Page 300 - Fundamentals of Reservoir Engineering

OILWELL TESTING 236

and since q = 300 rb/d, then the wellbore transmissibility is

kh 3500 300
×
T w = w = = 140 mD.ft / cp
µ 750

and therefore
k w = 8.4 mD

For values of ∆t greater than 150 minutes the actual buildup curve breaks away from
the parametric curve for T/F = 2500, indicating the presence of a positive skin factor.
For large values of ∆t the buildup matches the McKinley curve with parametric value
T/F = 5000, fig. 7.44. Even for this latter match, however, the buildup continues to be
dominated by afterflow. Therefore, a minimum value of the formation transmissibility
can be estimated as
(T/F )
f
T = × T w
f
(T/F )
w
giving

5000
k = × 8.4 16.8mD
=
f
2500
Thus the comparison between the Russell and McKinley techniques is quite
reasonable in this case.

REFERENCES

1) van Everdingen, A.F. and Hurst, W., 1949. The Application of the Laplace
Transformation to Flow Problems in Reservoirs. Trans. AIME. 1 86: 305-324.

2) Earlougher, R.C., Jr., 1971. Estimating Drainage Shapes from Reservoir Limit
Tests. J. Pet. Tech., October: 1266-1268.

3) Ramey, H.J., Jr. and Cobb, W.M., 1971. A General Pressure Buildup Theory for
a Well in a Closed Drainage Area. J. Pet. Tech., December: 1493-1505.Trans.
AIME.

4) Horner, D.R., 1951. Pressure Build Up in Wells. Proc., Third World Petroleum
Congress. E.J. Brill, Leiden. ll, 503.

5) Odeh, A.S. and Jones, L.G., 1965. Pressure Drawdown Analysis, Variable Rate
Case. J. Pet. Tech., August: 960-964. Trans. AIME.

6) Matthews, C.S. and Russell, D.G., 1967. Pressure Buildup and Flow Tests in
Wells. SPE Monograph: 130-133.

7) Matthews, C.S., Brons, F. and Hazebroek, P.,1954. A Method for the
Determination of Average Pressure in a Bounded Reservoir. Trans.
AIME.201: 182-191.