1. New Things Southwestern Energy Company IPAA London Oil & Gas Investment Symposium NYSE: SWN Presentation to

2. Forward-Looking Statements All statements, other than historical financial information, may be deemed to be forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, and Section 21E of the Securities Exchange Act of 1934, as amended. Although the company believes the expectations expressed in such forward-looking statements are based on reasonable assumptions, such statements are not guarantees of future performance and actual results or developments may differ materially from those in the forward-looking statements. Important factors that could cause actual results to differ materially from those in the forward-looking statements herein include, but are not limited to, the timing and extent of changes in commodity prices for gas and oil, the extent to which the Fayetteville Shale play can replicate the results of other productive shale gas plays, the potential for significant variability in reservoir characteristics of the Fayetteville Shale over such a large acreage position, the timing and extent of the company’s success in discovering, developing, producing and estimating reserves, property acquisition or divestiture activities, the effects of weather and regulation on the company’s gas distribution segment, increased competition, the impact of federal, state and local government regulation, the financial impact of accounting regulations and critical accounting policies, changing market conditions and prices (including regional basis differentials), the comparative cost of alternative fuels, conditions in capital markets and changes in interest rates, availability of oil field personnel, services, drilling rigs and other equipment, and any other factors listed in the reports filed by the company with the Securities and Exchange Commission (the “SEC”). For additional information with respect to certain of these and other factors, see reports filed by the company with the SEC. The company disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise.

3. Focused on domestic exploration and production of natural gas.  645 Bcfe of reserves; 92% natural gas; 11.9 R/P at year-end 2004. E&P strategy built on organic growth through the drillbit.  Over 80% of planned E&P capital allocated to drilling in 2005. Track record of adding significant reserves at low costs.  Since 1999, we’ve averaged annual production growth of 10%, reserve growth of 13%, 246% reserve replacement, and F&D cost of $1.28 per Mcfe. Proven management team has increased Southwestern’s market capitalization from $187 million at year-end 1998 to over $3 billion today. Strategy built on the Formula: The Right People doing the Right Things, wisely investing the cash flow from the underlying Assets will create Value +. About Southwestern

4. Current Highlights (1) EBITDA is a non-GAAP financial measure. 2004 Successful drilling programs in the Arkoma Basin, East Texas and Permian Basin. Record production and reserves of 54.1 Bcfe and 645 Bcfe, respectively, up 31% and 28% over 2003. Set records for net income, operating income and EBITDA (1). Began drilling in Fayetteville Shale play in Arkansas. 2005 Forecast Planned CapEx of up to $353.0 million, up 20% from 2004. Production guidance of 61.0 – 63.0 Bcfe, up 13 – 17% from 2004 production. Plan to significantly accelerate Fayetteville Shale drilling program. Forward-Looking Statement

5. Proven Track Record For the Periods Ended December 31 Note:Reserve data excludes reserve revisions. (1)EBITDA is a non-GAAP financial measure. Forward-Looking Statement EBITDA ($MM) (1) Production (Bcfe) Reserve Replacement F&D Cost ($/Mcfe) 9900 01 41.2 35.7 40.1 02 39.8 32.9 03 54.1 0405E 61-63E 351% 196% 209% 224% 150% 9900 01 0203 388% 04 $103.2 $99.8 $134.6 $152.3 $76.1 9900 01 0203 $256.4 04 $1.18 $0.99 $1.02 $1.11 9900 01 0203 $1.20 $1.34 04

