ENERVESTMANAGEMENT PARTNERS, LTD.

IPAA/TIPRO Luncheon Buying & Selling through the Cycles

John B. Walker

President and Chief Executive Officer

September 14, 2005

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Company Overview

Approximately $1 billion available for acquisitions and development of oil and gas properties

Consistently generated superior returns for its institutional partners across capital market and commodity price cycles

6 partnerships exited with a realized 28.1% internal rate of return after management fees, back-ins and hedge payments

Operate approximately 10,500 wells in 9 states

Experienced management team with extensive network of industry relationships

Over 300 employees with headquarters in Houston

Recognized in 2003, 2002 and 2001 by the Houston Business Journal as the “Best Place to Work in Houston” (across all industries)

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John B. Walker – President and CEO Co-founder of EnerVest Chairman of IPAA Member of National Petroleum Council and Natural Gas Council Former President and COO of Torch Energy Advisors, Inc. Former “All American” Energy Analyst on Wall Street

Jon Rex Jones – Chairman Co-founder of EnerVest Co-founder of JM Petroleum, Taurus Energy and Global Exploration Former “Oilman of the Year” and “Chief Roughneck” Past Chairman of IPAA National Petroleum Council Member

Mark Houser – Executive Vice President and COO Former Vice President, U. S. Operations of Occidental Petroleum (NYSE: OXY) Responsible for $3.65 Billion Acquisition of Elk Hills Naval Petroleum Reserve Former Vice President of Exploration for Canadian Occidental (NYSE: NXY)

Jim Vanderhider – Executive Vice President and CFO Former Executive Vice President and CFO of Torch Energy Former head of Internal Audit (Corporate) of The Coastal Corporation, now a

division of El Paso (NYSE: EP)

Experienced Executive Management Team

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What We Are Focused on making money and generating earnings for institutional

investors Second largest manager of oil and gas assets for institutional investors Acquisition, exploitation, and operating company focused on:

upstream property/corporate acquisitions in North America willingness to sell assets to maximize returns

Private company which operates wells and distributes a significant

monthly return to investors

What We Are Not Financiers/capital providers Explorationists

What We Are – What We Are Not

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Operating Areas – September 2005

Permian PropertiesReserves 101.1 BCFE

Production 10.4 MMCFE/D

South Louisiana PropertiesReserves 61.9 BCFE

Production 15.4 MMCFE/D

San Juan PropertiesReserves 57.5 BCFE

Production 7.8 MMCFE/D

Ark-La-Tex PropertiesReserves 107.8 BCFE

Production 13.2 MMCFE/D

Appalachian PropertiesReserves 224.1 BCFE

Production 44.6 MMCFE/D

Michigan PropertiesReserves 173.4 BCFE

Production 26.1 MMCFE/D

Proven + Probable Reserves (Risked)726 BCFE

78% Gas (16.3 year R/P)

Production 118 MMCFE/D

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EnerVest Management Partners, Ltd.

Eastern Division Ken Mariani

Southern DivisionBarbara King

Ark-La-Tex DivisionBill Page

Ohio PropertiesFund IX (CGAS, B&B)

Permian PropertiesFund IX

Monroe GE Capital

Olanta FieldAEGON

EnerVest WVLiberty Mutual

EnerVest AppalachiaGE Capital

Oriskany Horizontal DrillingEVMP, Jones, Sandefer

Michigan – FreuhaufFund IX

Jacobs Property EVMP

Coalbed MethaneEVMP

Bayou PropertiesEnerVest Energy

San JuanFund IX

ShilohFund IX

PITCOFund X

Belden & BlakeFund X

Primos PropertyEVMP

Below Red Line reflects

New Acquisitions since 1/05

EnerVest Assets/Partnerships

SellingSOLD Selling

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Bell Ringers

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Successfully Raised $550 Million in Equity for Fund X Raised an additional $47 million equity in an alongside investment Fund X now has approximately $1 billion of potential investment capacity

Significant Acquisition Activity since January Closed on 7 transactions totaling >$700 million All in costs - $1.74/mcfe Includes the largest deal ever done by EnerVest 6 of 7 transactions are direct negotiations

