Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 4, Pages: 681-686  
J. Environ. Treat. Tech.  
ISSN: 2309-1185  
Journal web link: http://www.jett.dormaj.com  
Material Composition of Near-surface Section  
Dispersed Gases as an Indicator of the Genetic  
Heterogeneity of the Migration Hydrocarbon Flow  
*
Mikhail ZAVATSKII , Olga VEDUTA, Danil KOBYLINSKII  
Industrial University of Tyumen, Tyumen, Russia  
Received: 22/06/2019  
Accepted: 25/02/2019  
Published: 03/09/2019  
Abstract  
The relevance of the work results from the insufficiency of criteria for assessing the oil-bearing potential of territories and local  
geological features while conducting land geochemical surveys. Geochemical surveys are aimed at identifying surface hydrocarbon  
anomalies, the genesis of which is associated with microfluid and diffusive migration from oil and gas deposits. However, as the  
evidence from practice shows, not all hydrocarbon anomalies on the surface identified by the quantitative criteria indicate petroleum  
accumulations within the earth. Therefore, when interpreting surface geochemical fields to find oil and gas deposits, it is necessary to  
take into account not only migration intensity indicators but also the material composition of the migration flow. The purpose of the  
work is to analyze the material composition of near-surface section dispersed gases and identify intercomponent correlations that would  
help to determine the genesis of detectable components. To solve this problem, the authors subjected core samples from shallow (up to  
30 m) wells drilled in an oil and gas-bearing territory of the north of Western Siberia to thermal vacuum degassing and then conducted  
statistical processing of data on the content of gas components. The obtained results showed the genetic heterogeneity of dispersed  
hydrocarbon and inorganic gases in the upper part of the sedimentary cover.  
Keywords: Hydrocarbon migration, Gas diffusion in sedimentary rocks, Near-surface section gases, Geochemical surveys,  
Geochemical field.  
1
movable hydrocarbons in the section are reliably determined,  
1
Introduction  
local marginal zones of formation fluid migration are  
identified, areas with an effective seal are mapped. Since gas  
occurrence intensity depends heavily on the fluid permeability  
of overlying strata, it is difficult to perform an adequate  
interpretation without additional, as a rule, seismic data.  
b) the matching principle (Gore-Sorber technology) (3)  
which considers as the main indicator the match between  
migration flow composition at each observation point in the  
area under investigation and migration flow composition in  
obviously productive and unproductive areas. To implement  
this approach, the maximum possible number of oil  
components (up to 80 substances) is determined.  
Geochemical surveys are aimed at locating hydrocarbon  
deposits by aureoles of reservoir content dispersion in surface  
environments: soil, snow, bottom sediments, etc. In the case of  
a hydrocarbon deposit, one has to deal with a complex  
multicomponent reservoir system, each component of which  
migrates in accordance with its physical and chemical  
properties (1). The concentration fields of various reservoir  
components do not always coincide because of a wide range of  
physical and chemical properties of oil components. This  
implies the importance of choosing geochemical mapping  
parameters, which will depend on the methodological  
principles of the technology.  
The technological diversity of modern geochemical  
methods can be summarized in two methodological principles:  
a) The intensity principle which implies studying the  
distribution of a small set of oil substances over the area, as a  
rule, saturated and aromatic gaseous and low-boiling  
hydrocarbons (2). Approaches to interpreting their spread on  
the surface are well developed. Areas with the absence of  
Depending on the degree of matching between gas  
material composition and  
a particular standard, each  
observation point in the area under investigation is assigned an  
index of matching with either the standard productive area or  
the standard unproductive one; using this index, the territory is  
mapped and a forecast of oil potential is done.  
Corresponding author: Mikhail ZAVATSKII, Industrial University of Tyumen, Tyumen, Russia. Email: eksis2005@yandex.ru.  
681  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 4, Pages: 681-686  
The approach implemented in the Gore-Sorber method is  
very reasonable, but its use in Western Siberia is not  
necessarily successful because of the difference in geological  
conditions of investigated and standard areas.  
extracted from the core samples. In total, 267 samples were  
studied. To identify patterns in the component composition,  
statistical data processing was performed. The authors used  
such statistical tools as two-factor analysis, correlation  
analysis, and frequency distribution.  
