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Home My WebLink About2007 Northstar Oil Pool Annual Reservoir Performance Report Northstar Field Northstar Oil Pool January 2007 through December 2007 March, 2007 Table of Contents A. Progress of Enhanced Recovery Project B. Voidage Balance by Month of Produced Fluid and Injected Fluids C. Summary and Analysis of reservoir pressure surveys within the pool D. Results and Analysis of Production and Injection Log surveys, tracer surveys, observation well surveys and any other special monitoring. E. Review of pool production allocation factors and issues over the prior year F. Review of Annual Plan of Operations and Development and Future Development Plans G. Status of wells shut-in for 365 days or more Attachment 1: Map of well Locations Attachment 2: Northstar Field 2007 Overview Statistical Summary Attachment 3: Northstar Field 2007 Reservoir Pressure Report, Form 10-412 Attachment 4: Revised Northstar Field 2005 and 2006 Overview Statistical Summaries and Voidage Balances by Month 2 3 Progress of Enhanced Recovery Project During 2007, two additional production wells (NS34 and NS33) started drilling, but were suspended without reaching the Ivishak reservoir due to drilling problems. The locations of these wells in addition to the other Northstar wells are shown in Attachment 1. Production and injection statistics are summarized in Attachment 2. Average oil production was 38,020 bopd and average gas injection was 458.8 mmscfpd. During 2007, gas injection was greater than reservoir voidage. At year end, the reservoir had an overall cumulative voidage replacement ratio of 1.00. 4A) Voidage Balance by Month of Produced Fluid and Injected Fluids – 2007 2007 MonthOil, MRBFree Gas, MRBWater, MRBTotal Voidage, MRBYearCum, MRBCum since start-up, MRBFormation Gas, MRBImport Gas, MRBTotal Injection, MRBYearCum, MRBCum since start-up, MRBNet Injection, MRBYearCum, MRBCum since start-up, MRBJan-20073,2797,11843110,39810,398438,2759,2871,23710,52410,524437,826127127-449Feb-20071,6954,0642325,76016,157444,0355,1861,3416,52717,052444,353767894318Mar-20072,3034,4913026,79422,952450,8296,0031,0707,07324,125451,4262791,173597Apr-20073,0717,44642310,51733,469461,3469,46889310,36134,486461,787-1561,017441May-20073,0257,61147410,63644,104471,9829,61085310,46344,949472,251-172845269Jun-20072,7197,2464289,96454,069481,9469,0467049,75054,699482,000-21563054Jul-20072,6697,1974749,86763,935491,8138,9638419,80464,503491,804-63567-9Aug-20072,5987,2174879,81573,750501,6288,9366979,63374,135501,436-182385-191Sep-20072,3186,5004478,81882,568510,4468,0239148,93783,072510,373118503-73Oct-20072,4087,1414469,54892,117519,9948,7248489,57292,644519,94524527-49Nov-20072,4687,72845910,196102,313530,1909,35983710,196102,840530,1420528-48Dec-20072,5398,41848710,957113,270541,14810,09687010,966113,806541,1088536-402007 Totals31,09282,1795,092113,270102,70111,105113,806536Produced FluidsInjected FluidsNet Injection (Injection - Production) B) Summary and Analysis of reservoir pressure surveys within the pool Static bottom hole pressures collected in 2007 are summarized below. Well Date Extrapolated Pressure at -11,100' TVDss Datum, psia Data Source NS06 2/18/2007 