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<TYPE>EX-10.1

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<FILENAME>ex10_1.txt

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Exhibit 10.1

[CHEVRON LOGO]



North America Upstream

Gulf of Mexico Land Division

935 Gravier Street

New Orleans, LA 70112

Tel 504-592-6751

Fax 504-592-7110



September 5, 2007



Ridgewood Energy Corporation

11700 Old Katy Road,

Suite 280

Houston TX, 77079

Attention: Mr. W. Greg Tabor



Marlin Coastal, L.L.C.

3861 Ambassador Caffery Parkway,

Suite 600

Lafayette, LA 70503

Attention: Mike Lipari



Helis Oil and Gas Company, LLC

228 St. Charles Ave.

Suite 912

New Orleans, LA 70130

Attention: Doug St. Clair



Houston Energy, L.P.

1415 Louisiana Street

Suite 2400

Houston, TX 77002

Attention: Allen Wihite



Participation Agreement

El Toro Prospect

--------------------------------------West Cameron Block 57 OCS-G 21534 No. 3

Offshore, Gulf of Mexico

Gentlemen:

This Participation Agreement ("PA"), when executed by each of the Parties

hereto, being Chevron Midcontinent, L.P., formerly named Pure Resources, L.P.

("Pure"), Marlin Coastal, L.L.C. ("Marlin"), Helis Oil and Gas Company, LLC

("Helis"), Houston Energy, L.P. ("Houston Energy"), hereinafter Pure, Marlin,

Helis and Houston Energy being referred as the "Co-owners", and Ridgewood Energy

Corporation ("Ridgewood"), all inclusive parties sometimes hereinafter referred

to as the "Parties", will evidence the agreement between the Parties to explore,

develop and operate certain rights in the "Contract Area", as defined below. The

Parties hereby agree to the following terms and conditions:

1.



CONTRACT AREA. The Contract Area is the leasehold acreage that covers the

following described property:

West Cameron Block 57 (OCS-G 21534) as said lease covers depths from

the surface of the earth down to the base of the CrisR-2 sand at a

depth of 15,500' vertical sub-sea or to the base of the stratigraphic

equivalent of the CrisR-2 sand, as seen in the Stone West Cameron

Block 45 OCS-299 #20 By-Pass-1, whichever is the deeper but limited

to the following acreage aliquots, hereinafter referred to as the

"Contract Area".

Page 1 of 16



Ridgewood El Toro PA

September 5, 2007

<PAGE>

N/2 NW/4 SW/4; S/2 SW/4 NW/4; NE/4 SW/4 NW/4; SW/4 SE/4 NW/4;

------------------------------------------------------------SW/4 NW/4 NE/4; S/2 NE/4 NW/4; SE/4 NW/4 NW/4; N/2 SE/4 NW/4;

------------------------------------------------------------The Co-owners' leasehold and that certain Joint Operating Agreement between IP

Petroleum Company, Inc., as Operator, and The William G. Helis Company, L.L.C.,

et al, as Non-Operators, covering West Cameron Area, Block 57, dated July 1,

2000 ("OA"), attached hereto as Exhibit "B", being both the Co-owners' leasehold

and the OA interest in the Contract Area, to the best of our information and

belief is set out as shown in Exhibit "A" attached hereto, and the Contract Area

is hereinafter referred to as the "El Toro Prospect". The division of interest

in Exhibit "A" shall control in any conflict between this agreement and Exhibit

"A".

The "Working Interest w/ Leverage Percentage" column, as shown under the

Division of Interest on said Exhibit "A", sets forth the promoted interest to be

borne by Ridgewood and the leveraged interests to be borne by the Co-owners as

described in the rights and obligations of Article 3 and Article 4 herein below.

It is stipulated by all Parties that the interest of Houston Energy in the El

Toro Prospect has been committed to and assumed by the parties, such that

Houston Energy will be deemed to participate in the exploration of such prospect

through the delivery of its interest in such prospect and in the Contract Area

to the Parties for its Working Interest After Leverage Percentage rights and

interests but will not participate in, and will not be obligated for, the costs

or risk of the well for the El Toro Prospect, until Ridgewood has earned an

interest in the Contract Area pursuant to this PA and the Working Interest After

Leverage Percentages apply. In the event this PA terminates without an earning,

or Ridgewood does not earn and this PA expires, the Co owners' interests in the

Contract Area will revert to the OA working interests shown on Exhibit "A".

The "Working Interest After Leverage Percentage" column, shown under the

Division of Interest on said Exhibit "A", sets forth the interest of the Parties

in the well and the Contract Area, once and if Ridgewood has earned an interest

in the Contract Area pursuant to this PA.

Subject to Article 6 herein below, Ridgewood shall be provided access to land

records and files at the offices of Pure or Marlin during business hours for its

own independent review of the title materials related to the interest of the

Co-owners and to any unrestricted geologic and geophysical data for its own

independent review and analysis. Ridgewood may withdraw from this PA for

material title defects, which cannot be timely cured or which Co-owners decline

to cure, at any time prior to Marlin accepting a turnkey bid proposal from

Applied Drilling Technology Inc. ("ADTI") for the drilling of the well

contemplated hereunder. Any Ridgewood withdrawal shall terminate this Agreement

as to and among all Co-owners. Ridgewood shall supply each of the Co-owners a

copy, free of cost to the Co-owners, of any Contract Area title analysis

conducted by Ridgewood.



