VINTAGE PETROLEUM, INC. PERFORMANCE-BASED CASH BONUS PROGRAM FOR CHIEF EXECUTIVE OFFICER

EXHIBIT 10.21

VINTAGE PETROLEUM, INC.

PERFORMANCE-BASED CASH BONUS

PROGRAM FOR CHIEF EXECUTIVE OFFICER

1. Purpose; Base Amount. Vintage Petroleum, Inc., a Delaware corporation (the “Company”), has established a performance-based cash bonus program for Charles C. Stephenson, Jr., the Chairman of the Board, President and Chief Executive Officer of the Company, the purpose of which is to enhance stockholder value by providing Mr. Stephenson with added incentive to achieve certain specific performance goals. The Company has established a base cash bonus amount of $1,200,000 (the “Base Amount”). Mr. Stephenson has the ability to earn a cash bonus in the amount of $0 to $2,400,000 (or 0% to 200% of the Base Amount) as described below. Any capitalized terms used herein that are not otherwise defined herein shall have the respective meanings provided in the Company’s 1990 Stock Plan, as amended (the “Plan”).

2. Calculation of Bonus Amount. On the 65th day following the close of the Performance Period (the “Date of Determination”), the amount of the cash bonus earned under this Program shall be determined and calculated as follows:

The amount of the cash bonus to be earned under this Program shall be based upon the Company’s Total Stockholder Return as compared to the Total Stockholder Return of the Company’s Peer Group during the Performance Period.

For this purpose, “Total Stockholder Return” shall be determined as follows, expressed as a percentage:

“Change in Stock Value” shall mean the Ending Stock Value minus the Beginning Stock Value; “Beginning Stock Value” shall mean $100, invested in common stock at the closing price on the New York Stock Exchange, American Stock Exchange or Nasdaq, as the case may be, of one share of common stock for the last trading day immediately prior to the first day of the Performance Period; “Ending Stock Value” shall mean the closing price on the New York Stock Exchange, American Stock Exchange or Nasdaq, as the case may be, of one share of common stock for the last trading day immediately prior to the last day of the Performance Period, multiplied by the sum of the number of shares represented by the Beginning Stock Value initial $100 investment plus such additional shares resulting from all dividends paid on common stock during the Performance Period being treated as though they are reinvested on the applicable ex-dividend dates at the applicable closing price on such dates. Shares used in determining Total Stockholder Return shall be appropriately adjusted for stock splits and stock dividends during the Performance Period.

Following the Total Stockholder Return determination, the Company’s “Percentile Rank” shall be determined as follows:

“Company Rank” shall be determined by listing from highest Total Stockholder Return to lowest Total Stockholder Return each company in the Peer Group (including the Company) and counting down from the company with the highest Total Stockholder Return (beginning with such company) to the Company’s position.

The percent of the Base Amount earned shall then be determined based on the following chart:

By way of illustration only, an example applying the above performance measure to determine the percent of the Base Amount earned utilizing a sample Peer Group of 16 companies (including the Company) is attached as Exhibit A hereto.

The amount of the cash bonus, if any, earned under this Section 2 shall be paid in full to Mr. Stephenson promptly after the Date of Determination.

3. Terminat