<SUBMISSION>
<ACCESSION-NUMBER>0001019687-10-001106
<TYPE>4
<PUBLIC-DOCUMENT-COUNT>1
<PERIOD>20100104
<FILING-DATE>20100324
<DATE-OF-FILING-DATE-CHANGE>20100324
<REPORTING-OWNER>
<OWNER-DATA>
<CONFORMED-NAME>van Houweninge Mathijs
<CIK>0001433610
</OWNER-DATA>
<FILING-VALUES>
<FORM-TYPE>4
<ACT>34
<FILE-NUMBER>000-51403
<FILM-NUMBER>10701069
</FILING-VALUES>
<MAIL-ADDRESS>
<STREET1>7805 NW 15TH STREET
<CITY>MIAMI
<STATE>FL
<ZIP>33126
</MAIL-ADDRESS>
</REPORTING-OWNER>
<ISSUER>
<COMPANY-DATA>
<CONFORMED-NAME>Blackwater Midstream Corp.
<CIK>0001292518
<ASSIGNED-SIC>4220
<IRS-NUMBER>262590455
<FISCAL-YEAR-END>0331
</COMPANY-DATA>
<BUSINESS-ADDRESS>
<STREET1>660 LABAUVE DRIVE
<CITY>WESTWEGO
<STATE>LA
<ZIP>70094
<PHONE>504-340-3000
</BUSINESS-ADDRESS>
<MAIL-ADDRESS>
<STREET1>660 LABAUVE DRIVE
<CITY>WESTWEGO
<STATE>LA
<ZIP>70094
</MAIL-ADDRESS>
<FORMER-COMPANY>
<FORMER-CONFORMED-NAME>Laycor Ventures Corp.
<DATE-CHANGED>20040602
</FORMER-COMPANY>
</ISSUER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>edgar.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-01-04</periodOfReport>

    <issuer>
        <issuerCik>0001292518</issuerCik>
        <issuerName>Blackwater Midstream Corp.</issuerName>
        <issuerTradingSymbol>BWMS</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001433610</rptOwnerCik>
            <rptOwnerName>van Houweninge Mathijs</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O BLACKWATER MIDSTREAM CORP.</rptOwnerStreet1>
            <rptOwnerStreet2>660 LABAUVE DRIVE</rptOwnerStreet2>
            <rptOwnerCity>WESTWEGO,</rptOwnerCity>
            <rptOwnerState>LA</rptOwnerState>
            <rptOwnerZipCode>70094</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2010-01-04</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>61176</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>.34</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>1098021</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Shares were awarded as per the Blackwater Midstream Corp. 2008 Incentive Plan in consideration for services rendered as a member of the Issuer's Board of Directors.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/  Mathijs van Houweninge</signatureName>
        <signatureDate>2010-03-24</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SUBMISSION>