Significant Divestiture Activity Property in Pennsylvania sold in August Sale of South Louisiana properties pending Sale of all Permian properties announced

2005 – Bell Ringers

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Most Acquisitive Companies (2005 YTD)

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Track Record/Performance History

FUND INSTITUTIONAL SIZE ACTUAL FUND# FUND ($MM) IRR STATUSI South Lake Arthur, L.P. 54.5 9.8% Exited

II EnerVest Acquisition - II, L.P. 12.7 27.7% Exited

III EnerVest East, L.P. 24.6 25.8% Exited

IV EnerVest Texoma, L.P. 60.9 33.9% Exited

V EnerVest San Juan, L.P. 85.6 38.1% Exited

VI EnerVest Monroe, L.P. 67.3 >15.0% Acquiring Add-On Interests

VII Specified Appalachian Investments: EnerVest Appalachia, L.P. 48.6 >15.0% Developing Fields EnerVest WV, L.P. 9.0 >15.0% Developing Fields EnerVest Olanta, L.P. 14.1 28.4% Exited

VIII EnerVest Energy, L.P. 194.1 >15.0% Preparing for Exit

IX EnerVest Energy Fund IX, L.P. 215.2 >40.0% Capital Fully Committed

X EnerVest Fund X, L.P. 1,029.0 Beginning Investment Period

1,815.6

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Institutional Fundraising History

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Taxable Non-Taxable Debt Belden & Blake Debt Co-Investment

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Proud Soccer Dad

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Acquisition Focus on extensive industry contacts and relationships with majors, independents,

and individuals active in the A&D market Constantly monitor the markets and update intelligence database Follow a strict discipline and stay patient Identify assets possessing our desired, pre-defined investment characteristics Engineer all properties in-house Acquire additional interests at higher IRR following the initial investment

Operation and Exploitation Reduce field operating costs immediately Conduct engineering and geological field studies Implement exploitation programs quickly and effectively Proactively hedge commodity prices to maximize investment IRR

Asset Divestiture Develop an asset exit strategy in connection with the acquisition Constantly assess the market for strategic/momentum buyers Exit assets when capital markets and industry cycles provide premium valuations

or where strategic buyers can be located

Strategies for the Investment Cycle

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Target IRR 6% - 10%

Bank Loan

Wildcat Funding

Target IRR 50%

Portfolio Investments

PDP Reserves

PDNP PUD Proved Reserves

Probable Possible Exploration

Target IRR 20%

EnerVest

Primarily Engineering Risk Increased Geological RiskSource: EnCap

Oil and Gas Industry Risk Spectrum

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Acquisitions and Divestitures

EnerVest M&A Activity

Year: 2000 2001 2002 2003 2004 2005 YTDDeals Scoped: 230 321 210 181 228 180Evaluations Performed: 49 40 37 35 50 32Bids/Offers Made: 28 25 31 23 39 22Bid Exposure (mm): $441.2 $853.1 $684.0 $1,101.6 $1,572.6 $1,671.8Avg Bid Size (mm): $15.8 $34.1 $22.1 $47.9 $40.3 $76.0Acquisitions Closed: 7 6 4 5 3 7 - % of Deals Scoped: 3% 2% 2% 3% 1% 4% - % of Bids: 25% 24% 13% 22% 8% 32%Divestitures Closed: 5 3 5 1 1 1Swaps Closed: 0 1 0 1 0 0Transactions Closed: 12 10 9 7 4 8Total Acquistion Value (mm): $82.4 $25.8 $0.2 $84.4 $16.0 $706.9Total Divestiture Value (mm): $124.6 $26.6 $65.7 $32.5 $26.5 $25.2

6 Year Results

Deals Scoped 240 per year

Evaluations Performed 43 per year

Bids Made 30 per year

% of Bids Closed 21% per year

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EnerVest Fund IX InvestmentsFocus on Minimizing Competition in Acquisition Marketplace

ACQUISITION NATURE OF ACQUISITIONCGAS Acquired out of bankruptcy

Belden & Blake Negotiated transaction, complementary Undeveloped Acreage to CGAS Acquisition

