----

| Delaware                                       |   | 75-2310852               |
|------------------------------------------------|--------|--------------------------|
| (State      or other jurisdiction              |   | (I.R.S.      Employer    |
| of      incorporation or organization)         |   | Identification      No.) |
|                                           |   |                     |
| 6 Desta Drive, Suite 6500, Midland,      Texas |   | 79705                    |
| (Address      of principal executive office)   |   | (Zip      Code)          |

| Indicate      by check mark if the registrant is a well-known seasoned issuer, as      defined in Rule 405 of the Securities Act.                                                                                                                                                                                                                                                 |  ̈    Yes | x  No      |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|------------|
|                                                                                                                                                                                                                                                                                                                                                                              |          |       |
| Indicate      by check mark if the registrant is not required to file reports pursuant      to Section 13 or Section 15(d) of the Act.                                                                                                                                                                                                                                            |  ̈    Yes | x  No      |
|                                                                                                                                                                                                                                                                                                                                                                              |          |       |
| Indicate      by check mark whether the registrant (1) has filed all reports required to      be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934      during the preceding 12 months (or for such shorter period that the      registrant was required to file such reports), and (2) has been subject to      such filing requirements for the past 90 days. | x    Yes      |  ̈  No |

| Indicate      by check mark if disclosure of delinquent filers pursuant to Item 405 of      Regulation S-K is not contained herein, and will not be contained, to the      best of registrant's knowledge, in definitive proxy or information      statements incorporated by reference in Part III of this Form 10-K or any      amendment to this Form 10-K.x |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| Indicate      by check mark whether the registrant is a large accelerated filer, an      accelerated filer, or a non-accelerated filer.  See definition      of “accelerated filer and large accelerated filer” in Rule 12b-2 of the      Exchange Act. |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Large      accelerated filer  ̈                                                                                                                                                                                                                                           |   | Accelerated      filer  ̈ |   | Non-accelerated      filer  x |   | Smaller      reporting company ̈ |   |

| Indicate      by check mark whether the registrant is a shell company (as defined in      Rule 12b-2 of the Act). |  ̈    Yes | x  No |
|-------------------------------------------------------------------------------------------------------------------|---------------|-------|

----

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | Page   |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|
| Part I                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      1.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Business                                                                                                                                                     | 3      |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      1A.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Risk      Factors                                                                                                                                            | 7      |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      1B.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Unresolved Staff      Comments                                                                                                                               | 8      |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      2.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Properties                                                                                                                                                   | 9      |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      3.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Legal      Proceedings                                                                                                                                       | 10     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      4.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Submission of Matters to a Vote of Security      Holders                                                                                                     | 10     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Part II                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      5.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Market for Registrant's Common Equity,      Related                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | Stockholder      Matters and Issuer Purchases of Equity Securities                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 11     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      6.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Selected Financial      Data                                                                                                                                 | 12     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      7.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Management's Discussion and Analysis of                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | Financial      Condition and Results of      Operations                                                                                                                          | 13     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      7A.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Quantitative and Qualitative Disclosures About Market      Risk                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | 15     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      8.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Financial Statements and Supplementary      Data                                                                                                             | 16     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      9.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   | Changes in and Disagreements with      Accountants                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | on Accounting      and Financial      Disclosure                                                                                                                                 | 29     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      9A.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Controls and      Procedures                                                                                                                                 | 29     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      9B.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Other      Information                                                                                                                                       | 30     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Part III                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      10.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Directors, Executive Officers and Corporate      Governance                                                                                                  | 31     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      11.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Executive      Compensation                                                                                                                                  | 31     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      12.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Security Ownership of Certain Beneficial Owners and      Management and                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           | Related      Stockholder      Matters                                                                                                                                            | 32     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      13.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Certain Relationships and Related Transactions, and      Director Independence                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 32     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      14.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Principal Accounting Fees and      Services                                                                                                                  | 32     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Part IV                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Item      15.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Exhibits and Financial Statement      Schedules                                                                                                              | 33     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Glossary of Oil and Gas      Terms                                                                                                                   | 34                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |
| Signatures                                                                                                                                           | 36                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |

