Exhibit 99.1

Cawley, Gillespie & Associates, Inc.

PETROLEUM CONSULTANTS



|                                |  |                               |  |                          
|------------------------------- |  | ----------------------------- |  | -------------------------
|AUSTIN OFFICE:                  |  | MAIN OFFICE:                  |  | HOUSTON OFFICE:          
|9601 AMBERGLEN BLVD., SUITE 117 |  | 306 WEST 7THSTREET, SUITE 302 |  | 1000 LOUISIANA, SUITE 625
|AUSTIN, TEXAS 78729             |  | FORT WORTH, TEXAS 76102-4987  |  | HOUSTON, TEXAS 77002-5008
|(512) 249-7000                  |  | (817) 336-2461                |  | (713) 651-9944           
|FAX (512) 233-2618              |  | FAX (817) 877-3728            |  | FAX (713) 651-9980       

January 11, 2010

Mr. Mark Fischer, President

Chaparral
Energy, Inc.

701 Cedar Lake Blvd.

Oklahoma City, Oklahoma 73114



| | Re: | Evaluation Summary  SEC Pricing Case
| | --- | -------------------------------------

| |  | Chaparral Energy, Inc. Interests
| |  | --------------------------------

| |  | Total Proved Reserves
| |  | ---------------------

| |  | Certain Oil and Gas Assets  Various States
| |  | -------------------------------------------

| |  | As of December 31, 2010
| |  | -----------------------

Dear
Mr. Fischer:

As requested, we are submitting estimates of total proved reserves and forecasts of economics attributable
to the Chaparral Energy, Inc. (Chaparral) interests in certain oil and gas properties located in various states. Cawley, Gillespie & Associates, Inc. (CG&A) evaluated the major properties, with
detailed tabular results presented in this report. Chaparral evaluated the minor properties, with a summary report being presented in page 2 of this report letter. Below are the composite results of all properties followed by the summary
of CG&A-evaluated major properties and the adjusted Chaparral-evaluated minor properties:



|                               |  |  |        |  |                          |  |             |                                       |  |  |                                           |  |  |                   |           |  |             |  |             |  |  |  |             | 
|------------------------------ |  |  | ------ |  | ------------------------ |  | ----------- | ------------------------------------- |  |  | ----------------------------------------- |  |  | ----------------- | --------- |  | ----------- |  | ----------- |  |  |  | ----------- | 
|                               |  |  |        |  | ProvedDevelopedProducing |  |             | ProvedDevelopedNon-Producing(Shut In) |  |  | ProvedDevelopedNon-Producing(Behind Pipe) |  |  | ProvedUndeveloped |           |  | TotalProved | 
|Net Reserves                   |  |  |        |  |                          |  |             |                                       |  |  |                                           |  |  |                   |           |  |             |  |             |  |  |  |             | 
|Oil                            |  |  | - Mbbl |  |                          |  | 28,719.2    |                                       |  |  | 1,322.3                                   |  |  |                   | 3,936.3   |  |             |  | 14,269.6    |  |  |  | 48,247.4    | 
|Gas                            |  |  | - MMcf |  |                          |  | 211,078.8   |                                       |  |  | 10,945.8                                  |  |  |                   | 35,600.0  |  |             |  | 77,464.9    |  |  |  | 335,089.5   | 
|Revenue                        |  |  |        |  |                          |  |             |                                       |  |  |                                           |  |  |                   |           |  |             |  |             |  |  |  |             | 
|Oil                            |  |  | - M$   |  |                          |  | 2,177,595.5 |                                       |  |  | 100,730.7                                 |  |  |                   | 293,173.3 |  |             |  | 1,076,224.6 |  |  |  | 3,647,724.2 | 
|Gas                            |  |  | - M$   |  |                          |  | 884,413.0   |                                       |  |  | 47,773.9                                  |  |  |                   | 143,259.9 |  |             |  | 331,328.8   |  |  |  | 1,406,775.4 | 
|Severance and Ad Valorem Taxes |  |  | - M$   |  |                          |  | 241,626.1   |                                       |  |  | 11,167.8                                  |  |  |                   | 35,973.1  |  |             |  | 110,744.3   |  |  |  | 399,511.3   | 
|Operating Expenses             |  |  | - M$   |  |                          |  | 1,155,965.0 |                                       |  |  | 42,259.3                                  |  |  |                   | 94,679.9  |  |             |  | 270,221.0   |  |  |  | 1,563,126.5 | 
|Other Deductions               |  |  | - M$   |  |                          |  | 7,202.3     |                                       |  |  | 0.0                                       |  |  |                   | 4,572.6   |  |             |  | 0.0         |  |  |  | 11,774.9    | 
|Investments                    |  |  | - M$   |  |                          |  | 88.7        |                                       |  |  | 10,813.3                                  |  |  |                   | 40,565.9  |  |             |  | 435,031.4   |  |  |  | 486,499.3   | 
|Net Operating Income (BFIT)    |  |  | - M$   |  |                          |  | 1,657,126.7 |                                       |  |  | 84,264.1                                  |  |  |                   | 260,641.8 |  |             |  | 591,556.9   |  |  |  | 2,593,588.6 | 
|Discounted @ 10%               |  |  | - M$   |  |                          |  | 879,820.3   |                                       |  |  | 35,464.6                                  |  |  |                   | 100,022.4 |  |             |  | 199,005.3   |  |  |  | 1,214,312.3 | 



