COPYRIGHT. Thickness of sand filter bed = 4 ft [1.22m]

Transcription

1 Problem 1 In a city water filtration plant, it was desired to filter 5,500 gallons of water per hour through a sand filter bed to remove suspended matters and solids from the water. The following data is available: Thickness of sand filter bed = 4 ft [1.22m] Cross-sectional area of pit = 1,980 ft 2 [184 m 2 ] Viscosity of water = 1 cp [0.001 Pa.s] Atmospheric pressure = 0 psig [0 kpag] Height of water above the filter = 7 ft [2.134 m] Determine the required filter bed permeability. 1

2 Problem 2 Gas flows through a core sample, 2 long [5.08 cm] and with 2 [5.08 cm] diameter at a rate of 1 SCF/hr [0.028 M 3 /hr]. The inlet pressure is 1,000 psia [6,895 kpa] and the outlet pressure is 14.7 psia [101 kpa]. The average viscosity and z factor are cp [ Pa.s] and 0.92 respectively. Assume the temperature is 80 F [26.7 C]. Calculate the permeability of the sample. 2

3 Problem 3 A well is producing at a rate of 300 bbl/day [47.7 m 3 /day]. pe is equal to 4,500 psia [31,026 kpa] and pwf is equal to 2,800 psia [19,305 kpa]. What is the value of productivity index? If the thickness is 40 feet [12.2 m], rw is 0.4 feet [0.122m], re is 1,000 feet [304.9 m], m is 0.5 cp [ Pa.s], what is the estimated value of permeability for the reservoir? 3

4 Problem 4 A gas well is producing from a dry gas reservoir. The reservoir pressure is 2,000 psia [13,790 kpa]; the permeability is 0.2 md, the thickness is 120 feet [36.6 m] and the wellbore radius is 0.4 feet [0.122 m]. Because of the surrounding wells, there is some uncertainty as to the drainage radius of the well. The estimate place the value between as low as 900 feet [274 m] to as much as 2,000 feet [610 m]. The reservoir temperature is 160 o F [71.4 o C], average viscosity is cp [ Pa.s], and the z factor is Calculate the inflow performance curve by using both the drainage radii. Do you see a large difference between the two? Why? 4

5 Problem 5 A well is producing from a circular reservoir at a rate of 180 STB/day [28.6 Sm 3 /day]. The average pressure is estimated to be 2,100 psia [14,479 kpa] and the p wf is 800 psia [5,516 kp]. Calculate the productivity index. If the reservoir has a thickness of 18 feet [5.49 m], viscosity of oil is 0.6 cp is [ Pa.s] and B o is 1.25 bbl/stb [1.25 m 3 /Sm 3 ], what is the estimated permeability? Assume that llll rr ee rr ww 3/4 7. If another well in the same field is drilled with an estimated thickness of 25 feet [7.62 m]\(assume that permeability does not change significantly), generate the IPR curve for a new well. Assume the reservoir pressure to be the same. Plot the IPR curve if the reservoir pressure declines to 1,800 psia [12,411 kpa]. 5

6 Problem 6 A gas well is producing from a reservoir with initial reservoir pressure of 7,000 psia [48,263 kpa] and bottom hole pressure of 2,100 psia [14,479 kpa]. The permeability is 1.0 md, h is 100 feet [30.49 m], r e is 2,000 feet [609.8 m], and r w is 0.5 feet [0.152 m]. The reservoir temperature is 230 F [110.3 C]. The gas gravity is 0.7. The porosity is Viscosity is cp [ Pa.s] and compressibility is 7.18x10-5 psi -1 [1.04x10-5 kpa -1 ].. Calculate the time required to reach pseudo-steady state. Calculate the rate at which the well will produce at different times until it reaches pseudo-steady state. Assume that the average reservoir pressure is reduced to 6,850 psia [47,229 kpa] at the beginning of pseudo-steady state period. Calculate the rate at the beginning of pseudo-steady state period and compare it to the end of transient period. What do you observe? Generate an IPR curve under pseudo-steady conditions for reservoir pressures of 6,850 psia [47,229 kpa], 5,000 psia [34,474] and 4,000 psia [27,579 kpa]. Use m(p) method. See table on next page. 6

7 p (psia) m(p), Psi2/cp p, kpa m(p), kpa2/pa.s E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+13 7