5113 SBHP NS06 7/29/2007 5110 SBHP NS08 3/4/2007 5139 Cidra Data NS08 3/18/2007 5151 Cidra Data NS08 4/9/2007 5150 Cidra Data NS08 5/22/2007 5145 Cidra Data NS08 6/6/2007 5150 Cidra Data NS08 6/10/2007 5146 Cidra Data NS08 6/30/2007 5143 Cidra Data NS08 7/7/2007 5136 Cidra Data NS08 8/30/2007 5143 Cidra Data NS08 10/21/2007 5137 Cidra Data NS08 12/25/2007 5133 Cidra Data NS09 2/19/2007 5114 SBHP NS09 7/31/2007 5108 SBHP NS11 9/17/2007 5091 SBHP NS12 2/17/2007 5025 SBHP NS13 1/12/2007 5098 Cidra Data NS13 2/23/2007 5094 Cidra Data NS13 3/4/2007 5095 Cidra Data NS13 3/14/2007 5104 Cidra Data NS13 4/12/2007 5139 SBHP NS13 9/11/2007 5062 Cidra Data NS13 9/18/2007 5081 Cidra Data NS13 10/21/2007 5077 Cidra Data NS13 12/24/2007 5076 Cidra Data NS14A 2/17/2007 5117 Cidra Data NS14A 3/18/2007 5122 Cidra Data NS14A 4/21/2007 5122 Cidra Data NS14A 8/29/2007 5095 Cidra Data NS14A 9/18/2007 5106 Cidra Data NS14A 10/17/2007 5107 Cidra Data NS14A 11/1/2007 5105 Cidra Data NS14A 11/24/2007 5105 Cidra Data 5 6 NS16 7/3/2007 5100 SBHP NS18 7/30/2007 5097 SBHP NS21 1/18/2007 5142 Cidra Data NS21 3/4/2007 5148 Cidra Data NS21 9/18/2007 5082 Cidra Data NS21 10/21/2007 5080 Cidra Data NS24 2/15/2007 5123 SBHP NS24 7/15/2007 5120 SBHP NS28 1/23/2007 5137 Cidra Data NS28 3/28/2007 5139 Cidra Data NS28 4/8/2007 5150 Cidra Data NS28 5/13/2007 5132 Cidra Data NS28 6/4/2007 5144 Cidra Data NS28 6/17/2007 5118 Cidra Data NS28 6/30/2007 5115 Cidra Data NS28 9/10/2007 5119 Cidra Data NS28 9/18/2007 5136 Cidra Data NS28 10/22/2007 5129 Cidra Data NS28 11/3/2007 5112 Cidra Data NS28 12/30/2007 5113 Cidra Data NS30 3/5/2007 5123 Cidra Data NS30 9/18/2007 5030 Cidra Data NS30 10/21/2007 4998 Cidra Data These pressures are graphically represented in the next figure that is a plot of pressure by well versus time. These data indicate average pressures were essentially unchanged during 2007 (from 5,115 psi to 5,112 psia). A complete listing of data from these surveys is shown in Attachment 3 on the AOGCC Reservoir Pressure Report form. Northstar Well Pressure Data 500050505100515052005250Oct-01Dec-01Feb-02Apr-02Jun-02Aug-02Oct-02Dec-02Feb-03Apr-03Jun-03Aug-03Oct-03Dec-03Feb-04Apr-04Jun-04Aug-04Oct-04Dec-04Feb-05Apr-05Jun-05Aug-05Oct-05Dec-05Feb-06Apr-06Jun-06Aug-06Oct-06Dec-06Feb-07Apr-07Jun-07Aug-07Sep-07Nov-07Reservoir Pressure (at Datum 11,100' TVD), PSIANS06NS07NS08NS09NS12NS13NS14NS15NS16NS17NS18NS19NS20NS21NS22NS23NS24NS25NS27NS29NS31NS05NS28NS11NS30 7 C) Results and Analysis of Production and Injection Log surveys, tracer surveys, observation well surveys and any other special monitoring. No injection profiles and 4 production profiles were obtained in 2007. The following table summarized these as well as previous profile results. NS08Producer4/10/2007Memory S/T/P2002753NS24Producer4/11/2007Memory S/T/P5050NS19Producer4/24/2007S/T/P/Grad/Ghost/Deft982NS13*Producer7/14/2007Memory S/T/P Gradio096---* NS13's memory S/T/P 7/14/07 did not log across the entire perforation interval. 96% of the logged flow came from the C3 with 4% coming from below the logged interval. 