Journal of Geological Research

Research Article

Gas Hydrate System of Shenhu Area, Northern South China Sea: Geochemical Results

Table 1

Gas composition and methane/ethane ratio in sediments of Shenhu Area, northern slope of SCS.


Sample no.	Depth (mbsf)	Gas composition			C₁/C₂
Sample no.	Depth (mbsf)	CH₄ (%)	C₂H₆ (ppm)	C₃H₈ (ppm)	C₁/C₂

SH2-1	70.73	96.10	440	LD	2185
SH2-2	73.31	96.72	477	LD	2027
SH2-3	146.46	98.49	646	97	1524
SH2-4	146.89	98.02	632	88	1551
SH2-5	150.00	99.53	552	67	1804
SH2-6	150.00	96.60	494	LD	1956
SH2-7	181.65	99.36	675	65	1473
SH2-8	182.07	97.75	533	LD	1833
SH2-9	185.39	99.21	581	61	1708
SH2-10	185.54	99.32	824	53	1205
SH2-11	195.40	99.32	1611	LD	616
SH2-12	197.50	99.82	1737	LD	575
SH2-13	197.50	99.80	1974	LD	506
SH2-14	197.50	99.77	2330	LD	428
SH2-15	197.50	99.72	2778	LD	359
SH2-16	197.50	99.57	3015	LD	330
SH2-17	221.71	99.68	1559	LD	639
SH2-18	228.00	99.70	1653	LD	603
SH2-19	238.58	99.06	1346	LD	736
SH3-1	68.63	99.12	632	ND	1569
SH3-2	71.32	99.78	692	LD	1443
SH3-3	74.55	99.77	640	LD	1560
SH3-4	117.01	99.77	644	LD	1548
SH3-5	117.60	99.80	658	LD	1516
SH3-6	119.85	99.69	618	LD	1613
SH3-7	121.15	99.83	703	LD	1419
SH3-8	125.00	99.91	659	LD	1516
SH3-9	125.00	99.89	695	LD	1438
SH3-10	128.71	99.80	696	LD	1434
SH3-11	129.06	99.73	661	ND	1510
SH3-12	132.34	99.78	726	LD	1374
SH3-13	132.80	99.79	721	LD	1385
SH3-14	190.50	99.87	1241	ND	805
SH3-15	190.50	99.87	1237	ND	807
SH3-16	190.50	99.21	1051	ND	944
SH3-17	192.95	99.21	3587	ND	277
SH3-18	201.31	99.85	1376	ND	718
SH3-19	201.70	99.73	2209	ND	451
SH7-1	97.52	97.52	158	84	6161
SH7-2	99.53	98.19	188	67	5233
SH7-3	100.83	97.40	139	70	6989
SH7-4	104.00	99.86	159	67	6286
SH7-5	131.81	96.44	80	LD	11995
SH7-6	132.84	95.56	102	LD	9377
SH7-7	135.00	99.68	88	55	11315
SH7-8	135.00	99.47	124	61	8009
SH7-9	155.00	99.89	1066	ND	937
SH7-10	155.00	99.85	1042	ND	958
SH7-11	155.00	99.84	1017	ND	981
SH7-12	155.00	99.81	1137	ND	878
SH7-13	155.00	99.74	1078	ND	925
SH7-14	168.67	99.55	2912	ND	342
SH7-15	176.12	99.21	7621	ND	130
SH7-16	185.00	99.76	2182	ND	457
SH7-17	185.00	99.54	2277	LD	437

Note. Mbsf: meters below seafloor; % of original gas, mole percent of each gas in the original sample: depressurization samples and void gas samples; ethane and propane (ppm), detection limit 50 parts per million; LD means lower than detection limit; ND means not detectable; C₁/C₂ is the molecule ratio of methane to ethane.