Page 2 of 16

Ridgewood El Toro PA

September 5, 2007

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2. INITIAL WELL AND OBJECTIVE. Subject to the other terms hereof, as well as

weather delays, delivery of materials (e.g. pipe), rig availability and

obtaining all requisite permits, Marlin, as the designated drilling



operator, shall use reasonable business-like efforts to commence or cause

to be commenced, on or before November 1, 2007, the drilling of the West

Cameron Block 57, OCS-G 21534 No. 3 well, hereinafter sometimes referred to

as the "Initial Well". Except as otherwise provided herein and after

execution of this PA, the Parties hereby obligate themselves to participate

in or support, in the case of Houston Energy, the drilling of the Initial

Well for the exploration and production of oil and gas according to the

terms and conditions of this PA. The Initial Well will be drilled and

logged, with due diligence and in accordance with good oilfield practice,

as per the final executed and approved Marlin Authority for Expenditure

("AFE") and well plan, as attached hereto as Exhibit "C", within the

Contract Area, on West Cameron Block 57 OCS-G 21534. The Initial Well will

be drilled and logged at a surface and bottom-hole location 6215' FNL &

2684' FWL at the target location of LA-S NAD27 State Plane Coordinates

X=1290829, Y=358059 of West Cameron Area, Block 57, to a depth of 15,500'

vertical sub-sea or the base of the stratigraphic equivalent of the CrisR-2

sand formation, where this sand top is expected to occur between -14,600'

and -14,900' vertical sub-sea elevation, as seen in the Stone West Cameron

Block 45 OCS-299 # 20 By-Pass-l, whichever depth is lesser, hereinafter

referred to as the "Objective". Until that time the Initial Well has

reached the Objective and all logging, testing and evaluation contemplated

in the AFE has been completed and a recommendation has been made by Marlin,

Ridgewood does not have the right to propose any operation but will hold a

voting rights interest for its Working Interest w/ Leverage Percentage in

operations proposed by others. Upon reaching the Objective and when all

logging, testing and evaluation contemplated in the AFE has been completed

and a recommendation has been made by Marlin, any recommendation or

proposals by the Parties will be subject to all appropriate terms and

conditions of the OA regarding subsequent operations, priority of

operations, voting rights and penalties. After earning Ridgewood will

become a rights holder under the OA for its Working Interest After Leverage

Percentage, and operations conducted after that earning shall be subject to

the OA provisions, including non-consent voting rights and penalty. For any

Party, including Ridgewood, electing not to participate in any proposed

operation after reaching the Objective and completion of all logging,

testing and evaluation, its Working Interest After Leverage Percentage will

be subject to the OA penalty for any exploratory well and its working

interest, only after satisfaction of the OA's non-consent conditions and

penalties, will be that as set out in Exhibit "A" of this PA, Division of

Interest, in the column labeled "Working Interest After Leverage

Percentage". Unless otherwise agreed by the Parties, each Party electing to

participate in the operation after reaching the Objective may, but is not

obligated to, elect to participate in any operations and bear that portion

of the costs and risks attributable to the interests of the

Non-participating Party in the ratio that the Participating Party's

interest listed in the column labeled "Working Interest After Leverage

Percentage" in Exhibit "A" bears to the total interest of all participating

Parties under the same column. Such non-consent operation shall not proceed

unless 100% of the costs and risks of that operation are assumed by the

participating Parties and any penalty recoupment shall inure only to the

participating Parties in proportion to its or their participation. As

between the Parties, the Initial Well is proposed as an exploratory well as

to financial penalties of the Contract Area during any recoupment period

Page 3 of 16

Ridgewood El Toro PA

September 5, 2007

<PAGE>

and is to be drilled and logged pursuant to the terms and conditions of the

AFE and OA. Such limited rights grant is not intended to vest ownership in

the Contract Area in Ridgewood until such vesting of ownership to Ridgewood

is earned as set out in Article 5 below. Upon earning an interest in the

Contract Area pursuant to this PA, Ridgewood agrees to adopt and ratify the



OA effective as of the date of earning. The terms and provisions of the OA

are incorporated herein as if set forth in full, are not, by that

incorporation, intended to create any operating rights area in which

Ridgewood owns an interest in the Contract Area and apply, prior to any

earning by Ridgewood but, solely to recognize the rights, privileges and

protections of Marlin as the drilling operator, and each of the nonoperating Co-owners, and for pre-earning notices, content and election

periods and access by Ridgewood to the rig floor, but not otherwise.

3. PROSPECT WELL COST SHARING. Marlin has proposed and each of the Co-owners

and Ridgewood have approved and agreed to participate for a share of the

costs for or support, in the case of Houston Energy, the drilling and

logging of the Initial Well in the Contract Area as set forth in the

attached Exhibit "C" AFE. By executing this PA and obligating itself to

participate in the Initial Well, Ridgewood holds the right to earn 33.4917%

of 100% working interest of the Co-owners' interest in the Contract Area,

upon meeting the obligations herein and in particular those set forth in

Article 5 below for the Initial Well or Substitute Well, by paying 50.2375%

(its Working Interest w/ Leverage percentage) of the costs, to the extent

applicable under this PA, of drilling and logging to the Objective, and/or

plugging and abandoning, as a dry hole if applicable, of the Initial Well

or Substitute Well, up to seventeen million two hundred thousand dollars

($17,200,000.00) gross of the dry hole costs, without regard to the AFE

amount. If the Initial Well's actual costs of drilling and logging to the

Objective and/or plugging and abandoning as a dry hole if applicable

exceeds the amount of seventeen million two hundred thousand dollars

($17,200,000.00) gross or upon reaching the Objective, whichever occurs

first, Ridgewood will thereafter pay and bear 33.4917% (its Working

Interest After Leverage Percentage) of the costs and risks of all

subsequent operations in such well for further drilling and/or plugging and

abandoning operations. Ridgewood will not hold the right to assume sole

ownership of the Initial Well or become a sole participating party, until

it earns as set out in Article 5. Marlin as drilling operator shall conduct

any Ridgewood sole account operations. The Parties agree that should a

Substitute Well, as specified in Article 10 below, be approved by the

Parties and commenced, Ridgewood's obligation to pay 50.2375% of the AFE

costs will cease at the point in time that the actual costs of drilling and

logging to the objective and/or plugging and abandoning as a dry hole if

applicable incurred in the Initial Well plus the actual costs incurred in

the Substitute Well combined equal seventeen million two hundred thousand

dollars ($17,200,000.00) gross; provided however, once the aggregate costs

of the Initial Well and Substitute Well equal seventeen million two hundred

thousand dollars ($17,200,000.00) gross, Ridgewood's share of all

subsequent drilling and logging costs will be 33.4917%, subject to further

rights, elections and provisions of this PA or the OA, as applicable.

