Exhibit 10.2

A GlobalSantaFe Company

4 December 2003

Reef Partners LLC

1901 N. Central Expressway, Suite 300

Richardson, TX 75080

Attn:                     Mr. H. Walt Dunagin

Vice President - Land

Re:                                Reef /CMI North Sea Joint Venture Agreement

North Sea & Atlantic Margin

Gentlemen:

Challenger Minerals Inc. (“CMI”), a California corporation, and Reef Partners LLC (“Reef”), a Nevada Limited Liability Company, collectively referred to herein as the “Parties” or individually as a “Party”, desire to enter into this agreement (“Agreement”) to facilitate the review of, and participation in, Prospects in the North Sea Region, as defined in Paragraph 2 below.  The terms and conditions governing this Agreement are as follows:

1.                                        Term :  Unless earlier terminated under the other provisions hereof, the term of this Agreement shall be for a period of three (3) years commencing 1 December 2003 (“Effective Date”) and expiring 30 November 2006 (“Termination Date”), each of which years commencing with the Effective Date or its anniversary shall be deemed a “Participation Year”; provided, however, that the confidentiality and non-competition provisions hereof shall survive termination of this Agreement for the contractual time period provided herein or in any applicable agreement with a third party to which Reef is or becomes bound or, if no such period is provided for, then for a period of two (2) years after the expiration date hereof.

2.                                        Prospects :  Reef shall have the right and option, but not the obligation, to acquire up to five percent (5%) of the interest made available to CMI in all offshore Prospects located in the North Sea Region, as defined below, as such Prospects are identified and initially reviewed by CMI during the term of this Agreement (“CMI North Sea Joint Venture”), subject however to the provisions of Paragraph 16 below regarding lapse of Prospects and of Paragraph 4.F. below as to potential exclusion of Reef by the Selling Party as to any particular Prospect for reasons that may include but are not limited to Reef’s failure to commit to participate for a minimum percentage interest in the Prospect or due to the number of CMI North Sea Joint Venture partners desiring to participate therein.  For the

Reef Partners LLC

4 December 2003

purposes of this Agreement, a “Prospect” is defined as (a) an interest in a well or wells located in offshore waters in the “North Sea Region”, defined herein to cover the North Sea and the Atlantic Ocean continental shelf margin of the countries of the United Kingdom, Ireland, Denmark, the Netherlands, Norway and Germany, or (b) a participation right or other interest in a lease, license or other agreement relating to the offshore waters of the North Sea Region, in either case regarding geologic targets in a specific geographic area related to a identified geologic structure, and/or stratigraphic interval or other trapping mechanism, and which is believed to be susceptible to commercial development of oil, gas and other minerals in accordance with standard and accepted industry practices from an open water drilling location or platform.  All existing Prospects previously or currently under review by CMI (except as to participation interest remaining available as of the Effective Date) and leases currently owned in whole or part by CMI are excluded from this Agreement.

3.                                        Participation Fee :  In consideration of its rights hereunder to consider participation in Prospects, Reef shall pay CMI as a Participation Fee the total sum of U.S. $225,000.00 during the term of this Agreement, in three equal annual payments of U.S. $75,000.00 each payable to CMI on or before 1 December in the years 2003, 2004 and 2005; provided, that the first such payment shall not be due until a date five (5) business days after this Agreement is fully executed.  Other than such Participation Fee, there shall be no fees or burdens in favor of CMI as to the interest Reef may elect to acquire in any Prospect, and no obligation upon Reef to acquire an interest in any particular Prospect or in a minimum number of Prospects during the term of this Agreement.

