Document:

EXHIBIT 10.5
                                 [WOODSIDE LOGO]

                           Woodside Energy (USA) Inc.

September 7, 2005

Mr. Martin V. Black                             Mr. Greg Tabor
Eni Petroleum                                   Ridgewood Energy Corporation
1201 Louisiana, Suite 3500                      11700 Old Katy Road, Suite 230
Houston, Texas 77002                            Houston, Texas 77079

Re:      Topaz Prospect Well Participation Agreement dated July 1, 2005
         East Breaks 157 No-4 (OCS-G 11412 #4)
         East Breaks Blocks 112 & 157, NG 15-1
         GOM

Gentlemen:

Enclosed please find your fully executed original Topaz Prospect Well
Participation Agreement dated July 1. 2005.

Pursuant to the terms of the Topaz Prospect Well Participation Agreement
Woodside respectfully requests that Eni Petroleum prepare and execute
Designation of Operator forms naming Woodside Energy (USA) Inc., GOM number
2407, as the operator of the East Breaks 157 No.4 (OCS-G 11412 #4).

It was a pleasure working with both of you on the Topaz contracts. Let me know
if you require anything further from Woodside.

Best Regards,

/s/ Brad L. Dowdell
Brad L. Dowdell
Director-Land
713-401-0014

<PAGE>
                                                                 [WOODSIDE LOGO]
                                  EXHIBIT "D"
     Attached to and made part of that certain Participation Agreement among
       Eni Petroleum Exploration Co. Inc., Woodside Energy (USA) Inc. and
                                Ridgewood Energy
                    Corporation dated Effective July 1, 2005

                      Topaz AFE East Breaks 157 - Well #4
                      -----------------------------------
RIG POSITIONING DAYS:   2.5 days      SHL:      UTM X:        1,077,753.0 US ft
            D&E DAYS:  32.5 days                UTM Y:       10,100,897 0 US ft
          TOTAL DAYS:  35.0 days      PBHL:     UTM X:        1,077,753.0 US ft
                                                UTM Y:       10,100,897.0 US ft
               DEPTH:  12,000    ft MD                                    AFE #
                       12,000    ft TVD             Rig: Unknown
         WATER DEPTH:  940       ft            Rev Date:  06/23/05
Assumptions:
1. Straight hole to 12,000 ft MD/TVD
2. Wireline logs at TD.

<TABLE>
                                                         Drill, Evaluate, T&A           Total
DESCRIPTION                          Rig Mob / Demob         Original Hole          Original Hole
-------------------------------------------------------------------------------------------------
   Section 1 : Time Sensitive
   --------------------------
<C>                                          <C>                 <C>                    <C>
1 Rig Rate                                   312,500             4,062,500              4,375,000
2 Support Vessels                            228,750               633,750                862,500
3 Woodside Supervision                         7,500                97,500                105,000
4 Well Site G&G                                    0                     0                      0
5 Aviaton                                     13,750               178,750                192,500
6 Mud Logging                                      0                19,200                 19,200
7 Mud Engineering                                  0                46,313                 46,313
8 Cementing Services                           7,625               124,125                131,750
9 Communications                               2,250                29,250                 31,500
10 Solids Control                                  0                     0                      0
11 Diving / ROV                               10,000               130,000                140,000
12 Directional Drilling                            0               132,500                132,500
13 Wellhead Services                               0                     0                      0
14 Metocean                                      750                 9,750                 10,500
16 Completion and Workover Services                0                     0                      0
17 Supply Base                                 8,750               113,750                122,500
19 Rental Tools                                8,625               112,125                120,750
20 Fishing / Cutting Services                      0                50,000                 50,000
21 Rig Contractor Additional Charges           3,750                48,750                 52,500
   Contingency 20%                           120,850             1,157,653              1,278,503
-------------------------------------------------------------------------------------------------
Total Time Sensitive                         725,100             6,945,915              7,671,015

   Section 2 : Non Time Sensitive
   ------------------------------
22 Rig Positioning                           103,000                     0                103,000
23 Site Survey                                     0                25,000                 25,000
24 HSE                                             0                     0                      0
25 Studies/ Analysis                               0               125,000                125,000
26 Wireline Logging                                0               178,000                178,000
27 Coring                                          0                     0                      0
28 Freight and Materials Handling              5,000                65,000                 70,000
29 Tubular Running Services                        0               120.000                120,000
30 Inspection and refurbishment                    0                40,000                 40,000
   Contingency 20%                            21,600               110,600                132,200
-------------------------------------------------------------------------------------------------
Total Non Time Sensitive                     129,600               663,600                793,200

   Section 3 : Tangibles & Consumables
   -----------------------------------
31 Wellhead Equipment                              0               287,200                287,200
32 Tubulars                                        0             1,085,700              1,085,700
33 Tubular Accessories                             0                45,000                 45,000
34 Mud and Chemicals                               0               800,000                800,000
35 Cement and Additives                            0               265,000                265.000
36 Drill Bits                                      0                90,200                 90,200
37 Completion Consumables                          0                     0                      0
38 Solids Control Equipment                        0                     0                      0
39 Rig Consumables                                 0                 5,000                  5,000
40 Fuel                                       79,750               464,750                544,500
   Contingency 20% on consumables             15,950               324,990                340,940
-------------------------------------------------------------------------------------------------
Total Tangibles & Consumables                 95,700             3,367,840              3,463,540

   Section 4 : Administration
   --------------------------
41 Overhead                                    4,752                54,949                 59,701
42 Training                                        0                     0                      0
43 Travel                                          0                12,544                 12,544
-------------------------------------------------------------------------------------------------
   Total Administration                        4,752                67,493                 72,245