6. SWN is One of the Lowest Cost Operators Note: All data as of December 31, 2002, 2003 and 2004. APC - Anadarko Petroleum, APA - Apache, BR - Burlington Resources, COG - Cabot Oil & Gas, CHK - Chesapeake Energy, XEC - Cimarex Energy, DNR - Denbury Resources, DVN - Devon Energy, ECA - EnCana, FST - Forest Oil, THX - Houston Exploration, NFX - Newfield Exploration, NBL - Noble Energy, PPP - Pogo Producing Co., PXD - Pioneer Natural Resources, RRC - Range Resources, REM - Remington Oil & Gas, SM - St. Mary Land & Exploration, SFY - Swift Energy, XTO - XTO Energy. Lifting Costs ($/Mcfe) Drillbit F&D Costs ($/Mcfe) Drillbit F&D Cost per Mcfe (3 year average) Lifting Cost per Mcfe of Production (3 year average) Source: John S. Herold Database 0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 XTODNRBRSWNNBLAPARRCAPCCOGECASFYTHXCHKSMREMDVNXECNFXPXDPPPFST 0.30 0.50 0.70 0.90 1.10 1.30 1.50 BRTHXREMSWNNFXPPPECACHKPXDNBLRRCCOGAPAAPCDVNXTOXECSFYSMFSTDNR

7. About the Company Utility Segment 145,000 customers in N. Arkansas 6th fastest growing region in U.S. Filed $9.7 MM rate case in Dec. 2004 Arkoma Reserves - 247.0 Bcf (38%) Production - 20.2 Bcf (37%) Permian Reserves - 60.8 Bcfe (9%) Production - 7.1 Bcfe (13%) East Texas Reserves - 299.1 Bcfe (47%) Production - 22.2 Bcfe (41%) Gulf Coast Reserves - 38.6 Bcfe (6%) Production - 4.6 Bcfe (9%) E&P Segment 2004 Reserves: 645 Bcfe 92% Natural Gas 83% Proved Developed Reserve Life: 11.9 years 2004 Production: 54.1 Bcfe Gas Distribution Ozark Pipeline Forward-Looking Statement

8. Capital Investments Exploration Drilling Development Drilling Leasehold & Seismic Capitalized Expenses Property Acquisitions Utility & Corporate (1) Net of $13.5 million reimbursement from Overton Field partnership. East Texas 43% Arkoma 17% Utility 3% Gulf Coast 1% Other E&P 6% Permian 1% Arkoma Fayetteville Shale 29% Forward-Looking Statement 0 130 260 390 20012002200320042005 Plan ($ Millions) $92.5 (1) $180.2 $295.0 $352.7 $92.1

9. East Texas - Overton Field Forward-Looking Statement Reserve Replacement: LOE Cost (incl. Taxes) ($/Mcfe): F&D Cost ($/Mcfe):$0.99 2002-2004 681% Overton Field $0.47 Avg Results* * Including reserve revisions. LEGEND Existing Wells at Year-End 2003 Overton Field Reserve Potential Approx.Reserve WellSpacingPotential Count(Acres)(Net Bcfe) Original Wells1664022 2001 - 2002 Development3336589 2003 Development57170102 2004 Development Wells 2004 Development83100142 2005 Development Wells Planned 2005 Development807595 Locations @ $6.00 Gas with PVI ≥ 1.3 926084 Potential Future Development

10. Overton Field Gross Production Forward-Looking Statement 0 20 40 60 80 100 Dec-00 Dec-01Dec-02Dec-03Dec-04 MMcfe/d Overton Net Production Bcfe 20000.3 20012.3 20025.9 200313.6 200421.8 2005 Forecast25 - 27 Accelerated Drilling Program with Equity Offering Added 5 th Rig

11. Overton Field - Improved Drilling Results Forward-Looking Statement Days Depth (feet) Drilling Days versus Depth 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 051015202530354045505560 Reduced drilling time by > 50%. Increased initial production by 200%. Increased gross reserves by 60% (avg. EUR of 2.0 Bcfe per well in 2004) FINA Avg: 55 Days 2001 Avg: 35 Days 2002 Avg: 27 Days 2003 Avg: 23 Days 2004 Avg: 19 Days

12. Arkoma Basin Forward-Looking Statement * Including reserve revisions. ** For illustrative purposes only. Shaded area does not delineate actual play area.

13. Ranger Anticline 1 mile SWN Exploratory Acreage SWN Producing Wells at 12/31/04 2005 Proposed Wells SWN HBP Acreage Ranger Anticline (inception thru 12/30/04)* Success: Net EUR: F&D/Mcf: 43/50 62.8 Bcf $.72 Count Ranger Anticline Potential Well 219TOTAL 20Successful Wells in 2004 (Net Bcfe) Potential Reserve 232 31 Producing Wells at 12/31/021320 Successful Wells in 200312 Potential Future Locations 10 133Other Contingent Locations121 432005 Drilling Program48 Forward-Looking Statement * Including reserve revisions.

