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USD ($)

USD ($) / shares

</KeyName><CurrencySymbol>$</CurrencySymbol><contextRef><ContextID>Jan-01-2010_Dec-31-2010</ContextID><EntitySchema>http://www.sec.gov/CIK</EntitySchema><EntityValue>0001358071</EntityValue><PeriodDisplayName /><PeriodType>duration</PeriodType><PeriodStartDate>2010-01-01T00:00:00</PeriodStartDate><PeriodEndDate>2010-12-31T00:00:00</PeriodEndDate><Segments /><Scenarios /></contextRef><UPS><UnitProperty><UnitID>USD</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema><MeasureValue>USD</MeasureValue><MeasureNamespace>iso4217</MeasureNamespace></StandardMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>USDEPS</UnitID><UnitType>Divide</UnitType><NumeratorMeasure><MeasureSchema>http://www.xbrl.org/2003/iso4217</MeasureSchema><MeasureValue>USD</MeasureValue><MeasureNamespace>iso4217</MeasureNamespace></NumeratorMeasure><DenominatorMeasure><MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema><MeasureValue>shares</MeasureValue><MeasureNamespace>xbrli</MeasureNamespace></DenominatorMeasure><Scale>0</Scale></UnitProperty><UnitProperty><UnitID>Shares</UnitID><UnitType>Standard</UnitType><StandardMeasure><MeasureSchema>http://www.xbrl.org/2003/instance</MeasureSchema><MeasureValue>shares</MeasureValue><MeasureNamespace>xbrli</MeasureNamespace></StandardMeasure><Scale>0</Scale></UnitProperty></UPS><CurrencyCode>USD</CurrencyCode><OriginalCurrencyCode>USD</OriginalCurrencyCode></MCU><CurrencySymbol>$</CurrencySymbol><Labels><Label Id="1" Label="12 Months Ended" /><Label Id="2" Label="Dec. 31, 2010" /></Labels></Column></Columns><Rows><Row><Id>2</Id><IsAbstractGroupTitle>true</IsAbstractGroupTitle><Level>0</Level><ElementName>cxo_MajorCustomersAndDerivativeCounterpartiesAbstract</ElementName><ElementPrefix>cxo</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>Major customers and derivative counterparties.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole /><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText /><NonNumericTextHeader /><FootnoteIndexer /><CurrencyCode /><CurrencySymbol /><IsIndependantCurrency>false</IsIndependantCurrency><ShowCurrencySymbol>false</ShowCurrencySymbol><DisplayDateInUSFormat>false</DisplayDateInUSFormat><hasSegments>false</hasSegments><hasScenarios>false</hasScenarios></Cell></Cells><OriginalInstanceReportColumns /><Unit>Other</Unit><ElementDataType>xbrli:stringItemType</ElementDataType><SimpleDataType>string</SimpleDataType><ElementDefenition>Major customers and derivative counterparties.</ElementDefenition><IsTotalLabel>false</IsTotalLabel><IsEPS>false</IsEPS><Label>Major customers and derivative counterparties [Abstract]</Label></Row><Row><Id>3</Id><IsAbstractGroupTitle>false</IsAbstractGroupTitle><Level>0</Level><ElementName>cxo_MajorCustomersAndDerivativeCounterpartiesTextBlock</ElementName><ElementPrefix>cxo</ElementPrefix><IsBaseElement>false</IsBaseElement><BalanceType>na</BalanceType><PeriodType>duration</PeriodType><ShortDefinition>Major customers and derivative counterparties.</ShortDefinition><IsReportTitle>false</IsReportTitle><IsSegmentTitle>false</IsSegmentTitle><IsSubReportEnd>false</IsSubReportEnd><IsCalendarTitle>false</IsCalendarTitle><IsTuple>false</IsTuple><IsEquityPrevioslyReportedAsRow>false</IsEquityPrevioslyReportedAsRow><IsEquityAdjustmentRow>false</IsEquityAdjustmentRow><IsBeginningBalance>false</IsBeginningBalance><IsEndingBalance>false</IsEndingBalance><IsReverseSign>false</IsReverseSign><PreferredLabelRole>verboselabel</PreferredLabelRole><FootnoteIndexer /><Cells><Cell><Id>1</Id><IsNumeric>false</IsNumeric><IsRatio>false</IsRatio><DisplayZeroAsNone>false</DisplayZeroAsNone><NumericAmount>0</NumericAmount><RoundedNumericAmount>0</RoundedNumericAmount><NonNumbericText>&lt;!--DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd" --&gt;
   &lt;!-- Begin Block Tagged Note 13 - cxo:MajorCustomersAndDerivativeCounterpartiesTextBlock--&gt;
   &lt;div style="font-family: 'Times New Roman',Times,serif"&gt;
   &lt;div align="justify" style="font-size: 10pt; margin-top: 12pt"&gt;&lt;b&gt;Note M. &lt;/b&gt;&lt;b&gt;&lt;i&gt;Major customers and derivative counterparties&lt;/i&gt;&lt;/b&gt;
   &lt;/div&gt;
   &lt;div align="justify" style="font-size: 10pt; margin-top: 10pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&lt;b&gt;&lt;i&gt;Sales to major customers. &lt;/i&gt;&lt;/b&gt;The Company&amp;#8217;s share of oil and natural gas production is sold to
   various purchasers. The Company is of the opinion that the loss of any one purchaser would not have
   a material adverse effect on the ability of the Company to sell its oil and natural gas production.