                                AFE Total  $ 955,152     $      11,044,848             12,000,000

                                Well Ownership                 %WI                  TOTAL COST
                                Woodside Energy - USA Inc.   37.5000                $4,500,000
                                ENI Petrolium                25.0000                $3,000,000
                                Ridgewood Energy             37.5000                $4,500,000
                                Total                       100.0000               $12,000,000
</TABLE>

PREPARED BY:  ___________________________  ___________________________
              DRILLING ENGINEER            DATE
APPROVED BY:  ___________________________  ___________________________
              OPERATIONS MANAGER           DATE
              ___________________________  ___________________________
              PRESIDENT                    DATE
APPROVED BY:  ___________________________  ___________________________
              JOINT OPERATED PARTNER       DATE

<PAGE>

                             PARTICIPATION AGREEMENT

THIS PARTICIPATION AGREEMENT is entered into effective this 1st day of July,
2005. by and between, WOODSIDE ENERGY (USA) INC., a corporation organized and
existing under the laws of the State of Delaware, U.S.A. (hereinafter referred
to as "Woodside"), RIDGEWOOD ENERGY CORPORATION, a corporation organized and
existing under the laws of the State of Delaware, U.S.A (hereinafter referred to
as "Ridgewood) and ENI PETROLEUM EXPLORATION CO. INC., a corporation organized
and existing under the laws of the State of Delaware, U.S.A., (hereinafter
referred to as "Eni").

For and in consideration of the mutual covenants set forth herein and other good
and valuable consideration, Woodside, Ridgewood and ENI hereby agree as follows:

                                   ARTICLE I.
                                   DEFINITIONS

As used in this agreement, the following terms shall have the meanings set forth
below:

1.1  "Accounting Procedure" means the rules, provisions and conditions set forth
     in Exhibit "C" to the Offshore Operating Agreement.

1.2  "Affiliate" means a company or partnership or other legal entity which
     controls, or is controlled by, or which is controlled by an entity which
     controls, a Party. Control means the ownership directly or indirectly of
     more than fifty percent (50%) of the voting rights in a company,
     partnership or legal entity.

1.3  "Agreed Interest Rate" means the rate set forth in Article 3.B. of the
     Accounting Procedure.

1.4  "Agreement" means this Agreement, together with the Exhibits attached to
     this Agreement, and any extension, renewal or amendment hereof agreed to in
     writing by the Parties.

1.5  "AFE" means the Authorization for Expenditure submitted by Woodside in the
     gross amount of $ 12,000,000.00 to cover the estimated costs to drill the
     Test Well, which is attached as Exhibit "D".

1.6  "Casing Point" means that point in time when the Test Well has reached the
     Objective Depth (as hereinafer defined) from the surface location and at
     the bottom hole location as originally proposed arid after all open hole
     logs, cores and other tests included in the AFE for such well, or as the
     Parties may otherwise mutually agree, have been conducted.

1.7  "East Breaks 112 Unit Participating Areas" means each of (i) the
     Participating Areas in the East Breaks 112 Unit, being 900 acres located in
     East Breaks Block 112, but limited to the sand reservoir outline as
     depicted on Exhibit B, and further limited to the stratigraphic equivalent
     of the interval shown on Exhibit B-1 as depicted on the electric log of the
     East Breaks 112 No.3 Well as the "E" Sand Reservoir and (ii) the

                                       1
<PAGE>

     Participating Area in East Breaks Block 157, being 2250 acres located in
     East Breaks 157, but limited to the sand reservoir outline(s) as depicted
     on Exhibit B, and further limited to (a) the stratigraphic equivalent of
     the interval shown on Exhibit B-1 as depicted on the electric log of the
     East Breaks 157 No. 2 Well as the "A" Sand Reservoir and (b) the
     stratigraphic equivalent of the interval shown on Exhibit B-1 as depicted
     on the electric log of the East Breaks 157 No. 1 Well as the "B" and "C"
     Sand Reservoirs, as each of the Participating Areas may after the Effective
     Date be enlarged.

1.8  "Excluded Area" means that area within East Breaks Blocks 112 and 157 that
     is comprised of the East Breaks 112 Unit Participating Areas, as limited in
     Article 1.7 above, as such exists at the Effective Date and as the same may
     be expanded after the Effective Date of this Agreement.

1.9  "Leases" means the federal oil and gas leases as identified in Exhibit "A."

1.10 "MMS" means the Minerals Management Service or any successor organization
     thereto having authority to issue and regulate federal oil and gas lease
     activity in the Outer Continental Shelf.

1.11 "Offshore Operating Agreement" means the instrument attached as Exhibit
     "C."

1.12 "Party" or "Parties" means any of the entities named in the first paragraph
     to this Agreement and any respective permitted successors or assigns.

1.13 "Operator" means Woodside for the drilling and plugging or temporary
     abandonment of the Test Well and Eni for the tie back operations and
     subsequent completion and development drilling.

1.14 "Subject Interests" means an undivided twenty-five percent (25%) operating
     rights interest to be earned by each of Woodside and Ridgewood and assigned
     by Eni to each of Woodside and Ridgewood in and to the Leases less and
     except the Excluded Area.

1.15 "Topaz" is the name of the geological prospect to be evaluated by the Test
     Well that is drilled pursuant to this Agreement.

1.16 "Well Participating Area" means the area for which the Subject Interests
     will apply and is to include all of East Breaks Blocks 112 and 157, less
     and except the Excluded Area,

                                   ARTICLE II.
                                      TERM

2.1  This Agreement shall continue in force and effect and be binding upon the
     Parties for a period commencing upon the effective date and expiring July
     1st, 2006. This Agreement shall also be amended and renewed by mutual
     agreement of the parties.