8 A tracer study was initiated in 2004. Unique chemical tracers were injected into the six Northstar gas injection wells (NS17, NS23, NS25, NS27, NS29 and NS31) on April 12, 2004. Gas samples are taken from each producer once every two weeks. Results to date are shown in the following plots. 9 NS05 Produced Tracer00.050.10.150.20.250.30.3501002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS25Tracer Response NS23Tracer Response NS31Tracer Response NS27Tracer Response NS29 10 NS06 Produced Tracer0.0.050.10.150.20.250.30.3501002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS25Tracer Response NS27Tracer Response NS29Tracer Response NS23 11 NS07 Produced Tracer0.0.050.10.150.20.250.30.3501002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS27Tracer Response NS17Tracer Response NS23Tracer Response NS29 12 NS08 Produced Tracer0.0.20.40.60.81.1.201002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS23Tracer Response NS31Tracer Response NS27Tracer Response NS29 13 NS09 Produced Tracer0.0.10.20.30.40.50.601002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS25Tracer Response NS23Tracer Response NS31Tracer Response NS27Tracer Response NS29 14 NS11 Produced Tracer00.020.040.060.080.10.1201002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS17Tracer Response NS23Tracer Response NS25Tracer Response NS31Tracer Response NS27Tracer Response NS29 15 NS12 Produced Tracer0.0.020.040.060.080.10.120.1401002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS25Tracer Response NS31Tracer Response NS27Tracer Response NS29Tracer Response NS17 16 NS13 Produced Tracer0.0.20.40.60.81.1.21.41.61.82.01002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS23Tracer Response NS17Tracer Response NS31Tracer Response NS27Tracer Response NS29Tracer Response NS25 17 NS14 Produced Tracer0.0.10.20.30.40.50.60.70.80.91.01002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS23Tracer Response NS29 18 NS14A Produced Tracer00.050.10.150.20.250.30.3501002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS25Tracer Response NS23Tracer Response NS29Tracer Response NS31Tracer Response NS27 19 NS15 Produced Tracer00.10.20.30.40.50.601002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS25Tracer Response NS23Tracer Response NS17Tracer Response NS27Tracer Response NS29Tracer Response NS31 20 NS16 Produced Tracer0.0.10.20.30.40.50.60.70.80.91.01002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS23Tracer Response NS29 21 NS18 Produced Tracer0.0.10.20.30.40.50.601002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS17Tracer Response NS27Tracer Response NS29Tracer Response NS23 22 NS19 Produced Tracer0.0.020.040.060.080.10.120.140.160.1801002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS25Tracer Response NS23Tracer Response NS31Tracer Response NS27Tracer Response NS29Tracer Response NS17 23 NS20 Produced Tracer00.050.10.150.20.2501002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS23Tracer Response NS17Tracer Response NS27Tracer Response NS29 24 NS21 Produced Tracer00.020.040.060.080.10.1201002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS29Tracer Response NS17 25 NS22 Produced Tracer0.0.050.10.150.20.2501002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS31Tracer Response NS27Tracer Response NS29Tracer Response NS17Tracer Response NS23Tracer Response NS25 26 NS24 Produced