-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 Hjy5Cc5OQrVLWA1+KizdsRozsNFiFkgjQZe5RQp8ZgBLI8NtmHoHCth8o1AJKBvG
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<SEC-DOCUMENT>0001127602-08-011164.txt : 20081215
<SEC-HEADER>0001127602-08-011164.hdr.sgml : 20081215
<ACCEPTANCE-DATETIME>20081215160047
ACCESSION NUMBER:		0001127602-08-011164
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20081211
FILED AS OF DATE:		20081215
DATE AS OF CHANGE:		20081215

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			KERLEY GREGORY D
		CENTRAL INDEX KEY:			0001103813

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-08246
		FILM NUMBER:		081249855

	BUSINESS ADDRESS:	
		BUSINESS PHONE:		2816184700

	MAIL ADDRESS:	
		STREET 1:		2350 N. SAM HOUSTON PARKWAY EAST
		STREET 2:		SUITE 300
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77032

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			SOUTHWESTERN ENERGY CO
		CENTRAL INDEX KEY:			0000007332
		STANDARD INDUSTRIAL CLASSIFICATION:	CRUDE PETROLEUM & NATURAL GAS [1311]
		IRS NUMBER:				710205415
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		2350 N. SAM HOUSTON PARKWAY EAST
		STREET 2:		SUITE 125
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77032
		BUSINESS PHONE:		2816184700

	MAIL ADDRESS:	
		STREET 1:		2350 N. SAM HOUSTON PARKWAY EAST
		STREET 2:		SUITE 125
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77032

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	ARKANSAS WESTERN GAS CO
		DATE OF NAME CHANGE:	19790917
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>form4.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
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<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2008-12-11</periodOfReport>

    <issuer>
        <issuerCik>0000007332</issuerCik>
        <issuerName>SOUTHWESTERN ENERGY CO</issuerName>
        <issuerTradingSymbol>SWN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001103813</rptOwnerCik>
            <rptOwnerName>KERLEY GREGORY D</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>SUITE 125</rptOwnerStreet1>
            <rptOwnerStreet2>2350 N. SAM HOUSTON PARKWAY EAST</rptOwnerStreet2>
            <rptOwnerCity>HOUSTON</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>77032</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isOfficer>1</isOfficer>
            <officerTitle>Executive Vice President &amp; CFO</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2008-12-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>9530</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                    <footnoteId id="F1"/>
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                <transactionAcquiredDisposedCode>
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            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1124436</value>
                </sharesOwnedFollowingTransaction>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        </nonDerivativeTransaction>
        <nonDerivativeHolding>
            <securityTitle>
                <value>Common Stock</value>
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            <postTransactionAmounts>
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                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
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                </directOrIndirectOwnership>
                <natureOfOwnership>
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                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeHolding>
    </nonDerivativeTable>

    <derivativeTable>
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            <conversionOrExercisePrice>
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            <transactionDate>
                <value>2008-12-11</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
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            <transactionTimeliness></transactionTimeliness>
            <transactionAmounts>
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                </transactionShares>
                <transactionPricePerShare>
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            <expirationDate>
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                <underlyingSecurityShares>
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        <derivativeHolding>
            <securityTitle>
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            <conversionOrExercisePrice>
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                    <footnoteId id="F5"/>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
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            <conversionOrExercisePrice>
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            <exerciseDate>
                <value>2001-12-14</value>
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            <expirationDate>
                <value>2010-12-14</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                    <footnoteId id="F6"/>
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            <ownershipNature>
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                    <value>D</value>
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        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.435</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2003-12-11</value>
            </exerciseDate>
            <expirationDate>
                <value>2012-12-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>152076</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>152076</value>
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            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
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        <derivativeHolding>
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            </securityTitle>
            <conversionOrExercisePrice>
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            <exerciseDate>
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            <expirationDate>
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            </expirationDate>
            <underlyingSecurity>
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                    <footnoteId id="F7"/>
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            <securityTitle>
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            <conversionOrExercisePrice>
                <value>6.225</value>
            </conversionOrExercisePrice>
            <exerciseDate>
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            <underlyingSecurity>
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            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2006-12-08</value>
            </exerciseDate>
            <expirationDate>
                <value>2012-12-08</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
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                <underlyingSecurityShares>
                    <value>47420</value>
                    <footnoteId id="F8"/>
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            <postTransactionAmounts>
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                    <value>47420</value>
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            <ownershipNature>
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        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>20.335</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2007-12-11</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-12-11</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>43700</value>
                    <footnoteId id="F9"/>
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            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>43700</value>
                </sharesOwnedFollowingTransaction>
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                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
        <derivativeHolding>
            <securityTitle>
                <value>Stock Options (Right to Buy)</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>27.18</value>
            </conversionOrExercisePrice>
            <exerciseDate>
                <value>2008-12-13</value>
            </exerciseDate>
            <expirationDate>
                <value>2014-12-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>43880</value>
                    <footnoteId id="F10"/>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>43880</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeHolding>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Restricted stock and incentive stock options granted in consideration of services as an officer.</footnote>
        <footnote id="F2">Incentive stock options become exercisable in three equal installments beginning on the first anniversary of the grant date specified in Column 3 or immediately upon death, disability, retirement at age 65, or a change in control.</footnote>
        <footnote id="F3">Each share of phantom stock represents the right to receive the economic equivalent of one share of Southwestern Energy Company common stock.</footnote>
        <footnote id="F4">Shares of phantom stock are payable in cash following termination of the reporting person's employment with Southwestern Energy Company.  The reporting person may transfer his phantom stock account into an alternative investment account at any time.</footnote>
        <footnote id="F5">The phantom stock is currently held in the Southwestern Energy Company Nonqualified Retirement Plan (the &quot;NQ Plan&quot;) investment fund, and has been adjusted to reflect the two-for-one stock split on March 25, 2008.</footnote>
        <footnote id="F6">This option was previously reported as covering 77,992 incentive stock options at an exercise price of $1.8594 per share, and has been adjusted as a result of a two-for-one stock split on March 25, 2008.</footnote>
        <footnote id="F7">This option was previously reported as covering 108,359 incentive stock options at an exercise price of $5.285 per share, and has been adjusted as a result of a two-for-one stock split on March 25, 2008.</footnote>
        <footnote id="F8">This option was previously reported as covering 23,710 incentive stock options at an exercise price of $35.49 per share, and has been adjusted as a result of a two-for-one stock split on March 25, 2008.</footnote>
        <footnote id="F9">This option was previously reported as covering 21,850 incentive stock options at an exercise price of $40.67 per share, and has been adjusted as a result of a two-for-one stock split on March 25, 2008.</footnote>
        <footnote id="F10">This option was previously reported as covering 21,940 incentive stock options at an exercise price of $54.36 per share, and has been adjusted as a result of a two-for-one stock split on March 25, 2008.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Melissa D. McCarty, Attorney-in-fact for Mr. Kerley</signatureName>
        <signatureDate>2008-12-15</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----