----

Part 

Item

----

----

----

----

Item

----

Item

----

Item

|                                    |   | Proved      Developed |    |   | Proved       |   |   | Total       |   |
|-----------------------------------------|--------|-----------------------|---------|--------|--------------|--------|--------|-------------|--------|
|                                    |   | Producing             |    |   | Nonproducing |   |   | Undeveloped |   |   | Proved |   |
| Oil      (Bbls)                         |   |                  | 112,000 |   |         |   | -      |        |   |   | - |   |   |   | 112,000 |   |
| Gas      (Mcf)                          |   |                  | 188,000 |   |         |   | -      |        |   |   | 1,000 |   |   |   | 189,000 |   |
| Total      (BOE)                        |   |                  | 143,000 |   |         |   | -      |        |   |   | - |   |   |   | 143,000 |   |
|                                    |   |                  |    |   |         |   |   |        |   |   |   |   |   |   |   |   |
| Standardized      measure of discounted |   |                  |    |   |         |   |   |        |   |   |   |   |   |   |   |   |
| future net cash      flows              |   |                  |    |   |         |   |   |        |   |   |   |   |   | $ | 3,425,000 |   |

|      |   | Proved      Reserves |    |   |   |   |
|-----------|--------|----------------------|---------|--------|--------|--------|
|      |   |                 |    |   |   |   |   | Total      Oil |   |   | Percent      of |   |
|      |   | Oil                  |    |   | Gas    |   |   | Equivalent |   |   | Total      Oil |   |
|      |   | (Bbls)               |    |   | (Mcf)  |   |   | (BOE) |   |   | Equivalent |   |
| Slaughter |   |                 | 53,000  |   |   |   | - |   |   |   | 53,000 |   |   |   | 37.1 | % |
| Anita     |   |                 | 14,000  |   |   |   | - |   |   |   | 14,000 |   |   |   | 9.8 | % |
| Jalmat    |   |                 | 9,000   |   |   |   | 31,000 |   |   |   | 14,000 |   |   |   | 9.8 | % |
| Other     |   |                 | 36,000  |   |   |   | 158,000 |   |   |   | 62,000 |   |   |   | 43.3 | % |
| Total     |   |                 | 112,000 |   |   |   | 189,000 |   |   |   | 143,000 |   |   |   | 100.0 | % |

----

Item

Item

----

Part 

Item 

|                |   | Total      Number |   |   |               |   |
|---------------------|--------|-------------------|--------|--------|--------------------|--------|
|                |   | of      Units     |   |   | Average      Price |   |
| Period              |   | Purchased         |   |   | Paid      Per Unit |   |
| January      2007   |   |              | 52     |   |               | $      | 65.56 |   |
| February      2007  |   |              | -      |   |               |   | - |   |
| March      2007     |   |              | -      |   |               |   | - |   |
| April      2007     |   |              | 201    |   |               |   | 53.64 |   |
| May      2007       |   |              | -      |   |               |   | - |   |
| June      2007      |   |              | -      |   |               |   | - |   |
| July      2007      |   |              | 20     |   |               |   | 36.76 |   |
| August      2007    |   |              | -      |   |               |   | - |   |
| September      2007 |   |              | -      |   |               |   | - |   |
| October      2007   |   |              | -      |   |               |   | - |   |
| November      2007  |   |              | -      |   |               |   | - |   |
| December      2007  |   |              | 36     |   |               |   | 34.77 |   |
| TOTALS              |   |              | 309    |   |               | $      | 52.35 |   |

----

Item

|                                |   | Years      ended December 31, |    |
|-------------------------------------|--------|-------------------------------|---------|
|                                |   | 2007                          |    |   | 2006 |   |   | 2005 |   |   | 2004 |   |   | 2003 |   |
| Revenues                            |   | $                             | 424,116 |   |   | $ | 412,625 |   |   | $ | 459,406 |   |   | $ | 275,491 |   |   | $ | 218,987 |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Income      before cumulative       |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| effect of accounting      change    |   |                          | 267,363 |   |   |   | 271,735 |   |   |   | 334,787 |   |   |   | 145,577 |   |   |   | 86,100 |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net      income                     |   |                          | 267,363 |   |   |   | 271,735 |   |   |   | 334,787 |   |   |   | 145,577 |   |   |   | 103,735 |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Partners'      share of net income: |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| General      partners               |   |                          | 28,886  |   |   |   | 28,688 |   |   |   | 34,570 |   |   |   | 15,807 |   |   |   | 11,873 |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Limited      partners               |   |                          | 238,477 |   |   |   | 243,047 |   |   |   | 300,217 |   |   |   | 129,770 |   |   |   | 91,862 |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Limited      partners' income per   |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| unit before cumulative      effect  |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| of accounting    change             |   |                          | 21.07   |   |   |   | 21.48 |   |   |   | 26.53 |   |   |   | 11.47 |   |   |   | 6.72 |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Limited      partners'              |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| net income per    unit              |   |                          | 21.07   |   |   |   | 21.48 |   |   |   | 26.53 |   |   |   | 11.47 |   |   |   | 8.12 |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Limited      partners'              |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| cash distributions per      unit    |   |                          | 18.33   |   |   |   | 26.35 |   |   |   | 27.04 |   |   |   | 11.97 |   |   |   | 4.01 |   |
|                                |   |                          |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Total      assets                   |   | $                             | 471,343 |   |   | $ | 426,228 |   |   | $ | 417,337 |   |   | $ | 407,709 |   |   | $ | 405,882 |   |

----

Item

----

|                                           |   | Year      Ended December 31, |    |
|------------------------------------------------|--------|------------------------------|---------|
|                                           |   | 2007                         |    |   | 2006 |   |   | 2005 |   |
| Oil      production in barrels                 |   |                         | 8,950   |   |   |   | 9,068 |   |   |   | 10,509 |   |
| Gas      production in mcf                     |   |                         | 26,947  |   |   |   | 29,075 |   |   |   | 29,455 |   |
| Total      (BOE)                               |   |                         | 13,441  |   |   |   | 13,914 |   |   |   | 15,418 |   |
| Average      price per barrel of oil           |   | $                            | 67.54   |   |   | $ | 61.88 |   |   | $ | 52.51 |   |
| Average      price per mcf of gas              |   | $                            | 7.41    |   |   | $ | 6.78 |   |   | $ | 7.61 |   |
| Partnership      distributions                 |   | $                            | 230,479 |   |   | $ | 331,623 |   |   | $ | 340,000 |   |
| Limited      partner distributions             |   | $                            | 207,366 |   |   | $ | 298,161 |   |   | $ | 306,000 |   |
| Per      unit distribution to limited partners |   | $                            | 18.33   |   |   | $ | 26.35 |   |   | $ | 27.04 |   |
| Number      of limited partner units           |   |                         | 11,316  |   |   |   | 11,316 |   |   |   | 11,316 |   |

----

Item

----

Item

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   | Page   |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|--------|
| Report of Independent Registered Public Accounting      Firm                                                                                                    |   | 17     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |   |
| Balance      Sheets                                                                                                                                             |   | 18     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |   |
| Statements of      Operations                                                                                                                                   |   | 19     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |   |
| Statements of Changes in Partners' Equity      (Deficit)                                                                                                        |   | 20     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |   |
| Statements of Cash      Flows                                                                                                                                   |   | 21     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |   |
| Notes to Financial      Statements                                                                                                                              |   | 22     |

----

INDEPENDENT 

----

Institutional 

|                                            |   | December      31, |      |
|-------------------------------------------------|--------|-------------------|-----------|
|                                            |   | 2007              |      |   | 2006 |   |
| Assets                                          |   |              |      |   |   |   |
|                                            |   |              |      |   |   |   |
| Current      assets:                            |   |              |      |   |   |   |
| Cash and cash      equivalents                  |   | $                 | 47,747    |   |   | $ | 18,571 |   |
| Receivable from Managing General      Partner   |   |              | 90,989    |   |   |   | 55,021 |   |
| New Mexico income tax      deposits             |   |              | 13,341    |   |   |   | 11,674 |   |
|                                            |   |              |      |   |   |   |   |   |
| Total current      assets                       |   |              | 152,077   |   |   |   | 85,266 |   |
|                                            |   |              |      |   |   |   |   |   |
| Oil      and gas properties - using the full-   |   |              |      |   |   |   |   |   |
| cost method of      accounting                  |   |              | 4,376,881 |   |   |   | 4,377,076 |   |
| Less accumulated      depreciation,             |   |              |      |   |   |   |   |   |
| depletion and      amortization                 |   |              | 4,057,615 |   |   |   | 4,036,114 |   |
|                                            |   |              |      |   |   |   |   |   |
| Net oil and gas      properties                 |   |              | 319,266   |   |   |   | 340,962 |   |
|                                            |   |              |      |   |   |   |   |   |
|                                            |   | $                 | 471,343   |   |   | $ | 426,228 |   |
| Liabilities and Partners' Equity      (Deficit) |   |              |      |   |   |   |   |   |
|                                            |   |              |      |   |   |   |   |   |
| Asset      retirement obligation                |   | $                 | 248,073   |   |   | $ | 239,842 |   |
|                                            |   |              |      |   |   |   |   |   |
| Partners'      equity (deficit):                |   |              |      |   |   |   |   |   |
| General Partner                                 |   |              | (2,417    | ) |   |   | (8,190 | ) |
| Limited partners                                |   |              | 225,687   |   |   |   | 194,576 |   |
|                                            |   |              |      |   |   |   |   |   |
| Total partners'      equity                     |   |              | 223,270   |   |   |   | 186,386 |   |
|                                            |   |              |      |   |   |   |   |   |
|                                            |   | $                 | 471,343   |   |   | $ | 426,228 |   |

