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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
 GMBUcfvxPQO/zbpC7koO8FdD4tMxfrA28TDghKKqj/Ovvi1rhUqB5wqM9ABIfQ11
 Jmx0njGWrX8gXtxp3RBj9Q==

<SEC-DOCUMENT>0001140361-03-001884.txt : 20030605
<SEC-HEADER>0001140361-03-001884.hdr.sgml : 20030605
<ACCEPTANCE-DATETIME>20030604192303
ACCESSION NUMBER:		0001140361-03-001884
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20030604
FILED AS OF DATE:		20030605

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			3TEC ENERGY CORP
		CENTRAL INDEX KEY:			0000903267
		STANDARD INDUSTRIAL CLASSIFICATION:	CRUDE PETROLEUM & NATURAL GAS [1311]
		IRS NUMBER:				631081013
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		700 MILAM STREET
		STREET 2:		SUITE 1100
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002-2
		BUSINESS PHONE:		7138217100

	FORMER COMPANY:	
		FORMER CONFORMED NAME:	MIDDLE BAY OIL CO INC
		DATE OF NAME CHANGE:	19930504

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			ENCAP ENERGY CAPITAL FUND III LP
		CENTRAL INDEX KEY:			0001086967

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-14745
		FILM NUMBER:		03733211

	BUSINESS ADDRESS:	
		STREET 1:		1100 LOUISIANA
		STREET 2:		SUITE 3150
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002
		BUSINESS PHONE:		7136596100

	MAIL ADDRESS:	
		STREET 1:		1100 LOUISIANA
		STREET 2:		SUITE 3150
		CITY:			HOUSTON
		STATE:			TX
		ZIP:			77002
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>doc1.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType>
<periodOfReport>2003-06-04</periodOfReport>
<notSubjectToSection16>0</notSubjectToSection16>
    <issuer>
        <issuerCik>0000903267</issuerCik>
        <issuerName>3TEC ENERGY CORP</issuerName>
        <issuerTradingSymbol>TTEN</issuerTradingSymbol>
</issuer>
<reportingOwner>
<reportingOwnerId>
            <rptOwnerCik>0001086967</rptOwnerCik>
            <rptOwnerName>ENCAP ENERGY CAPITAL FUND III LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector>
<isOfficer>0</isOfficer>
<isTenPercentOwner>1</isTenPercentOwner>
<isOther>0</isOther>
<officerTitle></officerTitle>
<otherText></otherText>
</reportingOwnerRelationship>
</reportingOwner>
<nonDerivativeSecurity>
<securityTitle>
<value>Common Stock</value>
</securityTitle>
<transactionDate>
<value>2003-06-04</value>
</transactionDate>
<transactionCoding>
<transactionFormType>4</transactionFormType>
<transactionCode>J</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
<footnoteId id="F1"/>
</transactionCoding>
<transactionTimeliness>
<value></value>
</transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>1590992</value>
</transactionShares>
<transactionValue>
<value>19.55</value>
<footnoteId id="F1"/>
</transactionValue>
<transactionAcquiredDisposedCode>
<value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>0</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value></value>
</natureOfOwnership>
</ownershipNature>
</nonDerivativeSecurity>
<derivativeSecurity>
<securityTitle>
<value>Warrant</value>
</securityTitle>
<conversionOrExercisePrice>
<value>30.00</value>
</conversionOrExercisePrice>
<transactionDate>
<value>2003-06-04</value>
</transactionDate>
<transactionCoding>
<transactionFormType>4</transactionFormType>
<transactionCode>J</transactionCode>
<equitySwapInvolved>0</equitySwapInvolved>
<footnoteId id="F2"/>
</transactionCoding>
<transactionTimeliness>
<value></value>
</transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>79939</value>
</transactionShares>
<transactionValue>
<value>0</value>
<footnoteId id="F2"/>
</transactionValue>
<transactionAcquiredDisposedCode>
<value>D</value>
</transactionAcquiredDisposedCode>
</transactionAmounts>
<exerciseDate>
<value>2001-05-22</value>
</exerciseDate>
<expirationDate>
<value>2004-02-03</value>
</expirationDate>
<underlyingSecurity>
<underlyingSecurityTitle>
<value>Common Stock</value>
</underlyingSecurityTitle>
<underlyingSecurityShares>
<value>79939</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>0</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>D</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value></value>
</natureOfOwnership>
</ownershipNature>
</derivativeSecurity>
<footnotes>
<footnote id="F1">Disposed of pursuant to a merger agreement between the Issuer and Plains Exploration &amp; Production Company in exchange for merger consideration of $8.50 per share in cash (being an aggregate cash amount of $13,523,428.52) and 0.85 shares of Plains Exploration &amp; Production Company common stock (being an aggregate 1,352,343 shares), which had a market value of $11.05 per share on June 4, 2003.</footnote>
<footnote id="F2">These warrants were assumed by Plains Exploration &amp; Production Company in the merger and each warrant will represent the right to receive 0.85 shares of Plains Exploration &amp; Production Company common stock and $8.50 in cash at an exercise price of $30.00.</footnote>
</footnotes>
<ownerSignature>
<signatureName>By: EnCap Investments L.L.C., its general partner</signatureName>
<signatureDate>2003-06-04</signatureDate>
</ownerSignature>
<ownerSignature>
<signatureName>By: David B. Miller, Managing Director</signatureName>
<signatureDate>2003-06-04</signatureDate>
</ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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