14. Arkoma - Fayetteville Shale Play Wedington Incongruity Forward-Looking Statement

15. How Have We Been Doing? Note: All metrics calculated exclude reserve revisions. (1) PVI metrics calculated using pricing in effect at year-end (except for 2000 which was calculated at $3.00 per Mcf natural gas price). F&D Cost PVI ($/$) F&D ($/Mcfe) Reserve Replacement (%) $0.50 $1.00 $1.50 $2.00 $2.50 19971998199920012002 0% 100% 200% 300% 400% 2000 (1) 2003 New Management New E&P Team New Strategy 2004 Reserve Replacement PVI

16. Outlook for 2005 Forward-Looking Statement Production target of 61.0 – 63.0 Bcfe in 2005 (estimated growth of 13 – 17%).  Net Income  EBITDA (1)  Operating Income Note: Guidance updated as of April 29, 2005. Per share estimates assume 75.0 million weighted average diluted shares outstanding for 2005. 2004 oil and gas prices represent actual average last-day NYMEX closing prices. 2005 oil and gas prices represent NYMEX price assumptions. (1)Net cash flow is net cash flow before changes in operating assets and liabilities. Net cash flow and EBITDA are non-GAAP financial measures.  EPS $6.00 Gas $40.00 Oil $100 - $110 MM $278 - $288 MM $185 - $195 MM 2005 Guidance $1.33 - $1.47 $7.00 Gas $50.00 Oil $120 - $130 MM $309 - $319 MM $218 - $228 MM $1.60 - $1.73  Net Cash Flow (1) $260 - $270 MM $290 - $300 MM  CapEx$352.7 MM $103.6 MM $256.4 MM $182.3 MM 2004 Actual $6.14 Gas $41.36 Oil $1.40 $237.7 MM $295.0 MM

