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HW 13 Gas Compressibility.docx
Petr 3520
HW 13: Gas Compressibility (cg)
Assigned: Thurs, Feb 26, 2015 Name:
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cg Equations: Ideal Gas: Real Gas:
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1. Derive cg for an ideal gas.
2. Derive cg for a real gas.
3. Calculate cg for an ideal gas at p = 300 psi.
4. Calculate cg for methane (treat as a real gas) at T = 320°F and p = 1500 psi. (Read z’s from pure methane chart, calculate z/p from discrete z and p values.) Compare with cg from Excel for pure methane.
5. Calculate cg for methane (treat as a real gas) at T = 176 °F and p = 3500 psi. (Read z’s from pure methane chart or from get from Excel, calculate z/p from discrete z and p values.) Compare with cg from Excel for pure methane.
Answers: 3. cg = 0.00333 psi-1 ; 4. cg = 646.86*10-6 psi-1 (Excel: 645.8*10-6 psi-1 ); 5. Z values read from chart: cg = 243*10-6 psi-1 ; Z values read from Excel DAK: cg = 242.4*10-6 psi-1 ; (Excel: cg = 232.5*10-6 psi-1 )
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HW 14 Intro to FVFs and Units(1).docx
Petr 3520
HW 14: Intro to FVF’s and Units
Assigned: Fri, Feb 27, 2015 Name:
1. Unit conversions:
(a) How many ft3 are in one (oil field) barrel?
(b) How many gallons are in one (oil field) barrel?
(c) How many ft3 are in one MCF?
(d) What is the typical (U.S.) standard temperature (Tsc) and pressure (psc)?
(e) What is a “reservoir barrel” (RVB) of oil?
(f) What is a STB of oil?
(g) What is a RCF of gas? An SCF of gas?
(h) What is an MCF (aka MSCF) of gas?
2. Describe what happens to a unit volume (1 RCF) of gas at TR, pR (reservoir conditions) when it is brought to the surface at Tsc, psc (surface conditions).
3. Describe what happens to a unit volume (1 RVB) of oil at TR, pR (reservoir conditions) when it is brought to the surface at Tsc, psc (surface conditions).
4. Define: (a) Oil formation volume factor, Bo.
(b) Gas formation volume factor, Bg.
5. (a) Draw Bo vs. p curve. (b) Derive the equation (using oil compressibility co) that defines the Bo curve above the bubble point pb; (c) For Bob = 1.3 RVB/STB, co = 8*10-6 psi-1, and pb = 4000 psi, determine Bo at p = 4400 psi.
6. Draw: (a) Bg vs. p curve; (b) Rs vs. p curve; (c) o vs. p curve.
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