# Determine formation permeability and the skin factor.

1. The core, well log, and PVT data for the discovery well (#1) in an oil reservoir were provided in the earlier homeworks. Upon the initial completion a pressure drawdown test was run on the well. The test results and other relevant data are provided below. Determine formation permeability and the skin factor.

t Pwf t Pwf
Hrs. Psia Hrs. Psia
0.5 1290 13 1157
1 1250 14 1155
2 1211 15 1153
3 1199 16 1151
4 1191 17 1149
5 1184 18 1148
6 1179 19 1146
7 1175 20 1145
8 1171 21 1143
9 1168 22 1142
10 1165 23 1141
11 1162 24 1139
12 1159 25 1138

2. Well 1 above, was subjected to a stimulation treatment and was produced for 645 days before it was shut-in for a buildup test. The test results and other relevant data are provided below. During this period (645 days), wells 2, 3, 4, and 10 were also producing from the reservoir. Determine if the stimulation treatment was successful in removing the damage and the average pressure in the drainage are of the well.

?t Pws ?t Pws ?t Pws
Hrs. Psia Hrs. Psia Hrs. Psia
0.5 1330.0 9 1445.5 18 1468.9
1 1360.0 10 1449.1 19 1470.8
2 1394.6 11 1452.3 20 1472.5
3 1408.3 12 1455.2 21 1474.1
4 1418.1 13 1457.9 22 1475.7
5 1425.6 14 1460.4 23 1477.2
6 1431.8 16 1465.0 24 1478.7
8 1441.5 17 1467.0 25 1480.0

3. Two separate flow tests were performed on a gas well. Given the tests results, reservoir data, and fluid properties determine:
A. k, s, and D
B. The deliverability equation coefficients, a, and b assuming 160-acre spacing.

q = 5 MMSCFD q = 10 MMSCFD
t Pwf Pwf
Hours Psia Psia
1 1950.0 1895.0
2 1941.8 1876.7
3 1940.5 1874.2
4 1939.6 1872.3
5 1939.0 1870.9
6 1938.4 1869.8
7 1937.9 1868.8
8 1937.5 1868.0
10 1936.9 1866.5
12 1936.3 1865.4
24 1934.7 1861.0

Pi = 2000 psia T = 100oF Gas Gravity = 0.688 rw = 0.5 ft.

Porosity = 0.091 Swi = 0.25 h = 30 ft.