                                       2
<PAGE>

                                  ARTICLE III.
                                DRILLING PROGRAM

3.1  Eni represents, without warranty of title, except by, through and under
     Eni, that it is the owner of one hundred percent (100%) record title
     interest in the Leases, and that the Subject Interests (as defined in 1.14)
     to be earned by Woodside and Ridgewood pursuant to this Agreement shall be
     free and clear of all liens, claims and encumbrances. The Leases, as to all
     depths, described on Exhibit "A" comprise all of and are subject to the
     East Breaks 112 Unit (Unit No. 754391005).

3.2  Subject to rig availability and acquisition of all required permits and
     approvals, by Eni as operator of the East Breaks 112 Unit, on or before the
     1st day of December, 2005, Woodside, as designated Operator, will commence
     and thereafter diligently conduct operations to drill or cause to be
     drilled, an exploratory test well on East Breaks Block 157 at a surface and
     bottom hole location of X =1,077,753 feet and Y = 10,100,897 feet UTM to a
     minimum total depth of 12,000 feet MD / TVD ("Objective Depth") or such
     greater depth as may be mutually agreed by the Parties to evaluate Eni's
     Topaz prospect (hereinafter referred to as "Test Well"). Woodside and
     Ridgewood will each pay thirty-seven and five-tenths percent (37.5%), being
     a combined seventy-five percent (75%) of the estimated dry hole cost to
     drill the Test Well to Casing Point or through the plugging or temporary
     abandonment to earn an undivided twenty-five percent (25%) each, being a
     combined fifty percent (50%) operating rights (as described in 3.3) in the
     Leases. The costs to drill the Test Well (or its substitute), on which
     Woodside and Ridgewood bear a disproportionate share is limited to the
     actual drilling cost to reach Casing Point, or through plugging and
     abandoning if a dry hole, or $ 13.2 million dollars, whichever is less
     ("Cap Amount") based on 110% of Woodside's AFE which is defined in Article
     1.5 and attached as Exhibit "D". Thereafter, Woodside and Ridgewood will
     each pay their prorata twenty-five percent (25%) working interest shares of
     any well costs in excess of the Cap Amount and all other costs incurred
     from and after the Effective Date (including P&A cost) in accordance with
     the terms of the Offshore Operating Agreement attached as Exhibit "C".

3.3  Upon satisfaction by Woodside and Ridgewood of their obligations to drill
     the Test Well to Casing Point or spend up to 110 % of the AFE and subject
     to the further provisions of this Article III, Eni shall assign to Woodside
     and Ridgewood each an undivided twenty five percent (25%) operating rights
     interest in and to the Leases less and except the Excluded Area. The
     Subject Interests being assigned to Woodside and Ridgewood shall be subject
     only to their proportionate share of the Lessor's royalty and no other
     burdens. The assignment of Operating Rights, if approved by the MMS, shall
     be made without warranty of title except by, through and under Eni and will
     be on a mutually acceptable form.

     3.3.1 The Assignment shall become validated upon the following:

          A.   Woodside and Ridgewood receiving approval from the MMS of the
               separate transfer and assignment of operating rights by Eni to
               Woodside and Ridgewood of the Subject Interests in accordance
               with all laws, rules and regulations applicable thereto and

                                        3
<PAGE>

          B.   Any assignment of Subject Interests or portion thereof that is
               not approved by the MMS will be handled in a manner that is
               mutually acceptable to the Parties to effect the transfer of the
               Subject Interests.

     Upon fulfillment of the foregoing conditions, the Assignments shall be
     effective retroactive to the Effective Date.

     3.3.2  Concurrently with Woodside and Ridgewood's execution of this
            Agreement Eni shall execute and deliver to Woodside the necessary
            "Designation of Operator" forms (MMS Form 1123) designating Woodside
            as the Operator of the Test Well subject to this Agreement, along
            with any other documents required to allow a Party to serve as
            Operator under the Offshore Operating Agreement or applicable
            regulations.

     3.3.3  The Assignments shall convey only the Subject Interests and ENI
            shall not assign, either its Geoscience Data or its Intellectual
            Property, as hereinafter defined.

          A.   Geoscience Data: All of Eni's ownership interest in any
               geological, geochemical or geophysical data, interpretations,
               maps, reports, geohazard surveys, or other information or
               derivatives of this information related to the Leases (the
               "Data");

          B.   Intellectual Property: All of Eni's ownership interest in any
               inventions, patents, copyrights, trademarks and other
               intellectual property related to the Leases.

          The provision of this Article 3.3.3 shall extend beyond the term of
          this Agreement.

     3.3.4 Woodside and Ridgewood agree to reimburse Eni for their proportionate
          share of all Leasehold maintenance costs, i.e. rentals and minimum
          royalties accruing under the terms of the Leases beginning as of the
          Effective Date of this Agreement for the next ensuing year and
          continuing, as to each such lease, for so long as the Lease remains
          subject to this Agreement.

3.4  If prior to reaching the Objective Depth for the Test Well, a decision is
     made in accordance with the terms of the Offshore Operating Agreement to
     abandon the well due to the existence of Gulf Coast Conditions as defined
     in the Offshore Operating Agreement, then any well (i) proposed in
     accordance with the Offshore Operating Agreement to test the same prospect
     as planned in the Test Well, and (ii) commenced within one hundred and
     twenty (120) days of the abandonment of the Test Well, shall be considered
     to be a substitute well for the Test Well. Each Party shall have the option
     (not obligation) to continue participation as per the Offshore Operating
     Agreement. All the provisions of this Agreement shall apply to such well
     with the same force and effect as to the abandoned well, provided, Woodside
     and Ridgewood's cost bearing share shall be reduced from seventy-five
     percent (75%), being 37.5% each to fifty percent (50%), being (50%), being
     25% percent each when the combined total costs of the Test Well and
     substitute well equal $13.2 million.

