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Home My WebLink About2008 Pretty CreekChevron February 23, 2009 Paul Winslow Petroleum Engineer Advisor MidContinent/Alaska SBU Mr. Dan Seamount, Chairman Alaska Oil and Gas Conservation Commission 333 W. 7th Avenue, Suite 100 Anchorage, AK 99501 Chevron North America Exploration and Production 3800 Centerpoint Dr., Ste 100 Anchorage, AK 99503 Tel (907) 263-7629 Email pwinslow@chevron.com Eg 2 2009 =ka Oil &Cas Cons. CQ�missiut� Re: Annual Material Balance Calculations of Production and Injection Volumes Pretty Creek Gas Storage Facility Pretty Creek Unit #4 Dear Commissioner Seamount: Attached for your review is the 2008 "Annual Performance Report" for the Pretty Creek Gas Storage Facility - Pretty Creek Unit #4 (PCU#4), as required by AOGCC Storage Injection Order No. 4 (SIO#4). This report contains material balance calculations of production and injection volumes from the inception of primary production, through 2008 gas storage operations. Attachment #1 is a table of monthly gas production and injection volumes for the PCU#4 well through February 22, 2009. The table includes all production and injection volumes beginning with the commencement of primary production in December 2001. Note that the January and February 2009 volumes are estimated from daily metered values. Attachment #2 is a table of calculated reservoir pressures over the life of the storage operation, with the associated cumulative gas voidage (production - injection) at the time of the pressure estimates. These pressures (divided by their respective Z -factors) are plotted versus net cumulative gas withdrawn on the standard P/Z plot in Attachment #3. Gas injection was initiated into the 51-5 sand in PCU#4 on November 15, 2005 and by July 1, 2007 the reservoir was within approximately 0.19 Bcf of being full. The 2007/2008 winter season production withdrawals, totaling 246.1 MMcf of gas, commenced in October 2007 and continued into April 2008. 2008 gas injection into the 51-5 reservoir, ran from May to September and a total of 365.7 MMcf of gas was injected back into storage. Although a relatively small amount of gas was taken out of storage in August, September, and October, the major 2008/2009 winter production commenced in mid November 2008. Due to high gas demands, production from the 51-5 reservoir in PCU#4 was continuous from November 18, 2008 to February 14, 2009. To date, approximately 580.2 MMcf of gas has been produced from the 51-5 reservoir during the 2008/2009 winter season. After being shut-in for 8 days, the PCU#4 shut-in tubing pressure (SITP) on 2/21/09 was 1,165 psig. This SITP converts to a bottomhole reservoir pressure of 1,264 psia. Attachment #3 shows the various injection and production cycles for the 51-5 reservoir. During the initial fill -up period (11/05 - 6/07), the plot shows a significant pressure deviation above the straight line path established with the primary depletion points. As the reservoir was filled, the pressure converged on the original reservoir pressure, indicating confinement of the gas storage volumes within the 51-5 sand. Since the initial fill -up, the MidContinent/Alaska SBU/Chevron North America Exploration and Production www.chevron.com Pretty Creek Gas Storage Facility 2008 Annual Performance Report Page 2 last two (2) production and one (1) injection cycles, have followed the primary depletion trend very closely. This is also a good indication that storage operations within the 51-5 reservoir have been contained. If you have any questions regarding this annual performance report, please contact Paul Winslow at your earliest convenience. Sincerely, Paul M. Winslow Petroleum Engineer Advisor Cc: Dave Whitacre Attachments Union Oil Company of California / A Chevron Company