-----BEGIN PRIVACY-ENHANCED MESSAGE-----
Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
Originator-Key-Asymmetric:
 MFgwCgYEVQgBAQICAf8DSgAwRwJAW2sNKK9AVtBzYZmr6aGjlWyK3XmZv3dTINen
 TWSM7vrzLADbmYQaionwg5sDW3P6oaM5D3tdezXMm7z1T+B+twIDAQAB
MIC-Info: RSA-MD5,RSA,
 LjEdCi1iXVvNzJWnCMbMjjQvTXj0SGcBz2AAEdGYvQPJg0nl3A8YYRIvtZbNkBrp
 ++0flHj9u3sZIuQZKHNoMg==

<SEC-DOCUMENT>0001140361-03-001890.txt : 20030605
<SEC-HEADER>0001140361-03-001890.hdr.sgml : 20030605
<ACCEPTANCE-DATETIME>20030605123805
ACCESSION NUMBER:		0001140361-03-001890
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 INVESTMENTS LLC
		CENTRAL INDEX KEY:			0001083297

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-14745
		FILM NUMBER:		03733697

	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>1</notSubjectToSection16>
    <issuer>
        <issuerCik>0000903267</issuerCik>
        <issuerName>3TEC ENERGY CORP</issuerName>
        <issuerTradingSymbol>TTEN</issuerTradingSymbol>
</issuer>
<reportingOwner>
<reportingOwnerId>
            <rptOwnerCik>0001083297</rptOwnerCik>
            <rptOwnerName>ENCAP INVESTMENTS LLC</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>3165368</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>I</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value>see note</value>
<footnoteId id="F2"/>
</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="F3"/>
</transactionCoding>
<transactionTimeliness>
<value></value>
</transactionTimeliness>
<transactionAmounts>
<transactionShares>
<value>159957</value>
</transactionShares>
<transactionValue>
<value>0</value>
<footnoteId id="F3"/>
</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>159957</value>
</underlyingSecurityShares>
</underlyingSecurity>
<postTransactionAmounts>
<sharesOwnedFollowingTransaction>
<value>0</value>
</sharesOwnedFollowingTransaction>
</postTransactionAmounts>
<ownershipNature>
<directOrIndirectOwnership>
<value>I</value>
</directOrIndirectOwnership>
<natureOfOwnership>
<value>see note</value>
<footnoteId id="F4"/>
</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 chase (being an aggregate cash amount of $26,905,628.51) and 0.85 shares of Plains Exploration &amp; Production Company common stock (being an aggregate 2,690,563 shares), which had a market value of $11.05 per share on June 4, 2003.</footnote>
<footnote id="F2">Represents 1,590,992 shares of common stock disposed of by EnCap Energy Capital Fund III, L.P., 1,189,527 shares of common stock disposed of by EnCap Energy Acquisition III-B, Inc., and 384,849 shares of common stock disposed of by BOCP Energy Partners, L.P.</footnote>
<footnote id="F3">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>
<footnote id="F4">Represents warrants to purchase 79,939 shares of common stock disposed of by EnCap Energy Capital Fund III, L.P., warrants to purchase 60,458 shares of common stock disposed of by EnCap Energy Acquisition III-B, Inc., and warrants to purchase 19,560 shares of common stock disposed of by BOCP Energy Partners, L.P.</footnote>
</footnotes>
<ownerSignature>
<signatureName>By: David B. Miller, Managing Director</signatureName>
<signatureDate>2003-06-04</signatureDate>
</ownerSignature>
</ownershipDocument>

</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
-----END PRIVACY-ENHANCED MESSAGE-----