                                        4
<PAGE>

3.5  Upon reaching Casing Point, each Party shall have the election as to their
     respective working interests (Eni 50%, Woodside 25%, Ridgewood 25% ) of
     either:

     (1)  conducting further operations in the Test Well, i.e. deepening,
          side-tracking, or completing the Test Well, in accordance with the
          priority for such operations set forth in the Offshore Operating
          Agreement, to be shared in the proportions of Eni 50%, Woodside 25%.
          Ridgewood 25%, or

     (2)  plugging and abandoning or temporarily abandoning of the Test Well to
          be shared in the proportion of Eni 25%, Woodside 37.50% and Ridgewood
          37.50% subject to the cap of Section 3.4.

     The notice and elections shall be made in accordance with the terms and
     conditions of Article 10.8 of the Offshore Operating Agreement attached as
     Exhibit "C".

3.6  A material default to drill the Test Well by Woodside and/or Ridgewood in
     performing the obligations as provided under this Article shall constitute
     a breach of this Agreement. A material default shall not give rise to Eni's
     right to terminate the contract unless the defaulting Party (ies) fails to
     cure such default within thirty (30) days of receipt from Eni of written
     notice stating the specifics of the default, or the defaulting Party's
     failure to commence the cure of such default and thereafter to prosecute
     such operations with due diligence to completion if the default cannot be
     cured within such time period.

3.7  In no event, shall any Party hereto be responsible to any other Party for
     consequential or punitive damages (including but not limited to loss of
     profit, business interruption and lost business opportunity).

3.8  The Leases and the Test Well drilled hereunder. shall be operated in
     accordance with the Offshore Operating Agreement which is attached hereto
     as Exhibit "C" and incorporated herein by reference. If any conflict exists
     between this Agreement and the Offshore Operating Agreement, this Agreement
     shall control. Eni shall remain the designated Operator of the Leases and
     Woodside shall, with Eni's assistance, attempt immediately to obtain all
     necessary governmental approvals and permits to drill the Test Well.

                                   ARTICLE IV.
                                   ASSIGNMENTS

4.1  No Party to this Agreement may assign all or any part of its interest in
     this Agreement without the prior written consent of the other Parties
     hereto, except that any Party may assign all or any part of its interest to
     an Affiliate upon giving prior notice to the other Parties and agreeing to
     remain liable for all of its obligations arising under this Agreement. Such
     granting of consent to a financially responsible party qualifying to hold
     leases with the MMS, shall not be unreasonably withheld. Notwithstanding
     the foregoing, Woodside shall have the right to assign to Explore Louisiana
     LLC all or part of its (Woodside's) interests in (i) this Well

                                        5
<PAGE>

     Participation Agreement, (ii) the Offshore Operating Agreement, and (iii)
     the earned Subject Interests (whether those interest be Operating Rights
     Interests or other mutually acceptable interests).

                                   ARTICLE V.
                             RELATIONSHIP OF PARTIES

5.1  The rights, duties, obligations and liabilities of the Parties under this
     Agreement shall be individual, but limited initially to the percentage each
     party is to pay for the drilling of the Test Well and thereafter to its
     respective and proportionate share of the Subject Interests earned and
     either assigned or assignable to it, and not joint and several. It is not
     the intention of the Parties to create, nor shall this Agreement be deemed
     or construed to create a mining or other partnership, joint venture,
     association or trust. This Agreement shall not be deemed or construed to
     authorize any Party to act as an agent, servant or employee for any other
     Party for any purpose whatsoever and in their relations with each other
     under this Agreement, the Parties shall not be considered fiduciaries.

                                   ARTICLE VI.
                                 CONFIDENTIALITY

6.1  All data and information acquired, interpreted, developed or disclosed
     pursuant to this Agreement shall be held confidential by all Parties in
     accordance with the confidentiality provisions of the Offshore Operating
     Agreement, Exhibit C. All other confidentiality provisions and/or
     agreements between the Parties being that certain Confidentiality Agreement
     between Eni and Woodside dated March. 22, 2005 and that certain
     Confidentiality Agreement between Eni and Ridgewood dated May 2, 2005,
     covering Subject Interests shall terminate and be superceded by the
     confidentiality provision of Exhibit "C".

                                  ARTICLE VII.
                                     NOTICES

7.1  All notices authorized or required between the Parties shall be addressed
     and effective when delivered to such persons as designated below. Each
     Party shall have the right to change its address at any time and/or
     designate that copies of all such notices be directed to another person at
     another address, by giving notice thereof to the other Parties:

                             Eni Petroleum Exploration Co Inc.
                             1201 Louisiana
                             Suite 3500
                             Houston, Texas 77002
                             Attn: Charles C. Barnes
                             Phone: 713.393.6107
                             Fax:   713.393.6208

                                        6
<PAGE>

                             Woodside Energy (USA) Inc.
                             Sage Plaza, 5151 San Felipe,
                             Suite 1200
                             Attn: Leon Hirsch
                             Houston, Texas 77056
                             Phone: 713.413,0021
                             Fax:   713.963.8868

                             Ridgewood Energy Corporation
                             11700 Old Katy Road, Suite 280
                             Houston, Texas 77079
                             Attn: Greg Tabor
                             Phone: 281.293.8449
                             Fax:   281.293.7705

                                  ARTICLE VIII.
                                 APPLICABLE LAW

8.1  This Agreement shall be governed by, construed, interpreted and enforced in
     accordance with the substantive laws of the State of Texas, to the
     exclusion of any conflicts of law rules that would refer the matter to the
     laws of another jurisdiction. Venue for any litigation arising from this
     Agreement shall be in Harris County, Texas.

