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Unformatted text preview: 1 PGE 312 Physical and Chemical Behavior of Fluids Home Work 9 Solutions Problem 91 Solution: A plot of the given data reveals that the pressure and producing gasoil ratio change slope at a pressure of 1980psia against the cumulative oil production. Therefore, the bubble point pressure is 1980psia which is close to 1932.4psia (lab data). We also know that producing gas oil ratio at the bubble point is the solution gas oil ratio. But, since the stock tank is vented we add the stock tank gas oil ratio correction from Fig. 9.3. Separator pressure = 100psig = 114.7psia Stock tank oil gravity = 46.0 o API Separator gas gravity = 0.788 Separator temperature = 67 o F Using the above values the stock tank gas oil ratio adjustment from Fig 9.3 is obtained as 100scf/STB The constant producing gas oil ratio above bubble point is the solution gas ratio at and above bubble point. The effect of venting out the stock tank gas should also be accounted. Adding we get solution gas oil ratio at bubble point as 500+100 =600 close to 623scf/STB (lab data) 2 Error % in p b = 1980 1934.2 1934.2 100 = 2.37% Error % in R s = 600 623 623 100 = 3.69% Problem 112 Given: Solution gasoil ratio = 589 ??? ? Specific Gravity = 0.95 API Gravity = 39.0 o API Temperature = 250 o F Solution: Using the above information in Fig. 111, we get bubble point pressure p b = 2050psia Problem 114 Given: Specific Gravity = 0.95 API Gravity = 39.0 o API Temperature = 250 o F Solution: Using Fig.111, we can get the solution gasoil ratio for different pressures. The values are tabulated below. Pressure, p psia Solution gas oil Ratio R s 1950 540 1800 490 1650 440 1500 395 1350 355 1200 310 3 1050 265 900 220 750 175 600 132 450 94 300 62 150  Problem 117 Given: Bubble point pressure, p b = 3385psia Temperature = 205 o F Specific gravity of heptanes plus o = 0.85 = 53.04 ?? ?? . ? Solution: We use a first trial value of 43.70lb/cu.ft, which corresponds to 0.70g/cc. The apparent liquid density of methane = 0.32g/cc (19.98 lb/cu.ft) and apparent liquid density of ethane = 0.47g/cc (29.34 lb/cu.ft) Component Composition mole fraction x j Molecular weight, lb /lb mole M j Mass, lb x j M j Liquid Density 60 o F & 14.7 psia lb/cu.ft oj Liquid Volume 60 o F & 14.7 psia cu.ft x j M j / oj methane 0.4642 16.043 7.4472 19.98 0.3727 ethane 0.0637 30.070 1.9155 29.34 0.0653 propane 0.0561 44.097 2.4738 31.62 0.0782 ibutane 0.0119 58.123 0.6917 35.11 0.0197 nbutane 0.0383 58.123 2.2261 36.42 0.0611 ipentane 0.0168 72.150 1.2121 38.96 0.0311 npentane 0.0195 72.150 1.4069 39.36 0.0357 Hexanes 0.0285 86.177 2.4560 41.40 0.0593 Heptanes plus 0.3010 202.000 60.8020 53.04 1.1463 1.0000 80.6313 lb 1.8696 cu.ft The first calculated value of pseudoliquid density = 80.6313 1.8696 = 43.12 ??...
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 Fall '08
 Peters

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