   &lt;/div&gt;
   &lt;div align="justify" style="font-size: 10pt; margin-top: 10pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;The following purchasers individually accounted for ten percent or more of the consolidated
   oil and natural gas revenues, including the revenues from discontinued operations and the results
   of commodity hedges, during the years ended December&amp;#160;31, 2010, 2009 and 2008:
   &lt;/div&gt;
   &lt;div align="center"&gt;
   &lt;table style="font-size: 9pt; text-align: left" cellspacing="0" border="0" cellpadding="0" width="98%"&gt;
   &lt;!-- Begin Table Head --&gt;
   &lt;tr valign="bottom"&gt;
       &lt;td width="64%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="3%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="1%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="3%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="3%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="1%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="3%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="5%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="3%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="1%"&gt;&amp;#160;&lt;/td&gt;
       &lt;td width="3%"&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 3px"&gt;
       &lt;td colspan="13" align="left" style="border-top: 2px solid #000000"&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 9pt" valign="bottom"&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="center" colspan="11" style="border-bottom: 1px solid #000000"&gt;&lt;b&gt;Years Ended December 31,&lt;/b&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 9pt" valign="bottom"&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="center" colspan="3"&gt;&lt;b&gt;2010&lt;/b&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="center" colspan="3"&gt;&lt;b&gt;2009&lt;/b&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="center" colspan="3"&gt;&lt;b&gt;2008&lt;/b&gt;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;!-- End Table Head --&gt;
   &lt;!-- Begin Table Body --&gt;
   &lt;tr style="font-size: 1px"&gt;
       &lt;td colspan="13" align="left" style="border-top: 1px solid #000000"&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom"&gt;&lt;!-- Blank Space --&gt;
       &lt;td&gt;
   &lt;div style="margin-left:20px; text-indent:-15px"&gt;&amp;#160;
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom" style="background: #cceeff"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:20px; text-indent:-15px"&gt;Navajo Refining Company, L.P.
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;32&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;38&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;59&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:20px; text-indent:-15px"&gt;ConocoPhillips Company
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;14&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;11&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;7&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom" style="background: #cceeff"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:20px; text-indent:-15px"&gt;DCP Midstream, LP
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;12&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;13&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;18&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom"&gt;
       &lt;td&gt;
   &lt;div style="margin-left:20px; text-indent:-15px"&gt;Plains Marketing and Transportation Inc.
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;11&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;
   &lt;div style="margin-right: 7px"&gt;-
   &lt;/div&gt;&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td nowrap="nowrap" align="right"&gt;&amp;#160;&lt;/td&gt;
       &lt;td align="right"&gt;
   &lt;div style="margin-right: 7px"&gt;-
   &lt;/div&gt;&lt;/td&gt;
       &lt;td nowrap="nowrap"&gt;%&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr valign="bottom"&gt;&lt;!-- Blank Space --&gt;
       &lt;td&gt;
   &lt;div style="margin-left:20px; text-indent:-15px"&gt;&amp;#160;
   &lt;/div&gt;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
       &lt;td&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;tr style="font-size: 1px"&gt;
       &lt;td colspan="13" align="left" style="border-top: 1px solid #000000"&gt;&amp;#160;&lt;/td&gt;
   &lt;/tr&gt;
   &lt;!-- End Table Body --&gt;
   &lt;/table&gt;
   &lt;/div&gt;
   &lt;div align="justify" style="font-size: 10pt; margin-top: 10pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;At December&amp;#160;31, 2010, the Company had receivables from Navajo Refining Company, L.P.,
   ConocoPhillips Company, DCP Midstream, LP and Plains Marketing and Transportation Inc. of $38.6
   million, $25.0&amp;#160;million, $15.7&amp;#160;million and $9.3&amp;#160;million, respectively, which are reflected in
   Accounts receivable &amp;#8212; oil and natural gas in the accompanying consolidated balance sheet.
   &lt;/div&gt;
   &lt;div align="justify" style="font-size: 10pt; margin-top: 10pt"&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&lt;b&gt;&lt;i&gt;Derivative counterparties. &lt;/i&gt;&lt;/b&gt;The Company uses credit and other financial criteria to evaluate
   the credit standing of, and to select, counterparties to its derivative instruments. The Company&amp;#8217;s
   credit facility agreements require that the senior unsecured debt ratings of the Company&amp;#8217;s
   derivative counterparties be (i)&amp;#160;not less than either A- by Standard &amp;#038; Poor&amp;#8217;s Rating Group rating
   system or A3 by Moody&amp;#8217;s Investors Service, Inc. rating system or (ii)&amp;#160;a lender to the Company&amp;#8217;s
   credit facility. At December&amp;#160;31, 2010 and 2009, the counterparties with whom the Company had
   outstanding derivative contracts met or exceeded the required ratings. Although the Company does
   not obtain collateral or otherwise secure the fair value of its derivative instruments, management
   believes the associated credit risk is mitigated by the Company&amp;#8217;s credit risk policies and
   procedures and by the credit rating requirements of the Company&amp;#8217;s credit facility agreements.
   &lt;/div&gt;
   &lt;!-- Folio --&gt;
   &lt;!-- /Folio --&gt;
   &lt;/div&gt;
   &lt;!-- PAGEBREAK --&gt;
   &lt;div style="font-family: 'Times New Roman',Times,serif"&gt;
   &lt;div align="center" style="font-size: 15pt; margin-top: 0pt"&gt;
   &lt;b&gt;
   &lt;/b&gt;
   &lt;/div&gt;
   &lt;/div&gt;
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