                                   ARTICLE IX.
                            AREA OF MUTUAL INTEREST

9.1  In the event any party acquires an interest in an oil and gas lease
     covering the Offshore Blocks described on Exhibit "A" (hereinafer referred
     to as "AMI Blocks"), or acquires any right to acquire an interest in an oil
     and gas lease covering the AMI Blocks or any portion thereof ("Acquiring
     Party") within the term of this Agreement, then the other Parties shall
     each have the right, but not the obligation, to acquire from the Acquiring
     Party it's non promoted share (Eni 50%, Woodside 25% and Ridgewood 25%) of
     the interest and/or right acquired. The other Parties shall each be
     notified in writing by the Acquiring Party within fifteen (15) days of such
     acquisition and shall have thirty (30) days after receipt of such notice to
     advise Acquiring Party whether or not it elects to acquire it's share of
     the interest and/or right acquired. In the event that a Party fails to give
     such responsive notice within the aforesaid thirty (30) day period, such
     failure shall be conclusively deemed to be an election not to acquire a
     share of the interest or rights acquired by Acquiring Party. Said notice is
     to include the actual acquisition costs if any, and other consideration
     offered (which shall include the monetary equivalent in U.S. Dollars based
     upon reasonable market value of any consideration other than cash) if any,
     and any obligations relative to the acquisition. If a Party elects to
     exercise its right under this Agreement, the consideration owed by the

                                       7
<PAGE>

     Party shall equal it's share of the actual costs and/or obligations paid
     and/or assumed for the acquired interest.

                                   ARTICLE X.
                               GENERAL PROVISIONS

10.1 Subject to the limitations on transfer contained in Article V., this
     Agreement shall inure to the benefit of and be binding upon the successors
     and assigns of the Parties.

10.2 No waiver by a Party of any one or more breaches or defaults by another
     party in the performance of this Agreement shall operate or be construed as
     a waiver of any future breach(s) or default(s) by the same Party, whether
     of a like or of a different character. Except as expressly provided in this
     Agreement no Party shall be deemed to have waived, released or modified any
     of its rights under this Agreement unless such Party has expressly stated,
     in writing, that it does waive, release or modify such right.

10.3 If and for so long as any provision of this agreement shall be deemed to be
     judged invalid for any reason whatsoever, such invalidity shall not affect
     the validity or operation of any other provision of this Agreement except
     only so far as shall be necessary to give effect to the construction of
     such invalidity, and any such invalid provision shall be deemed severed
     from this Agreement without affecting the validity of the Agreement.

10.4 There shall be no modification of this Agreement except by written consent
     of all Parties.

10.5 Reference to the singular includes a reference to the plural and vice
     versa.

10.6 The topical headings used in this Agreement are for convenience only and
     shall not be construed as having any substantive significance or as
     indicating that all of the provisions of this Agreement relating to any
     topic are to be found in any Article.

10.7 This Agreement is the entire agreement of the Parties with respect to the
     subject matter contained herein and supersedes all prior understandings and
     negotiations of the Parties.

IN WITNESS of their agreement each Party has caused its duly authorized
representative to sign this instrument on the date indicated below such
representative's signature. This Agreement may be executed in one or more
counterpart copies and shall be effective as of the Effective Date first above
written.

                                        8
<PAGE>

ENI PETROLEUM EXPLORATION CO. INC.          RIDGEWOOD ENERGY CORPORATION

By:   /s/ Charles C. Barnes                 By: /s/ W. Greg Tabor

Name: Charles C. Barnes                     Name: W. Greg Tabor

Title: Attorney-in-Fact                     Title: Executive VP

Date:  8-30-05                              Date:   9-2-05

WOODSIDE ENERGY (USA) INC.

By:  /s/ David M. McCubbin

Name: David M. McCubbin

Title: President

Date:  9/7/05

                                        9

<PAGE>

                                   Exhibit "A"
    Attached to and made a part of that certain Participation Agreement among
       Eni Petroleum Exploration Co. Inc., Woodside Energy (USA) Inc. and
            Ridgewood Energy Corporation dated effective July 1, 2005

I.   Description of Leases
     ---------------------

     a.   Oil and Gas Lease bearing Serial No. OCS-G 08195, effective November
          1, 1985 between the United States of America, as Lessor, and Agip
          Petroleum Co.. Inc. and Union Texas Petroleum Corporation, as Lessees,
          covering approximately 4847.75 acres, being all of Block 112, East
          Breaks, as shown on OCS Official Protraction Diagram NG 15-1.

                                                                  Net Revenue
          Current Owners                    Working Interest        Interest
          --------------                    ----------------        --------

          Eni Petroleum Exploration Co. Inc.     100.00%            83.3333%

     b.   Oil and Gas Lease bearing Serial No. OCS-G 11412, effective October 1,
          1989 between the United States of America, as Lessor, and Agip
          Petroleum Co. Inc. and Union Texas Petroleum Corporation, as Lessees,
          covering approximately 5760.00 acres, being all of Block 157, East
          Breaks, as shown on OCS Official Protraction Diagram NG 15-1.

                                                                  Net Revenue
          Current Owners                    Working Interest        Interest
          --------------                    ----------------        --------

          Eni Petroleum Exploration Co. Inc.     100.00%            83.3333%

II.  Depth Limitations within the Leases described in I. above derived from
     Participating Areas attributable to the East Breaks 112 Unit, OCS Unit No.
     754391005.

     a.   OCS-G 01895 East Breaks Block 112:
          -----------------------------------
          This Participation Agreement is limited to those rights in East Breaks
          Block 112 that are located within the Well Participating Area as
          defined herein under Article 1.16. Within said Well Participating Area
          the depths excluded from this Participation Agreement consist of the
          stratigraphic equivalent of the intervals depicted on the electric log
          of the East Breaks 112 No. 3 Well as the "E" Sand Reservoir as further
          depicted on Exhibit "B" and defined in Exhibit "B-1".