17. Gas Hedges in Place Through 2007 Forward-Looking Statement Note: Southwestern has approximately 360,000 barrels of oil hedged at a fixed WTI price of $33.17 per barrel in 2005 and 120,000 barrels of oil hedged at a fixed WTI price of $37.30 per barrel in 2006. 0 2,000 4,000 6,000 8,000 10,000 4Q MMcf 1Q2Q3Q 2005 $4.51 1.0 Bcf $4.49 1.0 Bcf $4.74 1.0 Bcf $4.70 1.0 Bcf $4.70 1.0 Bcf $4.90 1.0 Bcf $4.79.5 Bcf$4.78.5 Bcf $4.99.5 Bcf $4.94.5 Bcf $5.14.5 Bcf $5.12.5 Bcf $5.27.5 Bcf $4.50/$5.80 1.5 Bcf $4.50/$5.80 1.5 Bcf $4.50/$6.20 1.5 Bcf $4.50/$5.88 1.5 Bcf $4.50/$5.88 1.5 Bcf $4.50/$6.35 1.5 Bcf $4.50/$6.32 1.0 Bcf $4.50/$6.32 1.0 Bcf $4.50/$6.78 1.0 Bcf $4.75/$6.15.5 Bcf $4.50/$8.00 1.0 Bcf $4.50/$8.30.5 Bcf $5.93.5 Bcf $4.50/$8.50 1.5 Bcf $4.50/$8.40.5 Bcf $4.50/$8.68 1.5 Bcf $4.50/$9.64 1.0 Bcf $4.75/$10.00.5 Bcf $4.50/$13.50 1.0 Bcf $4.50/$8.65 1.0 Bcf $4.50/$8.60 1.0 Bcf $4.50/$10.10 1.0 Bcf $4.50/$7.40 1.5 Bcf $4.50/$7.40 1.5 Bcf $4.50/$8.20 1.5 Bcf $4.50/$12.00 1.5 Bcf $5.48.25 Bcf$5.47.25 Bcf$6.35.25 Bcf$5.67.25 Bcf $5.97.4 Bcf$6.11.4 Bcf$5.99.4 Bcf $6.89.4 Bcf $4.50/$11.95 1.0 Bcf $4.50/$7.00 1.0 Bcf $4.50/$7.00 1.0 Bcf $4.50/$8.00 1.0 Bcf 12,000 $5.00/$11.40 1.0 Bcf $5.00/$7.72 1.0 Bcf $5.00/$7.80 1.0 Bcf $5.00/$9.00 1.0 Bcf $5.00/$12.15 1.0 Bcf $5.00/$7.98 1.0 Bcf $5.00/$8.01 1.0 Bcf $5.00/$9.27 1.0 Bcf Collar NYMEX Fixed Price $4.75/$11.95 2.0 Bcf $4.75/$7.09 2.0 Bcf $4.75/$7.07 2.0 Bcf $4.75/$8.27 2.0 Bcf $6.565 1.0 Bcf $5.63 1.0 Bcf $5.625 1.0 Bcf $5.89 1.0 Bcf $5.00/$9.00 1.0 Bcf Avg Price per McfPercent Type Hedged Volumes (or Floor / Ceiling) Hedged 2005Swaps12.6 Bcf$5.04 Collars32.0 Bcf$4.65 / $8.29 2006 Collars38.0 Bcf$5.18 / $9.67 Swaps7.0 Bcf$6.27 - - $4.75/$12.65 1.0 Bcf $4.75/$7.42 1.0 Bcf $4.75/$7.35 1.0 Bcf $4.75/$8.63 1.0 Bcf $5.00/$18.00 1.0 Bcf 20 - 25% 50 - 55% $5.50/$13.50 1.0 Bcf $5.50/$7.60 1.0 Bcf $5.50/$7.60 1.0 Bcf $5.50/$8.75 1.0 Bcf $5.75/$15.25 1.0 Bcf $5.75/$8.30 1.0 Bcf $5.75/$8.44 1.0 Bcf $5.75/$9.40 1.0 Bcf $6.235 1.0 Bcf $6.235 1.0 Bcf $6.54 1.0 Bcf $6.21.5 Bcf$6.20.5 Bcf $6.50.5 Bcf $7.415 1.0 Bcf $7.445.5 Bcf 4Q1Q2Q3Q 2006 4Q1Q2Q3Q 2007 Swaps12.0 Bcf$6.66 - Collars14.0 Bcf$6.00 / $10.68 - $6.00/$15.65 1.0 Bcf $6.00/$9.79 1.0 Bcf $6.525.5 Bcf$6.51.5 Bcf $6.80.5 Bcf $6.00/$11.48.5 Bcf $6.00/$16.65 1.0 Bcf $6.00/$10.55 1.0 Bcf $7.21 1.0 Bcf $7.21 1.0 Bcf $6.00/$12.45 1.5 Bcf $6.66 1.5 Bcf $6.66 1.5 Bcf $6.95 1.5 Bcf $6.00/$13.55 1.0 Bcf $6.00/$8.05 1.0 Bcf $6.00/$8.13 1.0 Bcf $6.00/$9.43 1.0 Bcf $6.00/$15.15 1.0 Bcf $6.00/$8.75 1.0 Bcf $6.00/$8.75 1.0 Bcf $6.00/$10.01 1.0 Bcf $6.00/$15.28 1.0 Bcf $6.00/$8.78 1.0 Bcf $6.00/$8.88 1.0 Bcf $6.00/$10.28 1.0 Bcf $6.50/$15.05 1.0 Bcf $6.50/$10.85 1.0 Bcf $6.50/$9.35 1.0 Bcf $6.50/$9.40 1.0 Bcf

18. The Road to Invest in the Highest PVI Projects.  Accelerate Overton Development.  Accelerate Ranger Anticline Development. Pursue Fayetteville Shale Potential. Maximize Cash Flow. Deliver the Numbers.  Production and Reserve Growth.  Add Value for Every Dollar Invested. Continue to Tell Our Story.