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| Nevada                   | 95-2636730 |
| (State of Incorporation) | (I.R.S. Employer Identification No.) |

|                                                                                      |
|--------------------------------------------------------------------------------------|
|                                                                                      |  |
| Large accelerated filer  £                                            | Accelerated filer  x |
| Non-accelerated filer  £(Do not check if a smaller reporting company) | Smaller reporting company  o |

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Table of Contents

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|-----------------------------------|
|                                   |  |  |  |
|                              | PART I - FINANCIAL INFORMATION |   | Page |
|                              |   |   |   |
| Item 1.                           | Financial Statements |   | 5 |
|                              | Condensed Consolidated Balance Sheets |   | 5 |
|                              | Condensed Consolidated Statements of Operations |   | 6 |
|                              | Condensed Consolidated Statements of Cash Flows |   | 7 |
|                              | Notes to Condensed Consolidated Financial Statements |   | 8 |
|                              |   1.  Nature of Operations and Basis of Presentation |   |   |
|                              |   2.  Recent Accounting Standards |   |   |
|                              |   3.  Fair Value Measurements and Disclosures |   |   |
|                              |   4.  Derivative Financial Instruments |   |   |
|                              |   5.  Properties and Equipment |   |   |
|                              |   6.  Income Taxes |   |   |
|                              |   7.  Long-Term Debt |   |   |
|                              |   8.  Asset Retirement Obligations |   |   |
|                              |   9.  Commitments and Contingencies |   |   |
|                              | 10.  Common Stock |   |   |
|                              | 11.  Earnings Per Share |   |   |
|                              | 12.  Divestitures and Discontinued Operations |   |   |
|                              | 13.  Transactions with Affiliates and Other Related Parties |   |   |
|                              | 14.  Business Segments |   |   |
|                              | 15. Subsequent Events |   |   |
| Item 2.                           | Management’s Discussion and Analysis of Financial Condition and Results of Operations |   | 24 |
| Item 3.                           | Quantitative and Qualitative Disclosures About Market Risk |   | 37 |
| Item 4.                           | Controls and Procedures |   | 40 |
|                              |   |   |   |
| PART II – OTHER INFORMATION |
|                              |   |   |   |
| Item 1.                           | Legal Proceedings |   | 40 |
| Item 1A.                          | Risk Factors |   | 40 |
| Item 2.                           | Unregistered Sales of Equity Securities and Use of Proceeds |   | 43 |
| Item 3.                           | Defaults Upon Senior Securities |   | 44 |
| Item 4.                           | Mine Safety Disclosures |   | 44 |
| Item 5.                           | Other Information |   | 44 |
| Item 6.                           | Exhibits |   | 45 |
|                              |   |   |   |
|                              | SIGNATURES |   | 46 |

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|         |                                                                                                             |
|---------|-------------------------------------------------------------------------------------------------------------|
| • | changes in production volumes and worldwide demand, including economic conditions that might impact demand; |

|         |                                                                     |
|---------|---------------------------------------------------------------------|
| • | volatility of commodity prices for natural gas, NGLs and crude oil; |

|         |                                                                                                                                                                                                                                  |
|---------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| • | the impact of governmental fiscal terms and/or regulations, including changes in environmental laws, the regulation and enforcement related to those laws and the costs to comply with those laws, as well as other regulations; |

|         |                                                                                             |
|---------|---------------------------------------------------------------------------------------------|
| • | decline in the values of our natural gas and crude oil properties resulting in impairments; |

|         |                                          |
|---------|------------------------------------------|
| • | changes in estimates of proved reserves; |

|         |                                                                |
|---------|----------------------------------------------------------------|
| • | inaccuracy of reserve estimates and expected production rates; |

|         |                                                                                        |
|---------|----------------------------------------------------------------------------------------|
| • | the potential for production decline rates from our wells to be greater than expected; |

|         |                                                                                                    |
|---------|----------------------------------------------------------------------------------------------------|
| • | the timing and extent of our success in discovering, acquiring, developing and producing reserves; |

|         |                                                                                           |
|---------|-------------------------------------------------------------------------------------------|
| • | our ability to acquire leases, drilling rigs, supplies and services at reasonable prices; |

|         |                                                         |
|---------|---------------------------------------------------------|
| • | the timing and receipt of necessary regulatory permits; |

|         |                                                                                    |
|---------|------------------------------------------------------------------------------------|
| • | risks incidental to the drilling and operation of natural gas and crude oil wells; |

|         |                                                         |
|---------|---------------------------------------------------------|
| • | our future cash flow, liquidity and financial position; |

|         |                                          |
|---------|------------------------------------------|
| • | competition in the oil and gas industry; |

|         |                                             |
|---------|---------------------------------------------|
| • | the availability and cost of capital to us; |

|         |                                                             |
|---------|-------------------------------------------------------------|
| • | reductions in the borrowing base under our credit facility; |

|         |                                                                                                                                                  |
|---------|--------------------------------------------------------------------------------------------------------------------------------------------------|
| • | the availability of sufficient pipeline and other transportation facilities to carry our production and the impact of these facilities on price; |

|         |                                                           |
|---------|-----------------------------------------------------------|
| • | our success in marketing natural gas, NGLs and crude oil; |

|         |                                                                 |
|---------|-----------------------------------------------------------------|
| • | the effect of natural gas and crude oil derivatives activities; |

|         |                                                                                                                                    |
|---------|------------------------------------------------------------------------------------------------------------------------------------|
| • | the impact of environmental events, governmental responses to the events and our ability to insure adequately against such events; |

|         |                                           |
|---------|-------------------------------------------|
| • | the cost of pending or future litigation; |

|         |                                                                              |
|---------|------------------------------------------------------------------------------|
| • | the effect that acquisitions we may pursue have on our capital expenditures; |

|         |                                                                                     |
|---------|-------------------------------------------------------------------------------------|
| • | our ability to retain or attract senior management and key technical employees; and |

|         |                                                                                                   |
|---------|---------------------------------------------------------------------------------------------------|
| • | the success of strategic plans, expectations and objectives for future operations of the Company. |

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|                                                                                                                           |  |  |  |  |  |  |  |
|                                                                                                                      | March 31, 2012 |   | December 31, 2011 (1) |
| Assets                                                                                                                    |   |   |   |
| Current assets:                                                                                                           |   |   |   |
| Cash and cash equivalents                                                                                                 | $ | 1,655 |  |   | $ | 8,238 |  |
| Restricted cash                                                                                                           | 2,315 |  |   | 11,070 |  |
| Accounts receivable, net                                                                                                  | 64,019 |  |   | 59,923 |  |
| Accounts receivable affiliates                                                                                            | 9,534 |  |   | 8,518 |  |
| Fair value of derivatives                                                                                                 | 74,778 |  |   | 60,809 |  |
| Prepaid expenses and other current assets                                                                                 | 7,672 |  |   | 24,492 |  |
| Total current assets                                                                                                      | 159,973 |  |   | 173,050 |  |
| Properties and equipment, net                                                                                             | 1,329,460 |  |   | 1,301,716 |  |
| Assets held for sale                                                                                                      | — |  |   | 148,249 |  |
| Fair value of derivatives                                                                                                 | 36,751 |  |   | 41,175 |  |
| Accounts receivable affiliates                                                                                            | 2,147 |  |   | 2,836 |  |
| Other assets                                                                                                              | 37,238 |  |   | 30,979 |  |
| Total Assets                                                                                                              | $ | 1,565,569 |  |   | $ | 1,698,005 |  |
|                                                                                                                      |   |   |   |
| Liabilities and Equity                                                                                                    |   |   |   |
| Liabilities                                                                                                               |   |   |   |
| Current liabilities:                                                                                                      |   |   |   |
| Accounts payable                                                                                                          | $ | 56,152 |  |   | $ | 76,027 |  |
| Accounts payable affiliates                                                                                               | 11,682 |  |   | 10,176 |  |
| Production tax liability                                                                                                  | 19,170 |  |   | 18,949 |  |
| Fair value of derivatives                                                                                                 | 30,513 |  |   | 27,974 |  |
| Funds held for distribution                                                                                               | 30,093 |  |   | 28,594 |  |
| Accrued interest payable                                                                                                  | 5,069 |  |   | 11,243 |  |
| Other accrued expenses                                                                                                    | 12,583 |  |   | 22,083 |  |
| Total current liabilities                                                                                                 | 165,262 |  |   | 195,046 |  |
| Long-term debt                                                                                                            | 414,809 |  |   | 532,157 |  |
| Deferred income taxes                                                                                                     | 198,082 |  |   | 207,573 |  |
| Asset retirement obligations                                                                                              | 45,172 |  |   | 46,316 |  |
| Fair value of derivatives                                                                                                 | 25,815 |  |   | 21,106 |  |
| Accounts payable affiliates                                                                                               | 5,207 |  |   | 6,134 |  |
| Other liabilities                                                                                                         | 29,990 |  |   | 25,561 |  |
| Total liabilities                                                                                                         | 884,337 |  |   | 1,033,893 |  |
|                                                                                                                      |   |   |   |
| Commitments and contingent liabilities                                                                                    |  |   |  |
|                                                                                                                      |   |   |   |
| Shareholders' equity:                                                                                                     |   |   |   |
| Preferred shares, par value $0.01 per share;  authorized 50,000,000shares; issued: none                                   | — |  |   | — |  |
| Common shares, par value $0.01 per share; authorized 100,000,000shares; issued: 23,659,339 in 2012 and 23,634,958 in 2011 | 237 |  |   | 236 |  |
| Additional paid-in capital                                                                                                | 219,139 |  |   | 217,707 |  |
| Retained earnings                                                                                                         | 462,115 |  |   | 446,280 |  |
| Treasury shares, at cost: 6,944 in 2012 and 2,938 in 2011                                                                 | (259 | ) |   | (111 | ) |
| Total shareholders' equity                                                                                                | 681,232 |  |   | 664,112 |  |
| Total Liabilities and Equity                                                                                              | $ | 1,565,569 |  |   | $ | 1,698,005 |  |
|                                                                                                                      |   |   |   |