Effective upon and after reaching the Objective, but not before, the right

to non-consent further or subsequent drilling or logging operations

provided by the overexpenditure provision of the OA shall apply to

subsequent operations. Prior to reaching the Objective, the Parties remain

Page 4 of 16

Ridgewood El Toro PA

September 5, 2007

<PAGE>

bound to the obligations of the PA, subject to the other terms of Article

2. It is the intention of the Parties, subject to this Article 3 and

Article 4 below, that the 1.5:1 promote borne by Ridgewood in favor of the

Co-owners under the PA for the costs and risk of drilling and logging

operations conducted under the PA shall end upon the earlier of earning, as

detailed in Article 5 below, or the aggregate expenditure of seventeen

million two hundred thousand dollars ($17,200,000.00).

4. ADDITIONAL PROMOTE. The Parties further agree that, unless Ridgewood



conducts sole account operations in the Initial Well under its Article 3

right then otherwise, if the Initial Well or Substitute Well is completed

for production as a successful well, that Ridgewood agrees to pay an

additional promote by paying 50.2375% (its Working Interest w/ Leverage

Percentage) of the costs, to the extent applicable under this PA, of

completion, tie-back, flow-back and hook-up, up to ten million four hundred

thousand dollars ($10,400,000.00) gross costs of the completion, tie-back,

flow-back and hook-up costs. If the completion, tie-back, flow-back and

hook-up actual cost exceeds the amount of ten million four hundred thousand

dollars ($10,400,000.00) gross, Ridgewood will thereafter pay and bear

33.4917% (its Working Interest After Leverage Percentage) of the costs and

risks of all subsequent operations in such well over such completion,

tie-back, flow-back and hook-up costs for further operations.

5. EARNING, ASSIGNMENT, TIMING & INTEREST TRANSFERRED. Ridgewood shall earn,

Pure shall prepare and the Co-owners shall timely deliver, a mutually

acceptable Assignment of Operating Rights ("Assignment") in the form

attached hereto as Exhibit "F" in the Contract Area to Ridgewood, if and

only if:

a)

b)



c)



the Initial Well or Substitute Well is drilled and logged to the

Objective as described in Article 2 above, or

if the Initial Well, or its Substitute Well, either fails to reach the

Objective, or reaches the Objective, but the Parties have expended at

least seventeen million two hundred thousand dollars ($17,200,000.00),

whether such well is completed or not, then Ridgewood will be entitled

to an Assignment of the Co-owners' operating rights for its Working

Interest After Leverage Percentage, as set forth on Exhibit "A" as

provided for herein, and

Ridgewood complies with all of the terms of this PA.



Within thirty (30) days of satisfying a) and c) or b) and c) of the above

referenced events, the Co-owners will assign, without warranty of title,

express or implied and effective as of the date of its earning, to

Ridgewood 33.4917% of 8/8ths gross and 26.1235% of 8/8ths net of the

Co-owners' operating rights within the Contract Area, from the surface of

the earth to the sub sea true vertical depth of 15,500' or to the

stratigraphic equivalent of the base of the CrisR-2 sand as seen in the

Stone West Cameron Block 45 OCS-299 # 20 By-Pass-l, whichever is the lesser

depth. Such interest is further subject to and burdened by all of the

contracts, agreements and dedications recited herein or of public record

and lessor's royalty and the overriding royalty interests as set out on

Exhibit "A" or in this PA.

Notwithstanding a) and b) above but if the Initial Well or Substitute Well

fails to reach the Objective, but encounters, as mutually agreed by all

Parties, a zone(s) or formation(s) capable of producing in paying

Page 5 of 16

Ridgewood El Toro PA

September 5, 2007

<PAGE>

quantities, above the Objective, that is within the Contract Area, and is

completed for production under the PA where Ridgewood participates, and the

Co-owners mutually agree to cease further drilling operations prior to

reaching the Objective, Ridgewood will thereafter be entitled to an

Assignment of operating rights within the Contract Area for its Working

Interest After Leverage Percentage but limited to the total depth drilled

and logged plus 100 feet. Rights under the OA in the event of an election,

by any of the Co-owners, to non-consent to operations above Objective,

where the Initial Well has not reached Objective or the Parties have not

expended at least seventeen million two hundred thousand dollars

($17,200,000.00), are reserved solely to and among the Co-owners. That is,



Ridgewood shall not hold any right to penalty recoupment.

6. WARRANTY. The transfer of any interest in the Contract Area pursuant to

this PA to Ridgewood shall be made by the Co-owners without express or

implied warranty of any kind. The Co-owners shall grant and convey to

Ridgewood full subrogation and substitution to all the Co-owners' rights in

warranty against the predecessors in interest of the Co-owners and its

affiliates or merged entities. The Co-owners shall, subject to Article 1,

provide Ridgewood full access to the Co-owners' files and records related

to the Contract Area for independent review and analysis by Ridgewood. Such

files and records are not warranted as complete or accurate but were

maintained as business records upon which the Co-owners relied. Any

reliance by Ridgewood is at its own risk.

