectively. We moved forward on our major development projects, each of which will yield significant new production in future years; discovered new resources at Big Bend in the deepwater Gulf of Mexico and Carla, offshore Equatorial Guinea; and farmed into new opportunities offshore the Falkland Islands and Sierra Leone. Finally, we enhanced our portfolio with selective divestitures of non-core, onshore U.S. and North Sea properties, and maintained our strong balance sheet.

2012 operational and financial highlights include:

Our 2012 operational and financial results, along with the individual performance of our executive officers, served as key factors in determining compensation for 2012, including:

We encourage you to read this Compensation Discussion and Analysis for a detailed discussion and analysis of our executive compensation program, including information about the 2012 compensation of our Named Executive Officers and the link between compensation and Company performance.

We continue to seek ways to enhance our executive compensation program to ensure that it remains linked to Company performance, and are implementing a number of changes beginning in 2013: