EXHIBIT10.28**COMPLETION AND LIQUIDITY MAINTENANCE AGREEMENT**     **THIS COMPLETION AGREEMENT AND LIQUIDITY****MAINTENANCE****AGREEMENT**(“Agreement”) is made andentered into effective as of June 29, 2006 between**PRIMEENERGY CORPORATION**(“Prime”), **GUARANTYBANK, FSB**(“Guaranty”) and **PRIME OFFSHORE L.L.C.**(“Offshore”).     Prime is the majority shareholder of Prime Offshore L.L.C. (“Offshore”). Offshore andGuaranty are parties to a Credit Agreement dated June 29, 2006, by and between Offshore asBorrower and Guaranty, as Agent and Lender (“Credit Agreement”) wherein Guaranty is loaningcertain funds to Offshore to drill and complete wells and construct, install and operate in-fieldand flow pipelines, caissons, platforms and production facilities for wells in South Padre IslandArea OCS Blocks 1113, 1059, 1060, 1073 and 1133 and North Padre Island Area OCS Block 998(“Development Project”).1. Completion Commitment     Each of the South Padre Island Area OCS Blocks 1113, 1059, 1060, 1073 and 1133 and the NorthPadre Island Area OCS Block 998 shall be defined as a “Project Field.”     For purposes of this Agreement, Project Completion shall consist of two components and bedefined as: A) each Project Field in the Development Project having all planned in-field andflow pipelines, caissons, platforms and production facilities for all the wells in suchProject Field, for which Guaranty has loaned funds, installed and operational such thatthe production from all such wells can be transported to a readily available salespoint for natural gas. In addition, for each Project Field, Project Completion willinclude, but not limited to: a) obtaining required permits, easements and governmental approvals;  b) executing necessary construction contract(s);  c) completing tests considered usual and customary and required tobe conducted with results in accordance with those necessary to permitoperations;  d) ensuring that each Project Field is free and clear of all liensother than those in favor of Guaranty and Permitted Liens under theCredit Agreement and;  e) causing all costs of the Development Project to be paid when due; and, B) the 12-inch loop pipeline from North Padre Island Area OCS Block 996 to thepipeline owned by the Williams Companies Inc. having been constructed and installed inaccordance with the plans and specifications in the construction contract(s).
 

 
     As consideration for Guaranty entering into the Credit Agreement to provide such loans forthe Development Project and to ensure Project Completion, Prime absolutely and unconditionallywarrants to Guaranty to fund the payment to Offshore of all costs that exceed the availablecommitments under the Credit Agreement, including interest, for Project Completion. In the eventOffshore is in Default under Section 7.1(f), (g), (h) and/or (i) of the Credit Agreement, thenPrime absolutely and unconditionally warrants to Guaranty the assumption of all costs for ProjectCompletion.2. Liquidity Maintenance     Prime will, during the term of the Credit Agreement, maintain liquidity consisting of unusedrevolver availability under the Credit Agreement dated December 2, 2002, as amended, with Prime etal and Guaranty, and/or unrestricted cash and cash equivalents of $25,000,000. This requiredliquidity will reduce dollar-for-dollar with any additional shareholder advances and increasedollar-for-dollar to a maximum of $25,000,000 with any repayment of shareholder advances. To theextent that shareholder repayment has occurred, Prime agrees to fund additional shareholder loansequal to the amount repayed by the shareholder, as needed to ensure Project Completion.     This Agreement shall remain in force until each component of Project Completion is satisfied.Once a component is satisfied, Prime’s absolute and unconditional warranty to Guaranty to fund thepayment to Offshore of all costs that exceed the available commitments under the Credit Agreementfor that component, including interest, will expire.     Prime understands that a breach of obligations under this Agreement would result in an Eventof Default under the Credit Agreement with Offshore that would permit Guaranty to pursue itsavailable remedies under the Credit Agreement. Offshore is executing this Agreement to acknowledgethat a breach of this Agreement would result in an Event of Default under the Credit Agreement.     This Agreement shall be deemed a contract made under and shall be construed in accordance withand governed by the laws of the State of Texas and that actions arising out of this Agreement maybe litigated in courts having situs in Harris County, Texas.      This agreement is executed the date first hereinafter written,      **PRIMEENERGY CORPORATION**