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|                                                              |  |  |  |  |  |  |  |
|                                                         | Three Months Ended March 31, |
|                                                         | 2012 |   | 2011 |
| Revenues:                                                    |   |   |   |
| Natural gas, NGL and crude oil sales                         | $ | 75,310 |  |   | $ | 58,810 |  |
| Sales from natural gas marketing                             | 11,834 |  |   | 15,202 |  |
| Commodity price risk management gain (loss), net             | 11,501 |  |   | (23,882 | ) |
| Well operations, pipeline income and other                   | 1,701 |  |   | 1,843 |  |
| Total revenues                                               | 100,346 |  |   | 51,973 |  |
|                                                         |   |   |   |
| Costs, expenses and other:                                   |   |   |   |
| Production costs                                             | 19,189 |  |   | 18,472 |  |
| Cost of natural gas marketing                                | 11,492 |  |   | 14,993 |  |
| Exploration expense                                          | 2,063 |  |   | 1,669 |  |
| Impairment of natural gas and crude oil properties           | 653 |  |   | 453 |  |
| General and administrative expense                           | 14,708 |  |   | 13,873 |  |
| Depreciation, depletion and amortization                     | 39,814 |  |   | 30,985 |  |
| Gain on sale of properties and equipment                     | (154 | ) |   | — |  |
| Total costs, expenses and other                              | 87,765 |  |   | 80,445 |  |
|                                                         |   |   |   |
| Income (loss) from operations                                | 12,581 |  |   | (28,472 | ) |
| Interest income                                              | 2 |  |   | 9 |  |
| Interest expense                                             | (10,444 | ) |   | (9,062 | ) |
| Income (loss) from continuing operations before income taxes | 2,139 |  |   | (37,525 | ) |
|                                                         |   |   |   |
| Provision (benefit) for income taxes                         | 759 |  |   | (14,278 | ) |
|                                                         |   |   |   |
| Income (loss) from continuing operations                     | 1,380 |  |   | (23,247 | ) |
| Income from discontinued operations, net of tax              | 14,455 |  |   | 3,323 |  |
| Net income (loss)                                            | $ | 15,835 |  |   | $ | (19,924 | ) |
|                                                         |   |   |   |
| Earnings (loss) per share:                                   |   |   |   |
| Basic                                                        |   |   |   |
| Income (loss) from continuing operations                     | $ | 0.06 |  |   | $ | (0.99 | ) |
| Income from discontinued operations                          | 0.61 |  |   | 0.14 |  |
| Net income (loss)                                            | $ | 0.67 |  |   | $ | (0.85 | ) |
| Diluted                                                      |   |   |   |
| Income (loss) from continuing operations                     | $ | 0.06 |  |   | $ | (0.99 | ) |
| Income from discontinued operations                          | 0.60 |  |   | 0.14 |  |
| Net income (loss)                                            | $ | 0.66 |  |   | $ | (0.85 | ) |
|                                                         |   |   |   |
| Weighted average common shares outstanding                   |   |   |   |
| Basic                                                        | 23,609 |  |   | 23,428 |  |
| Diluted                                                      | 23,889 |  |   | 23,428 |  |
|                                                         |   |   |   |

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|                                                                                                                                |  |  |  |  |  |  |  |
|                                                                                                                           | Three Months Ended March 31, |
|                                                                                                                           | 2012 |   | 2011 |
| Cash flows from operating activities:                                                                                          |   |   |   |
| Net income (loss)                                                                                                              | $ | 15,835 |  |   | $ | (19,924 | ) |
| Adjustments to net income to reconcile to net cash provided by operating activities:                                           |   |   |   |
| Unrealized (gain) loss on derivatives, net                                                                                     | (1,533 | ) |   | 27,745 |  |
| Depreciation, depletion and amortization                                                                                       | 39,814 |  |   | 32,357 |  |
| Impairment of natural gas and crude oil properties                                                                             | 653 |  |   | 453 |  |
| Exploratory dry hole costs                                                                                                     | — |  |   | 35 |  |
| Loss (gain) from sale of properties and equipment                                                                              | (20,489 | ) |   | (3,928 | ) |
| Deferred income taxes                                                                                                          | 10,914 |  |   | (14,024 | ) |
| Stock-based compensation                                                                                                       | 1,946 |  |   | 1,545 |  |
| Amortization of debt discount and issuance costs                                                                               | 1,641 |  |   | 1,704 |  |
| Other                                                                                                                          | 699 |  |   | 136 |  |
| Changes in assets and liabilities                                                                                              | (5,181 | ) |   | (10,623 | ) |
| Net cash provided by operating activities                                                                                      | 44,299 |  |   | 15,476 |  |
| Cash flows from investing activities:                                                                                          |   |   |   |
| Capital expenditures                                                                                                           | (107,029 | ) |   | (71,079 | ) |
| Acquisition of natural gas and crude oil properties                                                                            | (10,000 | ) |   | — |  |
| Proceeds from sale of properties and equipment                                                                                 | 184,646 |  |   | 9,952 |  |
| Other                                                                                                                          | — |  |   | (101 | ) |
| Net cash provided by (used in) investing activities                                                                            | 67,617 |  |   | (61,228 | ) |
| Cash flows from financing activities:                                                                                          |   |   |   |
| Proceeds from credit facility                                                                                                  | 144,750 |  |   | — |  |
| Payment of credit facility                                                                                                     | (263,000 | ) |   | — |  |
| Contribution from noncontrolling interest                                                                                      | — |  |   | 6,407 |  |
| Other                                                                                                                          | (249 | ) |   | (328 | ) |
| Net cash provided by (used in) financing activities                                                                            | (118,499 | ) |   | 6,079 |  |
| Net decrease in cash and cash equivalents                                                                                      | (6,583 | ) |   | (39,673 | ) |
| Cash and cash equivalents, beginning of period                                                                                 | 8,238 |  |   | 54,372 |  |
| Cash and cash equivalents, end of period                                                                                       | $ | 1,655 |  |   | $ | 14,699 |  |
|                                                                                                                           |   |   |   |
| Supplemental cash flow information:                                                                                            |   |   |   |
| Cash payments (receipts) for:                                                                                                  |   |   |   |
| Interest, net of capitalized interest                                                                                          | $ | 14,975 |  |   | $ | 12,314 |  |
| Income taxes, net of refunds                                                                                                   | (1,100 | ) |   | 85 |  |
| Non-cash investing activities:                                                                                                 |   |   |   |
| Change in accounts payable related to purchases of properties and equipment                                                    | (21,044 | ) |   | 5,832 |  |
| Change in asset retirement obligation, with a corresponding increase to natural gas and crude oil properties, net of disposals | (1,962 | ) |   | 229 |  |
|                                                                                                                           |   |   |   |

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|                                       |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
|                                  | March 31, 2012 |   | December 31, 2011 |
|                                  | Significant otherobservableInputs(Level 2) |    | SignificantUnobservableInputs(Level 3) |    | Total |   | Significant otherobservableInputs(Level 2) |    | SignificantUnobservableInputs(Level 3) |    | Total |
|                                  | (in thousands) |
| Assets:                               |   |   |   |   |   |   |   |   |   |   |   |
| Commodity based derivatives contracts | $ | 84,707 |  |     | $ | 26,774 |  |     | $ | 111,481 |  |   | $ | 76,104 |  |     | $ | 25,837 |  |     | $ | 101,941 |  |
| Basis protection derivative contracts | 27 |  |   | 21 |  |   | 48 |  |   | 5 |  |   | 38 |  |     | 43 |  |
| Total assets                          | 84,734 |  |   | 26,795 |  |   | 111,529 |  |   | 76,109 |  |   | 25,875 |  |   | 101,984 |  |
| Liabilities:                          |   |     |   |     |   |   |   |     |   |     |   |
| Commodity based derivatives contracts | 18,710 |  |   | 7,151 |  |     | 25,861 |  |   | 9,888 |  |   | 3,768 |  |     | 13,656 |  |
| Basis protection derivative contracts | 30,467 |  |   | — |  |     | 30,467 |  |   | 35,424 |  |   | — |  |     | 35,424 |  |
| Total liabilities                     | 49,177 |  |   | 7,151 |  |   | 56,328 |  |   | 45,312 |  |   | 3,768 |  |   | 49,080 |  |
| Net asset                             | $ | 35,557 |  |   | $ | 19,644 |  |   | $ | 55,201 |  |   | $ | 30,797 |  |   | $ | 22,107 |  |   | $ | 52,904 |  |
|                                  |   |   |   |   |   |   |   |   |   |   |   |

