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    <periodOfReport>2013-12-16</periodOfReport>

    <notSubjectToSection16>true</notSubjectToSection16>

    <issuer>
        <issuerCik>0000778438</issuerCik>
        <issuerName>BERRY PETROLEUM CO</issuerName>
        <issuerTradingSymbol>BRY</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001191747</rptOwnerCik>
            <rptOwnerName>GAUL J HERBERT JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BERRY PETROLEUM COMPANY</rptOwnerStreet1>
            <rptOwnerStreet2>1999 BROADWAY, SUITE 3700</rptOwnerStreet2>
            <rptOwnerCity>DENVER</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80202</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>true</isDirector>
            <isOfficer>false</isOfficer>
            <isTenPercentOwner>false</isTenPercentOwner>
            <isOther>false</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

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            <deemedExecutionDate></deemedExecutionDate>
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                </directOrIndirectOwnership>
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            <expirationDate>
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            <exerciseDate>
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            <expirationDate>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>2007 Restricted Stock Unit</value>
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                <value>2013-12-16</value>
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                    <value>1319</value>
                    <footnoteId id="F4"/>
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                <transactionPricePerShare>
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                </transactionAcquiredDisposedCode>
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            <exerciseDate>
                <value>2008-01-01</value>
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            <expirationDate>
                <value>2017-12-13</value>
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            <underlyingSecurity>
                <underlyingSecurityTitle>
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                <underlyingSecurityShares>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>NSO 2007</value>
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            <transactionDate>
                <value>2013-12-16</value>
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            <deemedExecutionDate></deemedExecutionDate>
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                    <value>3956</value>
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                <transactionPricePerShare>
                    <value>0</value>
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                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
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            <exerciseDate>
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            </exerciseDate>
            <expirationDate>
                <value>2017-12-13</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                <directOrIndirectOwnership>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Nonstatutory Stock Option 12-15-05</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>30.645</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2013-12-16</value>
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            <deemedExecutionDate></deemedExecutionDate>
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                <equitySwapInvolved>false</equitySwapInvolved>
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                <transactionShares>
                    <value>10000</value>
                    <footnoteId id="F5"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
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                <transactionAcquiredDisposedCode>
                    <value>D</value>
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            </transactionAmounts>
            <exerciseDate>
                <value>2005-12-15</value>
            </exerciseDate>
            <expirationDate>
                <value>2015-12-15</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
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                    <value>10000</value>
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            <ownershipNature>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Nonstatutory Stock Option 12-15-06</value>
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            <conversionOrExercisePrice>
                <value>32.565</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2013-12-16</value>
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            <deemedExecutionDate></deemedExecutionDate>
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                <equitySwapInvolved>false</equitySwapInvolved>
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            <transactionAmounts>
                <transactionShares>
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                    <footnoteId id="F5"/>
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                <transactionPricePerShare>
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                <transactionAcquiredDisposedCode>
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                </transactionAcquiredDisposedCode>
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            <exerciseDate>
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            </exerciseDate>
            <expirationDate>
                <value>2016-12-14</value>
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            <underlyingSecurity>
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        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Phantom Stock Units</value>
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            <deemedExecutionDate></deemedExecutionDate>
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                <equitySwapInvolved>false</equitySwapInvolved>
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            <exerciseDate>
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                <underlyingSecurityTitle>
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        <derivativeTransaction>
            <securityTitle>
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            <exerciseDate>
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    <footnotes>
        <footnote id="F1">RSU Grant awarded to Board of Directors at completion of Merger pursuant to Board action as disclosed in the Merger Proxy materials.</footnote>
        <footnote id="F2">Phantom Stock Units acquired under the Company's Non-Employee Director Deferred Compensation Plan in a transaction exempt under Rule 16b-3(c).  Shares of Common Stock are issued under terms of the Plan upon resignation from the board of directors.</footnote>
        <footnote id="F3">Disposed of pursuant to the merger (the &quot;Merger&quot;) of Berry Petroleum Company (&quot;Berry&quot;) with LinnCo, LLC (&quot;LinnCo&quot;) in a stock-for-stock merger, which was completed on December 16, 2013. Following the transaction Berry is an indirect wholly-owned subsidiary of Linn Energy, LLC. Pursuant to the Merger agreement each share of Berry Common Stock was exchanged for 1.68 shares of LinnCo common shares.</footnote>
        <footnote id="F4">Disposed of pursuant to the merger (the &quot;Merger&quot;) of Berry Petroleum Company (&quot;Berry&quot;) with LinnCo, LLC (&quot;LinnCo&quot;) in a stock-for-stock merger, which was completed on December 16, 2013. Following the transaction Berry is an indirect wholly-owned subsidiary of Linn Energy, LLC. Pursuant to the Merger agreement each RSU was exchanged for 1.68 shares of LinnCo common shares.</footnote>
        <footnote id="F5">Disposed of pursuant to the merger (the &quot;Merger&quot;) of Berry Petroleum Company (&quot;Berry&quot;) with LinnCo, LLC (&quot;LinnCo&quot;) in a stock-for-stock merger, which was completed on December 16, 2013. Following the transaction Berry is an indirect wholly-owned subsidiary of Linn Energy, LLC. Pursuant to the Merger agreement each option to purchase Berry shares was exchanged for 1.682115 options to puchase LINN Units on the same terms and conditions as were applicable to Berry shares prior to the Merger.</footnote>
        <footnote id="F6">Disposed of pursuant to the merger (the &quot;Merger&quot;) of Berry Petroleum Company (&quot;Berry&quot;) with LinnCo, LLC (&quot;LinnCo&quot;) in a stock-for-stock merger, which was completed on December 16, 2013. Following the transaction Berry is an indirect wholly-owned subsidiary of Linn Energy, LLC. Pursuant to the Merger agreement each Phantom Stock Unit was exchanged for 1.68 shares of LinnCo common shares.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Kenneth A Olson under POA for J. Gaul</signatureName>
        <signatureDate>2013-12-19</signatureDate>
    </ownerSignature>
</ownershipDocument>