4.                                        Opportunity Evaluation :  CMI shall use its reasonable efforts to identify, evaluate and provide Reef with notice of potential opportunities to participate in Prospects.  Upon presentation to CMI of a potential opportunity to participate in a Prospect generated by a third party or upon generation of such a Prospect by CMI (such third parties, or CMI in the event it generates such a Prospect, being collectively called “Selling Parties”), CMI shall determine if or when a potential Prospect may be worthy of further consideration, and as to each such potential Prospect, CMI shall promptly notify Reef, providing a brief description of the Prospect, to include (when available) the initial well location, name of Operator, estimated leasehold, seismic and initial well costs, water depth and reserve potential (collectively, the “Initial Prospect Information”).  Reef shall then promptly advise CMI whether Reef is already pursuing the Prospect; and, if such is the case, Reef shall promptly advise CMI as to whether it will continue to pursue the Prospect on its own or jointly with CMI under either the terms of this Agreement or on other mutually acceptable terms.  If Reef elects to continue to pursue the Prospect on its own, the parties shall endeavor in good faith to resolve any areas of competition, if possible.  If Reef does not so notify CMI of its separate pursuit of any such potential Prospect(s) within ten (10) days after such initial notice by CMI (or such shorter period for Reef’s decision as is required, in CMI’s opinion, to prevent loss of an opportunity to acquire an interest in a Prospect), CMI and Reef shall jointly proceed as otherwise set forth in this Agreement.  With respect to any evaluations to be conducted by either Party hereunder, either

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individually or jointly, including an Initial Prospect Review or a further review under this Paragraph 4, each Party hereby acknowledges that any such review, and the methodologies employed therein, are necessarily subjective.  Accordingly, except as provided in Paragraph 4.B below, neither Party makes any representation or warranty (whether express, implied, statutory or otherwise) as to the accuracy, completeness or sufficiency of any such evaluation, and each Party disclaims any liability for accuracy of any Prospect evaluation conducted by the other Party during the term of this Agreement.  Each Party represents and warrants that it is independently qualified to make a decision whether to invest in any particular Prospect regardless as to whether it participates in or conducts an evaluation .

A.                                    Once CMI determines that a Prospect merits a detailed geo-technical review with the Selling Party (“Initial Prospect Review”), it shall promptly notify Reef and coordinate with Reef’s technical personnel in scheduling the Initial Prospect Review as soon as practicable.

B.                                      In conducting the Initial Prospect Review, and all subsequent geo-technical evaluations, CMI and Reef shall make a good faith effort to share data, knowledge, expertise and work product except as, and to the extent, such sharing may be restricted or prohibited by third-party Confidentiality Agreements (“CAs”) and/or Area of Mutual Interest Agreements (“AMIAs”), to which both CMI and Reef are not similarly bound.  In such cases, Reef will be requested to sign and return expeditiously the CA or AMIA to CMI before prospect reports or data will be sent to Reef.  In the event that Reef is unable to participate in an Initial Prospect Review, CMI, as soon as practicable thereafter, shall make a good faith effort to review with Reef the Selling Party’s data and interpretations and CMI’s data and interpretations regarding the Prospect in question, subject to any restraints posed by such third party CAs and/or AMIAs.

C.                                      Following the Initial Prospect Review or other review, if conducted, and if not, as soon as practical after Reef’s receipt of the Initial Prospect Information from CMI, either CMI or Reef may propose pursuing participation in a Prospect by providing written notice of such intent to the other Party.  The Party receiving such written notification shall have no less than five (5) business days (or such shorter response time as is required, in CMI’s opinion, to prevent loss of an opportunity to acquire an interest in a Prospect) within which to advise the other Party as to whether it wishes to pursue the Prospect and if so, its desired percentage of working interest, whether or not the parties have conducted an Initial Prospect Review or other review.  In the event that CMI and the Other Participants (as defined in Paragraph 7 below) do not wish to pursue the Prospect, then Reef shall have the right to pursue the Prospect for its own account.  Upon CMI’s request, Reef shall advise CMI the status of its pursuit of such opportunity. In the event that Reef decides to submit a formal participation offer to the Selling Party, Reef shall submit a copy thereof to CMI, and CMI shall have twenty-four (24)

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hours within which to elect to pursue the Prospect jointly with Reef in accordance with this Agreement. If the participation opportunity originated through a request by the Selling Party for a turnkey bid from CMI’s affiliate, Applied Drilling Technology Inc. (“ADTI”), then CMI shall control the timing and content of offers to participate in the Prospect.