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|                                                                                  |  |  |  |  |  |  |  |  |
|                                                                             |   | Three Months Ended March 31, |
|                                                                             |   | 2012 |   | 2011 (1) |
|                                                                             |   | (in thousands) |
|                                                                             |   |   |   |   |
| Fair value, net asset, beginning of period                                       |   | $ | 22,107 |  |   | $ | 10,762 |  |
| Changes in fair value included in statement of operations line item:             |   |   |   |   |
| Commodity price risk management gain (loss), net                                 |   | 1,416 |  |   | (9,885 | ) |
| Sales from natural gas marketing                                                 |   | 43 |  |   | 14 |  |
| Changes in fair value included in balance sheet line item (2):                   |   |   |   |   |
| Accounts receivable affiliates                                                   |   | — |  |   | 49 |  |
| Accounts payable affiliates                                                      |   | (52 | ) |   | (654 | ) |
| Settlements included in statement of operations line items:                      |   |   |   |   |
| Commodity price risk management gain (loss), net                                 |   | (3,797 | ) |   | (2,910 | ) |
| Sales from natural gas marketing                                                 |   | (73 | ) |   | (75 | ) |
| Fair value, net asset, end of period                                             |   | $ | 19,644 |  |   | $ | (2,699 | ) |
|                                                                             |   |   |   |   |
| Changes in unrealized gains (losses) relating to assets (liabilities) still held |   |   |   |   |
| as of period end, included in statement of operations line item:                 |   |   |   |   |
| Commodity price risk management gain, net                                        |   | $ | 1,282 |  |   | $ | (7,538 | ) |
| Sales from natural gas marketing                                                 |   | 3 |  |   | (7 | ) |
|                                                                             |   | $ | 1,285 |  |   | $ | (7,545 | ) |
|                                                                             |   |   |   |   |

|     |                                                                                                                                                                                                                                                                                                                                                                           |
|-----|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (1) | We reclassified our PEPL and CIG-based natural gas fixed-price swaps, crude oil fixed-price swaps, basis swaps and natural gas physical purchases from Level 3 to Level 2 (decreasing the previously reported net liability at the beginning of 2011 by $54.1 million). The amounts presented reflect these reclassifications and conform to current period presentation. |

|     |                                                                                                                                         |
|-----|-----------------------------------------------------------------------------------------------------------------------------------------|
| (2) | Represents the change in fair value related to derivative instruments entered into by us and designated to our affiliated partnerships. |

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|-------------------------------------------------------|
|                                                       |  |  |  |  |  |  |  |  |  |  |  |
|                                                  |   |   |   |   | Fair Value |
| Derivatives instruments not designated as hedges (1): |   | Balance sheet line item |   | March 31,2012 |   | December 31,2011 |
|                                                  |   |   |   |   | (in thousands) |
| Derivative assets:                                    | Current |   |   |   |   |   |   |
|                                                  | Commodity contracts |   |   |   |   |   |   |
|                                                  | Related to natural gas and crude oil sales |   | Fair value of derivatives |   | $ | 64,099 |  |   | $ | 51,220 |  |
|                                                  | Related to affiliated partnerships (2) |   | Fair value of derivatives |   | 8,959 |  |   | 8,018 |  |
|                                                  | Related to natural gas marketing |   | Fair value of derivatives |   | 1,691 |  |   | 1,528 |  |
|                                                  | Basis protection contracts |   |   |   |   |   |   |
|                                                  | Related to natural gas marketing |   | Fair value of derivatives |   | 29 |  |   | 43 |  |
|                                                  |   |   |   |   | 74,778 |  |   | 60,809 |  |
|                                                  | Non Current |   |   |   |   |   |   |
|                                                  | Commodity contracts |   |   |   |   |   |   |
|                                                  | Related to natural gas and crude oil sales |   | Fair value of derivatives |   | 31,514 |  |   | 34,938 |  |
|                                                  | Related to affiliated partnerships (2) |   | Fair value of derivatives |   | 5,207 |  |   | 6,134 |  |
|                                                  | Related to natural gas marketing |   | Fair value of derivatives |   | 11 |  |   | 103 |  |
|                                                  | Basis protection contracts |   |   |   |   |   |   |
|                                                  | Related to natural gas marketing |   | Fair value of derivatives |   | 19 |  |   | — |  |
|                                                  |   |   |   |   | 36,751 |  |   | 41,175 |  |
| Total derivative assets                               |   |   |   |   | $ | 111,529 |  |   | $ | 101,984 |  |
|                                                  |   |   |   |   |   |   |   |
| Derivative liabilities:                               | Current |   |   |   |   |   |   |
|                                                  | Commodity contracts |   |   |   |   |   |   |
|                                                  | Related to natural gas and crude oil sales |   | Fair value of derivatives |   | $ | 10,492 |  |   | $ | 7,498 |  |
|                                                  | Related to affiliated partnerships (3) |   | Fair value of derivatives |   | 276 |  |   | 211 |  |
|                                                  | Related to natural gas marketing |   | Fair value of derivatives |   | 1,585 |  |   | 1,384 |  |
|                                                  | Basis protection contracts |   |   |   |   |   |   |
|                                                  | Related to natural gas and crude oil sales |   | Fair value of derivatives |   | 15,166 |  |   | 15,762 |  |
|                                                  | Related to affiliated partnerships (3) |   | Fair value of derivatives |   | 2,992 |  |   | 3,116 |  |
|                                                  | Related to natural gas marketing |   | Fair value of derivatives |   | 2 |  |   | 3 |  |
|                                                  |   |   |   |   | 30,513 |  |   | 27,974 |  |
|                                                  | Non Current |   |   |   |   |   |   |
|                                                  | Commodity contracts |   |   |   |   |   |   |
|                                                  | Related to natural gas and crude oil sales |   | Fair value of derivatives |   | 13,378 |  |   | 4,357 |  |
|                                                  | Related to affiliated partnerships (3) |   | Fair value of derivatives |   | 123 |  |   | 113 |  |
|                                                  | Related to natural gas marketing |   | Fair value of derivatives |   | 7 |  |   | 93 |  |
|                                                  | Basis protection contracts |   |   |   |   |   |   |
|                                                  | Related to natural gas and crude oil sales |   | Fair value of derivatives |   | 10,281 |  |   | 13,820 |  |
|                                                  | Related to affiliated partnerships (3) |   | Fair value of derivatives |   | 2,024 |  |   | 2,723 |  |
|                                                  | Related to natural gas marketing |   | Fair value of derivatives |   | 2 |  |   | — |  |
|                                                  |   |   |   |   | 25,815 |  |   | 21,106 |  |
| Total derivative liabilities                          |   |   |   |   | $ | 56,328 |  |   | $ | 49,080 |  |
|                                                  |   |   |   |   |   |   |   |

|     |                                                                                                                      |
|-----|----------------------------------------------------------------------------------------------------------------------|
| (1) | As of March 31, 2012, and December 31, 2011, none of our derivative instruments were designated as hedges. |

|     |                                                                                                                                                                                                                                                         |
|-----|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (2) | Represents derivative positions designated to our affiliated partnerships; accordingly, our accompanying balance sheets include a corresponding payable to our affiliated partnerships representing their proportionate share of the derivative assets. |

|     |                                                                                                                                                                                                                                                                   |
|-----|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (3) | Represents derivative positions designated to our affiliated partnerships; accordingly, our accompanying balance sheets include a corresponding receivable from our affiliated partnerships representing their proportionate share of the derivative liabilities. |