     b.   OCS-G 11.412, East Breaks Block 157:
          ------------------------------------
          This Participation Agreement is limited to those rights in East Breaks
          Block 157 that are located within the Well Participating Area as
          defined herein under Article 1.16. Within said Well Participating Area
          the depths excluded from this Participation Agreement consist of 1)
          the stratigraphic equivalent of the interval depicted on the electric
          log of the East Breaks 157 No. 2 Well as the "A" Sand Reservoir as
          further depicted on Exhibit "B" and defined in Exhibit "B-l", and 2)
          the stratigraphic equivalent of the intervals depicted on the electric
          log of the East Breaks 157 No. 1 Well as the "B" and "C" Sand
          Reservoir as further depicted on Exhibit "B" and defined in Exhibit
          "B-1". The "B" and "C" reservoirs will require an expansion of the

                                       10

<PAGE>

          Unit Participating Area for the East Breaks 157 Lease (Proposed
          Revised Unit Outline) resulting in the exclusion of the additional
          outline area covering the acreage(s) as depicted on Exhibit "B" and
          further on Exhibit "B-1" to be added as the Proposed Revised Unit
          Outline.

The Excluded Area and Reservoirs Associated with the East Breaks 112 Unit are
further depicted on the map and the Schedule of Depth reservations attached
hereto as Exhibits "B" and "B-1".

III. AREA OF MUTUAL INTEREST (AMI) BLOCKS REFERRED TO IN ARTICLE IX. OF THE
     PARTICIPATION AGREEMENT ARE AS FOLLOWS:
     ---------------------------------------

AREA/BLOCK                LEASE NO.          OWNER             EXPIRATION
-------------------------------------------------------------------------------
East Breaks 113           OCS-G 22278        Unocal            09/30/2005
--------------------------------------------------------------------------------
East Breaks 114           OPEN                  -                   -
--------------------------------------------------------------------------------

                                       11
<PAGE>

                                   Exhibit "B"
     Attached to and made part of that certain Participation Agreement among
       Eni Petroleum Exploration Co. Inc., Woodside Energy (USA) Inc. and
           Ridgewood Energy Corporation dated Effective July 1, 2005

                           EAST BREAKS BLOCK 112 UNIT
                       PARTICIPATING AREAS AND APPLICABLE
                             RESERVOIR OUTLINES FOR
                      PARTIAL BLOCKS EAST BREAKS 112 & 157

                                 [MAP OMITTED]

<PAGE>

                                  EXHIBIT "B-1"
    Attached to and made a part of that certain Participation Agreement among
       Eni Petroleum Exploration Co. Inc., Woodside Energy (USA) Inc. and
           Ridgewood Energy Corporation dated Effective July 1, 2005

EAST BREAKS 112 UNIT DEPTH EXCLUSIONS:

E sand Reservoir in Agip EB 112 #3:     Top     7321'MD 6122'TVD    -6050' SS
                                        Base    7379'MD 6168'TVD    -6096' SS

A sand Reservoir in Agip EB 157 #2:     Top     4916'MD & TVD       -4843' SS
                                        Base    5045'MD & TVD       -4972' SS

B sand Reservoir in Agip EB 157 #1:     Top     5520'MD & TVD       -5436' SS
                                        Base    5696'MD & TVD       -5612' SS

C sand Reservoir in Agip EB 157 #1      Top     6187'MD & TVD       -6103' SS
                                        Base    6398'MD & TVD       -6304' SSEXHIBIT 10.6

                             PARTICIPATION AGREEMENT
                           EUGENE ISLAND 357 PROSPECT
                               OFFSHORE, LOUISIANA

     This Participation Agreement ("Agreement") is made and entered into
effective as of the 1st day of July, 2005 by and between Walter Oil & Gas
Corporation ("Walter"), and Ridgewood Energy Corporation ("Ridgewood").

                                    RECITALS

     WHEREAS, Walter has identified a prospect on Eugene Island block 357 and
has acquired Oil & Gas Lease OCS-G 23884 dated June 1, 2002 covering block 357
from the United States of America; and,

     WHEREAS, Walter plans to drill or participate in the drilling of an initial
test well on Eugene Island block 357, OCS-G 23884; and,

     WHEREAS, Walter has offered to Ridgewood the opportunity to participate in
the drilling of the initial test well and to acquire a 25% working interest in
block 357, OCS-G23884, less and except the NE/4 of the lease from the surface to
11,500' subsea (hereafter "Lease"), and Ridgewood has accepted Walter's offer
all in accordance with the terms set forth herein.

     NOW, THEREFORE, in consideration of the mutual covenants and agreement
herein contained, the parties hereto agree as follows:

                                    SECTION I
                                    ---------
                                  Initial Costs

1.01 Within ten (10) days of Ridgewood's execution of this Agreement, Ridgewood
     agrees to pay Walter $141,203.00 (which represents Ridgewood's 25% share of
     the Lease bonus, rental and shallow hazard survey costs incurred by
     Walter).

                                   SECTION II
                                   ----------
                                Initial Test Well

2.01 Walter plans to participate in the drilling of an initial test well on the
     Lease. The initial test well will be drilled from a surface location of
     approximately 5,625' FSL and 6,610' FEL of the Lease and drilled to a depth
     of 15,800' TVD (hereinafter "Initial Test Well"). As consideration for the
     opportunity to earn a twenty-five percent (25%) working interest in the
     Lease, Ridgewood shall bear Thirty-Three and One-Third percent (33.33%) of
     the costs to drill the Initial Test Well to casing point and through
     plugging and abandonment, if the Initial Test Well is not saved for
     production. This disproportionate cost sharing obligation shall be referred
     to as the "Promote." The Promote will be applicable to the dry hole costs
     of the Initial Test Well and will be limited to 110% of the Initial Test
     Well's estimated dry hole cost as noted in the attached AFE. The Promote
     will also apply to any substitute well or sidetrack of the Initial Test
     Well until Walter has received 110% of the original AFE dry hole costs.
     Concurrent with Ridgewood's execution of this Agreement, Ridgewood will be
     deemed to have approved the attached AFE and well plan.