----

Income 

|                                          |   | Years      ended December 31, |    |
|-----------------------------------------------|--------|-------------------------------|---------|
|                                          |   | 2007                          |    |   | 2006 |   |   | 2005 |   |
| Revenues                                      |   |                          |    |   |   |   |   |   |   |
|                                          |   |                          |    |   |   |   |   |   |   |
| Income from net profits      interests        |   | $                             | 423,146 |   |   | $ | 412,262 |   |   | $ | 459,406 |   |
| Interest income                               |   |                          | 936     |   |   |   | 363 |   |   |   | - |   |
| Other                                         |   |                          | 34      |   |   |   | - |   |   |   | - |   |
|                                          |   |                          | 424,116 |   |   |   | 412,625 |   |   |   | 459,406 |   |
|                                          |   |                          |    |   |   |   |   |   |   |   |   |   |
| Expenses                                      |   |                          |    |   |   |   |   |   |   |   |   |   |
|                                          |   |                          |    |   |   |   |   |   |   |   |   |   |
| Depreciation, depletion and      amortization |   |                          | 21,500  |   |   |   | 15,147 |   |   |   | 10,915 |   |
| Accretion    expense                          |   |                          | 21,387  |   |   |   | 13,926 |   |   |   | 11,749 |   |
| General and      administrative               |   |                          | 113,866 |   |   |   | 111,817 |   |   |   | 101,955 |   |
|                                          |   |                          | 156,753 |   |   |   | 140,890 |   |   |   | 124,619 |   |
|                                          |   |                          |    |   |   |   |   |   |   |   |   |   |
| Net      income                               |   | $                             | 267,363 |   |   | $ | 271,735 |   |   | $ | 334,787 |   |
|                                          |   |                          |    |   |   |   |   |   |   |   |   |   |
| Net      income allocated to:                 |   |                          |    |   |   |   |   |   |   |   |   |   |
|                                          |   |                          |    |   |   |   |   |   |   |   |   |   |
| Managing General      Partner                 |   | $                             | 25,998  |   |   | $ | 25,819 |   |   | $ | 31,113 |   |
|                                          |   |                          |    |   |   |   |   |   |   |   |   |   |
| General Partner                               |   | $                             | 2,888   |   |   | $ | 2,869 |   |   | $ | 3,457 |   |
|                                          |   |                          |    |   |   |   |   |   |   |   |   |   |
| Limitedpartners                               |   | $                             | 238,477 |   |   | $ | 243,047 |   |   | $ | 300,217 |   |
|                                          |   |                          |    |   |   |   |   |   |   |   |   |   |
| Per limited partner      unit                 |   | $                             | 21.07   |   |   | $ | 21.48 |   |   | $ | 26.53 |   |

----

Royalties 

|                              |   | General  |    |   | Limited  |   |     |   |   |
|-----------------------------------|--------|----------|---------|--------|----------|--------|----------|--------|--------|
|                              |   | Partners |    |   | Partners |   |     | Total  |   |
|                              |   |     |    |   |     |   |     |   |   |
| Balance      at December 31, 2004 |   | $        | (3,986  | )      |     | $      | 255,473  |   |   | $ | 251,487 |   |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Net income                        |   |     | 34,570  |   |     |   | 300,217  |   |   |   | 334,787 |   |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Distributions                     |   |     | (34,000 | )      |     |   | (306,000 | )      |   |   | (340,000 | ) |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Balance      at December 31, 2005 |   |     | (3,416  | )      |     |   | 249,690  |   |   |   | 246,274 |   |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Net income                        |   |     | 28,688  |   |     |   | 243,047  |   |   |   | 271,735 |   |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Distributions                     |   |     | (33,462 | )      |     |   | (298,161 | )      |   |   | (331,623 | ) |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Balance      at December 31, 2006 |   |     | (8,190  | )      |     |   | 194,576  |   |   |   | 186,386 |   |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Net income                        |   |     | 28,886  |   |     |   | 238,477  |   |   |   | 267,363 |   |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Distributions                     |   |     | (23,113 | )      |     |   | (207,366 | )      |   |   | (230,479 | ) |
|                              |   |     |    |   |     |   |     |   |   |   |   |   |
| Balance      at December 31, 2007 |   | $        | (2,417  | )      |     | $      | 225,687  |   |   | $ | 223,270 |   |

