Fluid inclusion studies in search for hydrocarbons in marine and mountain regions

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Fluid inclusion studies in search for
hydrocarbons in marine and mountain regions

• Katarzyna Jarmolowicz-Szulc POLISH GEOLOGICAL
  INSTITUTE CENTRE OF EXCELLENCEResearch on
  Abiotic EnvironmentREA

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Objectives

• The aims of the presentation are
• - to show characteristic features of fluid
  inclusions in the quartz and in the quartz
  cements
• - to interpret the results of the isotope,
  microthermometry and fluorescence studies in the
  context of fluid evolution and formation of the
  rocks.

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Quartz - one of the best known and studied
minerals in the world - has been occurring in
different geological environments, in that as the
cement in the sedimentary rocks in the
hydrocarbon reservoirs ,
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as well as the vein mineral of certain
characteristics called the Marmarosh diamonds.
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Localization and structures
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The Marmarosh diamonds

• The second variety of the quartz mentioned, has
  been studied for about a century in the
  Carpathians in Europe , aiming at explanation of
  the phenomena of its formation and
  characteristics (Tokarski, 1905 Hurai et al.,
  1989 Dudok et al., 1997 Jarmolowicz-Szulc,
  2001a).

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Methods used

• Double-sided-polished thin sections of the
  sandstones, and quartz crystals themselves, were
  prepared for fluid inclusion studies using two
  preparation techniques (Jarmolowicz-Szulc
  2001a,b).
• The microscopic studies performed in the
  Petrological Department of the Polish Geological
  Institute in Warsaw, Poland comprised
• - a microscope analysis of fluid inclusions
  (Leitz Orthoplan)
• - fluorescence studies together with a
  microphotography (Nikon microscope and UV
  device)
• - cold cathodoluminescence studies (CCL 8200
  mK3)
• - microthermometric analyses (homogenisation and
  freezing using Fluid Inc. System).

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Inclusions in the quartz cementOccur in the
early and late quartz cements. HCFI display
fluorescence in white blue colour. Oil is light
and mature. Densities from 41 to 45API . AQFI
are at the boundary of the detrital and the
authigenic quartz, in the early cement and in the
late filling of microfractures. The HCFI are most
frequent in the late filling of the fissures.

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Isotope studies in quartz overgrowths detrital
grains

• Quartz overgrowths studied by means of SIMS point
  method display delta oxygen values in the
  interval of 23.0 to 25.6 per mille.

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Results for sandstones

• The AQFI are at the boundary of the detrital and
  the authigenic quartz, in the early cement and in
  the late filling of microfractures. The
  hydrocarbon inclusions are most frequent in the
  late filling of the fissures, thus pointing out
  the late hydrocarbon migration to the reservoir

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Conclusions

• Oil is present in the late cements in the
  Cambrian sandstones, mostly in the fillings of
  tectonic microfractures and stylolitic sutures.
  It migrated together with water and was trapped
  in the late quartz in the conditions of 107?C and
  317 bars. It is light and mature. The abundance
  of HCFI is restricted to some boreholes and the
  upper parts of the profiles. 

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Features of the Marmarosh diamonds
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The isotope studies were conducted by means of
the method of a point analysis in quartz. SIMS
isotope analysis of the oxygen was performed at
the Arizona State University in Tempe (AZ, USA)
the procedure of Hervig et al. (1992) and
Williams et al. (1997). Three grains of quartz
(the Marmarosh diamonds) have been studied.
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Isotopic point analysis in quartz (the Marmarosh
diamonds)

• The d 18OSMOW values for quartz range from 15.7
  and 26.7 (SIMS).
• Data for the crystals from the eastern part are
  most scattered and lower.
• Average

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The Marmarosh diamonds from the Western and
Eastern Carpathians

• Represent a type of the bi-pyramidal quartz in
  euhedral, transparent crystals of an ideal
  crystal habit and a perfect reflection (Karwowski
  Dorda, 1974). The inclusions in this type of
  quartz are either of primary or of secondary
  origin.

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Presentation of types of inclusions
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Presentation of types of inclusions
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The first type of the quartz filling in the
porous space has been the object of numerous
petrological analyses for long years (e.g.
Sikorska Paczesna, 1997). The present case
concerns the Cambrian sandstones from the Polish
segment of the Baltic Sea, which are the
reservoir rocks for oil
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Microthermometry results and interpretation for
the Marmarosh diamonds
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Fluid iclusions

• The quartz crystals come from the tectonic zones
  and contain a spectrum of fluids - from methane,
  through oil to aqueous solutions.

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Conclusions

• The fluid inclusions and isotopic studies in both
  the quartz cement and the quartz crystals point
  to the hydrocarbon migration and the character of
  the palaeofluids responsible for the cement
  formation and/or the quartz crystallisation.
• The areas of the occurrence of the hydrocarbons
  in the inclusions in the quartz may be mostly
  prospective for the search for oil and gas

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Thank you!