Chemical and Noble Gas Isotope Compositions of Formation Gases from a 3 km Deep Scientific Borehole in the Koyna Seismogenic Zone, Western India
Table 1
Molecular composition of gas samples collected during water flushing after core run in the pilot hole KFD1 at Gothane, near Koyna, Western India.
Sample
Depth (m)
Flushing after core run #
40Ar (vol.-%) (±1%)
CH4 (ppmv) (±5%)
CO2 (ppmv) (±2%)
H2 (ppmv) (±5%)
He (ppmv) (±10%)
N2 (vol.-%) (±1%)
O2 (vol.-%)
C1 (ppmv)
C2 (ppmv)
C3 (ppmv)
i-C4 (ppmv)
n-C4 (ppmv)
He air-corrected (millimole)
RIH06
2084
5/6
0.983
10
965 (580)
57
6.1
77.8
21.1
14
—
0.4
—
0.3
n.d.
RIH07
2189
5/6
0.982
6
700 (310)
37
5.6
77.6
21.3
5
—
—
—
—
n.d.
RIH08
2295
5/6
0.985
14
32200 (31810)
63
5.7
77.3
18.4
9
—
—
—
—
n.d.
RIH13
1737
7/8
0.985
48
1005 (620)
45
5.5
77.6
21.3
48
—
—
0.3
—
n.d.
RIH14
1833
7/8
0.996
46
940 (550)
41
6.2
77.7
21.2
60
—
—
—
0.4
0.34
RIH15
1929
7/8
0.999
62
655 (270)
44
7.2
77.6
21.3
65
—
—
0.3
—
0.71
RIH16
2025
7/8
0.991
70
985 (600)
62
7.5
77.8
21.1
69
—
0.3
0.3
—
0.84
RIH17
2121
7/8
0.995
66
930 (540)
34
7.6
77.5
21.4
62
—
—
—
—
0.85
RIH18
2217
7/8
0.992
186
1200 (810)
78
12.8
77.8
21.0
180
—
0.4
—
0.4
2.86
RIH19
2313
7/8
0.989
88
1160 (770)
49
10.1
77.7
21.1
96
—
1.2
—
—
1.83
RIH20
2409
7/8
0.999
140
1180 (790)
139
11.1
77.8
21.1
104
—
—
0.3
—
2.21
RIH21
2514
7/8
0.980
76
1050 (660)
50
10.6
77.8
21.0
66
—
—
—
—
1.95
RIH22
2610
7/8
0.995
52
820 (430)
44
9.9
77.7
21.2
48
—
0.3
0.3
0.6
1.74
RIH23
2687
7/8
0.989
86
970 (580)
46
12.7
77.9
21.0
n.d.
n.d.
n.d.
n.d.
n.d.
3.05
RIH24
2763
7/8
0.999
88
1065 (680)
52
10
77.9
20.9
103
—
—
—
—
1.96
RIH25
2831
7/8
0.992
96
875 (490)
55
9.8
77.9
21.0
78
—
0.5
0.5
0.8
1.93
Gas samples collected during running in and flushing out of water are designated by the prefix RIH. Depths are referenced to the kelly bushing, which was located at 3.5 m elevation with respect to ground level. Values in parentheses are air-corrected according to . Probably an artefact from sample preparation. —: below detection limit (=0.3 ppmv); n.d.: not determined.