----

Royalties 

|                                                       |   | Years      ended December 31, |     |
|------------------------------------------------------------|--------|-------------------------------|----------|
|                                                       |   | 2007                          |     |   | 2006 |   |   | 2005 |   |
| Cash      flows from operating activities:                 |   |                          |     |   |   |   |   |   |   |
| Cash received from net profits      interests              |   | $                             | 372,551  |   |   | $ | 389,987 |   |   | $ | 458,045 |   |
| Cash paid for administrative      fees and general         |   |                          |     |   |   |   |   |   |   |   |   |   |
| and administrative      overhead                           |   |                          | (113,866 | ) |   |   | (111,817 | ) |   |   | (101,955 | ) |
| Interestreceived                                           |   |                          | 936      |   |   |   | 363 |   |   |   | - |   |
| Other                                                      |   |                          | 34       |   |   |   | - |   |   |   | - |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Net cash provided by operating      activities             |   |                          | 259,655  |   |   |   | 278,533 |   |   |   | 356,090 |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Cash      flows from financing activities:                 |   |                          |     |   |   |   |   |   |   |   |   |   |
| Distributions to      partners                             |   |                          | (230,479 | ) |   |   | (331,623 | ) |   |   | (340,000 | ) |
| Decrease in distributions      payable                     |   |                          | -        |   |   |   | - |   |   |   | (115 | ) |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Net cash used in financing      activities                 |   |                          | (230,479 | ) |   |   | (331,623 | ) |   |   | (340,115 | ) |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Net      increase (decrease) in cash and cash equivalents  |   |                          | 29,176   |   |   |   | (53,090 | ) |   |   | 15,975 |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Beginning ofyear                                           |   |                          | 18,571   |   |   |   | 71,661 |   |   |   | 55,686 |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| End of year                                                |   | $                             | 47,747   |   |   | $ | 18,571 |   |   | $ | 71,661 |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Reconciliation      of net income to net cash              |   |                          |     |   |   |   |   |   |   |   |   |   |
| provided by operating      activities:                     |   |                          |     |   |   |   |   |   |   |   |   |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Net      income                                            |   | $                             | 267,363  |   |   | $ | 271,735 |   |   | $ | 334,787 |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Adjustments      to reconcile net income to                |   |                          |     |   |   |   |   |   |   |   |   |   |
| net cash provided by operating      activities:            |   |                          |     |   |   |   |   |   |   |   |   |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Depreciation, depletion and      amortization              |   |                          | 21,500   |   |   |   | 15,147 |   |   |   | 10,915 |   |
| Accretionexpense                                           |   |                          | 21,387   |   |   |   | 13,926 |   |   |   | 11,749 |   |
| Settlement of asset retirement      obligations            |   |                          |     |   |   |   |   |   |   |   |   |   |
| for plugged and abandoned      wells                       |   |                          | (12,960  | ) |   |   | (22,543 | ) |   |   | (6,772 | ) |
| (Increase) decrease in      receivables and deposits       |   |                          | (37,635  | ) |   |   | 268 |   |   |   | 5,411 |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Net      cash provided by operating activities             |   | $                             | 259,655  |   |   | $ | 278,533 |   |   | $ | 356,090 |   |
|                                                       |   |                          |     |   |   |   |   |   |   |   |   |   |
| Noncash      investing and financing activities:           |   |                          |     |   |   |   |   |   |   |   |   |   |
| (Decrease) increase in oil and      gas properties – |   |                          |     |   |   |   |   |   |   |   |   |   |
| SFAS No. 143                                               |   | $                             | (196     | ) |   | $ | 77,396 |   |   | $ | 9,979 |   |