7. NO NEW LEASE BURDENS. Until Ridgewood earns an interest under this PA, or

until the right to earn a portion of the Co-owners' interest in the

Contract Area pursuant to this PA terminates, Ridgewood and the Co-owners

(except as specified in Article 15) agree that they have not and will not

create any additional lease burdens or dedications on the Contract Area. No

mortgage or pledge or financing arrangement by Ridgewood of this PA or any

interest earned, whether before or after any such interest is earned or

assigned, is ever permitted without the prior written consent of each of

the Co-owners, which consent shall not be unreasonably withheld. Such

condition shall be made express in any Assignment of earned area made to

Ridgewood.

8. TRANSFER SUBJECT TO APPLICABLE APPROVALS. In the event that the transfer of

any interest in and to the Contract Area requires approval of the lessor or

of any federal agency having jurisdiction, the obligation to obtain such

pertinent approval shall be Ridgewood's, at its cost and risk. The

Co-owners agree to assist Ridgewood as necessary to help Ridgewood secure

such approvals, including but not limited to the preparation of mutually

agreeable assignments or conveyance instruments appropriate for filing and

recordation purposes with the MMS and/or applicable parish records.

Notwithstanding anything to the contrary, but excluding any lessor consent

or approval, the Co-owners represent to Ridgewood that any consent to

assign requirements that may effect a transfer of interest into Ridgewood

upon its earning will be the responsibility of the Co-owners to effectuate

on behalf of Ridgewood.

9. ACCOUNTING MATTERS. As to the Contract Area, all costs and expenses, which

are accrued or incurred pursuant to this PA and under any transfer of

interest in the Contract Area executed pursuant hereto, if any, shall be

determined and accounted for in accordance with the Accounting Procedure,

which is in Exhibit "C" of the OA, attached hereto as Exhibit "B".

Page 6 of 16

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<PAGE>

10. SUBSTITUTE WELL. If the Initial Well is drilled and prior to reaching the

Objective, Marlin encounters mechanical difficulties, gulf coast conditions

or other conditions which render further drilling impractical, or if the

Parties agree, per Article 5 above, to complete the Initial Well above, but

without reaching the Objective, then without limiting the Parties' rights

pursuant to Article 5, then any of the Parties shall have the right to

propose the drilling of another well to the Objective, hereinafter referred

to as a "Substitute Well", at and to any legal location in the Contract

Area, but such operations must commence within 180 days after the date the

rig was released from the last operation on the Initial Well. If such well

is proposed and Ridgewood participates and the Substitute Well is timely

and properly commenced and drilled in compliance with all terms and



conditions provided herein for the Initial Well, then such Substitute Well

shall, in all respects (but, in any event, shall be subject to the Article

3 and Article 4 cumulative cost sharing limitation for the Initial Well and

Substitute Well) be considered as if it was the Initial Well and any

references in this PA to the Initial Well shall also include any Substitute

Well.

11. SUBSEQUENT OPERATIONS. Should Ridgewood earn hereunder as provided above

and the Parties mutually agree to complete the Initial Well in the

Objective, or should the Parties mutually agree, per Article 5 above, to

complete the Initial Well above but without reaching the Objective, any

such permitted wells and operations shall be conducted in accordance with

the OA. Should Ridgewood earn hereunder and the Initial Well be deemed a

dry hole, a subsequent well may be proposed by any of the Parties at any

time as a Substitute Well, in accordance with the provisions of the OA but

also subject to the other provisions of this PA bearing upon a Substitute

Well.

12. DESIGNATIONS. The Parties agree to execute the necessary designation of

operator forms and any other forms required by the MMS or other regulatory

authorities to carry out their operations and to make Marlin, the drilling

operator under the PA, if required, and Pure the Operator under the OA,

with any earning by Ridgewood.

13. OPERATING AGREEMENT. Before any earning by Ridgewood under this PA and any

ratification or execution of the Exhibit "B" OA after earning under the PA,

Ridgewood acknowledges the Co-owners' interest available to Ridgewood

hereunder remains bound under this PA and the OA. Should Ridgewood earn

hereunder, Ridgewood shall formally ratify the OA, attached hereto as

Exhibit "B", only as it pertains to the Contract Area and earned rights.

Notwithstanding any other provision of this PA that might indicate to the

contrary, if there is any conflict between any other provision of this PA

and a provision of the OA, the other provisions of this PA shall prevail,

as between the Parties, prior to any earning.

14. TERM. This PA shall automatically terminate, without liability or

obligation, in the event the Initial Well is not commenced on or before

November 1, 2007, subject only to weather delays, delivery of materials

(e.g. pipe), rig availability and obtaining all requisite permits.

Page 7 of 16

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<PAGE>

Once and if a well has been drilled and logged in which Ridgewood

participates and earns and which participation entitles Ridgewood to an

Assignment as provided above in Article 5, those PA rights and obligations

surviving the earning and the OA shall remain in effect as to such Contract

Area, so long as any obligations between the Parties remain unsatisfied.

Unless otherwise provided, the PA shall terminate with an earning by

Ridgewood as a dry hole and the end of the right to propose a Substitute

Well or with the completion, tie-back, and flow-back and hook-up for a

successful completion. Matters arising after either such event shall be

governed by the OA, with the exception, that the Tax Partnership and all

obligations not satisfied under the PA, the Dispute Resolution as set out

in Article 27 and Confidentiality Agreement and AMI as set out in Article

15.C 3, shall survive any such termination of this PA.

15. REPRESENTATIONS. The business records of the Co-owners reflect with respect

to the Contract Area and El Toro Prospect that:

A.

