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Unformatted text preview: §OKM FINAL EXAM
Fall 2006 MMS
Part 1 (3 points each) PGE 424 1. A rock strongly imbibes water but does not imbibe oil. What can you say about its wettability?
What can you say about its USBM index? it ix; Water, We)“
usem Lem i4 6—) 2. What is r’ubber sleeve coring primarily used for? To recover Wick ‘ 3. The most signiﬁcant characteristic of a semipermeable plate/membrane used for capillary
pressure measurements in the porous plate method is its 4. All other factors being equal, the ratio of the average pore size for a sample with a permeability of
100 md to that for a sample with permeability 400 md would be loom :HUDwL
\ :2, Wﬂie. 5. Deﬁne the capillary number (in words or as an equation). What is the effect of capillary number
on the relative permeability curves? Nca': Vietnam 6. How does the presence of gas affect the porosity measured by neutron and density logs? (PNan 434% QW‘Mg/k 7. The formation factor measured from resistivity logs is 16. A sonic log reads the following, Atlog
= 87.5, Atf = 189 usec/ft, and Atma = 53. Is this consistent with the resistivity log? Explain. (t): w : 875—53 : 34'5" 025
Alth — Aim l8 ‘1 v s; )3!» F : V491 : \e ) QWl‘ewlT MWHWQ log. 8. List two causes of hysteresis in capillary pressure and relative permeability curves. 9. What is the origin of the measured potential in an SP log? __—>L9V\— SAW W 056 W (NO‘QWMWW) a ———» RW‘F/Rw 10. What can you say about the relative magnitude of the end point relative permeabilities to oil and
water for a waterwet sample? k; > (WW M) .V. .mamw mm wrmmwmuy immﬂ mm. 11. In a producing gas well, is the gas volumetric ﬂow rate at the wellbore less than, more than, or the
same as the volumetric ﬂow rate far from the wellbore? Provide a reason for your answer. Q3 (new WAD > Q3 (1Com {mm welD OiML to 84/) ume QTWVWW”
W B {A WHQV. 12. Write down an equation that expresses the mass balance for 1dimensional, single phase ﬂow in a porous medium at steady state.
0 = 'W
k X BX 13. What does a Gammaray log measure? What is it most commonly used for? W Nanak Yummy“ m I Gammvvuao twaWvL 561*“ wok W to WWI”. W , /
14. From a SP, dual induction log measurement it is found that [ R“ J 1/2 ( RW ) 1 2 = 1 List two possible conclusions one can arrive at based on this. v No HQ 13W (we MVWM) 15. In two phase ﬂow, which phase ﬂows better through a porous medium (the wetting or the non—
wetting phase)? Explain why. fmmw Mshrmr I I . Part 2 1. A core is cleaned, dried and saturated with brine. Brine is then ﬂowed through a completely
brine saturated core (length = 3 inches, diameter = 1 inch) at a rate of 15 cm3/min. A pressure
drop of 19 psi is observed across the core. Oil is then ﬂowed through a core with q0 = 10.6
cm3/min. The pressure drop across the core at steady state was measured to be 29.4 psi. Calculate the following:
a. The absolute (single phase) permeability of the core in md. (5 points) b. The effective and relative permeability to oil at residual water saturation. What can you say about the wettability of the core on the basis of this measurement? (5 points) 0. If there is an error of +/ 1 psi in each of the measured pressure drops and an error or
+/ 0.05 inches in the measured diameter and length what is the error in the computed permeability. How would you improve the experiment to make it more accurate? (5
points) Given: uo = 1.2 cp po = 0.8 g/cm3
uw = 1 cp pw = 1.0 g/cm3 2. A cube of rock 2 inches on the side is subjected to a compressive load of 5000 1b in the X direction and 2000 lbs in the y and 2 directions. You are given that: Young’s modulus = 2 x 106 psi, and Poisson’s ratio = 0.25.
Assume that the rock is homogeneous and isotropic. a. Calculate the strain in the x direction. Assume that the pore pressure is 14.7 psi. (5 points). b. What would the strain be if the pore pressure were raised to 2000 psi (5 points) 3. An oil reservoir consists of a sequence of sands (A, B and C). The capillary pressure curve for the three sands measured with crude oil and water is shown in Figure 1. (a) Plot the water saturation as a function of depth. Assume that the water table is at a depth of 7200 feet. The density of the brine and the oil are 62 and 52 lb/ft3 respectively (10 points) (b) There are no relative permeability data available for this sand. Using the capillary pressure curve estimate the relative permeability to oil as a function of oil saturation for Sand A (only a few points will do) (10 points). SandA(7120 to 7100’) Sand C (7200’ to 7180’) 4. Permeability measurements made on core samples taken from Sands A, B and C show that the
three layers have the following perrneabilities and net pay thicknesses. Sand Permeability (md) Thickness (feet)
A 40 30 B 100 10
C 350 10 (a) What is the equivalent permeability of the pay zone? (5 points) (b) Assuming no cross—ﬂow between layers, what fraction of ﬂow will come from the highest
permeability layer? (5 points) (no/,mnoonumwwuymeHWanaowl/VS.9311 Pb 4...: 2. “9‘: 55:13.2 ZD_F<ED&KUU ZUUNFM.D mung}. Il<mﬂ ZHBNFHZH nzunzvm .DZ Engineer's Computation Pad N0. 937 811E é) STAIEDTLER® ’f"
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