http://www.chevron.com ATTACHMENT #1 PCU #4 PRODUCTION AND INJECTION VOLUMES Total Cumulative Primary Production (51-5 and 45-0 Sands) Month Monthly Gas Prod MCF Monthly Gas Inj MCF Cum Gas Withdrawn MCF Month Monthly Gas Prod MCF Monthly Gas Inj MCF Cum Gas Withdrawn MCF December -01 80,465 80,465 January -02 195,929 - 276,394 January -06 - - 2,719,005 February -02 196,257 - 472,651 February -06 - - 2,719,005 March -02 220,869 - 693,520 March -06 - 104,423 2,614,582 April -02 165,533 - 859,053 April -06 - 163,320 2,451,262 May -02 26,375 - 885,428 May -06 - 3,281 2,447,981 June -02 31,104 - 916,532 June -06 283 - 2,448,264 July -02 10,746 - 927,278 July -06 292 - 2,448,556 August -02 - - 927,278 August -06 292 - 2,448,848 September -02 33,163 - 960,441 September -06 2,927 59,329 2,392,446 October -02 183,163 - 1,143,604 October -06 - 140,560 2,251,886 November -02 157,256 - 1,300,860 November -06 3,315 96,880 2,158,321 December -02 138,233 - 1,439,093 December -06 - 116,573 2,041,748 January -03 117,103 - 1,556,196 January -07 49,440 85,109 2,006,079 February -03 85,932 - 1,642,128 February -07 3,706 85,162 1,924,623 March -03 79,775 - 1,721,903 March -07 58,089 74,450 1,908,262 April -03 17,030 - 1,738,933 April -07 - 184,212 1,724,050 May -03 196 - 1,739,129 May -07 - 116,641 1,607,409 June -03 - - 1,739,129 June -07 - 64,573 1,542,836 July -03 25,313 - 1,764,442 July -07 - - 1,542,836 August -03 20,306 - 1,784,748 August -07 - - 1,542,836 September -03 16,087 - 1,800,835 September -07 - - 1,542,836 October -03 9,758 - 1,810,593 October -07 339 - 1,543,175 November -03 3,544 - 1,814,137 November -07 94 - 1,543,269 December -03 52,856 - 1,866,993 December -07 37,071 - 1,580,340 January -04 57,353 - 1,924,346 January -08 99,982 - 1,680,322 February -04 55,318 - 1,979,664 February -08 107,659 - 1,787,981 March -04 45,931 - 2,025,595 March -08 634 - 1,788,615 April -04 - - 2,025,595 April -08 283 - 1,788,898 May -04 56,583 - 2,082,178 May -08 - 128,809 1,660,089 June -04 70,263 - 2,152,441 June -08 - 114,230 1,545,859 July -04 21,267 - 2,173,708 July -08 - 105,813 1,440,046 August -04 74,030 - 2,247,738 August -08 290 1,636 1,438,700 September -04 41,208 - 2,288,946 September -08 9,220 15,228 1,432,692 October -04 83,626 - 2,372,572 October -08 122 - 1,432,814 November -04 80,884 - 2,453,456 November -08 73,656 - 1,506,470 December -04 71,571 - 2,525,027 December -08 201,815 - 1,708,285 January -05 62,310 - 2,587,337 January -09 211,548 - 1,919,833 February -05 54,328 - 2,641,665 February -09 83,557 - 2,003,390 March -05 55,460 - 2,697,125 March -09 2,003,390 April -05 57,247 - 2,754,372 April -09 2,003,390 May -05 53,045 - 2,807,417 May -09 2,003,390 June -05 40,800 - 2,848,217 June -09 2,003,390 July -05 40,964 - 2,889,181 July -09 2,003,390 August -05 37,981 - 2,927,162 August -09 2,003,390 September -05 8,872 - 2,936,034 September -09 2,003,390 October -05 - - 2,936,034 October -09 2,003,390 November -051 59,329 1 2,876,705 November -091 1 2,003,390 December -0511 157,700 1 2,719,005 December -091 1 1 2,003,390 w a) E E 0 U N 0- F- N E N C N D D C d Ca 0 a +f° (6 Ea 7 N U ca C O_ 0 £ u _ = L m a 2 o o a 0 L d - N a � N O Z �+ W N = E 7 Q U � c F~ - Z ac c Q N NE @ m > N a = 4 E N O E E CL o U a=Coo �?ax d C� a C m F- N E N C N 0 a D U S 3 0 n C d O_ C N n o m a a a E - u dd� a f E E E a c c ac ac c c E E o E E E E E o E v o d b C m o N d = ° N N N - N a s ° Q v 3 3 - 3 3 3 - 3 O .-- (D ` V V� V N O ry Nrr.orr(n (D (D N M M r 0 0 0 (D N N r r 0 OD O N Cl) (D 00 -- N O— a s n. a as r (n 0(0(Dr r N 0 co N OM am) V N O 0 0 '000 0 N L m0o 0 co (n co 0 m V V M (D r co" 0 WNMMNNITV N m m N C (0 w w w w m w w m 0 m 0 0 0 0 0 0 0 0 0 0 00 m m m lD 11iOLO (f7 r (D M 00 (nr;::vcv n ID M M M co co co M co M M (n O w m O. 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