<PAGE>

2.02 Subject only to rig availability and the ability to obtain the required
     governmental permits, Walter and Ridgewood agree that if the Initial Test
     Well is not spudded on or before December 1, 2005 ("Commencement Date"),
     and such date has not been extended by Ridgewood, then this Agreement shall
     ipso facto terminate. Within 10 days of such termination, Walter shall
     reimburse Ridgewood for any payments it received in accordance with
     Paragraph 1.01 of this Agreement and Ridgewood shall submit assignments to
     Walter re-conveying Ridgewood's 25% working interest in the Lease
     previously received from Walter, which assignment shall be free and clear
     of any liens, charges, or lease burdens, overriding royalty interest, or
     any other encumbrance created by Ridgewood. For clarification purposes
     only, there shall be no other penalty(ies) assessable to either party
     hereto for failure of the Initial Test Well to be spudded on or before the
     Commencement Date.

2.03 It is understood and agreed that Newfield Exploration Company ("Newfield")
     will have a 50% working interest in the Lease and Initial Test Well and
     will be the designated operator.

                                   SECTION III
                                   -----------
                       Assignment and Assumption of Rights

3.01 Within ten (10) days from receipt of Ridgewood's payment described in 1.01
     above, Walter shall assign to Ridgewood Twenty Five percent (25%) operating
     rights interest in the Lease. The interest assigned to Ridgewood in the
     Lease shall be subject to the existing royalty burden and a 2.25% of 8/8ths
     overriding royalty interest ("ORRI") to be reserved by Walter, all
     proportionately reduced to Ridgewood's assigned interest. Walter represents
     to Ridgewood that total Lease burdens created by, through and under Walter
     as of the effective date of this Agreement, including lessor's royalty, are
     no greater than 18.917% (of 8/8ths). The form of Assignment is attached
     hereto as Exhibit "A."

                                   SECTION IV
                                   ----------
                               Operating Agreement

4.01 Contemporaneous with the execution of this Agreement, the parties hereto
     agree to execute a mutually agreeable operating agreement ("JOA"), naming
     Newfield operator of the Lease. Both parties hereto acknowledge that the
     JOA is a three-party agreement also requiring Newfield's signature. All
     operations on the Initial Test Well and any and all subsequent operations
     on the Lease shall be conducted in accordance with the terms and provisions
     of the JOA. If there are any conflicts between this Agreement and the JOA,
     the terms and provisions of this Agreement shall prevail and govern.

                                    SECTION V
                                    ---------
                                     Notices

5.01 All notices, requests or demands to be given under this Agreement shall be
     in writing and governed and directed to the representatives as specified
     below:

     Ridgewood Energy Corporation           Walter Oil & Gas Corporation
     11700 Old Katy Rd., Suite 280          1100 Louisiana Street, Suite 200
     Houston, Texas 77079                   Houston, TX 77002
     Attn: Mr. W. Greg Tabor                Attn: Mr. Ron Wilson
     Phone: 281-293-8449                    Phone: 713-659-1221
     Fax:   281-293-7705                    Fax:   713-756-1177

<PAGE>

                                   SECTION VI
                                   ----------
                      GOVERNING LAW AND BREACH OF CONTRACT

6.01 This Agreement shall be governed by the laws of the State of Texas except
     where the Maritime Laws of the United States of America are applicable. In
     the event that any dispute results in formal legal action, venue shall be
     appropriate in the federal or state courts of Harris County, Texas.

6.02 In the event of a breach of this Agreement by any party hereto, the non
     breaching party shall be entitled to all remedies available at law or
     equity, including but not limited to, specific performance, monetary
     damages and injunctive relief.

                                   SECTION VII
                                   -----------
                                  MISCELLANEOUS

7.01 Walter shall provide Ridgewood with full and complete access to Walter's
     files, records and data, so that Ridgewood may perform its due diligence
     review of Walter's acquisition, ownership and obligations associated with
     the Lease. Additionally, Walter shall provide Ridgewood with access to its
     technical data associated with the Lease, including seismic, maps, well
     data and geological data, subject however, to all confidentiality and data
     licensing restrictions.

7.02 A term, provision, covenant, representation, warranty, or condition of this
     Agreement may be waived only by written instrument executed by the party
     waiving compliance. The failure or delay of any party in the enforcement or
     exercise of the rights granted under this Agreement shall not constitute a
     waiver of said rights nor shall it be considered as a basis for estoppel.

7.03 This Agreement, together with all of its exhibits, is intended by the
     parties to be a complete and final statement of the agreement of the
     parties with respect to the subject matter hereof, and supersedes any prior
     oral or written statements or agreements between the parties hereto.

7.04 The terms and provisions hereof shall be binding upon and inure to the
     benefit of Walter and Ridgewood, and their respective heirs, legal
     representatives, successors and assigns, and shall be covenants running
     with the Lease.

<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
executed as of the date first set forth above.

WITNESSES
                                         WALTER OIL & GAS CORPORATION

/s/
------------------------------           /s/ Ron A. Wilson
                                         ------------------------------
/s/ Melissa Coronado                         Ron A. Wilson
------------------------------               Vice President
Melissa Coronado

                                         RIDGEWOOD ENERGY CORPORATION

/s/ Ken Webb
------------------------------           /s/ W. Greg Taber
Ken Webb                                 ------------------------------
                                             W. Greg Taber
/s/ Randy Bennett                            Executive Vice President
------------------------------
Randy Bennett

<PAGE>

                                   EXHIBIT "A"

       Attached to and made a part of that certain Participation Agreement
      dated July 1, 2005 between Walter Oil & Gas Corporation and Ridgewood
                               Energy Corporation.