----

Fund 

| 1. | Organization |
|----|--------------|

|                                           | Limited  |   | General  |
|------------------------------------------------|----------|--------|----------|
|                                           | Partners |   | Partners |
| Interest      income on capital contributions  | 100%     |   | -        |
| Oil      and gas sales                         | 90%      |   | 10%      |
| All      other revenues                        | 90%      |   | 10%      |
| Organization      and offering costs (1)       | 100%     |   | -        |
| Amortization      or organization costs        | 100%     |   | -        |
| Property      acquisition costs                | 100%     |   | -        |
| Gain/loss      on property disposition         | 90%      |   | 10%      |
| Operating      and administrative costs (2)    | 90%      |   | 10%      |
| Depreciation,      depletion, and amortization |     |   |     |
|  of      oil and gas properties           | 100%     |   | -        |
| All      other costs                           | 90%      |   | 10%      |

|   | (1) | All      organization costs in excess of 3% of initial capital contributions will      be paid by the Managing General Partner and will be treated as a capital      contribution.  The Partnership paid the Managing General Partner      an amount equal to 3% of initial capital contributions for such      organization costs. |
|--------|-----|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | (2) | Administrative      costs in any year, which exceed 2% of capital contributions shall be paid      by the Managing General Partner and will be treated as a capital      contribution. |
|--------|-----|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 2. | Summary of Significant      Accounting Policies |
|----|-------------------------------------------------|

----

| 2. | Summary of Significant      Accounting Policies -continued |
|----|------------------------------------------------------------|

----

| 2. | Summary of Significant      Accounting Policies -continued |
|----|------------------------------------------------------------|

|                                                             |   | 2007   |    |   | 2006   |   |
|------------------------------------------------------------------|--------|--------|---------|--------|--------|--------|
| Beginning      of year                                           |   | $      | 239,842 |   |   | $      | 171,063 |   |
| Additional      abandonment obligations from new wells           |   |   | -       |   |   |   | 123 |   |
| Reduction      of obligations due to farm-outs                   |   |   | (196    | )      |   |   | (710 | ) |
| Reduction      of obligations due to wells plugged and abandoned |   |   | (12,960 | )      |   |   | (22,543 | ) |
| Accretion      expense                                           |   |   | 21,387  |   |   |   | 13,926 |   |
| Revisions      of previous estimates                             |   |   | -       |   |   |   | 77,983 |   |
| End      of year                                                 |   | $      | 248,073 |   |   | $      | 239,842 |   |

----

| 4. | Commitments and      Contingent Liabilities |
|----|---------------------------------------------|

| 5. | Related Party      Transactions |
|----|---------------------------------|

----

| 6. | Oil and Gas Reserves      Information (unaudited) |
|----|---------------------------------------------------|

|                                 |   | Oil      (bbls) |    |   | Gas      (mcf) |   |
|--------------------------------------|--------|-----------------|---------|--------|----------------|--------|
| Total      Proved -                  |   |            |    |   |           |   |
|                                 |   |            |    |   |           |   |
| January      1, 2005                 |   |            | 108,000 |   |           |   | 310,000 |   |
|                                 |   |            |    |   |           |   |   |   |
| Revisions of previous      estimates |   |            | 58,000  |   |           |   | (34,000 | ) |
| Production                           |   |            | (11,000 | )      |           |   | (29,000 | ) |
|                                 |   |            |    |   |           |   |   |   |
| December      31, 2005               |   |            | 155,000 |   |           |   | 247,000 |   |
|                                 |   |            |    |   |           |   |   |   |
| Revisions of previous      estimates |   |            | (58,000 | )      |           |   | 9,000 |   |
| Production                           |   |            | (9,000  | )      |           |   | (29,000 | ) |
|                                 |   |            |    |   |           |   |   |   |
| December      31, 2006               |   |            | 88,000  |   |           |   | 227,000 |   |
|                                 |   |            |    |   |           |   |   |   |
| Revisions of previous      estimates |   |            | 32,000  |   |           |   | (12,000 | ) |
| Production                           |   |            | (9,000  | )      |           |   | (27,000 | ) |
|                                 |   |            |    |   |           |   |   |   |
| December      31, 2007               |   |            | 111,000 |   |           |   | 188,000 |   |
|                                 |   |            |    |   |           |   |   |   |
| Proved developed reserves      -     |   |            |    |   |           |   |   |   |
|                                 |   |            |    |   |           |   |   |   |
| December      31, 2005               |   |            | 155,000 |   |           |   | 247,000 |   |
| December      31, 2006               |   |            | 88,000  |   |           |   | 226,000 |   |
| December      31, 2007               |   |            | 111,000 |   |           |   | 188,000 |   |