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|                                                        |
|--------------------------------------------------------|
|                                                        |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
|                                                   |   | Three Months Ended March 31, |
|                                                   |   | 2012 |   | 2011 |
| Statement of operations line item                      |   | Reclassificationof RealizedGains (Losses)Included in Prior PeriodsUnrealized |   | Realized and UnrealizedGains(Losses) FortheCurrentPeriod |   | Total |   | Reclassificationof RealizedGains (Losses)Included in Prior PeriodsUnrealized |   | Realized and UnrealizedGains(Losses) FortheCurrentPeriod |   | Total |
|                                                   |   | (in thousands) |
| Commodity price risk management gain, net              |   |   |   |   |   |   |   |   |   |   |   |   |
| Realized gains                                         |   | $ | 8,628 |  |   | $ | 1,299 |  |   | $ | 9,927 |  |   | $ | 3,322 |  |   | $ | 466 |  |   | $ | 3,788 |  |
| Unrealized gains (losses)                              |   | (8,628 | ) |   | 10,202 |  |   | 1,574 |  |   | (3,322 | ) |   | (24,348 | ) |   | (27,670 | ) |
| Total commodity price risk management gain (loss), net |   | $ | — |  |   | $ | 11,501 |  |   | $ | 11,501 |  |   | $ | — |  |   | $ | (23,882 | ) |   | $ | (23,882 | ) |
| Sales from natural gas marketing                       |   |   |   |   |   |   |   |   |   |   |   |   |
| Realized gains                                         |   | $ | 684 |  |   | $ | 109 |  |   | $ | 793 |  |   | $ | 1,007 |  |   | $ | 135 |  |   | $ | 1,142 |  |
| Unrealized gains (losses)                              |   | (684 | ) |   | 759 |  |   | 75 |  |   | (1,007 | ) |   | (10 | ) |   | (1,017 | ) |
| Total sales from natural gas marketing                 |   | $ | — |  |   | $ | 868 |  |   | $ | 868 |  |   | $ | — |  |   | $ | 125 |  |   | $ | 125 |  |
| Cost of natural gas marketing                          |   |   |   |   |   |   |   |   |   |   |   |   |
| Realized losses                                        |   | $ | (591 | ) |   | $ | (154 | ) |   | $ | (745 | ) |   | $ | (770 | ) |   | $ | (190 | ) |   | $ | (960 | ) |
| Unrealized gains (losses)                              |   | 591 |  |   | (707 | ) |   | (116 | ) |   | 770 |  |   | 172 |  |   | 942 |  |
| Total cost of natural gas marketing                    |   | $ | — |  |   | $ | (861 | ) |   | $ | (861 | ) |   | $ | — |  |   | $ | (18 | ) |   | $ | (18 | ) |
|                                                   |   |   |   |   |   |   |   |   |   |   |   |   |

|                                      |
|--------------------------------------|
|                                      |  |  |  |  |
| Counterparty Name                    |   | Fair Value ofDerivative AssetsAs of March 31, 2012 |
|                                 |   | (in thousands) |
|                                 |   |   |
| JPMorgan Chase Bank, N.A. (1)        |   | $ | 55,769 |  |
| Crèdit Agricole CIB (1)         |   | 19,441 |  |
| Wells Fargo Bank, N.A. (1)           |   | 20,099 |  |
| Other lenders in our credit facility |   | 16,135 |  |
| Various (2)                          |   | 85 |  |
| Total                                |   | $ | 111,529 |  |
|                                 |   |   |

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|                                            |
|--------------------------------------------|
|                                            |  |  |  |  |  |  |  |
|                                       | March 31, 2012 |   | December 31, 2011 |
|                                       | (in thousands) |
| Properties and equipment, net:             |   |   |   |
| Natural gas and crude oil properties       |   |   |   |
| Proved                                     | $ | 1,738,596 |  |   | $ | 1,694,694 |  |
| Unproved                                   | 132,499 |  |   | 102,466 |  |
| Total natural gas and crude oil properties | 1,871,095 |  |   | 1,797,160 |  |
| Pipelines and related facilities           | 42,062 |  |   | 40,721 |  |
| Transportation and other equipment         | 32,878 |  |   | 32,475 |  |
| Land and buildings                         | 13,872 |  |   | 14,572 |  |
| Construction in progress                   | 61,584 |  |   | 69,633 |  |
| Gross properties and equipment             | 2,021,491 |  |   | 1,954,561 |  |
| Accumulated DD&A                       | (692,031 | ) |   | (652,845 | ) |
| Properties and equipment, net              | $ | 1,329,460 |  |   | $ | 1,301,716 |  |
|                                       |   |   |   |

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|                                                          |
|----------------------------------------------------------|
|                                                          |  |  |  |  |  |  |  |
|                                                     | March 31, 2012 |   | December 31, 2011 |
|                                                     | (in thousands) |
| Senior notes                                             |   |   |   |
| 3.25% Convertible senior notes due 2016:                 |   |   |   |
| Principal amount                                         | $ | 115,000 |  |   | $ | 115,000 |  |
| Unamortized discount                                     | (16,250 | ) |   | (17,079 | ) |
| 3.25% Convertible senior notes due 2016, net of discount | 98,750 |  |   | 97,921 |  |
| 12% Senior notes due 2018:                               |  |  |   |  |  |
| Principal amount                                         | 203,000 |  |   | 203,000 |  |
| Unamortized discount                                     | (1,691 | ) |   | (1,764 | ) |
| 12% Senior notes due 2018, net of discount               | 201,309 |  |   | 201,236 |  |
| Total senior notes                                       | 300,059 |  |   | 299,157 |  |
| Credit facilities                                        |   |   |   |
| Corporate                                                | 82,000 |  |   | 209,000 |  |
| PDCM                                                     | 32,750 |  |   | 24,000 |  |
| Total credit facilities                                  | 114,750 |  |   | 233,000 |  |
| Total long-term debt                                     | $ | 414,809 |  |   | $ | 532,157 |  |
|                                                     |   |   |   |

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|                                                                          |
|--------------------------------------------------------------------------|
|                                                                          |  |  |  |
|                                                                     | Amount |
|                                                                     | (in thousands) |
|                                                                     |   |
| Balance at December 31, 2011                                             | $ | 46,566 |  |
| Obligations incurred with development activities                         | 99 |  |
| Accretion expense                                                        | 818 |  |
| Obligations discharged with disposal of properties and asset retirements | (2,061 | ) |
| Balance at March 31, 2012                                                | 45,422 |  |
| Less current portion                                                     | (250 | ) |
| Long-term portion                                                        | $ | 45,172 |  |
|                                                                     |   |

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|                                  |
|----------------------------------|
|                                  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
|                             |   | For the Twelve Months Ending March 31, |   |   |   |   |
| Area                             |   | 2013 |   | 2014 |   | 2015 |   | 2016 |   | 2017 ThroughExpiration |   | Total |   | ExpirationDate |
|                             |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Volume (MMcf)                    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Piceance Basin                   |   | 17,951 |  |   | 36,126 |  |   | 34,656 |  |   | 29,407 |  |   | 104,851 |  |   | 222,991 |  |   | May 31, 2021 |
| Appalachian Basin (1)            |   | 15,572 |  |   | 20,117 |  |   | 22,630 |  |   | 23,856 |  |   | 183,965 |  |   | 266,140 |  |   | September 25, 2025 |
| NECO                             |   | 3,195 |  |   | 1,825 |  |   | 1,825 |  |   | 1,825 |  |   | 1,370 |  |   | 10,040 |  |   | December 31, 2016 |
| Total                            |   | 36,718 |  |   | 58,068 |  |   | 59,111 |  |   | 55,088 |  |   | 290,186 |  |   | 499,171 |  |   |   |
|                             |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Dollar commitment (in thousands) |   | $ | 16,818 |  |   | $ | 28,415 |  |   | $ | 28,146 |  |   | $ | 25,635 |  |   | $ | 121,056 |  |   | $ | 220,070 |  |   |   |
|                             |   |   |   |   |   |   |   |   |   |   |   |   |   |   |

|     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |
|-----|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (1) | Includes a precedent agreement that becomes effective when a planned pipeline is placed in service, currently expected to be September 2012, and represents 6,173 MMcf of the total MMcf presented for the twelve months ending March 31, 2013, 10,627 MMcf for each of the twelve months ending March 31, 2014 through 2016, respectively, and 68,277 MMcf thereafter. This agreement will be null and void if the pipeline is not completed. In August 2009, we issued a letter of credit related to this agreement, see Note 7. |

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|                                        |
|----------------------------------------|
|                                        |  |  |  |  |  |  |  |  |
|                                   |   | Three Months Ended March 31, |
|                                   |   | 2012 |   | 2011 |
|                                   |   | (in thousands) |
|                                   |   |   |   |   |
| Total stock-based compensation expense |   | $ | 1,946 |  |   | $ | 1,545 |  |
| Income tax benefit                     |   | (741 | ) |   | (587 | ) |
| Net expense                            |   | $ | 1,205 |  |   | $ | 958 |  |
|                                   |   |   |   |   |

|                                                  |
|--------------------------------------------------|
|                                                  |  |  |  |  |  |  |  |
|                                             | Three Months Ended March 31, |
|                                             | 2012 |   | 2011 |
|                                             |   |   |   |
| Expected term of the award                       | 6 years |  |   | 6 years |  |
| Risk-free interest rate                          | 1.1 | % |   | 2.5 | % |
| Volatility                                       | 64.3 | % |   | 60.2 | % |
| Weighted average grant date fair value per share | $ | 17.61 |  |   | $ | 25.22 |  |

|                                          |
|------------------------------------------|
|                                          |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
|                                     |   | Three Months Ended March 31, |
|                                     |   | 2012 |   | 2011 |
|                                     |   | NumberofSARs |   | Weighted                   AverageExercisePrice |   | Average Remaining ContractualTerm(in years) |   | Aggregate IntrinsicValue(in thousands) |   | NumberofSARs |   | Weighted                   AverageExercisePrice |   | Average Remaining ContractualTerm(in years) |   | Aggregate IntrinsicValue(in thousands) |
|                                     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Outstanding beginning of year, January 1 |   | 50,471 |  |   | $ | 31.61 |  |   | 8.6 |  |   | $ | 341 |  |   | 57,282 |  |   | $ | 24.44 |  |   | 9.3 |  |   | $ | 1,020 |  |
| Awarded                                  |   | 68,361 |  |   | 30.19 |  |   | 9.8 |  |   | — |  |   | 31,552 |  |   | 43.95 |  |   | 10.0 |  |   | — |  |
| Outstanding at March 31,                 |   | 118,832 |  |   | 30.80 |  |   | 9.2 |  |   | 875 |  |   | 88,834 |  |   | 31.37 |  |   | 9.4 |  |   | 1,478 |  |
| Vested and expected to vest at March 31, |   | 111,137 |  |   | 30.76 |  |   | 9.2 |  |   | 825 |  |   | 79,951 |  |   | 31.37 |  |   | 9.4 |  |   | 1,330 |  |
| Exercisable at March 31,                 |   | 16,822 |  |   | 31.61 |  |   | 8.4 |  |   | 135 |  |   | — |  |   | — |  |   | — |  |   | — |  |
|                                     |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |

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|                                 |
|---------------------------------|
|                                 |  |  |  |  |  |  |  |
|                            |   | Shares |   | Weighted AverageGrant-DateFair Value per Share |
|                            |   |   |   |   |
| Non-vested at December 31, 2011 |   | 527,801 |  |   | $ | 29.29 |  |
| Granted                         |   | 101,252 |  |   | 31.23 |  |
| Vested                          |   | (30,543 | ) |   | 31.74 |  |
| Forfeited                       |   | (7,576 | ) |   | 26.47 |  |
| Non-vested at March 31, 2012    |   | 590,934 |  |   | 29.58 |  |
|                            |   |   |   |   |

|                                                       |
|-------------------------------------------------------|
|                                                       |  |  |  |  |  |  |  |
|                                                  | As of / Three Months Ended March 31, |
|                                                  | 2012 |   | 2011 |
|                                                  | (in thousands, except per share data) |
|                                                  |   |   |   |
| Total intrinsic value of time-based awards vested     | $ | 1,104 |  |   | $ | 1,400 |  |
| Total intrinsic value of time-based awards non-vested | 21,918 |  |   | 25,629 |  |
| Market price per common share as of March 31          | 37.09 |  |   | 48.01 |  |
| Weighted average grant date fair value per share      | 31.23 |  |   | 43.95 |  |

|                                                  |
|--------------------------------------------------|
|                                                  |  |  |  |  |  |  |  |  |
|                                             |   | Three Months Ended March 31, |
|                                             |   | 2012 |   | 2011 |
|                                             |   |   |   |   |
| Expected term of award                           |   | 3 years |  |   | 3 years |  |
| Risk-free interest rate                          |   | 0.3 | % |   | 1.1 | % |
| Volatility                                       |   | 65.3 | % |   | 74.2 | % |
| Weighted average grant date fair value per share |   | $ | 36.54 |  |   | $ | 58.53 |  |

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|                                 |
|---------------------------------|
|                                 |  |  |  |  |  |  |
|                            | Shares |   | Weighted AverageGrant-DateFair Value per Share |
|                            |   |   |   |
| Non-vested at December 31, 2011 | 43,081 |  |   | $ | 42.05 |  |
| Granted                         | 30,541 |  |   | 36.54 |  |
| Non-vested at March 31, 2012    | 73,622 |  |   | 41.87 |  |
|                            |   |   |   |

|                                                                            |
|----------------------------------------------------------------------------|
|                                                                            |  |  |  |  |  |
|                                                                       | Three Months Ended March 31, |
|                                                                       | 2012 |   | 2011 |
|                                                                       | (in thousands) |
|                                                                       |   |   |   |
| Weighted average common shares outstanding - basic                         | 23,609 |  |   | 23,428 |  |
| Dilutive effect of share-based compensation:                               |   |   |   |
| Restricted stock                                                           | 212 |  |   | — |  |
| SARs                                                                       | 65 |  |   | — |  |
| Non employee director deferred compensation                                | 3 |  |   | — |  |
| Weighted average common and common share equivalents outstanding - diluted | 23,889 |  |   | 23,428 |  |
|                                                                       |   |   |   |

|                                                                          |
|--------------------------------------------------------------------------|
|                                                                          |  |  |  |  |  |
|                                                                     | Three Months Ended March 31, |
|                                                                     | 2012 |   | 2011 |
|                                                                     | (in thousands) |
| Weighted average common share equivalents excluded from diluted earnings |   |   |   |
| per share due to their anti-dilutive effect:                             |   |   |   |
| Restricted stock                                                         | 27 |  |   | 603 |  |
| Stock options                                                            | 7 |  |   | 10 |  |
| SARs                                                                     | 19 |  |   | 64 |  |
| Convertible debt                                                         | — |  |   | 161 |  |
| Non employee director deferred compensation                              | — |  |   | 3 |  |
| Total anti-dilutive common share equivalents                             | 53 |  |   | 841 |  |
|                                                                     |   |   |   |

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|                                                   |
|---------------------------------------------------|
|                                                   |  |  |  |  |  |  |  |  |
|                                              |   | Three Months Ended March 31, |
| Statement of Operations - Discontinued Operations |   | 2012 |   | 2011 |
|                                              |   | (dollars in thousands) |
| Revenues                                          |   |   |   |   |
| Natural gas, NGL and crude oil sales              |   | $ | 4,456 |  |   | $ | 5,516 |  |
| Well operations, pipeline income and other        |   | 34 |  |   | 43 |  |
| Total revenues                                    |   | 4,490 |  |   | 5,559 |  |
|                                              |   |   |   |   |
| Costs, expenses and other                         |   |   |   |   |
| Production costs                                  |   | 1,668 |  |   | 2,699 |  |
| Exploration expense                               |   | — |  |   | 29 |  |
| Depreciation, depletion and amortization          |   | — |  |   | 1,372 |  |
| Gain on sale of properties and equipment          |   | (20,335 | ) |   | (3,854 | ) |
| Total costs, expenses and other                   |   | (18,667 | ) |   | 246 |  |
|                                              |   |   |   |   |
| Income from discontinued operations               |   | 23,157 |  |   | 5,313 |  |
| Provision for income taxes                        |   | 8,702 |  |   | 1,990 |  |
| Income from discontinued operations, net of tax   |   | $ | 14,455 |  |   | $ | 3,323 |  |

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|                                            |
|--------------------------------------------|
|                                            |  |  |  |  |  |  |  |
|                                       | Three Months Ended March 31, |
|                                       | 2012 |   | 2011 |
|                                       | (in thousands) |
| Revenues:                                  |   |   |   |
| Oil and Gas Exploration and Production     | $ | 88,512 |  |   | $ | 36,771 |  |
| Gas Marketing                              | 11,834 |  |   | 15,202 |  |
| Total                                      | $ | 100,346 |  |   | $ | 51,973 |  |
|                                       |   |   |   |
| Segment income (loss) before income taxes: |   |   |   |
| Oil and Gas Exploration and Production     | $ | 28,627 |  |   | $ | (14,044 | ) |
| Gas Marketing                              | 342 |  |   | 209 |  |
| Unallocated                                | (26,830 | ) |   | (23,690 | ) |
| Total                                      | $ | 2,139 |  |   | $ | (37,525 | ) |
|                                       |   |   |   |

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|                                        |
|----------------------------------------|
|                                        |  |  |  |  |  |  |  |
|                                   | March 31, 2012 |   | December 31, 2011 |
|                                   | (in thousands) |
| Segment assets:                        |   |   |   |
| Oil and Gas Exploration and Production | $ | 1,509,577 |  |   | $ | 1,461,130 |  |
| Gas Marketing                          | 7,171 |  |   | 14,713 |  |
| Unallocated                            | 48,821 |  |   | 73,913 |  |
| Assets held for sale                   | — |  |   | 148,249 |  |
| Total                                  | $ | 1,565,569 |  |   | $ | 1,698,005 |  |
|                                   |   |   |   |