Practical results (2, 4) showed the insufficiency of each  
technique applied separately, but they revealed the expediency  
of a complex approach: the necessity of evaluating both the  
intensity of the migration flow and its material composition.  
To implement the complex approach, it is necessary to  
improve interpretational algorithms – to replace the empirical  
comparison of the compositions of studied and standard  
samples by clear geochemical criteria based on the universal  
characteristics of migration from a hydrocarbon deposit  
eliminating the influence of dispersed organic matter and  
diagenesis processes. This can be done by studying the  
composition of near-surface section occluded hydrocarbons.  
3
Results  
It was discovered that gas composition is characterized by  
sharp heterogeneity both between wells and along each hole.  
Methane was detected in all samples at concentrations from  
0
0
7
.00025 to 52.8% by volume with a modal range of 0.001-  
.003% by volume. Maximum values were found in wells Nos.  
(52.8% at a depth of 7.3 m and 11.4% at a depth of 18 m)  
and 8 (5.5% at a depth of 22.7 m).  
The analysis of methane correlations shows that its content  
does not depend on the depth: the weak correlation (C = 0.33)  
was detected only in the well No. 6. Methane correlation with  
other hydrocarbon gases is very complex and uneven in  
different wells. For example, in the wells Nos. 2, 3, 5, 6, 7, 8,  
the methane content is not correlated with the content of its  
nearest homologs and olefins.  
2
Materials and Methods  
To identify the patterns of dispersed gas distribution in the  
near-surface section, the authors studied the gas saturation of  
core samples from eight shallow (up to 30 m) wells drilled in  
an oil and gas-bearing area in the north of Western Siberia  
In the well No. 1, methane is correlated with its homologs  
(
Fig. 1). Drilling was carried out using the core method without  
circulating fluid; the core samples were taken at an interval of  
.8-1 m. The samples were represented by permafrost sandy or  
loamy rocks with ice interlayers.  
5 2  
to pentane inclusive (C from 0.57 with n-C to 0.92 with C );  
its correlation with ethylene is weaker (C = 0.58). The same  
can be observed in the well No. 4, but the correlation is weaker,  
C does not exceed 0.58 (with ethane).  
0
Methane is correlated with the following inorganic  
components: with CO  
the well No. 3, C = 0.64 in the well No. 8), more rarely with  
(C = 0.59 in the well No. 1, C = 0.59 in the well No. 4). The  
2
(C = 0.5 in the well No. 1, C = 0.74 in  
H
2
expected negative correlation with oxygen (biogenic methane  
is produced more by anaerobes) is weakly expressed: only in  
the wells No. 5 and 7, there is a near-significant C -0.37 – -  
0
.41.  
Methane homologs from ethane to hexane are identified in  
all wells in different concentrations. Non-zero values of their  
-6  
-3  
concentrations vary from n·10 to n·10 %. The common  
pattern: the average and maximum values of hydrocarbons fall  
with the increase in the hydrocarbon chain length, the  
concentration of isoalkanes is less than that of normal alkanes,  
olefins are less than alkanes with the same number of carbon  
atoms.  
Correlation analysis shows that the content of methane  
homologs does not depend on the sampling depth. Methane  
homologs are tightly interrelated: the correlation coefficients  
vary from 0.75 to 0.98. The correlation between the content of  
normal alkanes is equally high both between themselves and  
with branched structure alkanes. Their similar genesis is  
beyond doubt. The correlation between saturated and  
unsaturated hydrocarbons is expressed in significant  
coefficients, which are noticeably lower than those of alkanes  
between themselves. In other words, each alkane is better  
correlated with its isomers and homologs than with an olefin  
even with the same number of carbon atoms.  