---

Mr. Mark Fischer

Chaparral Energy, Inc. Interests

January 11, 2011

Page
 2



CG&As independent reserve estimates for the major properties
comprising the top 75 percent of Chaparrals net proved reserves (as estimated by Chaparral) are presented in the following table:



|                               |  |  |        |  |                          |  |             |                                       |  |  |                                           |  |  |                   |           |  |             |  |           |  |  |  |             | 
|------------------------------ |  |  | ------ |  | ------------------------ |  | ----------- | ------------------------------------- |  |  | ----------------------------------------- |  |  | ----------------- | --------- |  | ----------- |  | --------- |  |  |  | ----------- | 
|                               |  |  |        |  | ProvedDevelopedProducing |  |             | ProvedDevelopedNon-Producing(Shut In) |  |  | ProvedDevelopedNon-Producing(Behind Pipe) |  |  | ProvedUndeveloped |           |  | TotalProved | 
|Net Reserves                   |  |  |        |  |                          |  |             |                                       |  |  |                                           |  |  |                   |           |  |             |  |           |  |  |  |             | 
|Oil                            |  |  | - Mbbl |  |                          |  | 25,330.4    |                                       |  |  | 921.6                                     |  |  |                   | 2,190.7   |  |             |  | 9,163.9   |  |  |  | 37,606.4    | 
|Gas                            |  |  | - MMcf |  |                          |  | 120,898.0   |                                       |  |  | 5,879.2                                   |  |  |                   | 12,163.4  |  |             |  | 31,082.4  |  |  |  | 170,023.0   | 
|Revenue                        |  |  |        |  |                          |  |             |                                       |  |  |                                           |  |  |                   |           |  |             |  |           |  |  |  |             | 
|Oil                            |  |  | - M$   |  |                          |  | 1,923,775.4 |                                       |  |  | 70,364.0                                  |  |  |                   | 161,604.5 |  |             |  | 695,521.2 |  |  |  | 2,851,265.0 | 
|Gas                            |  |  | - M$   |  |                          |  | 499,169.0   |                                       |  |  | 25,288.6                                  |  |  |                   | 50,996.3  |  |             |  | 127,734.8 |  |  |  | 703,188.6   | 
|Severance and Ad Valorem Taxes |  |  | - M$   |  |                          |  | 190,271.7   |                                       |  |  | 7,105.3                                   |  |  |                   | 16,877.6  |  |             |  | 63,141.8  |  |  |  | 277,396.4   | 
|Operating Expenses             |  |  | - M$   |  |                          |  | 907,104.0   |                                       |  |  | 31,020.6                                  |  |  |                   | 40,850.7  |  |             |  | 165,228.8 |  |  |  | 1,144,205.3 | 
|Other Deductions               |  |  | - M$   |  |                          |  | 6,900.5     |                                       |  |  | 0.0                                       |  |  |                   | 0.0       |  |             |  | 0.0       |  |  |  | 6,900.5     | 
|Investments                    |  |  | - M$   |  |                          |  | 0.0         |                                       |  |  | 4,750.3                                   |  |  |                   | 17,782.8  |  |             |  | 233,540.7 |  |  |  | 256,073.8   | 
|Net Operating Income (BFIT)    |  |  | - M$   |  |                          |  | 1,318,668.3 |                                       |  |  | 52,776.4                                  |  |  |                   | 137,089.7 |  |             |  | 361,344.8 |  |  |  | 1,869,878.6 | 
|Discounted @ 10%               |  |  | - M$   |  |                          |  | 700,279.3   |                                       |  |  | 25,976.1                                  |  |  |                   | 64,156.9  |  |             |  | 130,851.3 |  |  |  | 921,263.4   | 