Tracer0.0.10.20.30.40.50.60.70.80.91.01002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS23Tracer Response NS31Tracer Response NS29 27 NS28 Produced Tracer00.050.10.150.20.250.30.350.40.450.501002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS27Tracer Response NS29Tracer Response NS25 28 NS30 Produced Tracer00.020.040.060.080.10.1201002003004005006007008009001000110012001300Days After Injectionconcentration (pm)Tracer Response NS25Tracer Response NS27Tracer Response NS29 29 D) Review of pool production allocation factors and issues over the prior year Theoretical production is calculated for each Northstar producing well on a daily basis. A well’s theoretical production is calculated using average wellhead flowing pressure and hours on production as follows: ltheoreticaaof n whsi whfproduced QQP Phours =×⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛ ⎟⎟ ⎠ ⎞ ⎜⎜ ⎝ ⎛−× 124 Where: hoursproduced = hours on line Pwhf = average wellhead flowing pressure Pwhsi = shut-in wellhead pressure n = flow exponent Qaof = absolute open flow of well with Pwhf = 0 psi Qtheoretical = theoretical production The input parameters (n, Qaof and Pwhsi ) for each well are determined from well test data and systems analysis and are reviewed each time new test data becomes available. The actual total production for a day is divided by the summation of the theoretical production from each well to calculate a daily allocation factor. This allocation factor is then multiplied by each well’s theoretical production to calculate allocated production. Allocation factors for 2007 had an average value of 1.12 30 31 E) Review of Annual Plan of Operations and Development and Future Development Plans Northstar concluded 2007 with six injection wells, nineteen producing wells and two Class I disposal wells on line. During 2007, NS33 and NS34 were suspended without reaching the Ivishak formation. Historical well count is summarized in the following table. Northstar - Year End Wells Year Count Producers Injectors Class I Disposal 1 NS07 NS27 NS10 2 NS08 NS29 3 NS09 NS31 4 NS13 5 NS14 2002 6 NS15 1 NS07 NS27 NS10 2 NS08 NS29 3 NS09 NS31 4 NS13 NS17 5 NS14 NS23 6 NS15 7 NS24 8 NS18 9 NS22 10 NS06 11 NS12 12 NS19 2003 13 NS20 1 NS07 NS27 NS10 2 NS08 NS29 NS32 3 NS09 NS31 4 NS13 NS17 5 NS14 NS23 6 NS15 NS25 7 NS24 8 NS18 9 NS22 10 NS06 11 NS12 12 NS19 13 NS20 14 NS16 2004 15 NS21 32 Northstar - Year End Wells Year Count Producers Injectors Class I Disposal 1 NS05 NS17 NS10 2 NS06 NS23 NS32 3 NS07 NS25 4 NS08 NS27 5 NS09 NS29 6 NS12 NS31 7 NS13 8 NS14 9 NS15 10 NS16 11 NS18 12 NS19 13 NS20 14 NS21 15 NS22 16 NS24 2005 17 NS28 1 NS05 NS17 NS10 2 NS06 NS23 NS32 3 NS07 NS25 4 NS08 NS27 5 NS09 NS29 6 NS11 NS31 7 NS12 8 NS13 9 NS14A 10 NS15 11 NS16 12 NS18 13 NS19 14 NS20 15 NS21 16 NS22 17 NS24 18 NS28 2006 19 NS30 1 NS05 NS17 NS10 2 NS06 NS23 NS32 3 NS07 NS25 4 NS08 NS27 5 NS09 NS29 6 NS11 NS31 7 NS12 8 NS13 9 NS14A 10 NS15 11 NS16 2007 12 NS18 33 Northstar - Year End Wells Year Count Producers Injectors Class I Disposal 13 NS19 14 NS20 15 NS21 16 NS22 17 NS24 18 NS28 19 NS30 MMS Wells in Bold Future Development Plans We recognize the possibility that satellite hydrocarbon accumulations may exist