Download Исследование вещественного состава и органического

THE STUDY OF BITUMINOUS ROCKS BY ELECTRON PARAMAGNETIC
RESONANCE
N.M.Khasanova, N.M.Nizamutdinov, R.A.Khasanov, A.L.Zakharchenko,
L.M.Sitdikova, E.U.Sidorova, V.G.Izotov
Kazan Federal University, Institute of Geology and Petroleum Technology, Kazan, RUSSIA
E-mail: [email protected]
It is known that the oil reservoir is a complex heterogeneous mineral-organic system, located in the
natural conditions of physical and chemical equilibrium. The introduction of active impact techniques
in the field, in particular thermal and chemical, of course is penalized physical and chemical properties
of the reservoir and mainly its elemental composition. To studying of dynamics of element structure
and organic substance of bituminous layer traditional methods and the electron paramagnetic
resonance (EPR) devoted the presented work.
In the period 1985-1990 in the laboratory of physics of minerals Kazan University headed by
Professor VM Vinokurov methods have been developed of correlation of coeval deposits (especially
"dumb" in paleontological terms) based on the study of paramagnetic properties of rocks using the
technique of electron paramagnetic resonance (EPR) [1-2].
The technique is based on the fact that metamorphism of carbonate rocks, buried organic matter and
epibitumov at fluctuations of erosion basis and the level of water contact leads to a change in the state
of organic and mineral matter of rocks, which can be easily installed in the EPR studies.
Study of the effects of thermal and radiation impact on the rock minerals represents also of practical
interest to obtain information about their genesis and evolution. The energy of these effects causes the
activation of the physic-chemical reactions in the formation of subsequent stages of metamorphism,
metasomatic.
The main tasks of the research were as follows: - Preparation of samples; Define the material
composition of the traditional methods; -record EPR spectra of initial samples in special scanning
range of the magnetic field; - Determination of the material composition and organic matter at fixed
lines of the EPR; - Analysis of changes in the distribution of the reference lines in the sequence and
interaction of the material composition with OM; - Separation of hydrocarbons from mineral
components with the subsequent control of the EPR spectra; - Thermochemical treatment of the
mineral component to determine the potential reserves of OM.
OBJECT AND RESEARCH METHODS
As a result, visual research of the bituminous core section of the well was determined
belonging model samples the following main 3 types of rocks: “Lingala clay”- siltstone rocks
clay packs (top of the reservoir) – sample №1, sandstone productive strata – three samples
№2-4 and clay-sand pack (outsole collectors) – sample №5.
For the study of rock samples by EPR the automated spectrometer the PS 100.X (Minsk,
"Adani") is used. Device measuring EPR spectra is designed for recording the EPR spectra of
solids and liquids in the range of electromagnetic radiation with a wavelength of 3 cm and to
define the parameters of these spectra. The spectrometer is a compact instrument personal use
with a high level of automation, is controlled by the PC. Standard quartz ampoule with the
investigated linkage crushed in an agate mortar rock sample is placed in a microwave
resonator. In the resonator is fixed in position in a particular orientation relative to the static
magnetic field specially selected single crystal of corundum (Al2O3) with impurity ions Cr3 +
as an internal standard.
Thermal treatment was performed in an electric furnace type SUOL in a quartz tube to the
vapor tube to change the atmosphere annealing to prevent the combustion of organic matter.
EXPERIMENTAL RESULTS
The original EPR spectra of model samples were obtained by scanning the magnetic field in
the range of 3600 and 900 gauss at a modulation amplitude of 200 mG (Fig. 1 a, b), and 50 G
at a modulation amplitude of 60 and 10 mG (Fig. 1 c, d).
Fig.1. EPR spectra scanning of core samples №1-5 in the following ranges: a) 400 – 4000 G; b) 280 –
3750 G; c) 3235 – 3285 G with an amplitude modulation of 60 mG; d) 50 G with an amplitude
modulation 10 mG.
The material composition of carbonates is determined by characteristic spectra of Mn2 + ions
in the structure of dolomite (sample 1) and calcite (samples 2-5). Presence of quartz minerals
in rocks by E’ center are determined. In bituminous rock samples (2-4) line is observed the
EPR spectrum of vanadyl ions VO2+ associated with porphyrin species and intense line R free
radical organic matter (Fig. 1). Parameters of paramagnetic centers are presented in the table.
Part of the rock powder was placed in weighing bottles (with ground covers) with chloroform
solution during one day. By this procedure the mineral part of the rock, characterized by the
EPR spectrum of Mn2+ ion and ion-radical SO3- in carbonates and E 'in quartz, and a number
of coal organic matter were separated from the bituminous part (Fig. 2a). The carbonates were
extracted from rocks with weak solution HCl. Then only lines EPR spectra of E' center and
the organic radicals R were recorded (Fig. 2b).
After thermal treatment of mineral rock for 30 min at 350 0C newly formed radical OM line
C350 appeared in the ESR spectrum (Fig. 3). This fact is indicative of the presence of planttype of organic matter and a source of hydrocarbon reserves (table).
Fig. 2. EPR spectrum in radical region (scanning 70 G): a) rocks after extraction of
hydrocarbons by chloroform; b) rock mineral part after treatment with a weak solution of
hydrochloric acid.
DISCUSSION AND CONCLUSIONS
Table. EPR data of paramagnetic centers (arbitrary units/g)
Paramagnetic centers
Breed, age
№
sample
Depth,
m
Mn2+ in
carbonat
e
E' in
quartz
R of
OM
С350
“ Lingala
clay”, Р2kz1
1
70
161
12,91
118
177,19
2
74,4
71
5,8
26,4
3
82,6
39
3,69
33,71
4
96,5
36
3,5
26,02
23,22
5
105,6
216
6,36
27,05
57,65
Bituminous
sandstone,
Р1u2
Clay, P1u2
Analysis of the studies leads to the following conclusions:
Fig. 3. The EPR spectrum of
the newly formed radical OM
during heat treatment at 350 0С
1. EPR spectra of Mn2+ ions are observed in the carbonates.
EPR spectra of Mn2+ions are not recorded after treatment breed
weak hydrochloric acid.
2. The distribution of Mn2+ ions in the sequence is patchy. In
bituminous thickness the intensity decrease of the EPR signal of
the manganese ions is observed as compared to the underlying
and overlying rocks. It is known that during the oil migration
occurs recrystallization of calcite and removal of manganese
ions [3].
3. The EPR spectra of vanadyl VO2+ ions are superimposed on
the Mn2+. It is necessary to carry out extraction by organic
solvents (chloroform, etc.).
4. Along the borehole observed EPR spectra of radical ions E
'quartz with a predominance of their content in the top and base.
This suggests that the radiation source is in the rock itself potassium feldspar.
5. Organic matter of the coal series is mainly in the roof and
part of the base, bituminous hydrocarbons in sandstone.
Refrences
in a hydrogen atmosphere.
1. Bulka G.R., Nizamutdinov N.M., Mukhutdinova N.G. et.all
Appl.Magn.Res.,- 1991, v.2. №1, p.107-115
2. Murav'ev F.A., Vinokurov V.M., Galeev A.A., et.all Paramagnetism and the nature of
dispersed organic matter in the Permian deposits RT. (in Russian) Int.J. of Science
Georesources. 2006. Vol. -2(19). P. 40-45.
3. Ronov A.B., Ermishkina A.I. The distribution of manganese in sedimentary rocks.
Geokhimiya, №3, pp 206-225, 1959;