The results of
Chaparrals reserve study of the minor properties comprising the remaining 25 percent of Chaparrals net proved reserves (as estimated by Chaparral) are presented below. The results were adjusted by applying a scaling factor
derived from the ratio of CG&As independent estimated reserves and economics for the major properties versus Chaparrals reserves and economics from their analysis of the major properties.



|                               |  |  |        |  |                          |  |           |                                       |  |  |                                           |  |  |                   |           |  |             |  |           |  |  |  |           | 
|------------------------------ |  |  | ------ |  | ------------------------ |  | --------- | ------------------------------------- |  |  | ----------------------------------------- |  |  | ----------------- | --------- |  | ----------- |  | --------- |  |  |  | --------- | 
|                               |  |  |        |  | ProvedDevelopedProducing |  |           | ProvedDevelopedNon-Producing(Shut In) |  |  | ProvedDevelopedNon-Producing(Behind Pipe) |  |  | ProvedUndeveloped |           |  | TotalProved | 
|Net Reserves                   |  |  |        |  |                          |  |           |                                       |  |  |                                           |  |  |                   |           |  |             |  |           |  |  |  |           | 
|Oil                            |  |  | - Mbbl |  |                          |  | 3,388.8   |                                       |  |  | 400.7                                     |  |  |                   | 1,745.7   |  |             |  | 5,105.7   |  |  |  | 10,640.9  | 
|Gas                            |  |  | - MMcf |  |                          |  | 90,180.8  |                                       |  |  | 5,066.7                                   |  |  |                   | 23,436.7  |  |             |  | 46,382.5  |  |  |  | 165,066.5 | 
|Revenue                        |  |  |        |  |                          |  |           |                                       |  |  |                                           |  |  |                   |           |  |             |  |           |  |  |  |           | 
|Oil                            |  |  | - M$   |  |                          |  | 253,820.2 |                                       |  |  | 30,366.7                                  |  |  |                   | 131,568.9 |  |             |  | 380,703.4 |  |  |  | 796,459.2 | 
|Gas                            |  |  | - M$   |  |                          |  | 385,244.0 |                                       |  |  | 22,485.2                                  |  |  |                   | 92,263.6  |  |             |  | 203,594.0 |  |  |  | 703,586.8 | 
|Severance and Ad Valorem Taxes |  |  | - M$   |  |                          |  | 51,354.3  |                                       |  |  | 4,062.5                                   |  |  |                   | 19,095.5  |  |             |  | 47,602.5  |  |  |  | 122,114.9 | 
|Operating Expenses             |  |  | - M$   |  |                          |  | 248,861.0 |                                       |  |  | 11,238.7                                  |  |  |                   | 53,829.2  |  |             |  | 104,992.2 |  |  |  | 418,921.3 | 
|Other Deductions               |  |  | - M$   |  |                          |  | 301.7     |                                       |  |  | 0.0                                       |  |  |                   | 4,572.6   |  |             |  | 0.0       |  |  |  | 4,874.3   | 
|Investments                    |  |  | - M$   |  |                          |  | 88.7      |                                       |  |  | 6,063.0                                   |  |  |                   | 22,783.1  |  |             |  | 201,490.7 |  |  |  | 230,425.4 | 
|Net Operating Income (BFIT)    |  |  | - M$   |  |                          |  | 338,458.5 |                                       |  |  | 31,487.7                                  |  |  |                   | 123,552.1 |  |             |  | 230,212.1 |  |  |  | 723,710.0 | 
|Discounted @ 10%               |  |  | - M$   |  |                          |  | 179,541.0 |                                       |  |  | 9,488.5                                   |  |  |                   | 35,865.5  |  |             |  | 68,154.0  |  |  |  | 293,048.9 | 

The discounted cash flow
values shown above in the previous three tables should not be construed to represent an estimate of the fair market value by Cawley, Gillespie & Associates, Inc.