Permian Basin Fields Assets marketed directly by seller Permian Add-ons Negotiated transaction

San Juan Negotiated transaction

Michigan Negotiated transaction

Michigan Add-on Negotiated transaction

Ark-La-Tex Negotiated transaction

>$200 Million in Total Fund IX Acquisitions

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EnerVest Acquisitions(Compared to Natural Gas Prices)

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Direct negotiated corporate transaction

Great fit with EnerVest’s existing assets

Large oil and gas asset base Reserves of over 300 BCFE Daily production of 46

MMCFE/Day 4,126 wells Approximately 565,000 net

acres Attractive benchmarks vs.

recent similar transactions Top 5 Producer in Appalachian

and Michigan Basins

Belden & Blake Acquisition

BBCAssets

Appalachia/Michigan Basin Assets

EnerVest Belden Combined

20.2 46.1 66.3 MMCFE/D

119.8 302.3 422.1 BCFE

680,000 627,988 1,307,988 Gross Acres

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Where’s Walker?

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Case Study: EnerVest East, L.P.

(Appalachia)

Purchased 4.1 MMCFD for $17.4 Million in July 1995 Acquired for PV 10% and tax credit value of $4.6 Million Average working interest 37% Initially valued as PDP only reserves

Increased working interest in fields by add-on acquisitions Average working interest increased to 72% Cost of additional reserves were $.48/mcf Field production essentially unchanged

Sold small, non-core assets

Engineering/Geoscience effort identified significant “non-PDP”

opportunities

Sold after 9 years for 26% ROR

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Case Study: Loma Vieja Field, South Texas

Overview Seller in lawsuit with mineral owners Purchased for $12MM in September 2000

Operating Achievements Drilled 1 well Reworked 3 wells Reconfigured compression Increased rate from 8 to 20 MMCF/D

Results Capital Spending: $3.1MM Net Cashflow: $9.4MM March 2002: Sold for $25.3MM ($2.12/mcf) Life-cycle ROR = 77%

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Case Study: San Juan

September, 1996 – Purchased $67 million of properties and tax

credits in San Juan Basin

67% of value was attributable to tax credits

Operated 48 of 50 wells (95% value)

Technical/Land Effort Quadrupled reserves

Drilled or performed workovers on 20 wells in 4 years

2nd Quarter 2000 – received regulatory approval for infill

development program, adding extensive value

Sold in January 2001 for $121 million (15% tax credits);

38 % IRR

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Glasscock

ScurryBorden

Howard

Sterling

Mitchell

SACROC

Sharon Ridge

Howard-Glasscock

Iatan

Conger

Westbrook

Westbrook Field (Acquired 2003) Production from Upper and

Middle Clearfork at 2,600’

Iatan Field (Acquired 2003) Production from San Andres,

Glorieta, Upper Clearfork at

2,600’

Ackerly Field (Acquired 2004) Martin County, Texas Spraberry Trend, Production from

Dean Sand at 8,500’

Consolidated acreage position ~

8,000 net acres

100% operated, 93% - 100% WI

R/P > 20 years

Case Study: Permian Basin Area

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Case Study: Permian Basin Area

Performed 2 year exploitation program:

Returned numerous wells to production

Performed 50+ workovers (refrac and add pay)

Drilled 27 infill / extension wells

5 distinct reservoirs / zones

$13.1 Million capital spending

Increased net production from 1,050 BOE/D to 1,790 BOE/D

Increased proved and probable reserves to 18.5 MMBOE

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Blue: booked. Red: unbooked. 15

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Identified Exploitation PotentialA potential capture of >15 MMBO may exist over a 4-7 year period

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Future Plans

Build on Institutional Franchise

Create Basin Dominance in a Few Areas

Create a Separate Public Vehicle

Be an even Greater Place to Work

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ENERVESTMANAGEMENT PARTNERS, LTD.

IPAA/TIPRO Luncheon Buying & Selling through the Cycles

John B. Walker

President and Chief Executive Officer

September 14, 2005