The Contract Area is dedicated and committed to the following

Contracts and Agreements;

1) Natural Gas Processing Agreement-Gulf of Mexico, between Chevron



U.S.A. Inc., Texaco Exploration and Production Inc. (predecessor

in interest to Chevron U.S.A. Inc.) and Dynegy Midstream Services

Limited Partnership (now called "TARGA Midstream Services,

Limited Partnership"), as amended, effective March 1, 2002.

2) Reserve Dedication and Discount Commodity Rate Agreement, between

Stingray Pipeline Company, L.L.C. and Pure Resources, L.P.,

effective June 15, 2003.

3) Amendment to Reserve Dedication and Discount Commodity Rate

Agreement June 15, 2003, between Pure Resources, L.P. and

Stingray Pipeline Company, L.L.C., effective April 29, 2005.

4) Reserve Dedication Agreement, between Stingray Pipeline Company,

L.L.C. and Marlin Coastal LLC, effective April 1, 2006.

B.



C.



All required filings have been made with the applicable

regulatory authorities and Co-owners are not aware of any

notices, pending or threatened violations of any applicable

regulation.

The Contract Area is subject to the following Contracts and

Agreements:

1) Oil and Gas Lease dated July 1, 2000 from the U.S. Department of

the Interior, Minerals Management Service, as Lessor, to IP

Petroleum Company, Inc., The William G Helis Company, L.L.C. and

Houston Energy, Inc., as Lessee, being Serial Number OCS-G 21534,

covering All of Block 57, West Cameron Area, OCS Leasing Map,

Louisiana Map No. 1, subject to;

a.

Assignment of Overriding Royalty and Reversionary

Interest in Oil and Gas Lease from IP Petroleum

Company, Inc., The William G Helis Company, L.L.C. and

Houston Energy, Inc. to Louisiana Offshore Ventures II,

effective July 1, 2000.

b.

Assignment of Record Title from IP Petroleum Company,

Inc. to Duke Energy Hydrocarbons, LLC, effective July

1, 2000.



Page 8 of 16

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September 5, 2007

<PAGE>

c.



2)



Assignment of Record Title from IP Petroleum Company,

Inc. to Pure Resources, L.P., effective October 1,

2000.

d.

Assignment of Record Title from The William G Helis

Company, L.L.C. to Pure Resources, L.P., effective July

1, 2001.

e.

Assignment of Record Title from Pure Resources, L.P. to

Houston Energy, L.P., effective July 1, 2001.

f.

Assignment of Record Title from Marlin Energy Offshore,

L.L.C. to Marlin Coastal, L.L.C., effective April 1,

2005.

Joint Operating Agreement between IP Petroleum Company, Inc., as

Operator, and The William G Helis Company, L.L.C., et al as

Non-Operators, covering West Cameron Area Block 57, dated July 1,

2000, as amended May 30, 2001, Memorandum of Joint Operating

Agreement to which has been recorded under File Number 267001,

Conveyance Book 918, Mortgage Book 254 of the Official Public

Records of Real Property of Cameron Parish, Louisiana and under

File Number 12-267001 of the UCC records of the State of

Louisiana and further amended by Amendment to Joint Operating

Agreement Outer Continental Shelf-Gulf of Mexico dated December

17, 2004.



3)

4)

5)



D.



MOPU Lease Agreement dated February 28, 2003 between Union Oil of

California and Blake Offshore, L.L.C., as amended and extended.

Confidentiality Agreement and AMI dated July 31, 2007 between

Pure Resources, L.P. and Ridgewood Energy Corporation.

Counter Proposal to Ridgewood's Offer to Participate letter dated

August 21, 2007, as Parties agreed and accepted on August 21,

2007.



The Co-owners represents, to the best of its knowledge, that with

respect to that portion of the Lease the Co-owners are contributing to

the Contract Area that:

1)

The Co-owners are in material compliance with the terms and

conditions of the Lease.

2)

The Lease is not subject to any royalty, overriding royalty, net

profits interest or other similar burden on production, except as

referenced above or of public record, and the lessor's royalty.

3)

There are no liens, mortgages, deeds of trust, judgments or other

encumbrances of any kind or nature on the Lease or the Co-owners

working interest in the Lease.

4)

There are no pending claims or litigation relative to the Lease.

5)

There are no preferential purchase rights, consents to assign or

other restrictions on the Co-owners ability to enter into this

Agreement or they are waived by the execution of this PA by each

of the Co-owners.

6)

There are no other owners of working interests in the Lease

included within the Contract Area, who are not a party to this

PA.



16. INTEGRATED AGREEMENT. Except as provided in Article 18 below, this PA and

the Exhibits attached hereto comprise the entire agreement between the

Parties and supersedes all prior agreements and understandings relating to

the subject matter hereof, including the Counter Proposal to Ridgewood's

Offer to Participate letter dated August 21, 2007, between the Parties.

Further, excepting what is provided in Article 18 below, in the event of

any conflicts between the provosions of this PA and any other agreement,

including any operating

Page 9 of 16

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September 5, 2007

<PAGE>

agreement or any agreement referenced herein as an exhibit or to be

executed by the Parties hereafter, the provisions of this PA shall control,

as between the Parties, prior to any earning by Ridgewood.

17. TAX PARTNERSHIP. The Parties understand and agree that the arrangement and

undertakings evidenced by this PA, taken together, result in a partnership

for purposes of Federal income taxation and for purposes of certain state

income tax laws which incorporate or follow Federal income tax principles

as to tax partnerships. Such partnership for tax purposes is hereinafter

referred to as the "Tax Partnership". For every other purpose of this PA,

however, and notwithstanding any other provision of this PA, express or

implied, to the contrary, the Parties understand and agree that their legal

relationship to each other under applicable state law with respect to all

property subject to this PA is one of tenants in common, or undivided

interest owners, or lessee-sublessees, and not one of partnership; that the

liabilities of the Parties shall be several and not joint or collective;

and that each Party shall be solely responsible for its own obligations.

