Page 513 - Petrophysics

PROBLEMS 481

S,, = 0.24
r, = 745 ft
@ = 16%
p = 4.2 CP

If the well drains 40 acres:

a. Calculate ideal flow rate from this well if pressure gradient in the
well location area is 0.45 psi/ft.
b. From production optimization studies, it was realized that the
well could have been completed with larger wellbore diameter
to produce at rate 134% of the rate from step (a). Determine the
diameter.
c. How long will oil take to reach the wellbore from the external
boundary of 745 ft?
d. After some time, a pressure buildup test indicated a skin of +2.5,
skin zone of 8 ft, and permeability of the damaged zone 125 mD.
A fraction of reservoir periphery is open to water encroachment.
If the bottomhole pressure is 2,000 psia, reservoir pressure
2,510 psia, and well flow rate 250 STB/D, calculate drainage
boundary index and drawdown to produce 500 STB/D.

7. A newly discovered TDM #4 is completed in a sandstone oil reservoir
at a depth of 11,324 ft with 7-in. production casing and drains
80 acres. After thorough economic feasibility evaluation of the
project, it is decided to develop the field with 14 wells. The net
production from the field is expected to be 24,500 STB/D (1,750
STB/D-well). Following are the rock and fluid data from the well:

Pi = 8,000 psia

Bo = 1.13 REijSTB
cti = 2.5 x psi-'
h=55ft

K=33mD
r, = 0.58 ft
p = 3.5 CP
@= 17%

a. Estimate the time to reach the bottomhole pressure equal to
bubble point pressure of 2,000 psia.