Problem 5-4 West Sparkle Material Balance [PDF]

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Problem 5-4 West Sparkle Material Balance Your asset team has selected 37.62 Bsm3 or 1,328 Bcf as the most likely value for the West Sparkle OGIP. Assume that rock compressibility is sufficiently low that rock compaction can be ignored. 1. What fraction of the OGIP can be recovered at an abandonment pressure of 1000 psia? 2. Assume that after 1.7 Bsm3 had been produced, a pressure survey indicated that the reservoir pressure was 4330 psia. What is the apparent value of OGIP? How does this compare with your volumetric estimate? What are the possible causes for any discrepancy? *West Sparkle Gas Properties During testing of the WS-2 well, a gas sample was obtained with the following composition. Initial pressure is estimated to be 4500 psia (31,000 kPa). Use a reservoir temperature of 180 F (82 C). Component N2 CO2 C1 C2 C3 i-C4 n-C4 i-C5 n-C5 C6 C7+ TOTAL



Mole Percent 0.1490 0.5970 91.4800 5.0060 1.6030 0.3470 0.3460 0.1310 0.0970 0.2440 0.0000 100.0000



Compound C1 C2 C3 i-C4 n-C4 i-C5 n-C5 C6 C7+ N2 CO2 H2S



yi 0.915 0.050 0.016 0.003 0.003 0.001 0.001 0.002 0.000 0.001 0.006 0.000 1.000



MWi 16.04 30.07 44.10 58.12 58.12 72.15 72.15 86.18 114.23 28.02 44.01 34.08 MWa = gg =



yiMWi 14.67 1.51 0.71 0.20 0.20 0.07 0.07 0.21 0.00 0.04 0.26 0.00 17.94 0.62



pci (psia) 673 709 618 530 551 482 485 434 361 227 1073 672 ppc =



Ppr @4500 6.681045157 Ppr @1000 1.484676702 Ppr @4330 6.428650117 Tpr = 1.747872834 p 4500 0



z 0.96 0



p/z 4687.5 0



Gp 0 37.62



p



z



p/z



1000



0.97



1030.93



Gp (Bsm3) 29.34247



z 0.96 0.955



p/z 4687.5 4534.03



Gp 0 1.7



z 0.96 0.955



p/z 4687.5 4534.03



Gp 0 1.227677



1. Ditanya:



Volumetrik: p 4500 4330 Actual: p 4500 4330



G fraction 78%



yipci (psia) 615.66 35.49 9.89 1.84 1.91 0.48 0.47 1.06 0.00 0.34 6.41 0.00 674



Tci, (oR) 344 550 666 733 766 830 847 915 1024 492 548 1306 Tpc =



yiTci (oR) 314.69 27.53 10.66 2.54 2.66 0.83 0.82 2.23 0.00 0.73 3.27 0.00 366



p/z vs Gp 5000 4000



p/z



3000 p/z vs Gp



2000



Linear (p/z vs Gp) y = -124.6x + 4687.5 1000



0 0



5



10



-1000



15



20



25



30



35



40



Gp (Bsm3)



p/z Vs Gp 4700 4680 4660 4640



p/z



4620 Volumetrik



4600



Actual 4580 4560 4540



4520 0



0.5



1 Gp (Bsm3)



1.5



2