D.                                     In the event that both CMI and Reef desire to pursue participation in a Prospect, they (together with any Other Participants that may also desire to pursue such participation) shall jointly develop and agree as to the terms and conditions of a written participation, offer to the Selling Party.  CMI shall have sole responsibility for direct negotiations with the Selling Party unless it requests the assistance of Reef.   Reef agrees not to directly contact the Selling Party regarding the Prospect during the negotiation process unless otherwise agreed to by CMI.  However, CMI shall keep Reef advised of the progress of ongoing negotiations and shall solicit Reef’s input and suggestions regarding counter-offers or subsequent revisions to original offers.  Notwithstanding any provision to the contrary herein, if CMI determines any situation merits negotiation with a Selling Party sooner than the response time periods provided for herein in order to avoid loss of an opportunity to acquire an interest in a Prospect, CMI shall have the right to do so and shall advise Reef of the progress thereof.

E.                                       Subject to the provisions of Paragraph 4.D. above, Reef shall be an active participant with CMI in drafting, reviewing, and formalizing Participation Agreements, Joint Operating Agreements, Farmout Agreements and all other contracts relating to Reef’s participation in a Prospect under this Agreement.  In the event of disagreement between CMI and Reef as to contract terms and provisions, however, CMI will make the final decision as to what is ultimately included in all agreements, with each Party reserving the right not to participate in the prospect as outlined in Paragraph 5 below.  CMI shall advise the Selling Party of Reef’s involvement with CMI prior to the formulation of any such contracts, and Reef shall be a signatory party to all agreements executed between CMI and Selling Party.  CMI and Reef shall each be entitled to concurrently receive, directly from the Selling Party, an assignment of any ownership interest acquired in a Prospect.

F.                                       In the event that a Selling Party (other than CMI) does not wish to include Reef as a candidate for working interest participation, then CMI shall so advise Reef, advising the reasons given by the Selling Party.  If the concerns raised by the Selling Party cannot be amicably resolved, CMI shall have the right to pursue the Prospect for its own account (subject to similar rights of Other Participants) and the Prospect shall not be covered by this Agreement.

G.                                      Except for Reef’s obligation to pay to CMI the Participation Fee as provided in Paragraph 3 above, and for CMI’s obligation at its expense to furnish to Reef the

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Initial Prospect Information and other reports and data as provided in this Agreement, each Party shall bear its own expenses hereunder, including but not limited to those associated with the evaluation of each Prospect and any subsequent negotiation of a Participation Agreement or other agreement with a Selling Party.

5.                                        Right to Withdraw :  CMI and Reef acknowledge that, at any time and for any reason during the process contemplated by Paragraph 4 above (prior to the execution of a binding participation agreement with a Selling Party), either Party may elect to discontinue the effort to participate in a Prospect.  In the event either CMI or Reef elects not to participate in a Prospect, the other party shall be free to continue to pursue the Prospect for its own account (subject to similar rights of Other Participants), and the non-participating Party shall not compete directly or indirectly against the other Party (or any participating Other Participants) in pursuing the Prospect for a period of two (2) years from the date of such election not to participate.

6.                                        Personnel :  During the term of this Agreement, CMI will provide and maintain a technically proficient, multi-disciplined, veteran staff comprising geology, geophysics, reservoir engineering and land expertise to screen and evaluate Prospects.

7.                                        Other Participants :  To facilitate the review of and participation in Prospects, CMI has entered into similar North Sea Region joint venture agreements with certain third parties (“Other Participants”).  The joint venture agreements entered into by CMI with Reef and with the Other Participants shall be collectively referred to as the “CMI North Sea Joint Venture”.  CMI and Reef agree that CMI reserves the right to terminate, amend or renew its joint venture agreement with any of the Other Participants and to enter into new joint venture agreements with other third parties.  The mention within this Agreement of Other Participants in the CMI North Sea Joint Venture is solely to provide Reef with notice of the existence of such Other Participants and their right to be allocated interests in Prospects under similar joint venture agreements with CMI.  The only relationship created pursuant to this Agreement, express or implied, is between Reef and CMI.  In no event shall it be construed that this Agreement has created any relationship, obligation or liability between Reef and any of the Other Participants.  The term “Other Participants” in this Agreement shall also include CMI as to its own CMI Interest in the CMI North Sea Joint Venture, the R