Page 261 - Introduction to Petroleum Engineering
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248 TRANSIENT WELL TESTING
Pressure Buildup Test
Production time (t ) 24.0 hr
F
Initial pressure (p ) 4000 psi
i
Initial time 0.0 hr
Reservoir temperature (T) 160.0 °F
Porosity (ϕ) 0.22
Thickness (h) 120.0 ft
Total compressibility (c ) t 6.0 × 10 /psia
−6
Viscosity (μ) 0.695cp
Formation volume factor (B) 1.32 RB/STB
Well flow rate (q) 100.0 STB/D
Fluid type Liquid
12.5 A. Well PI = well productivity index = flow rate divided by pressure draw-
down. Suppose the well originally produces 10 000 STBO/day at a
pressure drawdown of 10 psia. What is well PI?
b. The well PI declined 4% a year for the first three years of production.
What is the well PI at the end of year 3?
C. The well PI at the beginning of year 4 is 750 STBO/day/psia. A well test
showed an increase in skin and the skin is positive. Does the well need a
workover (Y or N)?