The Tax Partnership shall be governed by Exhibit "D" as attached to this

PA. Except as provided in such Exhibit "D", the Parties agree not to elect

to have the Tax Partnership excluded from the application of all or any

part of Subchapter K of Chapter One of Subtitle A of the Internal

Revenue Code of 1986, as amended (the "Code"), from any successor



provisions thereto under the Code, or from any provisions of state income

tax laws of substantially the same effect.

The Parties agree that the election to be excluded from the application of

Subchapter K of Chapter One of Subtitle A of the Code made in Article 20.1

of the OA is no longer operative for the El Toro Prospect Contract Area and

that the provisions of Exhibit "D" will survive the termination of this PA.

18. AREA OF MUTUAL INTEREST. Notwithstanding any other agreement to the

contrary, and both prior to and after any Ridgewood earning of any interest

in the Contract Area described herein in Article 1, the Confidentiality

Agreement and AMI dated July 31, 2007 between Pure Resources, L.P. and

Ridgewood Energy Corporation as referenced above in Article 15.C.3 shall

survive and will control any AMI obligations between the Parties and the

Parties further agree that the provisions of the referenced Confidentiality

Agreement and AMI shall take precedence over the PA.

19. PRODUCTION HANDLING AGREEMENT. Whereas the Co-owners may continue to

utilize the MOPU under terms of agreement referenced above or install a

permanent production facility to handle earned area production and others,

the Parties agree to handle and process Ridgewood production as set forth

below.

a)

It is recognized that the MOPU Lease requires at least 90 days notice

of termination prior to March 3, 2008. Pure, for the Co-owners, will

continue to utilize the MOPU to handle earned area production, if any,

up until that time. Should it be deemed economic by the Co-owners, the

Co-owners may propose a permanent facility, at the cost and risk of

the Co-owners solely, and not Ridgewood, or terminate the MOPU Lease

as of March 3, 2008, at the sole election of Pure with the consent of

the Co-owners. If warranted by the facts as of November 26, 2007 and

in the good faith opinion of Pure, Pure, for the Parties, agrees to

seek

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Ridgewood El Toro PA

September 5, 2007

<PAGE>

to negotiate a month-to-month MOPU Lease extension or exercise its

right to extend the MOPU Lease under its terms for an additional year.

In the event of a dry hole under this PA, the Co-owners are freed from

any obligations to Ridgewood for, and Ridgewood releases any right to,

the MOPU Lease and its utilization. Pure and the Co-owners make no

representation and disclaim that any extension of the MOPU Lease

beyond March 3, 2008 is assured; and,

b)



In the event Ridgewood participates in a completion for production

under this PA and during any period Ridgewood production is handled by

and at the MOPU, Ridgewood's charges and expenses for the receipt,

handling and re-delivery into a departing transportation pipeline at

the MOPU host facility of its share of production will be calculated,

invoiced and paid on a through-put basis on its share of the allocated

production from the West Cameron Block 57 OCS-G 21534 No. 3 El Toro

prospect well, being the Initial Well or a Substitute Well, at the

Ridgewood after earning interest of 33.4917% in the production from

and for such well as to all production handled at the MOPU under the

Accounting Procedure attached to the Operating Agreement as and for

facilities supplied by the operator. If Ridgewood's share of Contract

Area production is handled by and at any permanent facility set by,

and the cost, risk and expense of, the Co-owners, Ridgewood will not

be required to contribute capex towards such facility, however,

Ridgewood shall enter into a mutually acceptable production handling

agreement with the Co-owners, prior to first production handling into

an permanent facility, in which the following handling terms and fees



shall be incorporated into the production handling agreement; 1) $0.15

/MCF gas, 2) $1.00/bbl oil, 3) $1.00/bbl water, 4) $0.05 per stage of

compression, 5) annual escalation of such production handling fees and

any monthly minimum fee to adjust for inflation based on the Annual

Wage Index Percentage Adjustment recommended each year by the Council

of Petroleum Accountants Society ("COPAS"), 6) a monthly minimum fee

of $5000.00 for any month the cumulative production handling fees are

less than that dollar amount, 7) an allocation of natural gas for

fuel, vent, flare and loss, borne in kind or, alternatively, at the

cost of replacement, if Ridgewood volumes are insufficient, 8) a

reservation by the Co-Owners, as owners of such permanent facility,

for re-negotiation of the production handling fees for any unusual

market condition materially increasing the costs bearing upon the

materials or services provided under the PHA and 9) a unilateral

indemnity and insurance obligation in favor of Co-owners, as

processor, for losses and claims arising from the receipt, handling

and re-delivery of the production. Other generally accepted PHA terms

shall be incorporated but as to financial matters, Co-owners shall be

limited to the terms and fees above.