Legend  
-
1
-2  
-3  
Scale  
m
Fig. 1: Location of wells in the prospecting block territory:  
– hydrographic network; 2 – exploration well; 3 – core well  
1
The core samples were delivered to the laboratory in a  
frozen form and stored there under refrigeration until  
degassing. The gas was extracted from the core by thermal  
vacuum degassing and analyzed using the chromatographic  
method. The conducted analysis allowed obtaining the data on  
the content of saturated and unsaturated hydrocarbons from  
methane to octane, as well as inorganic gases (oxygen,  
hydrogen, carbon dioxide, and helium) in the dispersed gas  
The stable correlation between the contents of methane  
homologs and hydrogen is conspicuous. In one form or  
another, it is observed in all wells. The correlation coefficients  
of methane homologs and hydrogen are maximal with ethane  
(
C = 0.96 in the well No. 2) and fall with the increase in the  
hydrocarbon chain length. In the wells Nos. 4 and 8, weakly  
682  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 4, Pages: 681-686  
significant (0.44-0.48) correlation coefficients of methane  
homologs with carbon dioxide are also observed. Methane  
homologs are not correlated with other inorganic components.  
Olefins with the number of carbon atoms from two to five  
3-4%. The correlation analysis shows that carbon dioxide  
distribution in near-surface rocks is generally not correlated  
with other components of the gas mixture. Only in the well No.  
8, its content is correlated with hydrocarbon gases – methane,  
(
from ethylene to pentene) were found in all wells at  
ethylene, pentane, and hexane. In the well No. 4, the CO  
2
-3  
concentrations varying widely from zero to 8·10 % by  
volume. Their content is less than the content of alkanes with  
the same number of carbon atoms and their average values  
decrease with the increase in the hydrocarbon chain length.  
Correlation analysis shows that olefins are more highly  
correlated with each other than with saturated hydrocarbons,  
even if the number of carbon atoms in the olefin and alkane is  
the same. For example, propylene has a correlation coefficient  
with butylene of 0.95, and with propane – 0.78.  
Their content does not depend on depth. Olefins are  
correlated with hydrogen better than with any other inorganic  
components: in all wells except the well No. 6; there is a stable  
correlation between hydrogen and olefins with C from 0.6 to  
distribution along the hole is weakly inversely correlated with  
the depth (K = -0.56) and is correlated with the distribution of  
olefins.  
Hydrogen is found in almost all samples. The zero values  
of its content are found in the wells Nos. 7 and 8. Its  
concentrations vary from 0.004 to 6.7% by volume. The  
maximum is observed in the well No. 7 at a depth of 18 m. As  
mentioned above, the correlation analysis shows a stable  
correlation of hydrogen with methane homologs, to a lesser  
extent – with olefins. In the wells 3 and 5, hydrogen shows a  
pronounced negative (C = -0.64 and -0.68 respectively)  
correlation with oxygen, in the wells Nos. 1 and 4 – with  
methane (C = 0.59 in both wells). A high correlation between  
olefins and hydrogen is observed along some wells (Fig. 2),  
which can be explained by the hypothesis of the biochemical  
0
.93. In the well No. 6, the correlation coefficient between  
olefins and hydrogen is insignificant, but graphical  
constructions (Fig. 2) show their interdependent distribution  
over the section.  
Carbon dioxide was detected in 100% of samples. The  
minimum value of 0.072% by volume corresponds  
approximately to its concentration in the atmosphere. The  
2
origin of H , when bacteria decompose organic matter in  
water-bearing beds. In its turn, the olefin formation process is  
also directly related to the bacterial activity. At the depths of  
20-25 meters, an increased content of hydrogen and  
unsaturated hydrocarbons is observed, so this interval can be  
defined as water saturated.  
