Session: Name: PETROLEUM ENGINEERING 310 FIRST EXAM September 22, 2000 Do all your work on the test paper and the space provided for the answer, do no write on the back. Grading will be based on approach and answers. Remember to show all your work!!!! Answers with no evidence of calculations where they are required will not be graded. The point value of each question or problem is given in parentheses after the question or problem statement. Do not fold or un staple the examination booklet. Time allotted for the test is 120 minutes. This examination is closed book, closed notes, and closed mouth. Only interpretation questions to the instructor are allowed. Statement When you have finished the exam. Read and sign the statement below, then return in the examination booklet. I pledge that I have neither given nor received aid in completing this exam. I have followed the strictures of the Texas A&M University Aggie Code of honor during this exam. Signature: 1/13
2 1. Explain the process of ionic bonding and give one example of ionic bonding. (5) 2. Write down the molecular structure of each one of the following compounds (5) 2-methylheptane 2-methyl 1- pentene 3,3 dimethyl 1-pentyne Ethylcyclohexane Methylbenzene 2 of 13
3 3. Describe the homologous series alkanes. Items of interest are: distinguishing feature of molecules of the family, general formula other names for the family, physical and chemical properties of the family (5). 4. Describe the cause of "sour crude (3) 5. Sketch and explain the API trend versus time for the five reservoir fluids. (5) 3 of 13
4 6. List the rules of thumb by which a volatile oil can be identified from production data. (5) 7. Define Cricondenbar and Cricondentherm and ubble Point. (2) 8. Using the COX chart in the following page determine the following properties for propane. Indicate the points in the diagram as well. a. Saturation pressure for propane at 100 o F 4 of 13
5 Psat = psia b. Critical point Pc psia Tc= o F c. State (liquid, gas or two-phase) of propane at 50 o F and 150 psia and at 60 psia and 50 o F (5) 5 of 13
6 6 of 13
7 9. Using the following graph, which shows phase equilibrium data for methane and normal butane (C1 /n-c4) at 220 o F, indicate the following: (a) ubble point pressure for a mixture of 20% C1 (2.5) (b) Approximate critical pressure and composition (2.5) (c) Dew point pressure for a mixture of 30% C1 (2.5) (d) Retrograde composition range if any (2.5) (e) Equilibrium gas and liquid compositions and fraction of vapor for a mixture of 30% C1 at 600 psia. (5) 1600 PRESSURE-COMPOSITION DIAGRAM AT 220 F FOR A C1/n-C4 MIXTURE 1400 1200 Pressure, psia 1000 800 600 400 200 0 0 10 20 30 40 50 60 70 80 Methane, %mol 7 of 13
8 10. Given the following ternary phase diagram for mixtures of methane, n-butane and n-decane at 180 o F and 2000 psia, answer the following questions. (a) Mark on the diagram a mixture of 20% methane, 30% n-butane and 50% n-decane (3) (b) Estimate the overall composition and the composition of equilibrium liquid and gas if 100 moles of the mixture from part (a) are mixed with 60 moles of pure C1 and brought to equilibrium at 180 o F and 2000 psia. (7) Overall (zi) % C 1 % n-c 4 % n-c 10 Gas % C 1 Liquid % C 1 % n-c 4 % n-c 4 % n-c 10 % n-c 10 8 of 13
9 (c) Calculate the molar fraction of the mixture described in part (b) that is gas. (5) Gas = % (d) maximum number of moles of C1 that can be mixed with 100 moles of the mixture in part (a) and still be fully miscible (single liquid phase) (5) 9 of 13
10 Mixture C1 / nc4 / nc10 @ p=2000 psia, T=180 F 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 10 of 13
11 11. Assume the following gas mixture behaves like an ideal gas. Evaluate the mass and specific gravity of the gas mixture contained in a 1.5 ft 3 tank at 100 o F and 200 psia. Show intermediate calculations. (15) Composition Component (mole fraction) methane (C 1 ) 0.85 ethane (C 2 ) 0.10 propane (C 3 ) 0.05 1.00 Mw (lb/lbmol) = Density (lb/ft 3 ) = Mass (lb)= Specific Gravity = Useful Information Species Molecular Weight (lb/lb mol) Gas Constant Air 29 R = 10.732 psia ft 3 /lbmol o R Methane 16.043 Ethane 30.070 Propane 44.097 11 of 13
12 12. You want to apply your knowledge from PETE 310 to evaluate the percentage of liquid propane in your lighter. The following information is available: Temperature = 75 o F Liquid density of propane = 28.32 lb/ft 3 Volume of chamber in lighter = 2.12 X 10-04 ft 3 Mass of fuel charged in the lighter = 3 X 10-03 lb Hint: Use the COX charts and the ideal gas equation and write down your answers in the table provided. (15) Mass of Gas Mass of Liquid Total Mass (check) lb lb lb Volume of Gas ft 3 Volume of Liquid ft 3 Total Volume (check) ft 3 Volume Percent of liquid Pressure inside the lighter psia 12 of 13
13 13 of 13