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|                                                          |
|----------------------------------------------------------|
|                                                          |  |  |  |  |  |  |  |  |  |  |
|                                                     | Three Months Ended March 31, |
|                                                     | 2012 |   | 2011 |   | Change |
|                                                     | (dollars in millions, except per unit data) |
| Production (1)                                           |   |   |   |   |   |
| Natural gas (MMcf)                                       | 8,374.1 |  |   | 7,666.2 |  |   | 9.2 |  % |
| Crude oil (MBbls)                                        | 555.2 |  |   | 321.2 |  |   | 72.9 |  % |
| NGLs (MBbls)                                             | 228.8 |  |   | 148.8 |  |   | 53.8 |  % |
| Natural gas equivalent (MMcfe) (2)                       | 13,077.8 |  |   | 10,485.9 |  |   | 24.7 |  % |
| Average MMcfe per day                                    | 143.7 |  |   | 116.5 |  |   | 23.3 |  % |
| Natural Gas, NGL and Crude Oil Sales                     |   |   |   |   |   |
| Natural gas                                              | $ | 17.5 |  |   | $ | 23.4 |  |   | (25.2 | )% |
| Crude oil                                                | 51.4 |  |   | 28.8 |  |   | 78.5 |  % |
| NGLs                                                     | 6.4 |  |   | 6.6 |  |   | (2.5 | )% |
| Total natural gas, NGL and crude oil sales               | $ | 75.3 |  |   | $ | 58.8 |  |   | 28.1 |  % |
|                                                     |   |   |   |   |   |
| Realized Gain (Loss) on Derivatives, net (3)             |   |   |   |   |   |
| Natural gas                                              | $ | 12.5 |  |   | $ | 6.9 |  |   | 81.2 |  % |
| Crude oil                                                | (2.6 | ) |   | (3.1 | ) |   | (16.1 | )% |
| Total realized gain on derivatives, net                  | $ | 9.9 |  |   | $ | 3.8 |  |   | 160.8 |  % |
|                                                     |   |   |   |   |   |
| Average Sales Price (excluding gain/loss on derivatives) |   |   |   |   |   |
| Natural gas (per Mcf)                                    | $ | 2.09 |  |   | $ | 3.06 |  |   | (31.7 | )% |
| Crude oil (per Bbl)                                      | 92.61 |  |   | 89.62 |  |   | 3.3 |  % |
| NGLs (per Bbl)                                           | 28.12 |  |   | 44.32 |  |   | (36.6 | )% |
| Natural gas equivalent (per Mcfe)                        | 5.76 |  |   | 5.61 |  |   | 2.7 |  % |
|                                                     |   |   |   |   |   |
| Average Sales Price (including gain/loss on derivatives) |   |   |   |   |   |
| Natural gas (per Mcf)                                    | $ | 3.58 |  |   | $ | 3.95 |  |   | (9.4 | )% |
| Crude oil (per Bbl)                                      | 87.94 |  |   | 79.98 |  |   | 10.0 |  % |
| NGLs (per Bbl)                                           | 28.12 |  |   | 44.32 |  |   | (36.6 | )% |
| Natural gas equivalent (per Mcfe)                        | 6.52 |  |   | 5.97 |  |   | 9.2 |  % |
|                                                     |   |   |   |   |   |
| Average Lifting Cost (per Mcfe) (4)                      | $ | 0.88 |  |   | $ | 1.06 |  |   | (16.9 | )% |
|                                                     |   |   |   |   |   |
| Natural Gas Marketing (5)                                | $ | 0.3 |  |   | $ | 0.2 |  |   | 50.0 |  % |
|                                                     |   |   |   |   |   |
| Other Costs and Expenses                                 |   |   |   |   |   |
| Exploration expense                                      | $ | 2.1 |  |   | $ | 1.7 |  |   | 23.6 |  % |
| General and administrative expense                       | 14.7 |  |   | 13.9 |  |   | 6.0 |  % |
| Depreciation, depletion and amortization                 | 39.8 |  |   | 31.0 |  |   | 28.5 |  % |
|                                                     |   |   |   |   |   |
| Interest Expense                                         | $ | 10.4 |  |   | $ | 9.1 |  |   | 15.3 |  % |

|     |                                                                                                                                                           |
|-----|-----------------------------------------------------------------------------------------------------------------------------------------------------------|
| (1) | Production is net and determined by multiplying the gross production volume of properties in which we have an interest by the percentage interest we own. |

|     |                                                            |
|-----|------------------------------------------------------------|
| (2) | Six Mcf of natural gas equals one Bbl of crude oil or NGL. |

|     |                                                                                                                                                                                                   |
|-----|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (3) | Represents realized derivative gains and losses related to natural gas and crude oil sales segment, which does not include realized derivative gains and losses related to natural gas marketing. |

|     |                                                                                          |
|-----|------------------------------------------------------------------------------------------|
| (4) | Represents lease operating expenses, exclusive of production taxes, on a per unit basis. |

|     |                                                                                                                                                              |
|-----|--------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (5) | Represents sales from natural gas marketing, net of costs of natural gas marketing, including realized and unrealized derivative gains and losses related to |

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|                                |
|--------------------------------|
|                                |  |  |  |  |  |  |  |  |
|                           | Three Months Ended March 31, |
|                           | 2012 |   | 2011 |   | PercentageChange |
| Production                     |   |   |   |   |   |
| Natural gas (MMcf)             |   |   |   |   |   |
| Western                        | 6,880.2 |  |   | 6,787.5 |  |   | 1.4 |  % |
| Eastern                        | 1,485.5 |  |   | 866.9 |  |   | 71.4 |  % |
| Other                          | 8.4 |  |   | 11.8 |  |   | (28.8 | )% |
| Total                          | 8,374.1 |  |   | 7,666.2 |  |   | 9.2 |  % |
| Crude oil (MBbls)              |   |   |   |   |   |
| Western                        | 552.8 |  |   | 320.0 |  |   | 72.8 |  % |
| Eastern                        | 2.4 |  |   | 1.1 |  |   | 118.2 |  % |
| Other                          | — |  |   | 0.1 |  |   | (100.0 | )% |
| Total                          | 555.2 |  |   | 321.2 |  |   | 72.9 |  % |
| NGLs (MBbls)                   |   |   |   |   |   |
| Western                        | 227.2 |  |   | 147.5 |  |   | 54.0 |  % |
| Other                          | 1.6 |  |   | 1.3 |  |   | 23.1 |  % |
| Total                          | 228.8 |  |   | 148.8 |  |   | 53.8 |  % |
| Natural gas equivalent (MMcfe) |   |   |   |   |   |
| Western                        | 11,559.0 |  |   | 9,592.0 |  |   | 20.5 |  % |
| Eastern                        | 1,499.8 |  |   | 873.7 |  |   | 71.7 |  % |
| Other                          | 19.0 |  |   | 20.2 |  |   | (5.9 | )% |
| Total                          | 13,077.8 |  |   | 10,485.9 |  |   | 24.7 |  % |
|                           |   |   |   |   |   |

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|                                                         |
|---------------------------------------------------------|
|                                                         |  |  |  |  |  |  |  |  |  |  |  |
|                                                    |   | Three Months Ended March 31, |
| Average Sales Price(excluding gain/loss on derivatives) |   | 2012 |   | 2011 |   | PercentageChange |
| Natural gas (per Mcf) (1)                               |   |   |   |   |   |   |
| Western                                                 |   | $ | 2.01 |  |   | $ | 2.92 |  |   | (31.2 | )% |
| Eastern                                                 |   | 2.44 |  |   | 4.11 |  |   | (40.6 | )% |
| Other                                                   |   | 2.79 |  |   | 2.56 |  |   | 9.0 |  % |
| Weighted average price                                  |   | 2.09 |  |   | 3.06 |  |   | (31.7 | )% |
| Crude oil (per Bbl)                                     |   |   |   |   |   |   |
| Western                                                 |   | 92.60 |  |   | 89.67 |  |   | 3.3 |  % |
| Eastern                                                 |   | 98.95 |  |   | 76.00 |  |   | 30.2 |  % |
| Other                                                   |   | — |  |   | 85.61 |  |   | (100.0 | )% |
| Weighted average price                                  |   | 92.61 |  |   | 89.62 |  |   | 3.3 |  % |
| NGLs (per Bbl)                                          |   |   |   |   |   |   |
| Western                                                 |   | 28.01 |  |   | 44.10 |  |   | (36.5 | )% |
| Other                                                   |   | 43.55 |  |   | 69.50 |  |   | (37.3 | )% |
| Weighted average price                                  |   | 28.12 |  |   | 44.32 |  |   | (36.6 | )% |
| Natural gas equivalent (per Mcfe)                       |   |   |   |   |   |   |
| Western                                                 |   | 6.17 |  |   | 5.74 |  |   | 7.5 |  % |
| Eastern                                                 |   | 2.58 |  |   | 4.17 |  |   | (38.1 | )% |
| Other                                                   |   | 8.59 |  |   | 6.39 |  |   | 34.4 |  % |
| Weighted average price                                  |   | 5.76 |  |   | 5.61 |  |   | 2.7 |  % |

|     |                                                                                                                                                                                                                                                                                                                                                    |
|-----|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (1) | Our average sales price for natural gas is based on the "net-back" method of accounting for transportation, gathering and processing arrangements with natural gas purchasers. See our revenue recognition policy described in Note 2, Summary of Significant Accounting Policies, to the consolidated financial statements in our 2011 Form 10-K. |

|                                                                |
|----------------------------------------------------------------|
|                                                                |  |  |  |
| Increase in crude oil production                               | $ | 21.0 |  |
| Increase in natural gas production                             | 2.2 |  |
| Increase in average crude oil price                            | 1.6 |  |
| Decrease in average natural gas price                          | (8.1 | ) |
| Decrease in NGL sales                                          | (0.2 | ) |
| Total increase in natural gas, NGL and crude oil sales revenue | $ | 16.5 |  |
|                                                           |   |

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|                                                                 |
|-----------------------------------------------------------------|
|                                                                 |  |  |  |  |  |  |  |
|                                                            | Three Months Ended March 31, |
|                                                            | 2012 |   | 2011 |
|                                                            | (in millions) |
|                                                            |   |   |   |
| Lease operating expenses                                        | $ | 11.5 |  |   | $ | 11.1 |  |
| Production taxes                                                | 5.0 |  |   | 4.1 |  |
| Cost of well operations, overhead and other production expenses | 2.7 |  |   | 3.3 |  |
| Total production costs                                          | $ | 19.2 |  |   | $ | 18.5 |  |
|                                                            |   |   |   |