within expected drilling reach from the island. These targets will be the subject of additional appraisal. Infill wells and or sidetracks to optimize recovery from the Northstar pool are also possible. As of March 2008, drilling is ongoing on the infill-well sidetrack NS16A. It is also planned to resume drilling well NS-34, targeting a location outside the Northstar PA. It is anticipated to complete both wells this drilling season. F) Status of Wells Shut-in for 365 days or More (20 AAC 25.115) No Northstar wells were shut-in for 365 days or more during 2006. Sw Name Date Shut- In Re ason for Well Shut-In1 Current Mechanical Condition of We l l2 Future Utility Plans & Possibilities3 C omme n t s Northstar Shut-In Wells 2007 34 Attachment 1: MAP OF NORTHSTAR WELL LOCATIONS 35 Well Status 12/31/07 Bottomhole Locations Abandoned Disposal Well Gas Injector Not Complete Oil Producer Sidetracked Well Ivishak Boundary Lease Boundary Unit Boundary Township / Range Boundary Northstar Well Status for AOGCC Annual Performance Report E. M. Fueg 3/5/08 Projection Information Alaska State Plane Zone 4 Clarke 1866, NAD 1927R13ER12E R14E14E14N T13N R13ERT R13ER12ER13ER13ER14E ADL312799 Y0179 ADL312808 ADL312798 Y1645 Y0181 NS14NS15 NS13 NS26 NS33 NS05 NS06 NS07 NS08 NS09 NS10 NS11 NS12NS14A NS16 NS18 NS19 NS20 NS21 NS22 NS24 NS27 NS28 NS30 NS31 NS32 NS34 ADL312809 NS17 NS23 NS25 NS29 bp LEGEND T R A N S - A L A S K A PIP E LIN E 32 MILES 10 36 2007 Attachment 2 (12/31/07)Full year (1)As of 12/07 (2) Producers 19 18 Injectors 8 8 I P I NORTHSTAR FIELD 2007 OVERVIEW STATISTICAL SUMMARY WELL STATISTICS PRODUCTION/INJECTION STATISTICS P NOTES: (1) W ell count data reflects ONLY those wells which contributed to production/injection during the respective year (2) Active wells as of December 2007 2007 Cumulative Start-Up through 12/31/07 13,877,273 122,390,552 151,144,906 661,014,986 4,835,708 18,177,850 5,216,275 20,566,040 167,475,933 798,116,276 113,270 541,148 113,806 541,108 536 -40 38,020 414,096 13,249 14,291 458,838 5113 psiaAverage of surveys obtained in 2007 Oil, BOPD Gas, MCF/D W ater, BW PD W ater, BW PD Gas, MCFPD njection Balance AVERAGE RESERVOIR PRESSURE DAILY AVERAGE RATE DATA 2007 roduction Cum Production (MRB) Cum Injection (MRB) Over/Under (MRB) Gas (MCF) W ater (BBL) njection W ater (BBL) into NS10 & NS32Disposal W ell Gas (MCF) Oil (BBL) roduction Attachment 3: Reservoir Pressure Report 6. Oil Gravity:428. Well Name and Number:9. API Number 50-XXX-XXXXX-XX-XX10. Oil (O) or Gas (G)11. AOGCC Pool Code12. Final Test Date13. Shut-In Time, Hours14. Press. Surv. Type (see instructions for codes)15. B.H. Temp.16. Depth Tool TVDss17. Final Observed Pressure at Tool Depth18. Datum TVDss (input)19. Pressure Gradient, psi/ft.20. Pressure at Datum (cal)NS0850-029-23068-00-00O5901003/4/20079126OTHER19988344810111000.1395124NS0850-029-23068-00-00O5901003/18/2007286OTHER19988344822111000.1395136NS1350-029-23017-00-00O5901002/23/20078910OTHER245103904989111000.1265079NS1350-029-23017-00-00O5901001/12/200756OTHER244103904994111000.1265084NS1350-029-23017-00-00O5901003/4/2007217OTHER244103904990111000.1265080NS14A50-029-23026-01-00O5901002/17/200719OTHER250105565041111000.1125102NS14A50-029-23026-01-00O5901003/18/2007254OTHER249105565046111000.1125107NS2150-029-23126-00-00O5901003/4/2007366OTHER246105765015111000.2275134NS2150-029-23126-00-00O5901001/18/200730OTHER255105764907111000.4205127NS2850-029-23248-00-00O5901001/23/2007436OTHER245104805045111000.1245122NS2850-029-23248-00-00O5901003/28/20071220OTHER244104805047111000.1245124NS30 