----

| 6. | Oil and Gas Reserves      Information (unaudited) -continued |
|----|--------------------------------------------------------------|

|                                               |   | 2007   |       |   | 2006   |   |      | 2005   |   |
|----------------------------------------------------|--------|--------|------------|--------|--------|--------|-----------|--------|--------|
| Future      cash inflows                           |   | $      | 11,283,000 |   |   | $      | 5,795,000 |   |   | $ | 11,540,000 |   |
| Production,      development and abandonment costs |   |   | 4,729,000  |   |   |   | 2,731,000 |   |   |   | 4,744,000 |   |
| Future      net cash flows                         |   |   | 6,554,000  |   |   |   | 3,064,000 |   |   |   | 6,796,000 |   |
| 10%      annual discount for                       |   |   |       |   |   |   |      |   |   |   |   |   |
| estimated timing of cash      flows                |   |   | 3,129,000  |   |   |   | 1,417,000 |   |   |   | 3,532,000 |   |
| Standardized      measure of                       |   |   |       |   |   |   |      |   |   |   |   |   |
| discounted future net cash      flows              |   | $      | 3,425,000  |   |   | $      | 1,647,000 |   |   | $ | 3,264,000 |   |

|                                                        |   | 2007   |      |   | 2006   |   |       | 2005   |   |
|-------------------------------------------------------------|--------|--------|-----------|--------|--------|--------|------------|--------|--------|
| Sales      of oil and gas produced, net of production costs |   | $      | (423,000  | )      |   | $      | (412,000   | )      |   | $ | (459,000 | ) |
| Changes      in prices and production costs                 |   |   | 1,343,000 |   |   |   | (1,029,000 | )      |   |   | 1,127,000 |   |
| Changes      of production rates (timing) and others        |   |   | (29,000   | )      |   |   | 237,000    |   |   |   | 51,000 |   |
| Revisions      of previous quantities estimates             |   |   | 722,000   |   |   |   | (739,000   | )      |   |   | 871,000 |   |
| Accretion      of discount                                  |   |   | 165,000   |   |   |   | 326,000    |   |   |   | 152,000 |   |
| Discounted      future net cash flows -                     |   |   |      |   |   |   |       |   |   |   |   |   |
| Beginning      of year                                      |   |   | 1,647,000 |   |   |   | 3,264,000  |   |   |   | 1,522,000 |   |
| End      of year                                            |   | $      | 3,425,000 |   |   | $      | 1,647,000  |   |   | $ | 3,264,000 |   |

----

| 7. | Selected Quarterly      Financial Results –(unaudited) |
|----|--------------------------------------------------------------|

|                                      |   | Quarter |   |
|-------------------------------------------|--------|---------|--------|
|                                      |   | First   |   |   | Second |   |   | Third |   |   | Fourth |   |
| 2007:                                     |   |    |   |   |   |   |   |   |   |   |   |   |
| Total revenues                            |   | $       | 45,977 |   |   | $ | 130,000 |   |   | $ | 134,772 |   |   | $ | 113,367 |   |
| Total expenses                            |   |    | 30,590 |   |   |   | 42,516 |   |   |   | 41,203 |   |   |   | 42,444 |   |
| Net income                                |   | $       | 15,387 |   |   | $ | 87,484 |   |   | $ | 93,569 |   |   | $ | 70,923 |   |
|                                      |   |    |   |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net income per limited partners      unit |   | $       | 1.19   |   |   | $ | 6.90 |   |   | $ | 7.39 |   |   | $ | 5.59 |   |

|                                      |   | Quarter |    |
|-------------------------------------------|--------|---------|---------|
|                                      |   | First   |    |   | Second |   |   | Third |   |   | Fourth |   |
| 2006:                                     |   |    |    |   |   |   |   |   |   |   |   |   |
| Total revenues                            |   | $       | 132,756 |   |   | $ | 131,796 |   |   | $ | 86,300 |   |   | $ | 61,773 |   |
| Total expenses                            |   |    | 33,714  |   |   |   | 39,159 |   |   |   | 33,263 |   |   |   | 34,754 |   |
| Net income                                |   | $       | 99,042  |   |   | $ | 92,637 |   |   | $ | 53,037 |   |   | $ | 27,019 |   |
|                                      |   |    |    |   |   |   |   |   |   |   |   |   |   |   |   |   |
| Net income per limited partners      unit |   | $       | 7.85    |   |   | $ | 7.34 |   |   | $ | 4.20 |   |   | $ | 2.09 |   |