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|                                                                         |
|-------------------------------------------------------------------------|
|                                                                         |  |  |  |  |  |  |  |
|                                                                    | Three Months Ended March 31, |
|                                                                    | 2012 |   | 2011 |
|                                                                    | (in millions) |
| Commodity price risk management gain (losses), net:                     |   |   |   |
| Realized gains (losses):                                                |   |   |   |
| Natural gas                                                             | $ | 12.5 |  |   | $ | 6.9 |  |
| Crude oil                                                               | (2.6 | ) |   | (3.1 | ) |
| Total realized gains, net                                               | 9.9 |  |   | 3.8 |  |
| Unrealized gains (losses):                                              |   |   |   |
| Reclassification of realized gains included in prior periods unrealized | (8.6 | ) |   | (3.3 | ) |
| Unrealized gains (losses) for the period                                | 10.2 |  |   | (24.4 | ) |
| Total unrealized gains (losses), net                                    | 1.6 |  |   | (27.7 | ) |
| Total commodity price risk management gain (losses), net                | $ | 11.5 |  |   | $ | (23.9 | ) |
|                                                                    |   |   |   |

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|                                           |
|-------------------------------------------|
|                                           |  |  |  |  |  |  |  |
|                                      | Three Months Ended March 31, |
|                                      | 2012 |   | 2011 |
|                                      | (in millions) |
| Sales from natural gas marketing          |   |   |   |
| Natural gas sales revenue                 | $ | 10.9 |  |   | $ | 15.1 |  |
| Realized derivative gain                  | 0.8 |  |   | 1.1 |  |
| Unrealized derivative gain (loss)         | 0.1 |  |   | (1.0 | ) |
| Total sales from natural gas marketing    | 11.8 |  |   | 15.2 |  |
|                                      |   |   |   |
| Cost of natural gas marketing             |   |   |   |
| Cost of natural gas purchases             | 10.3 |  |   | 14.6 |  |
| Realized derivative loss                  | 0.8 |  |   | 1.0 |  |
| Unrealized derivative loss (gain)         | 0.1 |  |   | (0.9 | ) |
| Other                                     | 0.3 |  |   | 0.3 |  |
| Total cost of natural gas marketing       | 11.5 |  |   | 15.0 |  |
|                                      |   |   |   |
| Natural gas marketing contribution margin | $ | 0.3 |  |   | $ | 0.2 |  |
|                                      |   |   |   |

|                        |
|------------------------|
|                        |  |  |  |  |  |  |  |  |
|                   |   | Three Months Ended March 31, |
| Operating Region/Area  |   | 2012 |   | 2011 |
|                   |   | (per Mcfe) |
| Western                |   |   |   |   |
| Wattenberg Field       |   | $ | 3.44 |  |   | $ | 3.26 |  |
| Piceance Basin         |   | 2.80 |  |   | 2.54 |  |
| Weighted average       |   | 3.05 |  |   | 2.82 |  |
|                   |   |   |   |   |
| Eastern                |   | 1.77 |  |   | 2.52 |  |
|                   |   |   |   |   |
| Total weighted average |   | 2.90 |  |   | 2.79 |  |

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|                                |
|--------------------------------|
|                                |  |  |  |  |  |  |
|                           |   | Three Months Ended March 31, |
| Discontinued Operations        |   | 2012 |   | 2011 |
| Production                     |   |   |   |   |
| Natural gas (MMcf)             |   | 40.3 |  |   | 89.8 |  |
| Crude oil (MBbls)              |   | 39.2 |  |   | 54.0 |  |
| NGLs (per Bbl)                 |   | 13.0 |  |   | 18.1 |  |
| Natural gas equivalent (MMcfe) |   | 353.1 |  |   | 522.7 |  |

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|                         |
|-------------------------|
|                         |  |  |  |  |  |  |  |  |  |  |  |  |
|                    |   | Net Drilling Activity |
|                    |   | Three Months Ended March 31, |
|                    |   | 2012 |   | 2011 |
| Operating Region/Area   |   | Productive |   | In-Process (1) |   | Productive |   | In-Process |
| Development Wells       |   |   |   |   |   |   |   |   |
| Western                 |   |   |   |   |   |   |   |   |
| Wattenberg Field        |   | 2.3 |  |   | 3.7 |  |   | 9.3 |  |   | 18.6 |  |
| Piceance Basin          |   | — |  |   | — |  |   | — |  |   | 6.0 |  |
| Total Western           |   | 2.3 |  |   | 3.7 |  |   | 9.3 |  |   | 24.6 |  |
| Eastern                 |   | — |  |   | 1.5 |  |   | — |  |   | — |  |
| Total development wells |   | 2.3 |  |   | 5.2 |  |   | 9.3 |  |   | 24.6 |  |
| Exploratory Wells       |   |   |   |   |   |   |   |   |
| Western                 |   |   |   |   |   |   |   |   |
| Other                   |   | — |  |   | — |  |   | — |  |   | 1.0 |  |
| Total exploratory wells |   | — |  |   | — |  |   | — |  |   | 1.0 |  |
| Total drilling activity |   | 2.3 |  |   | 5.2 |  |   | 9.3 |  |   | 25.6 |  |

|     |                                                                                                                                                                                                                                |
|-----|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (1) | As of March 31, 2012, a total of 10.5 net wells, including the 5.2 net wells drilled during the three months ended 2012 and still in-process as of March 31, were waiting to be completed and/or for pipeline connection.  |

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|                                                          |
|----------------------------------------------------------|
|                                                          |  |  |  |  |  |  |  |
|                                                     | Three Months Ended March 31, |
|                                                     | 2012 |   | 2011 |
|                                                     | (in millions) |
| Adjusted cash flows from operations:                     |   |   |   |
| Adjusted cash flows from operations                      | $ | 49.5 |  |   | $ | 26.1 |  |
| Changes in assets and liabilities                        | (5.2 | ) |   | (10.6 | ) |
| Net cash provided by operating activities                | $ | 44.3 |  |   | $ | 15.5 |  |
|                                                     |   |   |   |
| Adjusted net income (loss) attributable to shareholders: |   |   |   |
| Adjusted net income (loss) attributable to shareholders  | $ | 14.9 |  |   | $ | (2.7 | ) |
| Unrealized gain on derivatives, net                      | 1.5 |  |   | (27.7 | ) |
| Tax effect of above adjustments                          | (0.6 | ) |   | 10.5 |  |
| Net income (loss) attributable to shareholders           | $ | 15.8 |  |   | $ | (19.9 | ) |
|                                                     |   |   |   |
| Adjusted EBITDA:                                         |   |   |   |
| Adjusted EBITDA                                          | $ | 74.7 |  |   | $ | 37.4 |  |
| Unrealized gain (loss) on derivatives, net               | 1.5 |  |   | (27.7 | ) |
| Interest expense, net                                    | (10.4 | ) |   | (9.0 | ) |
| Income tax benefit (expense)                             | (9.5 | ) |   | 12.3 |  |
| Impairment of natural gas and crude oil properties       | (0.7 | ) |   | (0.5 | ) |
| Depreciation, depletion and amortization                 | (39.8 | ) |   | (32.4 | ) |
| Net income attributable to shareholders                  | $ | 15.8 |  |   | $ | (19.9 | ) |
|                                                     |   |   |   |

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|         |                                                                                                                                                                                                                                                                                                                                                                  |
|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| • | For natural gas and crude oil sales, we enter into derivative contracts to protect against price declines in future periods. While we structure these derivatives to reduce our exposure to changes in price associated with the derivative commodity, they also limit the benefit we might otherwise have received from price increases in the physical market. |

|         |                                                                                                                                                                                                                                                                                                                                                                                                                  |
|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| • | For natural gas marketing, we enter into fixed-price physical purchase and sale agreements that qualify as derivative contracts. In order to offset the fixed-price physical derivatives in our natural gas marketing, we enter into financial derivative instruments that have the effect of locking in the prices we will receive or pay for the same volumes and periods, offsetting the physical derivative. |