20. REASSIGNMENT. Ridgewood agrees to reassign the interest assigned as per

Article 5 above, in the event that 1) Ridgewood has earned by reaching

Objective or expenditure of obligated funds but where no well drilled

hereunder is mutually deemed as capable of producing in paying quantities

from any portion of the Contract Area within 180 days from the lapse of the

right to propose a Substitute Well under the PA or 2) at any time after

production in paying quantities is established on, and Ridgewood has earned

in, the Contract Area, should there be a cessation of all production in

paying quantities from the Contract Area, Ridgewood will have one hundred

eighty (180) days after cessation of production in which to commence

additional

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September 5, 2007

<PAGE>

drilling, completion or reworking operations, and should operations fail to

result in production in paying quantities attributable to any of the

Contract Area, the Co-owners shall hold the right to elect that Ridgewood

reassign to the Co-owners holding an interest in the Lease and in

proportion to that Lease ownership all of the Ridgewood interest in the

Contract Area, where Ridgewood retains all prior obligations until

satisfied. This reassignment obligation due to cessation of operations or

production, as described above, shall apply for so long as the Co-owners,

their successors or assigns, an interest in the Contract Area. In the event

of any reassignment to the Co-owners, their successors or assigns, the

Contract Area or portion thereof shall be reassigned free from any

overriding royalty, lien, encumbrance, dedications or other burden placed

thereon by Ridgewood. In addition, reassignment shall not relieve Ridgewood

of liability for obligations assumed, which accrued prior to said

reassignment, including, without limitation, the obligation to plug and

abandon any well in which Ridgewood participated in or on the Contract

Area.

21. GOVERNING LAW. This PA shall be governed by and in accordance with the laws

of the State of Louisiana, without regard to any choice of law or rule

thereof that would direct the application of the laws of any other

jurisdiction.

22. INDIVIDUAL LIABILITY. The rights, duties, elections, obligations, and

liabilities of the Parties shall be several and not joint or collective,

and nothing contained herein is intended to create, nor shall it be

construed as creating, a partnership of any kind (except the tax



partnership specified in Article 17 above), joint venture, association, or

other business entity recognizable by law for any purpose. The Parties

shall be individually responsible only for their own obligations, except as

herein described.

23. NOTICES. All notices required hereunder shall be in writing sent by

certified mail or overnight mail delivery, or by facsimile

telecommunications to the addresses set forth below, and shall be deemed

effective when actually received by the addressee, as follows:

-------------------------------------------------------------------------------Ridgewood Energy Corporation

Chevron U.S.A. Inc.

11700 Old Katy Road, Suite 280

935 Gravier Street

Houston TX 77079

New Orleans, LA 70112

Tel: (281) 293-8449

Tel: (504) 592-6356

Fax: (281) 293-7705

Fax: (504) 592-7110

Attn: W. Greg Tabor

Attn: Gordon R. Cain

Executive Vice President

Land Manager

Houston Energy, L.P.

Marlin Coastal, L.L.C.

1415 Louisiana Street

3861 Ambassador Caffery Parkway

Suite 2400

Suite 600

Houston, TX 77002

Lafayette, LA 70503

Tel: (713) 650-8008

Tel: (337) 769-4339

Fax: (713) 650-8305

Fax: (337) 769-4342

Attention: Allen Wihite

Attention: Mike Lipari

-------------------------------------------------------------------------------Page 12 of 16

Ridgewood El Toro PA

September 5, 2007

<PAGE>

-------------------------------------------------------------------------------Helis Oil and Gas Company, LLC

228 St. Charles Ave.

Suite 912

New Orleans, LA 70130

Tel: (504) 681-3321

Fax: (504) 522-6486

Attention: Doug St. Clair

-------------------------------------------------------------------------------24. COUNTERPART EXECUTION. This PA may be executed by signing the original or a

counterpart thereof with the same force and legal effect as if all

executions were on one single instrument.

25. SUCCESSORS AND ASSIGNS. This PA shall be binding upon and inure to the

benefit of the Parties and their respective heirs, representatives,

successors and assigns. Ridgewood shall not assign, mortgage, pledge,

transfer or exchange their rights or interests in this PA or any rights

earned hereunder without the prior written consent of each of the

Co-owners, which consent shall not be unreasonably withheld.

26. INSURANCE. Ridgewood shall, to the extent of its before earning interest,

independently acquire the coverage and amounts as shown on Exhibit "B" OA

and provide evidence of such coverage to Pure prior to commencement of

operations hereunder. Such coverage and limits shall not in any way limit

any Ridgewood indemnity due the Co-owners.

27. DISPUTE RESOLUTION. Notwithstanding anything contained heretofore in this



PA to the contrary, the Parties specifically acknowledge and agree that any

claim, controversy or dispute arising out of, relating to, or in connection

with this PA, including the interpretation, validity, termination or breach

thereof, shall be resolved solely in accordance with the Dispute Resolution

Procedure set forth in Exhibit "E" attached hereto and made a part hereof.

28. INDEMNITY.

A.



Ridgewood, to the full extent of its rights and interests hereunder,

agrees to protect, indemnify, and save the Co-owners, its parents,

subsidiaries, affiliates, and/or successors and the directors,

officers, employees or agents of each ("Co-owners Company Group") free

and harmless from all obligations, business dealings, liabilities,

debts, charges, claims, damages, demands, costs (including attorneys'

fees and court costs), penalties and causes of action arising directly

or indirectly out of any dealing with third parties Ridgewood has with

regard to financing or the assignment of, in whole or in part, any

rights under this PA and to relieve the Co-owners Company Group from

any and all liability (exclusive of business debts and charges)

incurred as a result of such actions. The indemnities and covenants of

this Article 28 shall be effective whether or not such obligations,

Page 13 of 16

Ridgewood El Toro PA

September 5, 2007



<PAGE>

business dealings, liabilities, debts, charges, claims, damages, demands,

costs (including attorneys' fees and court costs), penalties and causes of

action aforesaid are caused wholly or partly by negligence attributed to

the Co-owners Company Group, or by any other means, excepting those

occurrences involving the gross negligence or willful misconduct of the

Co-owners Company Group.

B.