50-029-23293-00-00O5901003/5/2007404OTHER251104994972111000.2275109NS2450-029-23111-00-00O5901002/15/2007212SBHP251110485096111000.2275108NS1250-029-23091-00-00O5901002/17/20072SBHP250110374996111000.2275011NS0650-029-23088-00-00O5901002/18/200726SBHP251109765070111000.2275098NS0950-029-23052-00-00O5901002/19/200798SBHP251109885074111000.2275100NS1350-029-23017-00-00O5901003/14/2007181OTHER243103904999111000.1265089NS0850-029-23068-00-00O5901004/9/200797OTHER20088344821111000.1395135NS0850-029-23068-00-00O5901005/22/2007183OTHER20088344816111000.1395130NS0850-029-23068-00-00O5901006/6/2007154OTHER20288344821111000.1395135NS0850-029-23068-00-00O5901006/10/2007252OTHER20088344817111000.1395131NS0850-029-23068-00-00O5901006/30/200741OTHER20988344815111000.1395129NS1350-029-23017-00-00O5901004/12/20071320SBHP253110505113111000.2275125NS14A50-029-23026-01-00O5901004/21/200720OTHER252105565046111000.1125107NS2850-029-23248-00-00O5901004/8/2007170OTHER245104805058111000.1245135NS2850-029-23248-00-00O5901005/13/20071009OTHER244104805040111000.1245117NS2850-029-23248-00-00O5901006/4/200740OTHER246104805052111000.1245129NS2850-029-23248-00-00O5901006/17/2007369OTHER243104805026111000.1245103STATE OF ALASKAALASKA OIL AND GAS CONSERVATION COMMISSIONRESERVOIR PRESSURE REPORT1. Operator:2. Address:BP Exploration (Alaska) Inc.P.O. Box 196612, Anchorage, Alaska 99519-66127. Gas Gravity:Northstar UnitNorthstar Field / Northstar Oil Pool-11,1000.793. Unit or Lease Name:4. Field and Pool:5. Datum Reference: 37 8. Well Name and Number:9. API Number 50-XXX-XXXXX-XX-XX10. Oil (O) or Gas (G)11. AOGCC Pool Code12. Final Test Date13. Shut-In Time, Hours14. Press. Surv. Type (see instructions for codes)15. B.H. Temp.16. Depth Tool TVDss17. Final Observed Pressure at Tool Depth18. Datum TVDss (input)19. Pressure Gradient, psi/ft.20. Pressure at Datum (cal)NS2850-029-23248-00-00O5901006/30/2007263OTHER244104805023111000.1245100NS1650-029-23096-00-00O5901007/3/200732SBHP255110295074111000.1555085NS0850-029-23068-00-00O5901007/7/2007202OTHER21988344807111000.1395121NS2450-029-23111-00-00O5901007/15/20071206SBHP255110305093111000.1715105NS0650-029-23088-00-00O5901007/29/2007203SBHP256109645075111000.1475095NS1850-029-23102-00-00O5901007/30/200799SBHP255110005066111000.1605082NS0950-029-23052-00-00O5901007/31/200738SBHP255109995081111000.1195093NS14A50-029-23026-01-00O5901008/29/2007541OTHER253105565019111000.1125080NS0850-029-23068-00-00O5901008/30/2007198OTHER20188344814111000.1395128NS2850-029-23248-00-00O5901009/10/20071469OTHER245104805027111000.1245104NS1350-029-23017-00-00O5901009/11/200727OTHER226103904957111000.1275047NS1150-029-23303-00-00O5901009/17/200733SBHP259110505055111000.4205076NS14A50-029-23026-01-00O5901009/18/200747OTHER249105565030111000.1125091NS1350-029-23017-00-00O5901009/18/200750OTHER229103904976111000.1275066NS30 