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|                                   |
|-----------------------------------|
|                                   |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
|                              |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   | CIG |   |   |
|                              |   | Floors |   | Collars |   | Fixed-Price Swaps |   | Basis Protection Swaps |   |   |
| Commodity/ Index/ Maturity Period |   | Quantity(Oil - MBbls) |   | Weighted Average Contract Price |   | Quantity (Gas - BBtu (1) Oil - MBbls) |   | Weighted Average Contract Price |   | Quantity (Gas - BBtu (1) Oil - MBbls) |   | Weighted Average Contract Price |   | Quantity(BBtu) (1) |   | Weighted Average Contract Price |   | Fair Value as of March 31, 2012 (2)(in millions) |
|                              |   |   | Floors |   | Ceilings |   |   |   |   |   |
| Natural Gas                       |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| NYMEX                             |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 2012                              |   | — |  |   | $ | — |  |   | 3,629.7 |  |   | $ | 6.00 |  |   | $ | 8.27 |  |   | 14,374.5 |  |   | $ | 5.08 |  |   | 7,692.6 |  |   | $ | (1.81 | ) |   | $ | 37.7 |  |
| 2013                              |   | — |  |   | — |  |   | 4,438.0 |  |   | 6.10 |  |   | 8.60 |  |   | 18,120.9 |  |   | 4.93 |  |   | 9,383.3 |  |   | (1.81 | ) |   | 25.7 |  |
| 2014                              |   | — |  |   | — |  |   | — |  |   | — |  |   | — |  |   | 13,090.0 |  |   | 4.04 |  |   | — |  |   | — |  |   | 1.0 |  |
| 2015                              |   |   |   |   |   |   |   |   |   |   |   | 7,200.0 |  |   | 3.84 |  |   |   |   |   |   | (2.7 | ) |
| 2016                              |   |   |   |   |   |   |   |   |   |   |   | 7,200.0 |  |   | 3.84 |  |   |   |   |   |   | (4.4 | ) |
|                              |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| CIG                               |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 2012                              |   | — |  |   | — |  |   | — |  |   | — |  |   | — |  |   | 565.0 |  |   | 4.11 |  |   | — |  |   | — |  |   | 1.0 |  |
| 2013                              |   | — |  |   | — |  |   | 235.0 |  |   | 4.00 |  |   | 5.45 |  |   | — |  |   | — |  |   | — |  |   | — |  |   | 0.2 |  |
| 2014                              |   | — |  |   | — |  |   | 1,115.0 |  |   | 4.50 |  |   | 5.67 |  |   | — |  |   | — |  |   | — |  |   | — |  |   | 1.1 |  |
| 2015                              |   | — |  |   | — |  |   | 1,040.0 |  |   | 4.50 |  |   | 5.67 |  |   | — |  |   | — |  |   | — |  |   | — |  |   | 0.7 |  |
|                              |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| PEPL                              |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 2012                              |   | — |  |   | — |  |   | — |  |   | — |  |   | — |  |   | 998.2 |  |   | 6.18 |  |   | — |  |   | — |  |   | 3.8 |  |
| 2013                              |   | — |  |   | — |  |   | — |  |   | — |  |   | — |  |   | 990.4 |  |   | 6.18 |  |   | — |  |   | — |  |   | 2.9 |  |
|                              |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Total Natural Gas                 |   | — |  |   |   |   | 10,457.7 |  |   |   |   |   |   | 62,539 |  |   |   |   | 17,075.9 |  |   |   |   | 67.0 |  |
|                              |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Crude Oil                         |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| NYMEX                             |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| 2012                              |   | 18.0 |  |   | 65.38 |  |   | 496.6 |  |   | 81.83 |  |   | 106.62 |  |   | 597.4 |  |   | 92.70 |  |   | — |  |   | — |  |   | (9.2 | ) |
| 2013                              |   | — |  |   | — |  |   | 617.6 |  |   | 78.89 |  |   | 104.27 |  |   | 1,100.9 |  |   | 96.77 |  |   | — |  |   | — |  |   | (11.4 | ) |
| 2014                              |   | — |  |   | — |  |   | 268 |  |   | 89.05 |  |   | 107.04 |  |   | — |  |   | — |  |   | — |  |   | — |  |   | (0.2 | ) |
| 2015                              |   | — |  |   | — |  |   | 36 |  |   | 90.00 |  |   | 106.15 |  |   | — |  |   | — |  |   | — |  |   | — |  |   | 0.1 |  |
|                              |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Total Crude Oil                   |   | 18.0 |  |   |   |   | 1,418.2 |  |   |   |   |   |   | 1,698.3 |  |   |   |   | — |  |   |   |   | (20.7 | ) |
| Total Natural Gas and Crude Oil   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   | $ | 46.3 |  |
|                              |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |

|    |
|----|
|    |  |  |
| (1 | ) | A standard unit of measurement for natural gas (one BBtu equals one MMcf). |
| (2 | ) | Approximately 27.7% of the fair value of our derivative assets and 14.5% of our derivative liabilities were measured using significant unobservable inputs (Level 3); see Note 3, Fair Value Measurements and Disclosures, to the accompanying condensed consolidated financial statements. |

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|                                              |
|----------------------------------------------|
|                                              |  |  |  |  |  |  |  |
|                                         | Three Months Ended |   | Year Ended |
|                                         | March 31, 2012 |   | December 31, 2011 |
| Average Index Closing Price                  |   |   |   |
| Natural Gas (per MMBtu)                      |   |   |   |
| CIG                                          | $ | 2.62 |  |   | $ | 3.79 |  |
| NYMEX                                        | 2.74 |  |   | 4.04 |  |
| Crude Oil (per Bbl)                          |   |   |   |
| NYMEX                                        | 100.51 |  |   | 94.01 |  |
|                                         |   |   |   |
| Average Sales Price Realized                 |   |   |   |
| Excluding realized derivative gains/(losses) |   |   |   |
| Natural Gas (per Mcf)                        | $ | 2.09 |  |   | $ | 3.27 |  |
| Crude Oil (per Bbl)                          | 92.61 |  |   | 87.63 |  |
| Including realized derivative gains/(losses) |   |   |   |
| Natural Gas (per Mcf)                        | 3.58 |  |   | 4.23 |  |
| Crude Oil (per Bbl)                          | 87.94 |  |   | 80.69 |  |

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|                       |
|-----------------------|
|                       |  |  |  |  |  |  |  |  |  |  |  |  |  |
| Period                |   | Total Number of Shares Purchased (1) |   | Average Price Paid per Share |   | Total Number of Shares Purchased as Part of Publicly Announced Plans or Programs |   | Maximum Number of Shares that May Yet Be Purchased Under the Plansor Programs |
|                  |   |   |   |   |   |   |   |   |
| January 1 - 31, 2012  |   | 1,309 |  |   | $ | 33.92 |  |   | — |  |   | — |  |
| February 1 - 29, 2012 |   | 2,020 |  |   | 34.30 |  |   | — |  |   | — |  |
| March 1 - 31, 2012    |   | 6,839 |  |   | 37.21 |  |   | — |  |   | — |  |
| Total                 |   | 10,168 |  |   | 36.21 |  |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |

|     |                                                                                                                                                                                                    |
|-----|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| (1) | Purchases primarily represent shares purchased from employees for the payment of their tax liabilities related to the vesting of securities issued pursuant to our stock-based compensation plans. |

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|                       |
|-----------------------|
|                       |  |  |  |  |  |  |  |  |  |  |  |  |
|                  |   |   |   | Incorporated by Reference |   |   |
| Exhibit               |   |   |   |   |   | SEC File |   |   |   |   |   | Filed |
| Number                |    | Exhibit Description |   | Form |    | Number |    | Exhibit |   | Filing Date |    | Herewith |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 10.1                  |   | Third Amendment to the Second Amended and Restated Credit Agreement, dated as of May 4, 2012. |   |   |   |   |   |   |   |   |   | X |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 12.1                  |   | Computation of Ratio of Earnings to Fixed Charges. |   |   |   |   |   |   |   |   |   | X |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 31.1                  |   | Certification by Chief Executive Officer pursuant to Rule 13a-14(a) and 15d-14(a) of the Exchange Act Rules, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |   | X |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 31.2                  |   | Certification by Chief Financial Officer pursuant to Rule 13a-14(a) and 15d-14(a) of the Exchange Act Rules, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |   | X |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 32.1*                 |   | Certifications by Chief Executive Officer and Chief Financial Officer pursuant to Title 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 101.INS *             |   | XBRL Instance Document |   |   |   |   |   |   |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 101.SCH *             |   | XBRL Taxonomy Extension Schema Document |   |   |   |   |   |   |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 101.CAL *             |   | XBRL Taxonomy Extension Calculation Linkbase Document |   |   |   |   |   |   |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 101.DEF *             |   | XBRL Taxonomy Extension Definition Linkbase Document |   |   |   |   |   |   |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 101.LAB *             |   | XBRL Taxonomy Extension Label Linkbase Document |   |   |   |   |   |   |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| 101.PRE *             |   | XBRL Taxonomy Extension Presentation Linkbase Document |   |   |   |   |   |   |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |   |   |   |   |
| * Furnished herewith. |   |   |   |   |   |   |   |   |   |   |
|                  |   |   |   |   |   |   |   |   |   |   |

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Table of Contents

|                     |
|---------------------|
|                     |  |
|                | Petroleum Development Corporation |
|                | (Registrant) |
|                |   |
|                |   |
|                |   |
|                |   |
| Date:  May 10, 2012 | /s/ James M. Trimble |
|                | James M. Trimble, |
|                | President and Chief Executive Officer |
|                | (principal executive officer) |
|                |   |
|                | /s/ Gysle R. Shellum |
|                | Gysle R. Shellum |
|                | Chief Financial Officer |
|                | (principal financial officer) |
|                |   |
|                | /s/ R. Scott Meyers |
|                | R. Scott Meyers |
|                | Chief Accounting Officer |
|                | (principal accounting officer) |