2
maximum CO content (46.5%) was found in the well No. 7 at  
a depth of 11.6 m. In other wells, its content does not exceed  
Table 1: The table of paired coefficients of correlation between the dispersed gas components in the near-surface rocks (sampling for all wells)  
Depth, [m]  
1.00  
-0.04  
0.10  
-0.07  
0.06  
0.02  
0.03  
0.03  
-0.01  
0.05  
-0.03  
-0.04  
CH4  
C2H6  
1.00  
0.10  
1.00  
0.76  
0.95  
0.88  
0.86  
0.91  
0.67  
0.55  
0.76  
0.25  
C2H4  
1.00  
0.80  
0.93  
0.70  
0.76  
0.74  
0.32  
0.69  
0.34  
C3H8  
0.14  
0.06  
0.15  
0.14  
-0.02  
0.07  
0.11  
-0.04  
1.00  
0.89  
0.89  
0.97  
0.65  
0.51  
0.84  
0.22  
C3H6  
1.00  
0.77  
0.84  
0.80  
0.41  
0.71  
0.36  
iso-C4H10  
n- C4H10  
C4H8  
1.00  
0.94  
0.58  
0.72  
0.84  
0.30  
1.00  
0.63  
0.57  
0.90  
0.21  
1.00  
0.23  
0.65  
0.31  
iso-C5H12  
n- C5H12  
C5H10  
1.00  
0.48  
0.39  
1.00  
0.23  
1.00  
iso-C6H14  
n-C6H14  
CO2  
-0.07  
0.03  
-0.02  
-0.03  
0.35  
0.38  
0.77  
0.13  
-0.31  
0.36  
0.60  
0.15  
-0.19  
0.41  
0.76  
0.18  
-0.32  
0.37  
0.71  
0.11  
-0.17  
0.49  
0.75  
0.16  
-0.28  
0.50  
0.80  
0.15  
-0.30  
0.46  
0.70  
0.01  
-0.08  
0.29  
0.38  
0.09  
-0.14  
0.56  
0.83  
0.09  
-0.23  
0.08  
0.13  
0.01  
0.00  
1.00  
0.50  
0.01  
-0.11  
1.00  
0.02  
-0.16  
-0.06  
-0.02  
1.00  
O2  
-0.28  
-0.37  
1.00  
-0.43  
0.15  
H2  
He  
0.07  
0.16  
0.67  
0.58  
0.76  
0.63  
0.64  
0.71  
0.25  
-0.10  
83  
0.45  
0.52  
0.22  
0.20  
0.33  
0.23  
1.00  
-0.01  
-0.06  
-0.12  
-0.12  
-0.12  
-0.10  
-0.17  
-0.14  
-0.12  
-0.13  
-0.06  
-0.11  
-0.10  
-0.08  
-0.10  
1.00  
6
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 4, Pages: 681-686  
Oxygen is found in 100% of samples in concentrations  
from 8 to 22.5% by volume. Correlation analysis revealed no  
obvious correlation of the oxygen content with other  
indicators.The oxygen content distribution (Fig. 3) shows that  
this gas results from a buried atmosphere, there are no non-  
atmospheric sources of oxygen.  
Helium is not found along the well No. 8. In the other  
wells, its content varies from zero to 0.024% by volume. Its  
content in the samples is not correlated with other indicators:  
the maximum correlation coefficients (in the well No. 6 with  
some alkanes) are 0.34-0.51.  
9
8
7
6
5
4
3
2
1
0,0  
0,0  
0,0  
0,0  
0,0  
0,0  
0,0  
0,0  
0,0  
0
,0  
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25  
-
10,0  
Fig. 3: Frequency distribution of oxygen content values (vol%).  
2 2  
Fig. 2: Distribution of geochemical parameters (H , olefins) along the wells Nos. 8 – 6 – 5 – 2. 1 – H content (vol%) – along the upper horizontal  
axis; 2 – olefins content (vol %) – along the lower horizontal axis.  
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Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 4, Pages: 681-686  
1
1
20,0  
00,0  
8
6
4
2
0,0  
0,0  
0,0  
0,0  
0
,0  
-
20,0  
Fig. 4 Frequency distribution of carbon dioxide content values (vol%).  
Fig. 5: Distribution of geochemical parameters (methane and methane homologs) along the wells Nos. 8 – 6 – 5 – 2.  
1
2 6  
– content of methane (% vol.) – along the upper horizontal axis; 2 – content of methane homologs C – C (% vol.) – along the lower horizontal  
axis.  
microorganisms in weakly aerated interlayers of the near-  
surface section.  
The absence of pronounced oxygen correlation with  
carbon dioxide, which is typical to the areas of high  
4
Discussion  
The variations of O  
2
concentrations are associated  
exclusively with its low concentrations relative to the  
atmosphere, which is explained by its active consumption by  
2
microbiological activity, indicates the polygenic origin of CO .  
684  
Journal of Environmental Treatment Techniques  
2019, Volume 7, Issue 4, Pages: 681-686  
The modal values of CO  
the atmosphere, which indicates the presence of other CO  
sources in addition to the atmosphere.  