50-029-23293-00-00O5901009/18/200759OTHER249104994879111000.2265015NS2150-029-23126-00-00O5901009/18/200760OTHER252105764948111000.2275067NS2850-029-23248-00-00O5901009/18/2007181OTHER246104805044111000.1245121NS14A50-029-23026-01-00O59010010/17/2007426OTHER249105565031111000.1125092NS2150-029-23126-00-00O59010010/21/200748OTHER248105764946111000.2275065NS0850-029-23068-00-00O59010010/21/200767OTHER21288344808111000.1395122NS1350-029-23017-00-00O59010010/21/200771OTHER231103904972111000.1275062NS30 50-029-23293-00-00O59010010/21/200757OTHER243104994847111000.2264983NS2850-029-23248-00-00O59010010/22/2007721OTHER250104805037111000.1245114NS14A50-029-23026-01-00O59010011/1/200762OTHER248105565029111000.1125090NS2850-029-23248-00-00O59010011/3/2007225OTHER250104805020111000.1245097NS14A50-029-23026-01-00O59010011/24/2007366OTHER248105565029111000.1125090NS1350-029-23017-00-00O59010012/24/2007107OTHER226103904971111000.1275061NS0850-029-23068-00-00O59010012/25/2007132OTHER20088344804111000.1395118NS2850-029-23248-00-00O59010012/30/20071255OTHER250104805021111000.1245098Comments: Surveys indicated as "OTHER" were obtained from Cidra data.Robert O. Younger21. All tests reported herein were made in accordance with the applicable rules, regulations and instructions of the Alaska Oil and Gas Conservation Commission.I hereby certify that the foregoing is true and correct to the best of my knowledge.SignaturePrinted NameTitleDateBPXA Northstar Production Engineer 38 Attachment 4: Revised Northstar Field 2005 and 2006 Overview Statistical Summaries and Voidage Balances by Month Changes to the voidage calculation for years 2005-2006 have also changed the Overview Statistical Summaries filed with past Annual Reports. Updated Corrected Statistical Summaries for 2005-2006 follow. 2005 (12/31/05)Full year (1)As of 12/05 (2) Producers 17 16 Injectors 8 7 2005 Cumulative: Start-Up through 12/31/05 22,421,483 89,636,187 142,131,405 367,677,560 4,361,019 8,231,854 4,634,231 9,894,642 165,712,093 466,574,682 113,590 316,886 112,549 315,811 -1,041 -1,075 61,429 11,948 389,401 12,697 454,006 5,115 Oil (BBL) Production NOTES: (1) W ell count data reflects ONLY those wells which contributed to production/injection during the respective year (2) Active wells as of December 2005 W ater (BBL) into NS10 & NS32Disposal W ell Gas (MCF) NORTHSTAR FIELD 2005 OVERVIEW STATISTICAL SUMMARY WELL STATISTICS PRODUCTION/INJECTION STATISTICS Gas (MCF) W ater (BBL) Injection Balance AVERAGE RESERVOIR PRESSURE DAILY AVERAGE RATE DATA 2005 Production Cum Production (MRB) Cum Injection (MRB) Over/Under (MRB) Average of surveys obtained in 2005, psia Oil, BOPD Gas, MCF/D W ater, BW PD W ater, BW PD Gas, MCFPD Injection 39 40 2006 (12/31/06)Full year (1)As of 12/06 (2) Producers 19 19 Injectors 8 8 Aver Oi Ga W a W a Ga In Bala AVER DA Prod Cum Cum Over Ga W at In W at Ga NORTHSTAR FIELD 2006 OVERVIEW STATISTICAL SUMMARY WELL STATISTICS PRODUCTION/INJECTION STATISTICS Oil ( Prod NOTES: (1) W ell count data reflects ONLY those wells which contributed to production/injection during the respective year (2) Active wells as of December 2006 2006 Cumulative: Start-Up through 12/31/06 18,877,092 108,513,279 142,192,520 509,870,080 