ASSIGNMENT OF OPERATING RIGHTS TO OIL AND GAS LEASE

                                                               OCS-G 23884
UNITED STATES OF AMERICA    ss.

OUTER CONTINENTAL SHELF     ss.

OFFSHORE LOUISIANA          ss.

     For and in consideration of the sum of One Hundred Dollars ($100.00) and
other good and valuable consideration, the receipt and sufficiency of which are
hereby acknowledged, Walter Oil & Gas Corporation, a Texas Corporation, whose
mailing address is 1100 Louisiana, Suite 200, Houston, Texas 77002 (hereinafter
called "Assignor"), does SELL, TRANSFER, ASSIGN, SET OVER AND CONVEY unto
Ridgewood Energy Corporation, a_________________________________ Company, whose
mailing address is 11700 Old Katy Rd., Suite 280, Houston, TX 77079,
(hereinafter called "Assignee"), a 25.0000% operating rights interest in and to
the following federal oil and gas Lease ("Lease"):

     Oil and Gas Lease No. OCS-G 23884 dated June 1, 2002 from the United States
     of America, as Lessor, to Walter Oil & Gas Corporation, as Lessee,
     covering Eugene Island Area, Block 357, OCS Leasing Map, Louisiana Map No.
     4A, containing 4999.88 acres;

     LESS AND EXCEPT the Northeast Quarter (NE/4) of the Lease from the surface
     down to 11,500' subsea (hereinafter referred to as ("Assigned Interest").

Subject to the matters set forth herein, this Assignment is made without
warranty of title, express, implied or statutory, even for return of any
consideration paid therefor; provided only that Assignor warrants that it has
not heretofore granted or conveyed to any other party any interest in or any
lien or encumbrance on the interest being assigned hereunder in the Lease except
as described herein.

<PAGE>

WITH RESPECT TO ANY PERSONALTY OR CHATTELS CONVEYED HEREBY, ASSIGNOR HEREBY
NEGATES AND DISCLAIMS THE IMPLIED WARRANTY OF MERCHANTABILITY AND THE IMPLIED
WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE AND ANY IMPLIED WARRANTY OF
CONFORMITY TO MODELS OR SAMPLES OF MODELS. ASSIGNEE AND ASSIGNOR AGREE THAT, TO
THE EXTENT REQUIRED BY APPLICABLE LAW TO BE EFFECTIVE, THE DISCLAIMERS OF
CERTAIN WARRANTIES CONTAINED IN THIS INSTRUMENT ARE "CONSPICUOUS" DISCLAIMERS.

     TO HAVE AND TO HOLD the Assigned Interests hereby conveyed, together with
all and singular rights and appurtenances thereto in anyway belonging unto
Assignee, its successors and assigns.

     This Assignment is made by Assignor and accepted by Assignee subject to the
following:

1}   the terms, provisions and conditions of the Lease and any limitation on or
     contained in the Lease;

2)   That certain Participation Agreement dated July 1, 2005 by and between
     Assignor and Assignee and covering the Assigned Interest;

3)   That certain Offshore Operating Agreement dated July 1, 2005 by and between
     Newfield Exploration Company, as Operator, and Assignor and Assignee, as
     Non-Operators, and covering the Assigned Interest;

4)   Assignor reserves unto itself, and retains an overriding royalty interest
     equal to 2.25% of eight-eights (8/8ths) in and to all hydrocarbons that are
     produced, saved, and sold from the Lease. Said overriding royalty shall be
     free of all costs of any kind whatsoever including but not limited to costs
     associated with exploration, development, production or operating, but
     shall bear its proportionate share of severance and production taxes unless
     provided otherwise in the Lease. Said overriding royalty shall be
     calculated and paid or delivered to Assignee in the same manner as provided
     in the Lease affected thereby for the calculation and payment or delivery
     of royalties therein reserved to the Lessor.

     a) It is understood that the overriding royalty interest reserved
     hereinabove is an 8/8ths number and that Assignee shall bear its
     proportionate share of such overriding royalty interest based on the
     Assigned Interest herein.

4)   The terms and conditions of this Assignment shall extend to and be binding
     upon the successors and assigns of the parties.

<PAGE>

     IN WITNESS WHEREOF, this Assignment of Operating Rights Interest is
executed and effective this ____ day of _________, 2005.

WITNESSES:                                        ASSIGNOR:

                                         Walter Oil & Gas Corporation

______________________________
______________________________
                                         By:______________________________
                                             Ron A. Wilson
                                             Vice President

WITNESSES:                                        ASSIGNEE:

                                         Ridgewood Energy Corporation

______________________________
______________________________
                                         By:______________________________
                                             W. Greg Tabor
                                             Executive Vice President

STATE OF TEXAS

COUNTY OF HARRIS

     On this _____ day of _________, 2005 before me appeared W. Greg Tabor, to
me personally known, who, being by me duly sworn, did say that he is the
Executive Vice President of Ridgewood Energy Corporation, and that the foregoing
instrument was signed on behalf of said company, and said W. Greg Tabor
acknowledged said instrument to be the free act and deed of said corporation.

                                             ______________________________
                                                      NOTARY PUBLIC

My Commission Expires __________________.

<PAGE>

STATE OF TEXAS

COUNTY OF HARRIS

     On this _____ day of ________, 2005 before me appeared Ron A. Wilson, to me
personally known, who, being by me duly sworn, did say that he is the Vice
President of Walter Oil & Gas Corporation, and that the foregoing instrument was
signed on behalf of said partnership, and said Ron A. Wilson acknowledged said
instrument to be the free act and deed of said corporation.

                                             ______________________________
                                                      NOTARY PUBLIC

My Commission Expires __________________.

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