2
(Fig. 4) are higher than its content in  
association with the bioreduction of alkanes in the upper layers  
of the sedimentary cover.  
2
Obviously, this is microbiological and abiogenic oxidation  
of organic matter, but there is also a possibility of CO  
References  
2
1. Kuznetsov AV, Petukhov AV, Zorkin LM, Zubayraev SL.  
Physical and Chemical Basis of Direct Searches for Oil and Gas  
Deposits. Nedra, Moscow. 1986.  
migration from the underlying layers where it is actively  
released during the diagenesis and catalysis of dispersed  
organic matter. Since both gases are present in the atmosphere,  
their content is affected by the degree of aeration, which  
depends on the lithology and moisture of the rocks above the  
sampling point.  
2
.
Zavatskii MD. Dependence of surface fields concentration of  
hydrocarbon gases on the oil content of the sedimentary cover  
within the West-Siberian oil and gas-bearing basin. Proceedings  
of Higher Educational Establishments. Oil and Gas. 2008;2: 9-  
1
6.  
One should take into account the complex role of the  
microbiological factor in the formation of near-surface section  
gases. Methane generation is associated with archaeal activity  
under anaerobic conditions with pH < 7. On the contrary,  
microbiological reduction of alkanes occurs in an aerobic  
environment (5).  
Oxygen was discovered in all samples, and therefore both  
catagenetic and biogenic methane is migratory for the studied  
section with the difference that biogenic methane comes from  
the anaerobic zone of dispersed organic matter diagenesis.  
The analysis of gas distribution across the section (Fig. 5)  
to some extent confirms the correlation analysis data: in the  
wells Nos. 1, 4 and (to some extent) 8, there is a joint  
distribution of methane and its homologs.  
3
4
5
.
.
.
Khisamov RS. Harrington P, Chernishova MG, et al. Using the  
Gore-Sorber method in the complex of geophysical and  
geochemical investigations at diagnostics of the oilfields.  
Georesourses. 2009;1(29): 29-32.  
Zavatskii MD, Tseplyaeva AI. Geochemical indicators of  
informativity for searching of hydrocarbons in Western Siberia  
(by results of the geochemical snow survey). Estestvennye i  
tekhnicheskie nauki. 2016;10: 70-73.  
Bazhin NM. Methane in the Environment. Analytical Review.  
Siberian Branch of RAS, Novosibirsk, 2010.  
6. Zorkin LM. Genesis of gases of the underground hydrosphere in  
connection with prospecting of hydrocarbon accumulations.  
Geoinformatics. 2008;1: 45-54.  
The relatively low values of methane in the wells Nos. 1  
and 4 show that both methane and other light alkanes have the  
same source in the catagenesis zone, and it is likely to be a  
hydrocarbon accumulation. In these wells, the methane  
correlation with hydrogen is observed. In the well No. 8, the  
methane content is two orders of magnitude higher than in the  
wells Nos. 1 and 4.  
In the other wells, methane and its homologs are  
distributed independently, which indicates the presence of a  
powerful competitive source of methane.  
The maximum values of methane are observed in the well  
No. 7 – more than 50% at a depth of 8 m. Along the rest of the  
well, its content is also high; the average value is 3.6%. This  
may be a sign of hydrate formation in permafrost rocks.  
5
Conclusion  
Statistical indicators of measured components and  
intercomponent correlations show the complex genesis of gas  
obtained by degassing samples of the near-surface rocks.  
The following processes are involved in the formation of  
the dispersed gas composition:  
-
hydrocarbon and inorganic gas migration from the zone  
of organic matter diagenesis;  
-
-
-
-
hydrocarbon migration from oil-bearing strata;  
aerobic microbiological oxidation of migration alkanes;  
anaerobic methane generation by archaea;  
formation of gas hydrates in permafrost rocks.  
The genesis of hydrogen and olefins is of particular  
interest. There are practically no olefins in the composition of  
oil and gas accumulations in the north of Western Siberia, and  
hydrogen is rarely found and only in small quantities.  
However, hydrogen is often found in the composition of water-  
dissolved gases (6). The high correlation of hydrogen and  
olefins with methane homologs may point to their genesis  
483