5,110,288 13,342,142 5,455,123 15,349,765 164,065,661 630,640,343 110,991 427,877 111,490 427,301 499 -576 51,718 389,569 14,001 14,946 449,495 5,107age of surveys obtained in 2006, psia l, BOPD s, MCF/D ter, BW PD ter, BW PD s, MCFPD jection nce AGE RESERVOIR PRESSURE ILY AVERAGE RATE DATA 2006 uction Production (MRB) Injection (MRB) /Under (MRB) s (MCF) er (BBL) jection er (BBL) into NS10 & NS32Disposal W ell s (MCF) BBL) uction Voidage Balance by Month of Produced Fluid and Injected Fluids – 2005 MonthOil, MRBFree Gas, MRBWater, MRBTotal Voidage, MRBYearCum, MRBCum since start-up, MRBFormation Gas, MRBImport Gas, MRBTotal Injection, MRBYearCum, MRBCum since start-up, MRBNet Injection, MRBYearCum, MRBCum since start-up, MRBJan-20054,7254,8063739,5319,531212,8277,9148428,7568,756212,018-775-775-809Feb-20053,9804,5893538,56918,100221,3967,2121,2088,42117,177220,439-148-923-957Mar-20054,8266,88440111,70929,809233,10610,07969410,77327,950231,212-936-1,860-1,894Apr-20054,3004,6163648,91638,725242,0217,4581,6049,06237,012240,274147-1,713-1,747May-20054,7174,7564359,47248,197251,4947,8691,7519,62046,632249,894147-1,566-1,600Jun-20054,0474,6243958,67156,869260,1657,3031,3898,69255,324258,58621-1,545-1,579Jul-20054,2285,1354009,36366,232269,5287,9331,5349,46764,791268,054105-1,440-1,474Aug-20053,9985,2263929,22475,456278,7527,8731,4969,36974,160277,422145-1,296-1,330Sep-20053,2834,2723117,55583,010286,3076,4401,3727,81281,972285,234257-1,039-1,073Oct-20054,2655,82741810,09293,103296,3998,6431,36610,00991,981295,243-84-1,122-1,156Nov-20054,0366,46136610,497103,600306,8969,1141,52110,634102,615305,877138-985-1,019Dec-20053,8206,1703839,990113,590316,8868,6761,2579,934112,549315,811-56-1,041-1,0752005 Totals50,22463,3664,592113,59096,51416,035112,549-1,041Net Injection (Injection - Production)Produced FluidsInjected Fluids 41 Voidage Balance by Month of Produced Fluid and Injected Fluids – 2006 MonthOil, MRBFree Gas, MRBWater, MRBTotal Voidage, MRBYearCum, MRBCum since start-up, MRBFormation Gas, MRBImport Gas, MRBTotal Injection, MRBYearCum, MRBCum since start-up, MRBNet Injection, MRBYearCum, MRBCum since start-up, MRBJan-20063,4315,1583838,5898,589325,4757,4178948,3108,310324,121-279-279-1,354Feb-20063,2445,6483458,89217,481334,3677,7891,1938,98217,292333,10390-189-1,264Mar-20063,6967,28838910,98528,466345,3529,7311,32411,05628,348344,15971-118-1,193Apr-20063,8166,54144410,35838,823355,7099,0641,39910,46338,811354,622105-13-1,088May-20063,7174,7984618,51547,338364,2247,2391,0668,30647,116362,927-209-222-1,297Jun-20063,7784,1355477,91355,251372,1376,6311,1647,79454,910370,721-119-341-1,416Jul-20063,5715,2904938,86164,112380,9987,6481,3739,02063,931379,742159-182-1,257Aug-20063,8905,8315279,72173,833390,7198,4061,4259,83073,761389,572110-72-1,147Sep-20063,5785,7864939,36483,197400,0838,1551,2719,42683,187398,99862-10-1,085Oct-20063,5156,0464789,56192,758409,6448,3701,2099,57992,767408,578188-1,067Nov-20062,9375,7144068,650101,409418,2957,6531,3088,961101,728417,539311319-756Dec-20063,1506,4334169,583110,991427,8778,5121,2519,763111,490427,301180499-5762006 Totals42,32268,6695,381110,99196,61514,875111,490499Produced FluidsInjected FluidsNet Injection (Injection - Production) 42