---

Mr. Mark Fischer

Chaparral Energy, Inc. Interests

January 11, 2011

Page
 3



Presentation

The accompanying tabulations present the results of our evaluation. The report is divided into two main sections: Major Properties and Minor Properties. The Major Properties section is further divided
into five reserve sections: Total Proved, Proved Developed Producing (PDP), Proved Developed Non-Producing Shut In (PDNP-SI), Proved Developed Non-Producing Behind Pipe (PDNP-BP) and Proved Undeveloped
(PUD) reserves. Within each reserve category section is a Table I and Table II. The Table I presents composite reserve estimates and economic forecasts for the particular reserve category. Following each Table I is a Table II
oneline summary that presents estimates of ultimate recovery, gross and net reserves, ownership, net revenue, taxes, expenses, investments, net income, and discounted cash flow for the individual properties that make up the corresponding
Table I. In the PDP section, the Table II is followed by sequentially numbered tables that represent the tabular details of reserves and economics for each property listed in Table II. The Minor Properties section consists of summary tables for PDP,
PDNP-SI, PDNP-BP and PUD. For a more detailed explanation of the report layout please refer to the Table of Contents following this letter. The data presented in the individual tables are explained in page 1 of the Appendix. The methods employed in
estimating reserves are described in page 2 of the Appendix.

Hydrocarbon Pricing

As requested, adjustments were applied to the Chaparral furnished initial oil and gas prices of $79.432 per bbl and $4.377 per MMBtu,
respectively as quoted on December 31, 2010. Prices were not escalated. Oil and gas price differentials were forecast on a per property basis. Gas price differentials include adjustments for heating value, gas shrinkage, transportation and
basis differential.

Expenses and Taxes

Lease operating costs and investments were forecast on a per property basis as furnished by your office and were not escalated. Per well operating expenditures were applied against a projected well-count
as provided by your office. Severance tax values were applied at normal state percentages of oil and gas revenue. Ad Valorem tax rates were forecast as provided by your office.

Miscellaneous

An on-site field inspection of the properties has
not been performed nor has the mechanical operation or condition of the wells and their related facilities been examined, nor have the wells been tested by Cawley, Gillespie & Associates, Inc. Possible environmental liability related
to the properties has not been investigated nor considered.

The proved reserve classifications used herein conform to
the criteria of the Securities and Exchange Commission as defined in pages 3-4 of the Appendix. The reserves and economics are predicated on regulatory agency classifications, rules, policies, laws, taxes and royalties in effect on the effective
date, except as noted herein. The possible effects of changes in legislation or other Federal or State restrictive actions have not been considered. All reserve estimates represent our best judgment based on data available at the time of
preparation, and assumptions as to future economic and regulatory conditions. It should be realized that the reserves actually recovered, the revenue derived therefrom and the actual cost incurred could be more or less than the estimated amounts.

The reserve estimates and forecasts were based upon interpretations of data furnished by your office and available from our
files. Production data, ownership information, price differentials, expenses, projected well count, investments and tax rates were furnished by your office and were accepted as furnished. To some extent, information from public records was used to
check and/or supplement these data. The basic engineering and geological data were utilized subject to third party





---

Mr. Mark Fischer

Chaparral Energy, Inc. Interests

January 11, 2011

Page
 4



reservations and qualifications. Nothing has come to our attention, however, that would cause us to believe that we are not justified in relying on such data.

Our work papers and related data are available for inspection and review by authorized, interested parties.



Yours very truly,Cawley, Gillespie & Associates, Inc.Texas Registered Engineering Firm F-693