The Co-owners, to the full extent of their rights and interests

hereunder, agree to protect, indemnify, and save Ridgewood, its

parent, subsidiaries, affiliates, and/or successors and the directors,

officers, employees or agents of each ("Ridgewood Company Group") free

and harmless from all obligations, business dealings, liabilities,

debts, charges, claims, damages, demands, costs (including attorneys'

fees and court costs), penalties and causes of action arising directly

or indirectly out of any dealings with third parties the Co-owners has

with regard to financing or the assignment of, in whole or in part,

any rights under this PA and to relieve the Ridgewood Company Group

from any and all liability (exclusive of business debts and charges)

incurred as a result of such actions. The indemnities and covenants of

this Article 28 shall be effective whether or not such obligations,

business dealings, liabilities, debts, charges, claims, damages,

demands, costs (including attorneys' fees and court costs), penalties

and causes of action aforesaid are caused wholly or partly by

negligence attributed to the Ridgewood Company Group, or by any other

means excepting those occurrences involving the gross negligence or

willful misconduct of the Ridgewood Company Group.



C.



The Co-owners shall, as between the Co-owners, remain solely liable

for all liabilities, costs and risks of any kind or nature arising out

of its operations relating to the OA that are not related to this PA

and in which Ridgewood does not participate, including, but not

limited to the plugging and abandonment and remediation of all

existing wells, platforms and other facilities on the Contract Area,

if any.



29. DISCLAIMER OF WARRANTY.



THIS PA IS MADE WITHOUT ANY WARRANTY OF TITLE. THE CO-OWNERS FURTHER DO NOT

WARRANT EITHER EXPRESS, STATUTORY OR IMPLIED, AS TO TITLE, MERCHANTABILITY,

CONDITION, QUALITY OR FITNESS FOR A PARTICULAR PURPOSE AS TO THE LEASE IN

THE CONTRACT AREA, AND ALL OTHER PROPERTY COVERED BY THIS PA, INCLUDING,

BUT NOT LIMITED TO THE WELL BORES, EQUIPMENT AND FACILITIES UTILIZED BY THE

PARTIES HEREUNDER, OR ANY OTHER SORT OF WARRANTY AND IS WITHOUT RECOURSE

AGAINST THE CO-OWNERS WHATSOEVER, EVEN AS TO THE RETURN OF CONSIDERATION.

THE CO-OWNERS MAKE NO REPRESENTATIONS OR WARRANTIES REGARDING RIDGEWOOD'S

RIGHT OF INGRESS TO AND EGRESS FROM THE CO-OWNERS LEASE ACROSS ADJACENT OR

ADJOINING LANDS.

Page 14 of 16

Ridgewood El Toro PA

September 5, 2007

<PAGE>

THE CO-OWNERS SPECIFICALLY DISCLAIM, AND RIDGEWOOD EXPRESSLY WAIVES ANY

IMPLIED WARRANTY OF TITLE WITH RESPECT TO THE LEASE IN THE CONTRACT AREA.

RIDGEWOOD ACKNOWLEDGES THAT THIS EXPRESS WAIVER SHALL BE CONSIDERED A

MATERIAL AND INTEGRAL PART OF THIS PA AND PART OF THE CONSIDERATION GIVEN

THEREFOR. RIDGEWOOD FURTHER ACKNOWLEDGES THAT THIS WAIVER HAS BEEN

SPECIFICALLY BROUGHT TO RIDGEWOOD'S ATTENTION AND THAT RIDGEWOOD HAVE

VOLUNTARILY AND KNOWINGLY CONSENTED TO THIS WAIVER. THE PARTIES AGREE THAT

FOR THE PURPOSES OF THIS WAIVER OF THE IMPLIED WARRANTY OF TITLE, CO-OWNERS

SHALL BE CONSIDERED AS A SELLER.

RIDGEWOOD ACKNOWLEDGES THAT (i) IT IS A SOPHISTICATED INVESTOR NON-OPERATOR

IN THE OIL AND GAS BUSINESS; (ii) IT UNDERSTANDS THE RISKS INVOLVED IN OIL

AND GAS EXPLORATION AND DEVELOPMENT; AND (iii) IT UNDERSTANDS THAT UNDER

ITS PARTICIPATION RIDGEWOOD ASSUMES ALL OF THE RISKS ATTENDANT TO THE

EXPLORATION AND PRODUCTION OPERATIONS CONTEMPLATED UNDER THIS PA AND THAT

THE RIDGEWOOD INVESTMENT MADE HEREUNDER IN THOSE OPERATIONS CONDUCTED UNDER

THIS PA IS FULLY AT RISK.

Please indicate your agreement to the terms and conditions as set forth by

executing this PA and the set of four (4) signature pages in the space provided

and return to the attention of Ron Munn at the letterhead address on or before

October 5, 2007 and Pure will distribute original signature pages to all the

parties.



Page 15 of 16

Ridgewood El Toro PA

September 5, 2007

<PAGE>

AGREED TO AND ACCEPTED this 26 day of Sept, 2007.

CHEVRON MIDCONTINENT, L.P.

By Chevron Midcontinent Operations Company, Its General Partner

By:



/s/ Michael C. Smith

-------------------Michael C. Smith



Title: Assistant Secretary



AGREED TO AND ACCEPTED this _____ day of ____________, 2007.



HELIS OIL AND GAS COMPANY, LLC

By:



_________________________



Title:________________________

AGREED TO AND ACCEPTED this _____ day of ____________, 2007.

HOUSTON ENERGY, L.P.

By:



_________________________



Title:________________________

AGREED TO AND ACCEPTED this _____ day of ____________, 2007.

MARLIN COASTAL, L.L.C.

By:



_________________________



Title:________________________

AGREED TO AND ACCEPTED this 27th day of September 2007.

RIDGEWOOD ENERGY CORPORATION

By:



/s/ W. A. Tabor

--------------W. Greg Tabor



Title: Executive Vice President

Page 16 of 16

Ridgewood El Toro PA

September 5, 2007

</TEXT>

</DOCUMENT>