----

Item

Item

----

Item

----

Part 

Item

Item

----

Item

Item

Item

| For      the Year Ended December 31, |   | 2007   |   |   | 2006   |   |
|--------------------------------------|--------|--------|--------|--------|--------|--------|
| Audit      Fees                      |   | $      | 16,932 |   |   | $      | 15,084 |   |
| Audit      Related Fees              |   |   | -      |   |   |   | - |   |
| Tax      Fees                        |   |   | -      |   |   |   | - |   |
| All      Other Fees                  |   |   | -      |   |   |   | - |   |
|                                 |   |   |   |   |   |   |   |   |
| TOTAL                                |   | $      | 16,932 |   |   | $      | 15,084 |   |

----

Part 

Item

| (a)    | (1)    | Financial      Statements:                                                                                                                                                                                          |
|--------|--------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |   |                                                                                                                                                                                                                |
|   |   | Included in Part II of this      report                                                                                                                                                                             |
|   |   |                                                                                                                                                                                                                |
|   |   | Report of Independent Registered      Public Accounting Firm                                                                                                                                                        |
|   |   | Balance Sheets                                                                                                                                                                                                      |
|   |   | Statements of      Operations                                                                                                                                                                                       |
|   |   | Statements of Changes in      Partners' Equity (Deficit)                                                                                                                                                            |
|   |   | Statements of Cash      Flows                                                                                                                                                                                       |
|   |   | Notes to Financial      Statements                                                                                                                                                                                  |
|   |   |                                                                                                                                                                                                                |
|   | (2)    | Schedules      required by Article 12 of Regulation S-X are either omitted because they      are not applicable or because the required information is shown in the      financial statements or the notes thereto. |
|   |   |                                                                                                                                                                                                                |
|   | (3)    | Exhibits:                                                                                                                                                                                                           |

| 4      | (a)    | Certificate      of Limited Partnership of Southwest Royalties Institutional Income Fund      X-A, L.P., dated January 29, 1990.  (Incorporated by reference      from Partnership's Form 10-K for the fiscal year ended December 31,      1990.) |
|--------|--------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|   |   |                                                                                                                                                                                                                                                        |
|   | (b)    | Agreement      of Limited Partnership of Southwest Royalties Institutional Income Fund      X-A, L.P. dated January 29, 1990.  (Incorporated by reference      from Partnership's Form 10-K for the fiscal year ended December 31,      1990.)    |
|   |   |                                                                                                                                                                                                                                                        |
|   | 31.1   | Rule      13a-14(a)/15d-14(a) Certification                                                                                                                                                                                                                 |
|   | 31.2   | Rule      13a-14(a)/15d-14(a) Certification                                                                                                                                                                                                                 |
|   | 32.1   | Certification      of Chief Executive Officer and Chief Financial Officer Pursuant to 18      U.S.C. Section 1350, as adopted Pursuant to Section 906 of the      Sarbanes-Oxley Act of 2002                                                                |

----

Glossary

----

----

Signatures

|   | Southwest      Royalties Institutional Income Fund |
|--------|----------------------------------------------------|
|   | X-A,      L.P., a Delaware limited partnership     |
|   |                                               |
| By:    | Southwest      Royalties, Inc., Managing           |
|   | General      Partner                               |
|   |                                               |
|   |                                               |
| By:    | /s/      L. Paul Latham                            |
|   | L.      Paul Latham                                |
|   | President      and Chief Executive Officer         |
|   |                                               |
| Date:  | March      28, 2008                                |

|                                                                                       |   |                                                                                       |
|--------------------------------------------------------------------------------------------|--------|--------------------------------------------------------------------------------------------|
| /s/      Clayton W Williams                                                                |   | /s/      L. Paul Latham                                                                    |
| Clayton      W. Williams, Chairman of the Board                                            |   | L.      Paul Latham, President and a Director                                              |
| and      a Director                                                                        |   |                                                                                       |
|                                                                                       |   |                                                                                       |
| Date:           March      28, 2008 |   | Date:           March      28, 2008 |
|                                                                                       |   |                                                                                       |
|                                                                                       |   |                                                                                       |
|                                                                                       |   |                                                                                       |
|                                                                                       |   |                                                                                       |
| /s/      Mel G. Riggs                                                                      |   |                                                                                       |
| Mel      G. Riggs, Vice President – Finance,                                         |   |                                                                                       |
| Treasurer      and a Director                                                              |   |                                                                                       |
|                                                                                       |   |                                                                                       |
| Date:           March      28, 2008 |   |                                                                                       |
|                                                                                       |   |                                                                                       |
|                                                                                       |   |                                                                                       |